bluuebunny/crossref_metadata_2025 huggingface dataset:
Sex pheromones of Phyllonorycter acerifoliella and Ph. heegerella and communication peculiarities in three species of leafmining moths
Authors: Mozūraitis R. , Būda V. , Jonušaite V. , Borg‐Karlson A.‐K. , Noreika R.
Published: October 2003

Females of the leaf miner moth Phyllonorycter acerifoliella (Z.) [=Ph. sylvella (Hw.)] and Ph. heegerella (Z.) (Lepidoptera: Gracillariidae: Lithocolletinae) release their sex pheromone at the beginning of photophase. The periodicity of the ‘calling’ behaviour of Ph. acerifoliella females was established. Three compounds from calling virgin Ph. heegerella females were collected by the Solid Phase Micro Extraction (SPME) technique and identified as (Z)‐8‐tetradecenyl acetate (Z8‐14:OAc), tetradecyl acetate (14:OAc) and (Z)‐8‐tetradecenol (Z8‐14:OH) in the ratio (88±3):(2±0.6):(10±5) by capillary gas chromatography and mass spectrometry. Field trapping experiments demonstrated that the first two compounds are important for the attraction of conspecific males. Z8‐14:OAc was found to be attractive when tested separately, while 14:OAc acted as synergist. The attractivity of the three component blend was reduced by 10% admixture of either (E)‐10‐dodecenyl acetate (E10‐12:OAc) or (Z)‐10‐tetradecenyl acetate (Z10‐14:OAc).

Field tests of Z10‐, Z8‐ and E10‐14:OAc, identified from Ph. acerifoliella females, demonstrated that the first two compounds were essential for the attraction of conspecific males; so both are sex pheromone components. The attractivity of the three component blend of Z10‐ Z8‐ and E10‐14:OAc was reduced by 10% admixture of (E)‐10‐dodecenol (E10‐12:OH). The following four semiochemical compounds, Z8‐14:OAc, Z8‐14:OH, E10‐14:OAc and 14:OAc, identified from phyllonoryctid females, as well as two sex attraction antagonists for Ph. acerifoliella and Ph. heegerella males, E10‐12:OAc and Z10‐14:OAc, are new for the family Gracillariidae. The results of field trapping experiments revealed mechanisms ensuring the specificity of the chemocommunication systems in Ph. acerifoliella, Ph. heegerella and Ph. ulmifoliella (Hb.) moths.
Hunting strategy of a generalist ant species proposed as a biological control agent against termites
Authors: Kenne Martin , Schatz Bertrand , Durand Jean‐Luc , Dejean Alain
Published: October 2003

We studied the hunting behaviour of Myrmicaria opaciventris (Hymenoptera: Formicidae) in order to evaluate if it can be used as a biological control agent against the termites that damage sugarcane plantations. Hunting workers foraged in groups and recruited nestmates at short‐range when they encountered large termite soldiers or groups of small termite workers. Differences in prey capture concerned the: (1) means of detection (from a distance or by contact); (2) termite body part seized (small termites seized by the body; large termites by an appendage); (3) percentages of prey abandoned; and (4) use of venom. The sting of the workers is spatulated implying a topical application of the venom on the prey. Large termites were stretched by several workers whose adherence to the substrate is facilitated by well‐developed arolia and claws on the legs while others spread venom on the body and carved it up. An adaptation to termite capture was noted with a distribution of tasks between the workers which subdued prey, and those which transported it. In the former case, the workers easily eliminated termite soldiers, successively attacked several termite workers and even captured new individuals while holding the first ones captured between their mandibles before retrieving them all at once. The remaining individuals were retrieved by the transporting workers. Given this particularly effective predatory strategy, we concluded that, under certain conditions, M. opaciventris can be used as a biological control agent against termites.
Fecundity and fertility reductions in adult leafrollers exposed to surfaces treated with the ecdysteroid agonists tebufenozide and methoxyfenozide
Authors: Sun X. , Barrett B.A. , Biddinger D.J.
Published: October 2003

