bluuebunny/crossref_metadata_2025 huggingface dataset:
The behavioural ecology of host selection in Anopheles implexus (Theobald) (Diptera, Culicidae)
Authors: McCrae A. W. R. , Boreham P. F. L. , Ssenkubuge Y.
Published: July 2009

Anopheles implexus (Theo.) was studied at the Zika Forest near Entebbe, Uganda, from 1966 to 1971, with central reference to biting activities and host selection. Seasonal fluctuations of populations appeared to be correlated with lake levels, not with local rainfall. Results of biting, resting and nectar-feeding catches at various points across the forest floor indicated that diel activity patterns of man-biting were related primarily to the proximity of resting female A. implexus and only secondarily to the influence of environmental variables. Latent effects of moon phase on day-time man-biting activity patterns support this view. Blood-meal identifications showed that the great majority of blood-fed females resting in forest had fed on cattle, indicating that they left the forest at night. This was confirmed by direct catching from cattle outside forest, while the virtual absence of A. implexus resting near these bait animals, together with the fact that man is very seldom attacked away from forest, indicated that different kinds of host selection strategy were involved. The diel activity pattern of biting on cattle taken into forest was then found to be very different from that on man. Age-grading studies helped to substantiate these differences. Hourly sampling of A. implexus arriving at representative resting sites in forest indicated an exodus of most of the adult mosquito population from forest at dusk and a return shortly after sunrise. The two basic host selection strategies evidently involved (a) active or (in effect) ‘hunting’ flight, mainly outside forest with a tendency to restrict choice to most strongly attractive hosts, and (b) passive or opportunistic attack from rest, in which some of the unfed females sheltering may be activated by the proximity of a host which need not be strongly attractive. The latter situation was investigated further through analysis of short-term day-time patterns of attack on man in forest which are postulated to be a function of mosquito response delay (involving both resident and incoming elements of the sheltering population), which in turn determines depletion rates (involving only the resident element available at the time of the host's arrival). In A. implexus the response delay appears to vary according to time of day. Anomalous results are finally re-considered and it is concluded that the different patterns of active and passive host selection could arise from a single circadian rhythm of responsiveness, with flight characteristics and day-time inhibition modulating responses to specific and non-specific host stimuli in different ways.
The association between larval parasitic water mites (Hydracarina) and Anopheles implexus (Theobald) (Diptera, Culicidae)
Authors: McCrae A. W. R.
Published: July 2009

The parasitic larvae of two species of water mites were studied on resting and biting Anopheles implexus (Theo.) from the Zika Forest near Entebbe, Uganda. Details are given of the mites' morphology, positions of attachment, growth stages and visible effects on hosts. Living larvae of the more numerous mite species (designated as species F, Limnesiidae) were only moderately reliable indicators of the nulliparous state of female hosts, whereas those of the other species (species G, Arrenuridae) were more reliable nullipar indicators, evidently owing to their far more rapid development. The presence of living larvae of either species not completely full-grown denoted the nulliparous state of female hosts with certainty. Male mosquitoes showed consistently lower infestation rates than females from the same resting samples, but the incidence of the different growth classes of species F indicated that these mites departed from hosts of either sex with equal facility and therefore regardless of whether the hosts returned to oviposition sites or not. Frequency distributions of species F on each host sex fitted most closely to highly clumped negative binomials, and biological interpretation of patterns of decline in mite numbers on females in successive Sella's stage groups, and other data, provided evidence of there being at most a negligible amount of mite-mediated host mortality.

The study confirms the usefulness as well as the limitations of the presence of parasitic water mites as a rapid means of age-grading female mosquitoes, and suggests several new applications.
Methods for detecting multiple blood-meals in mosquitoes (Diptera, Culicidae)
Authors: Boreham P. F. L. , Lenahan J. K.
Published: July 2009

Two techniques have been developed to investigate the incidence of multiple feeding by mosquitoes. One system detects the ABO blood group substances and can be used up to 24 h after feeding in the case of Anopheles stephensi List. and 30 h for Aedes aegypti (L.). It is limited by cross-reactions which develop between blood group substances as digestion occurs in the stomach of the mosquito. The second system detects the serum protein haptoglobins (Hp) and it is possible to detect the Hp type of blood in single feeds 20 h after feeding for Ae. aegypti and 16 h for A. stephensi. Multiple feeds taken within a short time of each other can be identified up to 16 h after completion of the meal. The minimum amount of blood necessary to effect an identification in a fresh two-part meal is 0·1 mg, which is approximately one-tenth of the total amount of blood taken. It is now therefore possible to measure multiple ‘cryptic meals’ taken from man, if they are of different Hp types. Identification of Hp from A. gambiae sp. A blood-meals has been successfully carried out using material sent from the tropics. Limitations of the techniques as applied to field collections are discussed.
Species distribution and abundance ofCulicoidesLatreille (Diptera, Ceratopogonidae) in Nigeria
Authors: Dipeolu O. O.
Published: July 2009

