the black-bellied storm petrel ( fregetta tropica ) is a species of seabird in the family oceanitidae .

it is found in antarctica , argentina , australia , bouvet island , brazil , chile , falkland islands , french polynesia , french southern territories , madagascar , mozambique , new zealand , oman , peru , saint helena , são tomé and príncipe , solomon islands , south africa , south georgia and the south sandwich islands , uruguay , and vanuatu .

they are usually black with a white band over the rump .

a white under the wings and on the flanks .

there is a broad black stripe runs down the center of the belly , but may be broken or absent altogether sometimes .

they have long legs , so that the feet can be seen beyond the tail in flight .

the legs and feet are black .

they are silent mostly at sea .

noises can be seen on the breeding colonies , birds on the ground give a drawn-out shrill whistle .

black - bellied storm petrel

black - bellied storm - petrel , first records for madeira and the canary islands .
nobody uploaded sound recordings for black - bellied storm - petrel ( fregetta tropica ) yet .
black - bellied storm petrel . adult in flight , ventral . at sea off campbell island , april 2013 . image © phil battley by phil battley
the diet of black - bellied storm petrel is poorly known , but includes crustaceans , small fish and squid taken from the surface of the water .
southey , i . 2013 [ updated 2018 ] . black - bellied storm petrel . in miskelly , c . m . ( ed . ) new zealand birds online . urltoken
a medium - sized black - and - white storm petrel , black above with a white band over the rump , white under the wings and on the flanks , a broad black stripe usually running down the centre of the belly which may be broken or absent altogether . large and very bulky for a storm petrel , they have long black legs so the black feet can be seen beyond the tail in flight .
similar species : the most commonly seen black - and - white storm petrel around new zealand is wilson’s storm petrel which is smaller and entirely black underneath ( though with a similar white band over the rump ) and has yellow webs on the black feet . off the northern new zealand coast new zealand storm petrel is a smaller , more slightly built bird that is white , not solidly black under the tail . the white belly of new zealand storm petrel is characteristically and obviously streaked . the white - bellied storm petrel is rarely seen away from subtropical water and is very difficult to distinguish . it is a little smaller with shorter legs that do not extend beyond the tail . they usually have a clean white belly but the birds breeding on lord howe island may be darker , with varying amounts of smudgy black on the belly and under - wing , some birds being entirely black .
today , during our zino ' s petrel pelagic expedition in oceanodroma a black bellied storm - petrel fregetta tropica was seen and photographed briefly . this bird didn ' t stay with us more than one minute flying over the slick . during this trip great shearwater puffinus gravis , european storm - petrel hydrobates pelagicus and wilson ' s storm - petrel oceanites oceanicus were seen .
neither black - bellied storm - petrel nor white - bellied storm - petrel has been positively identified in the northeast atlantic . there are three sight records of unidentified fregettas in the northeast atlantic . all three descriptions in our opinion suggest white - bellied birds . records fall in the period mid - august to mid - december : about 500 miles north of cape verde mid - august 1986 , off norfolk ( uk ) 10th december 2007 , and in the severn estuary ( uk ) 25th november 2009 . we include the norfolk sighting having read the description , although it was judged ‘not proven’ to be a fregetta storm - petrel by british birds rarities committee .
( excerpt from multimedia id guide to north atlantic storm - petrels & bulwer ' s petrel , bob flood & ashley fisher , urltoken )
voice : black - bellied storm petrels are silent at sea ; on the breeding colonies , birds on the ground give a drawn - out shrill whistle .
black - bellied storm petrels are black with a white band over the rump , and with white under the wings and on the flanks . a broad black stripe usually runs down the centre of the belly but it may be broken or absent altogether . they are large and very bulky for a storm petrel and have long legs so that the feet can be seen beyond the tail in flight . the legs and feet are black .
19·5–21 cm ; 43–63 g ; wingspan 43–46 cm . near - black storm - petrel with toes projecting slightly beyond tail tip , white uppertail - coverts , most of . . .
after breeding , black - bellied storm petrels migrate to tropical and sub - tropical seas . they travel north in may and june and south in october and november .
black - bellied storm petrels are pelagic seabirds that feed over the continental shelf and the very deep water beyond . they are usually solitary but may gather into small groups .
in the new zealand region they are something of a mystery . although not uncommon at sea , black - bellied storm petrels are poorly known on land . few ornithologists have been on breeding colonies when they are active , as they breed during the autumn after most research expeditions have departed . in fact the eggs of the black - bellied storm petrel have been seen three times only in the new zealand region – in 1929 and 2018 – and chicks have never been seen .
the black - bellied storm - petrel has a circumpolar distribution from islands of the scotia archipelago , through the southern indian ocean to the antipodes islands ( new zealand ) . outside the breeding season it migrations north into the subtropical and tropical zones of the atlantic , indian and pacific oceans , regularly occurring north up to the equator ( del hoyo et al . 1992 ) .
black - bellied storm petrels are often seen gliding close to the surface of the water with the wings held horizontally or about 45° up , kicking with one foot , the other trailing and may cut the water by dropping a foot to leave an obvious wake .
black - bellied storm petrels are poorly known in the new zealand region , but the local population has been estimated at 50 , 000 to 100 , 000 pairs . tens of thousands of pairs were estimated as being on the main antipodes island and colonies on the auckland islands are thought to be larger .
carboneras , c . , jutglar , f . & kirwan , g . m . ( 2018 ) . black - bellied storm - petrel ( fregetta tropica ) . in : del hoyo , j . , elliott , a . , sargatal , j . , christie , d . a . & de juana , e . ( eds . ) . handbook of the birds of the world alive . lynx edicions , barcelona . ( retrieved from urltoken on 9 july 2018 ) .
black - bellied storm petrels are found throughout the southern ocean , where they breed on many subantarctic islands , and may sometimes be seen off the southern new zealand coast during the breeding season . after breeding they migrate to tropical seas south of the equator , hence the scientific name which was based on birds taken just south of the equator in the atlantic .
black - bellied storm petrels nest in colonies , in cavities among loose rocks or excavated burrows in soil and peat . they are monogamous and pair bonds appear to be maintained until one partner dies . the only known nests with eggs found in new zealand were found on adams island , auckland islands on 1 february 1929 . the eggs were in two tiny burrows about 45 cm long , in a nest of dry fine grass .
on the auckland islands , black - bellied storm petrels breed on outlying islands in the absence of exotic mammalian predators and are likely to have been exterminated from campbell island and the main auckland island by norway rats and cats respectively . on the main antipodes island they co - occur with mice , but no nests with eggs or chicks have been found , and so it is not known if the storm petrels are able to breed successfully . the actual colonies there may be restricted to the smaller mouse - free islands of the group , some of which have never been landed on .