The effects on the fecundity and fertility of redbanded leafroller, Argyrotaenia velutinana (Walker), and obliquebanded leafroller,Choristoneura rosaceana (Harris), exposed as adults to surfaces treated with the ecdysone agonists tebufenozide (RH‐5992) and methoxyfenozide (RH‐2485) were examined. The first part of the study consisted of recently emerged moths being exposed to treated surfaces continuously throughout their lives (including mating and oviposition). Continuous exposure to tebufenozide‐ or methoxyfenozide‐treated surfaces significantly reduced the mean number of eggs laid and the percent of eggs that hatched in both species. The second part of the study involved exposure of recently emerged virgin moths (by sex) to treated surfaces for 24 h, after which, the exposed moths were paired with a nontreated partner to mate and oviposit on nontreated surfaces. In this experiment, for A. velutinana, significant reductions in fecundity occurred only when the female was exposed to methoxyfenozide‐treated surfaces. Significant reductions in A. velutinana egg fertility occurred with both male and female exposure in the methoxyfenozide treatments and only female exposure in the tebufenozide treatments. For C. rosaceana, significant reductions in fecundity occurred with both male and female exposure in the tebufenozide and methoxyfenozide treatments. Significant reductions in C. rosaceana egg fertility occurred with both male and female exposure in the tebufenozide treatments and only with female exposure in the methoxyfenozide treatments.
Injection of essential amino acids substitutes for bacterial supply in aposymbiotic pea aphids (Acyrthosiphon pisum)
Authors: Wilkinson T.L. , Ishikawa H.
Published: October 2003

The symbiotic bacteria Buchnera contribute to the nutrition of pea aphids, Acyrthosiphon pisum, through the provision of essential amino acids which are lacking in the diet. However, chemically defined diets, containing nutritionally adequate amounts of essential amino acids, fail to rescue aposymbiotic aphids, in which the bacteria have been disrupted with antibiotics. In this study the injection of a mixture of essential amino acids into the haemocoel of aposymbiotic aphids was shown to alleviate, at least partially, the impact of symbiont loss. Specifically, the total amino acid content in the tissues of aposymbiotic aphids was reduced by approximately 40% to levels comparable with symbiotic insects, and there was a 1.7‐fold increase in the number of embryos, suggesting that the availability of essential amino acids promotes aphid protein synthesis by rejuvenating the free amino acid pool of aposymbiotic aphids. In addition, a similar effect on the total amino acid content was observed when phenylalanine alone, but not glutamine, lysine or tryptophan, was injected into the haemocoel of aposymbiotic aphids, and there was also a significant increase in the number of embryos following injection of phenylalanine or tryptophan alone. The impact of amino acid injection on the embryo complement of aposymbiotic aphids was limited to an increase in the number of embryos, with no increase in basal embryo size. It is proposed that older embryos may rely on their own complement of symbiotic bacteria for essential amino acid provisioning. Taken together, the data highlight the importance of bacterial provisioning of essential amino acids, particularly the aromatic amino acids, in the intact symbiosis.
The biology of two Eretmocerus spp. (Haldeman) and three Encarsia spp. Forster and their potential as biological control agents of Bemisia tabaci biotype B in Australia
Authors: De Barro P.J. , Hart P.J. , Morton R.
Published: October 2003