In a country-wide survey ofCulicoidesin Nigeria 31 species were caught in light-traps set on the eaves of livestock pens. Three species, namelyC. imicolaKieff.,C. schultzei(End.) andC. milneiAust., were most numerous and were found in all parts of the country.C. austeniC., I. & M. was predominant in mangrove swamps,C. schultzeiin the hot Sudan zone andC. milneiwas dominant on the plateaux.C. imicolaandC. milneiwere predominant in the forest zone whileC. schultzeiandC. imicolawere dominant in the savanna zones.C. quinquelineatusGoetgh. was a southern species and was replaced in the north byC. moreliClastrier. Peak catches of most species were between 01.00 and 05.00 h and a large proportion of theCulicoideswere engorged with blood. The presence of large numbers of engorgedCulicoides, especiallyC. imicolaand C.milnei, around livestock indicates the danger of bluetongue virus transmission.
The effects of selective elimination of hosts on a population of tsetse flies (Glossina morsitans morsitans Westwood (Diptera, Glossinidae))
Authors: Vale G. A. , Cumming D. H. M.
Published: July 2009

Monthly observations were made of the numbers and nutritional state of Glossina morsitans morsitans Westw. and the numbers of game animals in an 11 km2 block of woodland in Rhodesia. After 31 months the block was enclosed by a warthog-proof fence and nearly all of the warthog inside were removed rapidly. Tsetse diet switched from 80% warthog to 40–80% bovid (mainly kudu), 20–50% elephant and 0–20% warthog. Six months later elephants were driven from the block and bovids then formed about 90% of tsetse diet for the next year. Although the selective removal of hosts produced a clear stress, it had no drastic effect on the numbers and nutritional state of tsetse when compared to these features of a control population. Movement of tsetse into the enclosed area can account partly, but not fully, for this. The effects of routine hunting operations on a tsetse population are also reported.
Survival and behaviour of tsetse flies (Diptera, Glossinidae) released in the field: a comparison between wild flies and animal-fed and in vitro-fed laboratory-reared flies
Authors: Vale G. A. , Hargrove J. W. , Jordan A. M. , Langley P. A. , Mews A. R.
Published: July 2009

Male and female Glossina morsitans morsitans Westw. which emerged from puparia produced by animal-fed and in vitro-fed colonies in England were marked distinctively with non-toxic paint and released into a natural habitat of G. morsitans and G. pallidipes Aust. in Rhodesia. Concurrently, adults of both species which emerged from locally-collected puparia were marked and released. Recaptures from artificial refuges, odour attractants and mobile baits at periods up to 59 days after release and at distances up to 1800 m from the release site indicated no clear differences between native G. morsitans and the two laboratory-reared groups in respect of body size, amount of fat present at emergence, survival, dispersal, availability to a range of baits, diet, speed of taking a first meal, wing damage and insemination rate. Although the blood-meal identifications for marked female G. morsitans were similar to those for both sexes of unmarked flies, blood-meals from marked males showed a relatively high proportion of bovid identifications. Unmarked flies caught were generally older than marked catches. The ratio of females to males in unmarked samples (1:1 for G. morsitans, 2:1 for G. pallidipes) was roughly double that in marked catches.
Descriptions of two new species of Neotropical Eulophidae (Hymenoptera) of economic interest, with taxonomic notes on related species and genera
Authors: Bouček Z.
Published: July 2009

Chrysocharis caribeasp. n., a parasite of agromyzid leaf miners, mainly ofLiriomyza sativaeBlanch, in the West Indies, andEmersonella palmaesp. n., parasite ofHispoleptis subfasciataPic, a hispine leaf miner on oil palms in Colombia, are described. New generic and specific synonymies and new combinations are established inChrysocharisFörster,ProacriasIhering (=DidymotropisDe Santis syn. n.),ChrysonotomyiaAshmead (=AchrysocharisGirault syn. n.),TeleopterusSilvestri,PediobiusWalker,EmersonellaGirault,EuplectrusWestwood,StenomesiusWest-wood,DiglyphomorphaAshmead,MiotropisThomson,ArdalusHoward andGrotiusomyiaGirault. Additional taxonomic comments onChrysocharodesAshmead andAstichusFörster and tentative keys to the species ofProacriasandEmersonellaare included. Lectotypes are designated for 24 specific names.
Taxonomy of the long brown scale Coccus longulus (Douglas), stat. n. (Homoptera: Coccidae)
Authors: BEN-DOV Y.
Published: July 2009

Examination of type specimens and other authentic material established that the earliest available name for the long brown scale is Coccus longulus (Douglas), stat. n. and that Lecanium elongation Signoret is a junior synonym of Parthenolecanium persicae (F.), syn. n. Detailed, illustrated descriptions of adult female C. longulus are given, based on collections from England, Australia, Israel and the U.S.A. Lectotypes are designated for C. longulus, Lecanium frontale Green and Lecanium acaciae Newstead. Coccus acaciae (Newstead), stat. n. is raised from synonymy and seven synonyms of C. longulus are listed.
A revision ofApodiphusSpinola (Heteroptera: Pentatomidae)
Authors: Ghauri M. S. K.
Published: July 2009