molecular evidence revealed that traditional grouping of all storm - petrels in a single family was paraphyletic # r # r ; precise relationships at higher levels within this order are still disputed , but storm - petrels now generally split into two families , comprising “southern” oceanitidae and “northern” hydrobatidae # r .
black - bellied storm petrels are highly pelagic birds that feed close to or beyond the continental shelf . in summer the birds feed in the southern ocean , spread between the ross sea in the south and as far north as the southern coasts of new zealand . locally they breed on the auckland and antipodes islands ( with eggs recorded from adams , rose and enderby islands in the auckland islands ) . as yet no nests have been found on the antipodes islands and it has been suggested that the active colonies are on the smaller islands of the group , with mice not allowing successful breeding on the main island .
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thank you for taking the time to provide feedback on the iucn red list of threatened species website , we are grateful for your input .
turbott , e . g . 1990 . checklist of the birds of new zealand . ornithological society of new zealand , wellington .
justification : this species has an extremely large range , and hence does not approach the thresholds for vulnerable under the range size criterion ( extent of occurrence < 20 , 000 km2 combined with a declining or fluctuating range size , habitat extent / quality , or population size and a small number of locations or severe fragmentation ) . despite the fact that the population trend appears to be decreasing , the decline is not believed to be sufficiently rapid to approach the thresholds for vulnerable under the population trend criterion ( > 30 % decline over ten years or three generations ) . the population size is very large , and hence does not approach the thresholds for vulnerable under the population size criterion ( < 10 , 000 mature individuals with a continuing decline estimated to be > 10 % in ten years or three generations , or with a specified population structure ) . for these reasons the species is evaluated as least concern .
brooke ( 2004 ) estimated the global population to number around 500 , 000 individuals . trend justification : the population is suspected to be in decline owing to predation by invasive species .
this species rarely associates with land , except when breeding , and may be associated with cool currents where its diet appears to consist of squid and small fish ( data lacking ) . its breeding season begins in november , forming loose colonies on bare rocky slopes , in thick vegetation or peat of offshore islands or stacks . it lays one egg in burrows or rocky crevices ( del hoyo et al . 1992 ) .
to make use of this information , please check the < terms of use > .
heather , b . d . ; robertson , h . a . 1996 . the field guide to the birds of new zealand . viking , auckland .
imber , m . j . ; bell , b . d . ; bell , e . a . 2005 . antipodes islands birds in autumn 2001 . notornis 52 : 125 - 132 .
marchant , s . ; higgins , p . j . ( eds ) 1990 . handbook of australian , new zealand and antarctic birds . vol . 1 , ratites to ducks . oxford university press , melbourne .
taylor , g . a . 2000 . action plan for seabird conservation in new zealand . part b : non - threatened seabirds . threatened species occasional publication no . 17 , biodiversity recovery unit , department of conservation , wellington .
tennyson , a . ; taylor , r . ; taylor , g . ; imber , m . ; greene , t . 2002 . unusual bird records from the antipodes islands in 1978 - 1995 , with a summary of other species recorded at the island group . notornis 49 : 241 - 245 .
dull white with a few dull reddish - brown markings at the larger end .
this species has an extremely large range , and hence does not approach the thresholds for vulnerable under the range size criterion ( extent of occurrence < 20 , 000 km2 combined with a declining or fluctuating range size , habitat extent / quality , or population size and a small number of locations or severe fragmentation ) . despite the fact that the population trend appears to be decreasing , the decline is not believed to be sufficiently rapid to approach the thresholds for vulnerable under the population trend criterion ( > 30 % decline over ten years or three generations ) . the population size is very large , and hence does not approach the thresholds for vulnerable under the population size criterion ( < 10 , 000 mature individuals with a continuing decline estimated to be > 10 % in ten years or three generations , or with a specified population structure ) . for these reasons the species is evaluated as least concern .
recommended citation birdlife international ( 2018 ) species factsheet : fregetta tropica . downloaded from urltoken on 09 / 07 / 2018 . recommended citation for factsheets for more than one species : birdlife international ( 2018 ) iucn red list for birds . downloaded from urltoken on 09 / 07 / 2018 .
in past , often lumped with f . grallaria ; relationships between these two are complicated and confused , especially at tristan da cunha and gough i ; proposed race melanoleuca ( tristan da cunha ) may be invalid or may be referable to f . grallaria . considerable individual variation in plumage tends to obscure geographical variation in this complex ; most forms described as races are usually ascribed to f . grallaria . monotypic .
tropical and subtropical major oceans ; circumpolar breeding , from islands of scotia arc through s indian ocean to antipodes is . possible presence at tristan da cunha and gough i requires confirmation .
two main vocalizations , both usually given from within or close to nest - sites ( it is currently . . .
marine and highly pelagic , rarely approaching land except near colonies ; may be associated with . . .
squid , crustaceans and small fish recorded during breeding season , with diet at south georgia estimated at 90 % crustacea and 10 % fish ( by . . .
most complete studies on signy i ( south orkneys ) , the crozets and south shetlands . return to colonies starts sept ( prince edward is , crozet . . .
during breeding season is mainly found s of antarctic polar front . post - breeding , migrates n into . . .
not globally threatened ( least concern ) . widespread , with total population estimated at c . 100 , 000–150 , 000 breeding pairs and c . 500 , 000 individuals , broken down as . . .
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an individual in flight among the waves , on the ocean ( 50 % speed ) .
a bird flying low over the ocean seen from a boat well off the coast .
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) , in neotropical birds online ( t . s . schulenberg , editor ) . cornell lab of ornithology , ithaca , ny , usa . retrieved from neotropical birds online :
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compiled by worthy , t . h . ; holdaway , r . n . ; tennyson , a . j . d . , king , c . m . ; roberts , c . d . ; bell , b . d . ; fordyce , r . e . ; nicol , r . s . ; worthy , t . h . ; paulin , c . d . ; hitchmough , r . a . ; keyes , i . w . ; baker , a . n . ; stewart , a . l . ; hiller , n . ; mcdowall , r . m . ; holdaway , r . n . ; mcphee , r . p . ; schwarzhans , w . w . ; tennyson , a . j . d . ; rust , r . ; macadie , i . 24 : phylum chordata : lancelets , fishes , amphibians , reptiles , birds , mammals , living and recently extinct birds . in : new zealand inventory of biodiversity volume 1 .
urn : lsid : biodiversity . org . au : afd . taxon : 4cc578eb - d15e - 4288 - ad1f - 42cc2d89edf3
urn : lsid : biodiversity . org . au : afd . taxon : e7a37d20 - f0b0 - 446d - 8508 - 0c35d55b432b
urn : lsid : biodiversity . org . au : afd . taxon : 0f85170e - 5051 - 4e7a - a975 - 2af4f84b8465
urn : lsid : biodiversity . org . au : afd . name : 312170
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the european corn worm or european corn borer ( ostrinia nubilalis ) , also known as the european high-flyer , is a pest of grain , particularly maize .