The genusApodiphusSpinola is redefined on the basis of external structures and male and female genitalia and is compared withParanevisanusDistant. This new definition ofApodiphus, based on its type-species,A. amygdali(Germ.), excludesA. pilipesHorváth.NeonevisanusDistant is synonymised withApodiphusSpinola and the type-species of the genusNeonevisanus, (N. rugosusDist.) is synonymised withA. integricepsHorváth.Neonevisanus pallidusHoberlandt (=A. siazoviKirich. syn. n.) is transferred toApodiphusandA. amygdali,A. integriceps, A. pallidusandA. murghzarussp. n. are described in detail, with illustrations. The species ofApodiphusfeed on almond, apple and other deciduous trees. The genus ranges from Italy in the west to N. India in the east, generally at relatively low altitudes up to 1600 m. Its probable centre of origin is Iran, where three out of the four species are found.A. amygdaliis the only European species.
Mortality of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) non-freezing temperatures
Authors: Miller G.W.
Published: July 2009

Eggs, larvae and pupae of Spodoptera littoralis (Boisd.) were exposed to five non-freezing constant temperatures (13°, 10°, 7°, 4° and 1°C). The period of exposure required to kill eggs and larvae, and to affect pupae seriously, was determined at each temperature. Distinction was made between dead pupae and pupae which were not killed but developed into deformed adults incapable of mating or laying fertile eggs. Probit line analysis was applied to the mortality results and response lines were plotted for all developmental stages at each constant temperature. Observed 100% mortality and computed LD 99 estimates showed that at all temperatures, except 1°C, resistance to cold was minimal at the egg stage, increased in maturing larvae and was at a maximum in the pupal stage, so that the order of the LD 99 values was: pupae (dead)>larvae>eggs. At 1°C the order was: pupae (dead)>30-day-old larvae>eggs>15-day-old and 1-day-old larvae. The LD 99 (days) value decreased with decreasing temperature for all larval stages and for pupae; and for eggs it was greater at 1°C than at 4° and 7°C.
A new electric trap for tsetse flies
Authors: Rogers David J. , Smith David T.
Published: July 2009

A new electric trap for tsetse flies (Glossina spp.), based on a circuit producing the necessary high voltages from a small 2-V battery, is described. Power consumption is reduced to less than 1% of its level in other circuits designed for the same purpose so that in theory up to 300 h operation per charge is available from a single 2-V dry cell with a 7-Ah capacity (weight approximately 460 g). In practice this time is more likely to be limited by the shelf-life of the cell in tropical climates. The new circuit and a modified grid were tested against G. morsitans submorsitans Newst. during field trials in Ethiopia and the results are discussed. A high percentage of females was obtained only when a stunning capacitor was introduced across the output. The capacitor stores the charge from the circuit and gives a bigger impulse as flies land across the wires. It seems that, in the absence of the capacitor, females that visit the catching device escape from the electrified grid. When they are caught they are stunned for about the same length of time as male flies.
Damage to coconut palms by Azteca sp. (Hymenoptera: Formicidae) and insecticidal control with bait, in Guyana
Authors: Rai B. K.
Published: July 2009

A general survey of coconut plantations in Guyana in 1976 indicated that in the total area of about 18 700 ha, 1000 of the 3000 ha of coconut palms on the east coast of Demerara were infested by Azteca sp. Detailed crop loss assessments on four plantations in 1970–72 indicate that the overall loss of crop to this pest in Guyana in 1976 was about 3·7 million coconuts, valued at G$372 000. Damage is partly due to mealybug, Nipaecoccus nipae (Mask.), and scale insect, Aspidiotus destructor Sign., colonies maintained by the ants and may also be partly attributed to interference with pollinating insects. Chemical control with aldrin and dieldrin sprays applied to tree trunks to create insecticide barriers and applied to whole trees with a power-sprayer and extension lance did not give adequate long-term control. Baits based on minced bovine intestine with 2% v/w ethyl alcohol were therefore assessed in field trials. Aldrin at 0·3–2·4% a.i., nonachlor at 0·3–2·0% and mirex at 0·05–0·6% were tested. Bait containing 0·1% mirex gave best results with complete kill of ants' nests 60 days after application at about 5 kg bait/ha. Mealybug and scale infestations were also eliminated by this treatment with subsequent reductions of leaf-yellowing and increases of leaf number 100 days after treatment. Up to September 1976, 0·15% mirex bait had been used to control Azteca sp. on 200 ha of coconut palms in Guyana.
Migrations ofDysdercusspp. (Hemiptera: Pyrrhocoridae) related to movements of the Inter-Tropical Convergence Zone in West Africa
Authors: Duviard Dominique
Published: July 2009

The possibilities of migrations in the West African species ofDysdercusare discussed and a hypothesis of long-range migrations associated with the Inter-Tropioal Convergence Zone and its wind systems is proposed. Catches of adultDysdercusin four light-traps distributed from south to north of the Ivory Coast showed that the phenology of assumed migratory activity inD. voelkeriSchmidt differs with latitude and may be correlated with particular types of weather; stainer migrations taking place during the warm, wet and sunny part of the year. The whole life cycle of the insects as well as their flight activity occur under these climatic conditions, prevailing in a belt of 600–900 km width, situated immediately to the south of the Inter-Tropical Front. Colonisation of newly available habitats is thus only possible when climatic factors allow: (i), migratory flight activity and (ii), survival in the colonised area. A close examination of the timing of both migrations in the two main species,D. voelkeriandD. melanoderesKarsch, and of annual movements of the I.T.F. leads to the only logical hypothesis that the transportation of migrating insects is effected by atmospheric convergence, prevailing wind currents and air mass displacements.
The height and direction of flight of mosquitoes in West African savanna, in relation to wind speed and direction
Authors: Snow W. F.
Published: July 2009

The height and direction of mosquito flight related to wind speed and direction, in the absence of a host, was investigated in open savanna in The Gambia, West Africa. Non-directional suction traps (at heigts of 0·68, 2·13 and 3·15 m); directional flight traps facing four directions ar three levels (0·00–1·37 m, 1·45–2·82 m and 2·90–4·27 m) and directional suction traps facing two directions at three heights (0–1·2 m, 2·4–3·7 m nd 4·9–6·1 m) were used. Catches form the non-directional suction traps and pooled data from all flight traps at each level showed an inverse relationship between wind speed and the height of flight ofAnopheles melas(Theo.), of gravid females and of male mosquitoes. There was no indication of a similar relationship for theCulex decensTheo. group or forC. thalassiusTheo. The results from flight traps and directional suction traps showed that all mosquitoes were apparently flying upwind at all the levels investigaed. It is concluded that, although upwind flight probably does not occur naturally in the open at eights of more than 1 or 2 m, these experiments indicate that upwind flight could occur at higher levels, in the lee of tree and other obstacles.
A latex agglutination test for the identification of blood-meals ofCulicoides(Diptera: Ceratopogonidae)
Authors: Boorman J. , Mellor P. S. , Boreham P. F. L. , Hewett Rosemary S.
Published: July 2009

A latex agglutination test to identify the sources of blood-meals ofCulicoidesis described. The method requires the minimum amounts of reagents and apparatus and would be suitable for rapid tests under field conditions. Blood-meals ofCulicoides nubeculosus(Mg.) andC. variipennis(Coq.) from laboratory cultures, which had engorged on blood from several species of domestic animals, were differentiated without difficulty. In a series of ‘blind’ tests, the blood-meals of 49C. variipennisfrom seven species of domestic animal were identified with 100% accuracy. The differentiation of blood-meals from closely related hosts, such as mouse and guineapig or ox and sheep, is entirely dependent upon the specificity of the antisera conjugated to the latex. Blood-meals could be identified reliably for about 48 h after ingestion at 20–25°C, but at higher temperatures the reaction became less reliable after 24 h. Detergents commonly used in collecting midges had no effect on the latex agglutination test, but 0–01% mertbiolate, often used as a preservative, caused auto-agglutination and cannot be used when this test is to be applied.
Field trials of double translocation heterozygote males for genetic control ofAedes aegypti(L.) (Diptera: Culicidae)
Authors: Petersen J. L. , Lounibos L. P. , Lorimer Nancy
Published: July 2009

For nine weeks from 14 April to 13 June 1975 an average of over 500 double translocation heterozygote maleAedes aegypti(L.) were released daily into a village where the estimated adult mosquito population was 1200. The two purposes of this release were to suppress theA. aegyptipopulation by sterility induced by chromosomal translocations and to assess the effect of rainy season conditions on the population dynamics of the indigenous and released mosquitoes. As a result of the releases, hatchabirity of eggs from females collected during landing-biting catches dropped from over 93% to 30–40%. For eight weeks following the termination of the releases, hatchability remained below 70% while that of the reference village averaged between 80 and 99% hatch. A relative population decline observed in the release village is not attributed solely to the effect of the releases, partly because it occurred before sufficient time had elapsed to allow induced sterility to build up in the field population.
The relationship of Zonocerus variegatus (L.) (Acridoidea: Pyrgomorphidae) with cassava (Manihot esculenta)
Authors: Bernays E. A. , Chapman R. F. , Leather E. M. , McCaffery A. R. , Modder W. W. D.
Published: July 2009

Field and laboratory studies at Ibadan, Nigeria, showed that the young nymphs of Zonocerus variegatus (L.) normally reject cassava after biting it and die if they are confined on growing leaves. Later instars will eat cassava, especially when deprived of food for some time, but the adults progressively lose weight when restricted to feeding on growing cassava. On cut cassava, on the other hand, extensive feeding occurs and normal growth is maintained. The change from unpalatability to acceptability occurs within about an hour of cutting and is apparently associated with wilting. Cassava produces latex, but this was not distasteful to Zonocerus. The readiness to feed on growing cassava was associated with low levels of hydrogen cyanide production by the leaves; wilted leaves still produced hydrogen cyanide, but at a lower rate than turgid, growing leaves. In the area around Ibadan, Zonocerus regularly defoliates cassava in the latter part of the dry season, probably because a shortage of attractive foods forces the insect to eat cassava.
Descriptions and morphometrics of the nymphs of Zonocerus variegatus (L.) (Orthoptera: Acridoidea)
Authors: Chapman R. F. , Cook A. G. , Mitchell G. A. , Page W. W.
Published: July 2009