the insect is native to europe , originally infesting varieties of millet , including broom corn .

the european corn borer was first reported in north america in 1917 in massachusetts , but was probably introduced from europe several years earlier .

since its initial discovery in the americas , the insect has spread into canada and westward across the united states to the rocky mountains .

european corn borer caterpillars damage the ears of corn , as well as the stalks , by chewing tunnels , which cause the plants to fall over .

biological control agents of corn borers include the hymenopteran parasitoid trichogramma spp. , the fungus beauveria bassiana and the protozoa nosema pyrausta .

bt corn , a variety of genetically modified maize , has had its genome modified to include a gene from the bacillus thuringiensis ssp. kurstaki .

as a result , the corn variety produces a protein that kills lepidoptera larvae , in particular , european corn borer .

immature maize shoots accumulate a powerful antibiotic substance , dimboa that serves as a natural defense against a wide range of pests and is also responsible for the relative resistance of immature maize to the european corn borer .

european corn borer

european corn borer larvae feed on several crops species including corn , cotton , and grain sorghum .
( left ) european corn borer adult male on corn leaf . image by dennis calvin . ( right ) european corn borer adult females . image by faruque - uz zaman .
ostrinia nubilalis ( hbn . , 1796 ) – pyrale du maïs , european corn borer
european corn borer is a significant pest of corn in south dakota . the caterpillars tunnel into corn stalks resulting in broken stalks and secondary infection by fungi . there have been few reports of european corn borer damaged fields in the past decade ; however , the transition to non - bt corn in other states has been followed by fields with heavy european corn borer infestation . although bt corn can successfully manage european corn borer , farmers planting non - bt hybrids should scout cornfields for potentially damaging populations .
ygcb – the yieldgard ® corn borer gene offers a high level of resistance to european corn borer , southwestern corn borer and southern cornstalk borer ; moderate resistance to corn earworm and common stalk borer ; and above average resistance to fall armyworm . yieldgard ® , the yieldgard corn borer design and roundup ready ® are registered trademarks used under license from monsanto company .
good decisions for managing european corn borer depend on several biological and economic factors . in regions where intensive management of corn production occurs , european corn borer is usually not the only pest . learn more about pest management models .
check out our economic threshold calculator to determine the most economical time to spray for european corn borer .
in northern south dakota , where european corn borers are univoltine , corn is more susceptible to economic losses because caterpillar feeding occurs throughout the season . in areas where bivoltine european corn borer are more prevalent , the first generation of european corn borer causes more injury than the second generation because first generation caterpillars feed during more sensitive corn growth stages .
note : the european corn borer most likely arrived in the united states during the early 1900’s in imported corn which was used to make brooms .
figure 1 . male ( right ) and female ( left ) european corn borer moths . photo courtesy of adam sisson .
univoltine and bivoltine european corn borer populations can occur within the same field . this phenomenon is typically observed in central south dakota .
figure 4 . adult female european corn borer , ostrinia nubilalis ( hübner ) . photograph by john l . capinera , university of florida
european corn borer damages corn when the boring disrupts the plant vascular tissues and interferes with the internal transfer of water , sugars , and nutrients . additionally , some infectious diseases can establish after borer damage . finally , stalk and ear shank strength can be compromised , and severe lodging and ear drop can result . read more about how corn is damaged by the european corn borer .
rice me , pilcher cd . 1998 . potential benefits and limitations of transgenic bt corn for management of the european corn borer . american entomologist 44 : 75 - 78 .
figure 1 . eggs , soon after being laid , of the european corn borer , ostrinia nubilalis ( hübner ) . photograph by usda .
figure 3 . window pane and shot hole injury caused by early instar european corn borer caterpillars . photo courtesy of eugene e . nelson .
hx1 – contains the herculex® i insect protection gene which provides protection against european corn borer , southwestern corn borer , black cutworm , fall armyworm , lesser corn stalk borer , southern corn stalk borer , and sugarcane borer ; and suppresses corn earworm . hxx – herculex® xtra contains both the herculex i and herculex rw genes . herculex® insect protection technology by dow agrosciences and pioneer hi - bred . herculex® and the hx logo are registered trademarks of dow agrosciences llc .
caffrey dj , worthley lh . 1927 . a progress report on the investigations of the european corn borer . usda bulletin 1476 . 154 pp .
figure 5 . newly laid ( above ) and ready to hatch ( below ) european corn borer egg masses . photo courtesy of john gavloski .
figure 2 . mature larva of the european corn borer , ostrinia nubilalis ( hübner ) . photograph by john l . capinera , university of florida .
the european corn borer , an introduced species , has been an important pest of corn in the midwest since the 1920 ' s . besides feeding on all types of corn , european corn borer also attacks and damages hundreds of crop and weed species ( e . g . , peppers , apples , soybean , cotton , foxtails , pigweeds , ragweeds , smartweeds , etc . ) .
figure 3 . adult male european corn borer , ostrinia nubilalis ( hübner ) , pinned specimen . photograph by john l . capinera , university of florida .
european corn borer ( ecb ) is a common pest of corn in ohio that may cause economic losses during the growing season . european corn borer infestations differ over time and among geographic regions in the state . where ecb is active , the development of borers in corn stalks interferes with the flow of nutrients in the host plant , enhances infection by stalk diseases , causes stalk breakage and ear drop , and reduces corn yield .
baker wa , bradley wg , clark ca . 1949 . biological control of the european corn borer in the united states . usda technical bulletin 983 . 185 pp .
bt corn hybrids that target european corn borer are very effective for management of this pest . for farmers not planting bt hybrids , scouting for caterpillars is recommended . moths are attracted to the tallest corn plants , so begin scouting cornfields that were planted earlier for egg masses ( figure 5 ) , leaf feeding , and caterpillars . for areas with univoltine european corn borer , scout corn from v8 through r1 stages . for areas with bivoltine european corn borer , scout for the first generation during v8 through v14 and for the second generation between r1 and r2 . if you observe significant feeding injury or caterpillar abundance in your cornfields , please contact sdsu extension .
a donor organism may be a bacterium , fungus or even another plant . in the case of bt corn , the donor organism is a naturally occurring soil bacterium , bacillus thuringiensis , and the gene of interest produces a protein that kills lepidoptera larvae , in particular , european corn borer . this protein is called the bt delta endotoxin . growers use bt corn as an alternative to spraying insecticides for control of european and southwestern corn borer .
hudon m , leroux ej . 1986b . biology and population dynamics of the european corn borer ( ostrinia nubilalis ) with special reference to sweet corn in quebec . ii . bionomics . phytoprotection 67 : 81 - 92 .
see ohio state university extension bulletin 545 , control of insect pests of field crops , for those insecticides labeled for european corn borer , or for all insecticides labeled on corn . bulletin 545 can be accessed at urltoken .