The nymphal instars of Zonocerus variegatus (L.) are described from insects collected near Ibadan, Nigeria. Most insects reared in the laboratory passed through six nymphal instars, although more had only five nymphal instars when reared in crowded conditions. The proportions with five or six instars were not altered by different food-plants. Femur length, head width and pronotal length of laboratory-reared insects were measured. The sizes were only slightly affected by food-plants; they fall into fairly discrete classes corresponding with each instar. The form of antennae, genitalia and wing pads in successive instars is also described. The early-instar nymphs are almost entirely black, with a few yellow markings. In later instars, the extent of the yellow increases. Field data from insects collected during the dry season can be interpreted on the basis of the laboratory studies and indicate that most insects in the field pass through six nymphal instars. More data are needed before nymphs collected in the wet season can be characterised with certainty.
Cumulative and sensitisation effects of repeated applications of methomyl to the housefly, Musca domestica L. (Diptera: Muscidae)
Authors: Gerolt P.
Published: July 2009

Repeated sublethal doses of methomyl and certain of its analogues have been found fully cumulative against adult Musca domestica L. Successive dose treatments were at least as effective as, and in many cases more effective than, a single dose treatment of equivalent amount. Treatment with sublethal doses of methomyl also enhanced the efficacy of insecticides of other chemical groups applied subsequently. The cumulative effect is not due to persistence of the compound in the tissues, to interference with the detoxification mechanism for the insecticides or to prolonged inhibition of acetylcholinesterase. Only a very tentative explanation can be suggested at present.
Effect of farming on population movements and acoustic behaviour of two bush crickets (Orthoptera: Tettigoniidae)
Authors: Samways M. J.
Published: July 2009

Mature, singing adults of the bush cricketsPlatycleis intermedia(Serv.) andP. affinisFieb. are normally separated in the field through differences in habitat preference. At some localities in southern France, nymphs and young adults of the two species occurred mixed together in herbaceous vegetation surrounding barley fields. Occasionally, there was acoustic interference between them, with modification of the song ofP. intermedia. This was overcome byP. intermediamoving into the bushes andP. affinisinto the barley. Cutting of the barley resulted in an invasion of theP. intermediahabitat byP. affinisso that there was further interspecific acoustic interference. Sheep grazing caused vegetation mosaics, which again created the conditions for acoustic interaction between the two species.
The distribution and migration of Spodoptera littoralis (Boisduval) (Lepi-doptera: Noctuidae), in relation to meteorology on Cyprus, interpreted from maps of pheromone trap samples
Authors: Campion D. G. , Bettany B. W. , McGinnigle J. B. , Taylor L. R.
Published: July 2009

A network of 51 pheromone traps was distributed throughout Cyprus for a period of seven months during 1972, and catches of males of Spodoptera littoralis (Boisd.) were recorded each day. The aim was to find whether Spodoptera adults were immigrating from elsewhere by mapping changes in their distribution and density in relation to current meteorological conditions, especially wind-flow patterns. No major immigration was demonstrated during the investigation period, even when favourable winds from neighbouring countries occurred at times when the insect was abundant. The major increases in catch in the island trap network were explained by population growth within the island, together with localised. movements away from areas of high population density.
Comparative studies on Tetrastichus hagenowii (Ratzeburg) and T. asthenogmus (Waterston), two primary parasites of cockroach oothecae, and on their hyperparasite Tetrastichus sp. (T. miser (Nees) group) (Hymenoptera: Eulophidae)
Authors: Narasimham A. Uma
Published: July 2009

Tetrastichus hagenowii (Ratz.) and T. asthenogmus (Wtstn.) are parasitic in cockroach oothecae and may themselves be attacked by a species of Tetrastichus of the group of T. miser (Nees). In Bangalore in 1976–79, the primary parasites were reared from oothecae of Periplaneta americana (L.), P. australasiae (F.) and P. brunnea Burm., and laboratory colonies of them were established on oothecae of P. americana. The hyperparasite, reared from field-collected oothecae of Periplaneta spp., was bred in the laboratory on oothecae of P. americana containing larvae of T. hagenowü. The immature stages of the three species of parasites were compared and their biologies studied. The eggs of the three species can be differentiated on the basis of their shape as can the pupae, but the larvae of the two primary parasites are indistinguishable. The duration of the developmental stages of the three species overlapped but the hyperparasite had a slightly shorter pupal period. Host finding by the T. hagenowii female was investigated. The two primary parasites were similar in most of their biological attributes. However, T. asthenogmus was inherently superior to the Bangalore strain of T. hagenowii in having lower levels of female sterility and its greater preference for the oothecae of P. brunnea, the predominant species of cockroach in Bangalore. T. hagenowii proved to be more tolerent of low temperatures than T. asthenogmus. The hyperparasite had an advantage over the other two species in possessing longer life-span and synovigenic females, and individual females parasitised more oothecae in their life-span than the primary parasites; but it was unable to distinguish healthy oothecae from those containing larvae of the other two species until it had drilled into them.
Studies of elemental composition as a biological marker in insects. I. The influence of soil type and host-plant on elemental composition of Noctua pronuba (L). (Lepidoptera: Noctuidae)
Authors: Bowden J. , Digby P. G. N. , Sherlock P. L.
Published: July 2009

Wavelength dispersive X-ray fluorescence spectrometry was used to make quantitative determinations of the elemental composition of adults of Noctua pronuba (L.) that had been reared on eight soil-plant combinations and a semi-synthetic diet. There were two host-plants, beans and lettuce, each grown in two clay soils of different acidity, a sand and a commercial potting compost. Analyses were done for fifteen elements: K, P, S, Mg, Ca, Cl, Zn, Si, Al, Fe, Cu, Mn, Ni, Cr and Ti. Two groups of elements were distinguished; the first six, or major elements, each with an average content about equal to or more than 1000 μg/g, and the last nine, or minor elements, each with an average content of <1000 μg/g. The second group was subdivided into four, Zn, Si, Al, Fe, each with an average content of >100 μg/g and four, Cu, Mn, Ni, Cr, of <100 μg/g; Ti was of erratic occurrence and was excluded from most statistical analyses. When all elements in all soil-plant combinations were considered, principal components analyses showed no distinction between insects reared on any soil-plant combination, probably because of interactions between host-plants and soils. When data were grouped into two host-plant subsets and only the major elements were analysed, soils were separable within each host-plant subset. In each case, the two clay soils were clearly separable from the other two soils but not from each other. In both host-plant subsets, sexes were distinguishable by a consistently higher K content in males. No clear separations were evident in either host-plant subset when all eight minor elements were considered or when these were separated into two further groups. This work indicates that (i) characteristic elemental compositions, or chemoprints, are present in N. pronuba; (ii) choice, not necessarily number, of elements is likely to be critical in describing and interpreting chemoprints; (iii) chemoprinting is unlikely to enable sources of populations to be identified in polyphagous species like N. pronuba; and (iv) the environmentally linked variation in chemical composition, affecting biologically essential elements, may have important consequences in the population dynamics of migratory and parthenogenetic species.
Esterase activity and associated insecticide resistance in the damson-hop aphid,Phorodon humuli(Schrank) (Hemiptera: Aphididae)
Authors: Lewis G. A. , Madge D. S.
Published: July 2009

Phorodon humuli(Schr.) was obtained from both wild and cultivated hop plants, cultured, and bioassayed using seven different foliar spray insecticides, and the results were assesssed by probit analysis to determine LC50s and LC95s. The wild aphids and their progeny were highly susceptible to the insecticides, whereas those from cultivated hops were generally resistant to them. The level of resistance was related to the source of the original aphid population and the insecticide used. Clones of insecticide-resistant and susceptible aphids were maintained under identical conditions, and individual adult apterae were assayed for total esterase and esterase isoenzyme activities. Total esterase activity was appreciably higher in resistant aphids than in susceptible ones. Resistant aphids were associated with high esterase isoenzyme activity of complex bands II–V, while in susceptible aphids these bands were virtually missing. An insecticide-resistant clone ofP. humuliwas selected for low esterase activity and a susceptible clone was selected for high esterase activity, over eight generations. Selection pressure was then reversed for a further eight generations. The resistant clone lost its esterase activity by generation six and it remained low thereafter, whereas that of the control stock remained high. By contrast, the esterase activity of the susceptible clone remained unaltered by selection. The resistant clone also lost its resistance to both methomyl and methidathion.
The attraction of Zonocerus variegatus (L.) (Orthoptera: Pyrgomorphidae) to the weed Chromolaena odorata and associated feeding behaviour
Authors: Modder W. W. D.
Published: July 2009

In studies in Nigeria, all instars of Zonocerus variegatus (L.) were found to be strongly attracted to flowers of the common exotic composite weed Chromolaena odorata. Experiments in the field and with caged nymphs suggested that the attraction is due to a volatile compound(s) concentrated in the conspicuous stigmas and released when the buds open. Although very palatable, the flowers seemed inadequate as food, and most of the nymphs roosting on C. odorata even during the flowering season had fed on leaves of C. odorata or other plants. Feeding diminished the attraction to the inflorescences in experimental cages, and of the field nymphs attracted between 11.00 and 15.00 h, a significantly higher proportion than on other plants had relatively empty foreguts. The numbers of field nymphs attracted were maximal at 08.00–10.00h and minimal at 11.00–12.00 h. Both in the cages and in the field, interest in the inflorescences diminished after about 17.00 h, when the highest points within reach are being looked for as roosting sites. Reduction of C. odorata around plantations is unlikely to lessen crop damage by Z. variegatus, but insecticides for Z. variegatus control could be applied conveniently to the tops of C. odorata at roosting time during the flowering season.
The seasonal biology ofSitona discoideusGyllenhal (Coleoptera: Curculionidae), an introduced pest of New Zealand lucerne
Authors: Goldson S. L. , Frampton E. R. , Barratt B. I. P. , Ferguson C. M.
Published: July 2009