nault ba , kennedy gg . 1996a . timing insecticide applications for managing european corn borer ( lepidoptera : pyralidae ) infestations in potato . crop protection 15 : 465 - 471 .
figure 4 . european corn borers caterpillar tunneling into ear shank . photo courtesy of iowa state university , department of entomology .
hudon m , leroux ej . 1986c . biology and population dynamics of the european corn borer ( ostrinia nubilalis ) with special reference to sweet corn in quebec . iii . population dynamics and spatial distribution . phytoprotection 67 : 93 - 115 .
bt corn has become popular in recent years . this is genetically modified corn in which genetic material from a toxin produced by the bacterium bacillus thuringiensis var . kurstaki is inserted into corn . the expression of the genetic material makes the plant toxic to corn borers and related insects , but not to other animals . widespread planting of bt corn has greatly reduced the abundance of european corn borer ( burkness et al . 2001 , hutchinson et al . 2010 ) .
first found in north america near boston , massachusetts in 1917 , european corn borer , ostrinia nubilalis ( hübner ) , now has spread as far west as the rocky mountains in both canada and the united states , and south to the gulf coast states . european corn borer is thought to have originated in europe , where it is widespread . it also occurs in northern africa . the north american european corn borer population is thought to have resulted from multiple introductions from more than one area of europe . thus , there are at least two , and possibly more , strains present . this species occurs infrequently in florida .
note : refer to the european corn borer computer decision management software available in your local ( kentucky ) county cooperative extension office and / or ask them for a copy of ent - 49 for further information .
nault ba , kennedy gg . 1996b . sequential sampling plans for use in timing insecticide applications for control of european corn borer ( lepidoptera : pyralidae ) in potato . journal of economic entomology 89 : 1468 - 1476 .
hudon m , leroux ej . 1986a . biology and population dynamics of the european corn borer ( ostrinia nubilalis ) with special reference to sweet corn in quebec . i . systematics , morphology , geographical distribution , host range , economic importance . phytoprotection 67 : 39 - 54 .
european corn borer is not only a major pest on all types of corn , but it also causes losses in several other crops . for some crops subjected to unusually high infestations , the economic losses can amount to hundreds of dollars per acre . see what other crops are affected .
nault ba , kennedy gg . 1996c . evaluation of colorado potato beetle ( coleoptera : chrysomelidae ) defoliation with concomitant european corn borer ( lepidoptera : pyralidae ) damage on potato yield . journal of economic entomology 89 : 475 - 480 .
pepper cultivars differ in their susceptibility to corn borer . hot pepper cultivars are most resistant , and most green bell peppers are susceptible .
in south dakota , european corn borer can have either one or two generations per year depending on location . in northern south dakota , european corn borer typically has only one generation per year ( univoltine ) . moths of univoltine populations begin flying in mid - june , with peak populations occurring in mid - july . eggs are laid on the underside of corn leaves from june to july depending on seasonal temperatures , and hatch within one week . caterpillars initially feed on leaf tissue , but will eventually tunnel into corn stalks . late instar ( or late stage ) caterpillars overwinter in stalk residues and pupate the following spring .
transgenic or bt corn - field corn producers may choose to manage corn borers through the use of hybrids with a corn borer toxin that is genetically built into the plant . these genetically modified corn hybrids contain a gene derived from a naturally occurring bacterium , bacillus thuringiensis , which produces a protein that is toxic to corn borers . this eliminates the need for the application of a corn borer insecticide . this technology allows producers who regularly experience problems with corn borers to use this as a tool to effectively manage this insect . it reduces the need for laborious scouting for this pest , although producers should spot check areas within bt corn fields to determine the effectiveness of this management strategy . obviously , scouting should not be eliminated as a result of bt corn plantings . other above and below ground insects may be present during the season and bt corn provides little to no protection against these .
originally found near boston , massachusetts in 1917 , this destructive pest is now common across much of the country . learn how to identify and get rid of european corn borers here .
( left ) ecb larvae on a corn ear . ( right ) ecb larva tunneled into corn stalk . images by eric bohnenblust .
the european corn borer passes the winter as full - grown larva in corn stalks and other plant refuse such as weed stems . the mature larva is about 1 inch ( 25 mm ) long , creamy to grayish in color , and marked by rather inconspicuous rows of small , round , brown spots running the length of its body .
hudon m , leroux ej , harcourt dg . 1989 . seventy years of european corn borer ( ostrinia nubilalis ) research in north america . in russell ge . ( ed . ) . agricultural zoology reviews . vol . 3 . intercept , wimborne , dorset , uk .
the european corn borer ( ecb ) typically overwinter as fully grown larvae lodged in the stem or cob of the host plant , though they can also be found in other host plants such as large - stemmed grasses and various vegetables . pupation occurs in early sp . . .
first generation - early planted corn is most likely to develop problems with first generation borers because moths are attracted to the tallest , greenest corn for egg laying . during june and early july when the corn is over 18 inches ( 45 cm ) in extended leaf height , look for the characteristic
shot hole
leaf feeding damage in the whorl of the corn . corn shorter than this normally has high levels of a plant aglucone , dimboa , which acts as a antifeedant and prevents borer establishment . if you do find signs of corn borer activity , sample to ascertain the extent of infestation .
sparks an , chiang hc , triplehorn ca , guthrie wd , brindley ta . 1967 . some factors influencing populations of the european corn borer , ostrinia nubilalis ( hübner ) in the north central states : resistance of corn , time of planting and weather conditions part ii , 1958 - 1962 . iowa agricultural experiment station research bulletin 559 . 103 pp .
beneficial insects , such as ladybugs and lacewing larvae , will consume a large number of borer eggs .
note : second generation borers are considered to be the most damaging to corn .
this is a very serious pest of both sweet corn and grain corn , and before the availability of modern insecticides this insect caused very marked reductions in corn production . young larvae feed on tassels , whorl and leaf sheath tissue ; they also mine midribs and eat pollen that collects behind the leaf sheath . sometimes they feed on silk , kernels , and cobs , or enter the stalk . older larvae tend to burrow into the stalk and sometimes the base of the corn ear , or into the ear cob or kernels . feeding by older larvae is usually considered to be most damaging , but tunneling by even young larvae can result in broken tassels . the presence of one to two larvae within a corn stalk is tolerable , but the presence of any larvae within the ear of sweet corn is considered intolerable by commercial growers , and is their major concern . european corn borer is considered to be the most important sweet corn pest in northern production areas , and second - generation borers are the principal source of ear damage . heavily tunneled stalks of grain corn suffer from lodging , reducing the capacity for machine harvesting . lodging is not a serious threat to sweet corn . boring by corn borers also allows several fungi to affect corn plants .
genetically modified foods are foods derived from gmo crops . for example , corn produced through biotechnology is being used in many familiar foods , including corn meal and tortilla chips . in addition , corn is used to make high fructose corn syrup , which is used as a sweetener in many foods such as soft drinks and baked goods . while the fda ( u . s . food and drug administration ) regulates genetically modified foods , it considers bt - corn to be nutritionally equivalent to traditional corn .
management of ecb has changed significantly over the past few years , shifting to the use of bt - corn hybrids , which provide virtually 100 % protection against ecb infestation . these products are used as preventive measures against ecb . transgenic corn hybrids are available containing a bt corn borer gene alone or more commonly in combination with a bt gene for control of corn rootworm larval root feeding . currently , there are three transgenic families from different companies with the bt - corn borer gene : agrisure , herculex , and yieldgard . hybrids from these families with the bt - corn borer gene provide excellent control of ecb . when using any of these transgenic corn hybrids whether with the transgenic cb trait alone or in combination , growers need to follow certain epa regulations that include the use of a 20 % refuge . growers should see their seed dealers for all the requirements and guidelines to follow when planting transgenic hybrids .
extensive use of this technology could result in resistance to the toxin developing in the corn borer population . to reduce the probability of this happening , corn without the bt - like gene should also be grown in bt corn areas . this non - bt corn will act as a refuge for some of the corn borers , thus preserving the genetic diversity that is now in the corn borer population . if these refuge are not included in plantings of bt corn , the technology may be short lived or seed companies will constantly have to introduce new genes , if available , or stack genes to combat this situation . with this in mind , producers should develop resistance management strategies that reduce this risk . contact your state cooperative extension service for resistance management plans . in general , it is suggested that at least 20 % of the acreage in an area be grown in non - bt corn .
a major pest of corn , the european corn borer ( ostrinia nubilalis ) will also feed on over 300 different garden plants including peppers , snap beans , potatoes , tomatoes , apples and gladiolus . damage to corn is caused by the young larvae which chew leaves and tassels . later they tunnel all parts of the stalks and ears , resulting in reduced plant vigor , broken stalks , poor ear development and dropped ears . other crops are damaged primarily by the tunneling of the stalks , pods or stems by the larvae .
techniques other than adult capture can be used to estimate borer phenology . plant phenology can be used to predict corn borer development . thermal summations are also highly predictive . moths seek shelter during the daylight hours in dense grass and weeds near corn fields . flushing moths from such habitats gives an estimate of population densities . eggs can be sampled by visual examination , but this is a very time - consuming effort .
host plant resistance . extensive breeding research has been conducted , and resistance has been incorporated into grain corn , especially against corn borer populations with only a single annual generation . a principal factor in seedling resistance to young larvae is a chemical known as dimboa , which functions as a repellent and feeding deterrent . it has proven difficult to incorporate the known resistance factors into sweet corn without degradation of quality .
biological control . biological control has been attempted repeatedly in sweet corn and other vegetables susceptible to european corn borer attack . bacillus thuringiensis products can be as effective as many chemical insecticides , but often prove to be less effective than some . most single - factor approaches , with the exception of newer formulations of bacillus thuringiensis , have proven to be erratic . release of native trichogramma spp . ( hymenoptera : trichogrammatidae ) , for example , provides variable and moderate levels of suppression .
in crops other than corn , the pattern of damage is variable . european corn borer larvae damage both the stem and fruit of beans , pepper , and cowpea . in celery , potato , rhubarb , swiss chard , and tomato , it is usually the stem tissue that is damaged . in beet , spinach , and rhubarb , leaf tissue may be injured . entry of borers into plant tissue facilitates entry of plant pathogens . the incidence of potato blackleg caused by the bacterium erwinia carotovora atroseptica , for example , is higher in potato fields with stems heavily infested by corn borers . direct damage by corn borers to potato vines , however , results in negligible yield loss .
in southern south dakota , european corn borer can have up to two generations per year ( bivoltine ) . bivoltine moths begin flight in mid - may and eggs are laid on the underside of v6 - v9 corn leaves . these caterpillars will also feed on corn leaves and tunnel into stalks . pupation occurs within corn stalks and emerging adults begin laying eggs on the underside of leaves , leaf collars , and on ear husks during tasseling ( vt ) and silking ( r1 ) . eggs hatch roughly a week later , and caterpillars tunnel into the stalks and ear shanks where they feed on developing kernels . late instar caterpillars overwinter in stalk residues and pupate the following spring .
the first generation occurs in late may to late june . early planted corn has greatest potential for damage . the second generation occurs in late june to august . late planted corn is most attractive to this generation . a third generation occurs in late july and overwinters in the corn stems .
yield loss associated with european corn borer is due to caterpillar feeding , as adult moths do not injure corn . newly hatched caterpillars feed on leaf collars and sometimes migrate towards the tassels to feed on pollen . young caterpillars often feed on the leaf surface and midribs , often referred to as “window pane” injury ( figure 3 ) . midway through development caterpillars will feed within the whorl , creating “shot hole” type injury that becomes visible when the leaves unfurl ( figure 3 ) . near the end of development , caterpillars will tunnel into corn stalks , ear shanks , and into the ears .
fully grown corn borer larvae ( 3 / 4 – 1 inch long ) are extremely destructive flesh - colored caterpillars with a reddish or dark brown head and several distinct spots on the top of each abdominal ring or segment . the adult borer is a night - flying yellowish - brown colored moth ( 1 inch wingspan ) with dark wavy bands across its wings .
corn borer larvae will feed on many crop or weed species that have suitable stems or fruit sufficiently large for a boring larva . evidence of corn borer infestation on corn plants appears a few days after first generation egg hatch . early damage is characterized by small pin holes in the leaves and fine sawdust - like frass ( excrement ) scattered over the upper surface of damaged leaves . another typical symptom is a noticeable amount of chewing damage and frass in the whorl of the plant . when larvae enter stalks , they leave visible , small , round holes with wet frass exuding from the holes . stalk feeding can weaken the stalk to the point of breaking . damage to field corn resulting from first generation corn borer larvae is seldom great enough to warrant insecticide application . activity of the second generation larvae , which appear from mid - july through august , is similar to the spring generation with several exceptions . second generation larvae commonly move to the tassel area , causing infested tassels and the upper portion of the plant to break . some larvae also enter the shanks and ears . weakening of shanks often results in dropped ears that cannot be harvested . greatest field corn losses from second generation corn borer appear to occur on either late - planted or late - maturing varieties . field corn planted before may 20 is generally not damaged by the second - generation while corn planted later than may 20 is much more susceptible to damage because these plants are still attractive hosts .