Sitona discoideusGylh., an introduced pest of lucerne in New Zealand, exhibits univoltine, aestivatory seasonality in Canterbury and Otago, with each generation appearing in late December. Some two weeks after the December emergence of adults, flights to aestivation sites commenced. These sites were commonly remote from the lucerne stands and included such places as under stones or at the base of trees, fence posts, etc. At the commencement of aestivation, the indirect flight muscles atrophied rapidly, only to redevelop some 6–8 weeks later when autumnal post-aestivatory return flights to lucerne began. During the winter,S. discoideusfed on lucerne foliage and became reproductively mature. By October, age-related adult mortality had begun, and for about two weeks in December no adult weevils were present at all in one Canterbury site. In Otago, there was a distinct generation overlap of 2–3 weeks. The eclosion of new generation weevils was closely synchronised; it is suggested that this may have been the product of differential egg development and egg-laying temperature thresholds and a high fourth instar and pupal develoment threshold. Synchronised emergence of adults tended to accentuate the problem of defoliation caused by their feeding.
An infra-red remote sensing system for the active detection and automatic determination of insect flight trajectories (IRADIT)
Authors: Schaefer G. W. , Bent G. A.
Published: July 2009

A non-technical description is given of a new, powerful, low cost field system (Infra-red Active Determination of Insect Flight Trajectories or IRADIT) for detailed and automatic remote sensing studies of natural insect flight behaviour. The special requirements and difficulties of the detection problem are defined. A series of examples of field devices and techniques are presented to illustrate the key factors of the optical sensing and tracking of insects in flight. In the finally adopted IRADIT system, flying insects are differentially illuminated, under all natural light conditions, by an intense beam of pulsed near-infra-red radiation and detected using a shuttered image intensifier linked with a video camera operating at a rate of 50 frames per second. Immediate fully-automatic determination of the flight trajectories of several simultaneously detected insects was achieved, at this same high rate and in the presence of sky background photon noise, by processing the video signals with electronic circuits and a microcomputer. Flight trajectories are influenced by the local wind, whose vector must be subtracted to study insect flight behaviour. This was achieved by the use of a specially developed sensitive three-vector vane anemometer, providing digital data to the microcomputer at a minimum rate of 5 Hz. In tests of the prototype IRADIT-anemometer system in the field, insects with wing area of only 1·5 mm2 and flying against the midday sky were readily tracked at ranges up to 15 m. A range of at least 100 m is expected for nocturnal moth tracking.
Latitudinal and seasonal changes of nocturnal illumination with a hypothesis about their effect on catches of insects in light-traps
Authors: Bowden John
Published: July 2009

An account is given of changes in nocturnal illumination at the spring and autumn equinoxes and summer and winter solstices at latitudes between 50 and 60°N. A Relative Trap Index (RTI) was devised to describe changes in light-trap effectiveness and used to adjust catches of Noctuidae and Geometridae for change in trap effectiveness caused by seasonal and latitudinal change in nocturnal illumination at latitudes between 50 and 58°N. When so adjusted, catches were frequently larger in northern than in southern latitudes, not smaller as unadjusted catches show. It is clear that unless light-trap catches are adjusted to allow for changes of illumination, comparisons over time and space, particularly those which involve assumptions about sample constancy, are suspect. Because of the large differences in RTI that may exist between northern and southern traps, particularly in summer and between the summer solstice and other times, it may be necessary to use different light sources at different times of year to maintain a consistent trap sample.
Sex ratio distortion inGlossina morsitans submorsitansNewstead (Diptera: Glossinidae)
Authors: Rawlings P. , Maudlin I.
Published: July 2009

A laboratory colony ofGlossina morsitans submorsitansNewst. originating from Nigeria exhibits an excess of females over males. The sex ratio distortion of more than two females to one male was studied by the maintenance of individual flies. Five males sired more than ten daughters without producing any sons when mated to several females, whilst other males fathered approximately equal numbers of male and female offspring; there was no evidence for selective abortion of male embryos. The presence of these ‘distorter’ males, which produce only female offspring, was found to cause the sex ratio distortion. The results are discussed with reference to data from the field which indicate that this genetic aberration is not confined to the laboratory; possible implications for chemical control programmes are assessed.
Genetic studies of malathion resistance in Anopheles arabiensis Patton (Diptera: Culicidae)
Authors: Lines J. D. , Ahmed M. A. E. , Curtis C. F.
Published: July 2009

Crosses of Sudanese strains of Anopheles arabiensis Patt. resistant and susceptible to malathion indicated that the resistance was incompletely dominant. The results of tests of male progeny of successive backcrosses agreed well with the hypothesis of control of the resistance by a single gene. However, the results from females suggested the additional involvement of a sex-limited modifier. Tests of mixtures initiated with a 1:1 ratio of resistant and susceptible first-instar larvae gave little evidence for selective mortality during the larval stage. However, the mortalities in tests on malathion recorded among adults emerging on successive days from these mixtures, and also from F2 and backcross progenies, indicated that the development of the resistant larvae was significantly faster than that of the susceptible ones. The fact that this occurred in the F2 and backcross progenies indicates that it may be due to a pleiotropic effect of the resistance gene, but it is pointed out that results from much more prolonged backcrossing would be necessary to rule out the possible effects of linked genes.
Comparative biology of some Cicadulina species and populations from various climatic zones in Nigeria (Hemiptera: Cicadellidae)
Authors: Okoth V. A. O. , Dabrowski Z. T. , Emden H. F. Van
Published: July 2009