there are many reports that weather influences european corn borer survival . heavy precipitation during egg hatch , for example , is sometimes given as an important mortality factor . low humidity , low nighttime temperatures , and heavy rain and wind are detrimental to moth survival and oviposition . however , during a 10 - year , 3 - state study , sparks et al . ( 1967 ) reported no consistent relationship between weather and survival .
second generation - because of the difficulty in readily detecting second generation borers and their damage , concentrate sampling efforts on fields that are late planted and / or actively pollinating during the period of peak egg laying . check with your local extension personnel , as to when it is necessary to start sampling . windshield
splatter
of corn borer moths while driving county roads after dusk will alert one to the flight , mating , and egg laying of corn borer moths in an area .
bt - corn is a type of genetically modified organism , termed gmo . a gmo is a plant or animal that has been genetically modified through the addition of a small amount of genetic material from other organisms through molecular techniques . currently , the gmos on the market today have been given genetic traits to provide protection from pests , tolerance to pesticides , or improve its quality . examples of gmo field crops include bt - potatoes , bt - corn , bt - sweet corn , roundup ready soybeans , roundup ready corn , and liberty link corn .
native predators and parasites exert some effect on european corn borer populations , but imported parasitoids seem to be more important . among the native predators that affect the eggs and young larvae are the insidious flower bug , orius insidious ( say ) ( hemiptera : anthocoridae ) ; green lacewings , chrysoperla spp . ( neuroptera : chrysopidae ) ; and several ladybird beetles ( coleoptera : coccinellidae ) . insect predators often eliminate 10 to 20 % of corn borer eggs . avian predators such as downy woodpecker , dendrocopos pubescent ( linnaeus ) ; hairy woodpecker , dendrocopos villosus ( linnaeus ) ; and yellow shafted flicker , colaptes auratus ( linnaeus ) have been known to eliminate 20 to 30 % of overwintering larvae .
with the widespread use of bt corn hybrids , ecb populations have been reduced to very low levels in corn and are more likely to be found in other host crops . only those fields not planted with a bt hybrid are at risk . no - till fields with high residue are susceptible , along with frequent corn crops in the rotation .
note : ladybugs will consume almost 60 borer eggs a day . stink bugs , damsel bugs , spiders and hover fly larvae feed on young caterpillars .
in new england , european corn borer and pepper maggot are the most common insect pests of pepper fruit . in many locations , peppers picked at the green stage are only marginally affected by ecb , but those left in the field long enough to ripen fall prey to ecb , then to soft rots . during the 2012 season , the umass ipm team worked with several growers to see if releases of trichogramma could increase their yield of healthy bright red and yellow fruit .
trichogramma ostriniae are tiny parasitic wasps that seek out and kill the egg masses of the european corn borer ( ecb ) . the use of these wasps in commercial sweet corn fields in massachusetts has resulted in the reduction or elimination of foliar insecticide sprays , saving time , labor , pesticides , and fuel , reducing soil compaction , and maintaining and improving ear quality . the good news is that trichogramma wasps can also be used to control ecb in peppers . trichogramma reduces fruit infestation , resulting in fewer culls and potentially greater success with high - quality , high value , ripe red peppers .
adult moths are approximately ½ inch in length with triangular wings . female moths have yellow - brown wavy markings on their wings while males are slightly smaller and darker in color ( figure 1 ) . european corn borer caterpillars are light tan to pink in color and are approximately 1 inch in length when fully mature . distinguishing characteristics of the caterpillars include dark brown head capsules , dark spots on each body segment , and three pairs of true legs with four pairs of abdominal prolegs ( figure 2 ) .
the pupal stage of the corn borer is rarely visible . pupae remain inside the host plant , and adults emerge in late spring and in july . the pupae are smooth , light to dark brown in color , and 1 / 3 to 5 / 8 of an inch in length .
early planted corn is taller and attractive to ovipositing female moths , so late planting has been recommended , but this is useful mostly in areas with only a single generation per year . if a second generation occurs , such late planted corn is heavily damaged .
cultural practices . destruction of stalks , the overwintering site of larvae , has long been recognized as an important element of corn borer management . disking is not adequate ; plowing to a depth of 20 cm is necessary for destruction of larvae . mowing of stalks close to the soil surface eliminates greater than 75 % of larvae , and is especially effective when combined with plowing . minimum tillage procedures , which leave considerable crop residue on the surface , enhance borer survival .
sampling for first - brood injury should be initiated when corn is in the whorl stage and early shot - hole foliar injury is evident . sampling should be based on inspection of a series of 20 plant samples from five or more locations in a field . notes should be taken on the proportion of the stand exhibiting whorl injury . the whorls of at least two plants from each sample of 20 plants should be dissected to determine the number of larvae per injured plant and the predominant stage of ecb larvae development . sampling second - brood corn borer is more difficult than first brood , since detection of early larvae on corn in the tassel stage or later is complicated by the size of the corn plant .
begin scouting first generation larvae once moths have been detected in pheromone traps and corn has reached the six - leaf stage . ( usually late may to early june in central missouri ; seven to ten days earlier in the southeastern counties ) . scout earliest planted corn fields first .
with the widespread use of bt corn hybrids , ecb populations have been reduced to very low levels in corn and are more likely to be found in other host crops . only those fields not planted with a bt hybrid are at risk . no - till fields with high residue . . .
insecticides . liquid formulations of insecticide are commonly applied to protect against damage to corn , particularly from the period of early tassel formation until the corn silks are dry . recommendations vary from a single application prior to silking , to weekly applications . liquid applications are usually made to coincide with egg hatch in an effort to prevent infestation . if corn borers are present in a field , however , the critical treatment time is just before the tassels emerge , or at tassel emergence from the whorl . this plant growth period is significant because the larvae are active at this time and more likely to contact insecticide . a popular alternative to liquid insecticides is the use of granular formulations , which can be dropped into the whorl for effective control of first generation larvae because this is where young larvae tend to congregate . insecticide is more persistent when applied in a granular formulation . in grain corn , insecticide applications for suppression of second generation corn borers can be made outside the corn fields in areas of thick grass , or action sites , where adults tend to aggregate . this approach has not been assessed for sweet corn . for borer suppression on potato , a single application of insecticide timed to coinide with the presence of first instar larvae provides optimal yield .
yield losses due to corn borer can be attributed to a combination of stalk injury by first - or second - brood larvae , ear drop due to second - brood injury to shanks and ears , and enhancement of stalk rot due to microbial infection of injured stalks . in general , if one larva tunnels and completes its development per stalk , the assumption is that a 5 % yield reduction may be expected . the severity of ear drop and stalk breakage depends on the incidence and location of borer cavities and environmental conditions favoring plant infections by microbial agents .
leaf feeding typically does not cause serious injury to corn . however , tunneling into stalks and ear shanks ( figure 4 ) can result in significant yield losses . tunnels can result in stalk breakage and reduce water and nutrient transport by corn plants . furthermore , tunnel entrances can permit secondary infections of mycotoxin - producing fungi .
the european corn borer ( ecb ) typically overwinter as fully grown larvae lodged in the stem or cob of the host plant , though they can also be found in other host plants such as large - stemmed grasses and various vegetables . pupation occurs in early spring and adults emerge in early june to july . larvae initially feed on the leaves and work their way to the whorl of the plant . pinholes or shot holes are signs of borers already moving into the plant . depending on the strain of ecb , growing conditions and the growing region , populations can go through one or two full generations and , in some cases , a partial third generation in a single season .
hutchinson , w . d . , e . c . burkness , p . d . mitchell , r . d . moon , t , w leslie , s . j . fleischer , m . abrhahamson , k . l . hamilton , k . l . steffey , m . e . gray , r . l . hellmich , l . v . kaster , t . e . hunt , r . j . wright , k . pecinosvsky , t . l . rabaey , b . r . flood , and e . s . raun . 2010 . areawide suppression of european corn borer with bt maize reaps savings to non - bt maize growers . science 330 : 222 - 225 .
1st generation : field corn controls should be considered if 50 % of the plants show
shot hole
or
window pane
feeding damage and larvae are present . treatment may be justified for popcorn and seed corn fields if 25 % or more of the plants are infested . once larvae have bored into the stalks , treatment will not be effective .
however , if a new food product developed through biotechnology does not contain substances that are significantly different from those already in the diet , it does not require premarket approval . products that are genetically engineered to provide pesticide traits , such as resistance to the corn borer , are also subject to regulation by the environmental protection agency . currently , genetically modified foods in the united states do not require special labeling to notify consumers .
several microbial disease agents are known from corn borer populations . the common fungi beauveria bassiana and metarhizium anisopliae are sometimes observed , especially in overwintering larvae . the most important pathogen seems to be the microsporidian nosema pyrausta , which often attains 30 % infection of larvae and sometimes 80 to 95 % infection . it creates chronic , debilitating infections that reduce longevity and fecundity of adults , and reduces survival of larvae that are under environmental stress .
overwintering larvae pupate in the spring , emerging as moths in late may and early june . female moths are pale yellow - brown with irregular darker bands running in wavy lines across their wings ; male moths are distinctly darker and usually smaller . mating takes place in early june ( first generation ) and in late july and early august ( second generation ) in dense grassy areas around corn fields . female moths generally lay their eggs on the underside of corn leaves ( often along the leaf midrib ) , leaf sheaths , and / or ears , depending on the generation , in masses of 15 to 30 eggs overlapping like scales of a fish . tall , lush , early planted corn is the preferred oviposition site for the first generation moths ; whereas second generation moths target actively pollinating corn , which is usually planted late . after 5 to 6 days , the eggs develop what appears to be black spots , which are actually the head capsules of young borer larvae . once the black head is visible , hatching is imminent .
check plants for egg masses and signs of borer feeding . examine closely the lower surface of leaves and at the ear . when an egg mass is found , record the hatching stage according to following : white , cream , black head , hatched .
second generation borer attack may result in stalk or tassel breakage and / or boring into the ear shanks , which may cause ears to drop off . larvae may bore into the ears where they feed on the kernels and cob , resulting in yield losses , as well as avenues for attack from secondary insects and pathogens ( e . g . , ear rots ) . no matter where they may attack the plant , second generation borer damage can result in grain losses , harvesting problems , and poor grain quality .
the bt delta endotoxin was selected because it is highly effective at controlling lepidoptera larvae , caterpillars . it is during the larval stage when most of the damage by european corn borer occurs . the protein is very selective , generally not harming insects in other orders ( such as beetles , flies , bees and wasps ) . for this reason , gmos that have the bt gene are compatible with biological control programs because they harm insect predators and parasitoids much less than broad - spectrum insecticides . the bt endotoxin is considered safe for humans , other mammals , fish , birds , and the environment because of its selectivity . bt has been available as a commercial microbial insecticide since the 1960s and is sold under many trade names . these products have an excellent safety record and can be used on many crops until the day of harvest .
fifteen to 35 white eggs are laid in masses on the underside of corn leaves , often near the midrib . the individual eggs overlap each other much like fish scales . prior to hatching , the mass darkens .
first generation borers are usually present during june in the whorl of corn plants . as the larvae feed and grow , some may be found tunneled into the midrib of leaves . this damage can cause leaves to break at the point of borer entry . as the borers feed on the leaves , they typically produce a characteristic random or
shot hole
damage pattern . these holes become apparent as the leaves grow out of the whorl . by the time the first generation borers are half grown , they will have moved down the stalk and bored into it , leaving behind their sawdust - like excrement called frass at the stalk entry hole . the boring damage may weaken the plant enough to cause subsequent stalk breakage later in the season , typically occurring below the ear . or it may cause corn to become stunted , resulting in yield reductions caused by the inability of the plant to transport water and nutrients through its damaged stalk . after boring into the stalk , the larvae usually feed inside the plant until they reach maturity and pupate . stalk entry and tunneling by corn borer may predispose the plant to pathogens which may lead to stalk rots later in the season . they emerge as adults during july and early august beginning the second generation .
the number of generations varies from one to four , with only one generation occurring in northern new england and minnesota and in northern areas of canada , whereas three to four generations occur in virginia and other southern locations . in many areas generation number varies depending on weather , and there is considerable adaptation for local climate conditions even within strains . european corn borer overwinters in the larval stage , with pupation and emergence of adults in early spring . diapause apparently is induced by exposure of last instar larvae to long days , but there also is a genetic component . moth flights and oviposition usually occur during june - july and august - september in areas with one to two generations annually . in southern locations with three generations , moth flights and oviposition typically occur in may , late june , and august . in locations with four generations , adults are active in april , june , july , and august - september .