Significant differences in nymphal development period and fecundity were observed between five populations of Cicadulina mbila (Naudé) and C. triangula Ruppel from three climatic zones in Nigeria: rain forest (Ibadan), southern part of Sudan savanna (Kadawa, Kano) and the Jos Plateau. The C. triangula population that is used in mass rearing for resistance screening at the International Institute of Tropical Agriculture (IITA), Ibadan, developed much more rapidly than the wild C. triangula population from Ibadan. Similarly, the C. mbila population from the Kadawa Irrigation Scheme, Kano, developed more rapidly than the population from the Jos Plateau. All Cicadulina populations were 3–4 times as prolific on pearl millet as on maize, sorghum or the grass Digitaria exilis. The IITA colony of C. triangula was significantly more fecund than C. mbila. It is clear that Cicadulina species and populations with high reproductive potential would be most suitable for mass rearing for resistance screening to the maize streak virus disease.
An automatic sticky trap for aphids (Hemiptera: Aphididae) that segregates the catch daily
Authors: Rohitha B. H. , Stevenson B. E.
Published: July 2009

An automatic sticky trap for aphids which segregates each day's catch is described. The trap is driven by a mechanical clock which operates for seven days. Each day, a yellow-coloured drum covered with a sticky coated transparent cellulose acetate sheet is automatically exposed and the one for the previous day stored in a holding cylinder.
The effect of larval phase on flight performance of African armyworm moths, Spodoptera exempta (Walker) (Lepidoptera: Noctuidae)
Authors: Woodrow K. P. , Gatehouse A. G. , Davies D. A.
Published: July 2009

The characteristics of the high and low density forms of noctuid moths, including Spodoptera exempta (Walker), exhibiting a density-dependent phase polyphenism have frequently been discussed in relation to migration. However, the only previous (unpublished) demonstration of an effect of larval phase on adult flight performance, using a tethered-flight technique, was invalidated by the recent discovery that the principal determinant of flight potential in S. exempta is genetic. When the incidence of prolonged flight was measured in moths derived from genetically-matched (full-sib) samples, there was a clear increase in long flights by females derived from the high-density gregaria phase larvae compared with those from solitaria phase larvae. The reasons for the apparent absence of a similar effect in males is not clear, but it is possible that the tethered-flight technique provides a less reliable index of flight capacity in this sex. The characteristics and significance of phase polyphenism in migratory noctuids are discussed. It is suggested that, in S. exempta and possibly some other comparable species, the high-density phase is adapted to accelerate re-dispersal after populations become concentrated, in order to escape the detrimental consequences of high larval densities.
Studies on low temperature survival, reproduction and development in scottish clones of Myzus persicae (Sulzer) and Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae) susceptible and resistant to organophosphates
Authors: Pozarowska Barbara J.
Published: July 2009

Investigation of 16 Scottish clones of Myzus persicae (Sulzer) and four of Aulacorthum solani (Kaltenbach) indicated that anholo-and androcyclic clones were predominant. A high incidence of organophosphorus resistance was found in androcyclic clones of M. persicae, but there was no indication of such resistance in A. solani. At 5°C as compared to 20°C, reproduction was decreased and development of nymphs was slower in both species. In addition, the pre-reproductive period and nymphal development time of A. solani were longer than those of M. persicae. Clonal differences in M. persicae at 5°C could not be related to origin, annual cycle or level of organophosphorus resistance, however A. solani clones from the west of Scotland may have been less affected by this temperature than those from the east. The lower limit of reproduction and development in both species was near 2°C. Neither adult survival nor fecundity of clones at this temperature were related to annual cycle, origin or organophosphorus resistance, but anholocyclic M. persicae nymphs survived longer at 2°C than holo- or androcyclic nymphs. A. solani adults survived significantly longer than those of M. persicae. M. persicae survived sub-zero temperatures better than A. solani. In neither species could percentage survival be related to stage of development, gut contents, presence or absence of wings, annual cycle, origin or organophosphorus resistance. Acclimation did, however, increase percentage survival.
The migration of Nilaparvata lugens (stål) (delphacidae) and other hemiptera associated with rice during the dry season in the Philippines: a study using radar, visual observations, aerial netting and ground trapping
Authors: Riley J. R. , Reynolds D. R. , Farrow R. A.
Published: July 2009

The migratory flight behaviour of Nilaparvata lugens (Stål), other delphacid and cicadellid pests of rice and some of their heteropteran predators was investigated during the dry-season crop in an irrigated rice-growing area of the Philippines. A combination of radar (including an X-band and a newly-developed Q-band system (8 mm wavelength)), aerial netting, ground trapping and visual observations was used to determine diel changes in aerial density and composition of arthropods in flight over the study site. The most abundant migrant caught in the aerial nets was Cyrtorhinus lividipennis Reuter (a mirid predator of N. lugens), with Nephotettix spp. and Nilaparvata lugens the next most abundant species. Flight activity in all migrants was found to be very largely confined to periods of about 30 min at dusk and dawn, with minimal activity at other times of the day and night. Migration distance in the dusk flight was generally limited to 6–30 km, depending on wind speed, and the dawn migration covered shorter distances due to the lighter winds. Small numbers of rice cicadellids and delphacids including N. lugens were occasionally detected later in the night, and these may have had the potential to migrate longer distances.