the larvae are dirty white , often having a pinkish tinge . the skin is smooth and free of hairs . there are numerous dark spots scattered over the sides and top of the body . the head is dark brown to black . it is the larval ( borer ) stage that causes damage to crops .
larvae of the first brood pupate in the stalks and emerge again as adult moths in late july and early august . these adults prefer to deposit their eggs on late - planted corn . the larvae hatching from this generation are referred to as the second brood ; they will overwinter as late - instar larvae in corn stubble . larvae will feed on the surface of the leaves before tunneling into the corn stalk where the predominant feeding occurs ( fig . 3 ) . injury caused by the second brood includes stalk breakage , ear drop due to infestation of shanks , and infestations of the ear ( fig . 4 ) . larvae of the second brood are also susceptible to adverse weather , predators , and parasites . the overwintering larvae are very susceptible to insect , avian , and mammalian predators that become active during the late fall , winter , or early spring .
example : a field that is shedding pollen has 60 % of the plants infested with larvae and / or egg masses . the number of actual larvae observed averages 2 per plant . the number of egg masses averages 1 / 4 per plant . for 1 / 4 egg mass / plant , an average of 1 borer would survive per plant ( assuming survival of 4 borers / egg mass ) . therefore , two live borers plus one borer from egg masses equals 3 borers / plant . anticipated yield is 150 bu / a and the crop is valued at $ 2 . 75 per bushel . the cost of the insecticide and application is $ 12 . 00 and 65 % control can be expected . would it pay to apply the insecticide ?
assessment of second - brood injury in early september with an emphasis on evaluation of stalk quality and ear shank infestation ( fig . 5 ) will provide relevant information on the need for scheduling timely harvest of corn stands that may be susceptible to significant ear drop or stalk breakage if harvest is delayed .
during late july and early august adults mate in grassy areas ( e . g . , roadsides , waterways , weed patches , etc . ) . egg masses , which will produce second generation borers , are laid in corn during late july and throughout august . newly hatched larvae typically move from the leaves to protected areas of the leaf axils and sheaths to feed on pollen and plant tissue . second generation borers normally concentrate their attack in the ear zone , roughly the middle third of the plant . after undergoing several molts , the larvae bore into the corn plant as did the first generation borers .
ecb overwinters as late instar or stage larvae in corn stalks . in the early spring , the overwintering larvae pupate and then emerge as moths that prefer to deposit their egg masses on the underside of leaves of mid - whorl stage corn . each egg mass appears like a small mass of fish scales and may include 15 to 20 eggs ( fig . 1 ) . the eggs hatch into early - instars that initially feed on foliage , causing window - pane injury , and on the tender central whorl , which subsequently leads to shot - hole injury in the emerging foliage ( fig . 2 ) . as the larvae become third - and fourth - instars ( about 1 / 2 - inch long ) , they tunnel into the mid - ribs and stalks . there they complete their larval development as fifth - instars and transform into pupae from which adult moths will emerge in midsummer . this larval generation , which occurs in the spring on whorl - stage corn , is called the first brood . during the period of larval development , significant proportions of larvae perish due to natural elements such as heavy rains or predation by beneficial insect predators . although 15 to 20 larvae may emerge from a single egg mass , it is rare to find one or more mature larvae in a corn stalk or adjacent stalks to which larvae may have migrated .
fully grown larvae pass the winter concealed in corn stubble or other plant parts on which they have been feeding . pupation takes place in late spring with the adult moths appearing in may and june . when mature , the females begin laying clumps of white eggs on the undersides of the lower leaves of host plants . ( adult females may lay up to 500 eggs over their short lifetime . ) under ideal conditions , these first generation eggs hatch within 3 - 7 days . tiny caterpillars begin feeding on host plants and complete their development in 3 - 4 weeks . pupation occurs deep inside the corn stalks and second generation moths emerge and begin laying eggs in early summer . produces 1 - 3 generations per year depending upon the climate .
larvae : pinkish tan body , boring into corn , and leaves . adults : small , tan , night fliers about 1 / 2 inch in length that hold their wings in a delta shape at rest . females have a thick body and light colored wings , whereas the males have darker tan - to - brown wings and a thinner body . click here for an identification key .
burkness , e . c . , w . d . hutchinson , p . c . bolin , d . r . bartels , d . f . warnock , and d . w . davis . 2001 . field efficacy of sweet corn hybrids expressing a bacillus thuringiensis toxin for management of ostrinia nubilalis ( lepidoptera : crambidae ) and helicoverpa zea ( lepidoptera : noctuidae ) . journal of economic entomology 94 : 197 - 203 .
life table studies conducted on corn borer populations in quebec with a single annual generation perhaps provide insight into the relative importance of mortality factors ( hudon and leroux 1986c ) . these workers demonstrated that egg mortality ( about 15 % ) was low , stable and due mostly to predators and parasites . similarly , mortality of young larvae , due principally to dispersal , dislodgement , and plant resistance to feeding was fairly low ( about 15 % ) but more variable . mortality of large larvae during the autumn ( about 22 % ) and following spring ( about 42 % ) was due to a number of factors including frost , disease and parasitoids , but parasitism levels were low . pupal mortality ( about 10 % ) was low and stable among generations . the factor that best accounted for population trends was survival of adults . dispersal of moths and disruption of moth emergence by heavy rainfall are thought to account for high and variable mortality ( 68 to 98 % , with a mean of 95 % ) , which largely determines population size of the subsequent generation . overall generation mortality levels were high , averaging 98 . 7 % .
first brood rescue treatment may be needed when 75 % or more of stand is infested and larvae are susceptible to treatment , that is , they have not tunneled into the stalk . second brood rescue treatment is warranted when egg masses or early larvae are found on 50 % or more of plants . abundant activity of ecb adults along field edges indicates a need for inspection for egg masses or early larvae in corn . however , in a year of heavy second - brood activity , the problem may be forecasted by observation of an abundant summer flight of adults .
do bt - corn hybrids differ only in that they possess the genetic code to produce the bt protein ? not exactly . to add a trait to a crop plant , the gene must be inserted along with some additional genetic material . this additional genetic material includes a promoter sequence that , in part , determines how the new trait is expressed in the plant . for example , the promoter may cause to protein to be expressed in certain parts of the plants or only during a particular period of time . there is a marker gene that allows plant breeders to easily determine which plants have been transformed . herbicide and antibiotic tolerance promoters are commonly used to identify transformed plants . there may also be a plasmid or vector sequence that allows for rapid multiplication of the gene of interest in a bacterial host prior to insertion in the crop plant .