The performance, as measured by daily rate of parasitism and total parasitism, of five aphelinid species found in Australia parasitising Bemisia tabaci were compared on cotton, hibiscus, rockmelon, soybean and tomato. Two Eretmocerus spp., both indigenous to Australia, gave the highest levels of parasitism on each of the plant host species tested. The tritrophic interactions between B. tabaci, host plant species and Eret. mundus (Australian parthenogenetic form) (APF) were also examined. In general, more whiteflies were parasitised when cotton was the source host or rockmelon the test host. Parasitism was always low when tomato was either the source or test host. When parasitoids were transferred from rockmelon to cotton, parasitism declined. In contrast, parasitism increased when parasitoids were transferred from cotton to rockmelon. Parasitism also increased when parasitoids were transferred from soybean to rockmelon, yet failed to do so when shifted from soybean to cotton despite cotton normally being a better host. However, when parasitoids were transferred from cotton to soybean there was a marked increase in parasitism. Possible causes are discussed. The field cage trial demonstrated that parasitism by both Eretmocerus spp. increased with increasing whitefly density. Further, the increase in parasitism was not due to the presence of more parasitoids as neither the parasitoid‐whitefly ratio nor the total number of parasitoids present had a significant effect on parasitism. The combination of the two species, gave similar levels of parasitism to that achieved by Eret. mundus (APF) alone. Subsequent identification of the emerged individuals indicated that over 50% of the parasitism was due to this species suggesting that it out‐competed Eret. queenslandensis. Despite this competition, there was no evidence that overall control was compromised.
Oviposition site selection of Episyrphus balteatus
Authors: Scholz D. , Poehling H.‐M.
Published: October 2003

The oviposition behaviour of Episyrphus balteatus DeGeer (Diptera: Syrphidae) was investigated in four‐choice experiments in screen cages and in experiments with direct behavioural observations. Females laid hardly any eggs in the absence of aphids and preferred larger aphid colonies to small ones. Honeydew attracted the females via olfaction and elicited oviposition. Females were able to perceive the presence of conspecific eggs and oviposited less often in aphid colonies in which eggs were present. The oviposition deterring stimulus was also active when the eggs were removed, hence, the deterrent did not act visually, but probably olfactorily.
Effects of undersown clover on host‐plant selection by Thrips tabaci adults in leek
Authors: den Belder E. , Elderson J. , Vereijken P.F.G.
Published: October 2003

The suppressive effects of undersown clover on Thrips tabaci Lindeman infestation in leek is known but not the stages in thrips population dynamics that are affected by intercropping and the mechanisms involved. Colonization or settling of adult onion thrips (T. tabaci) in monocropped leek (Allium porrum L.) and in leek intercropped with strawberry clover (Trifolium fragiferum L.) was studied in two potted plant experiments. Potted leek plants with and without undersown clover were placed for a short period (2 and 5 days) in monocropped or intercropped field plots when high thrips infestation was expected. Thrips adults were counted on all leaves and in the shaft during this observation period. Thrips populations were monitored weekly in the field plots throughout the entire growing season.

In both potted plant experiments, there were consistently fewer thrips adults on intercropped leek plants than on monocropped plants. The plant growth parameters – number of leaves and stem diameter – were similar in all treatments and thus did not explain differences in thrips adults. Natural enemies were absent on both leek and clover, and thus cannot explain the differences in adult thrips numbers. Furthermore, no adults of T. tabaci were found on the clover in the potted plant experiment and only very few in the field experiment. Thus it was concluded that strawberry clover was not an effective trap crop for thrips.

In the second potted plant experiment, clover was removed just before the leek plants were introduced to the field, thus eliminating direct physical, visual and olfactory interference by clover. After the undersown clover was removed, the leek plants harboured only one‐third of the number of thrips adults, as compared to the monocropped plants. This study supports the notion that there are subtle links between intercropping and plant quality, and indicates that host‐plant quality is an underlying cause of the reduction in adult thrips numbers in leek/clover intercropping.
Behavioural responses of Oryzaephilus surinamensis, Tribolium castaneum and Tribolium confusum to naturally and artificially damaged durum wheat kernels
Authors: Trematerra P. , Sciarreta A. , Tamasi E.
Published: October 2003

Observations on behavioural activity involved in the host selection by secondary pests of stored grains, Oryzaephilus surinamensis (Linnaeus), Tribolium castaneum (Herbst) and Tribolium confusum J. du Val, with respect to intact and mechanically or naturally damaged kernels are reported. Our results indicate that the attraction of secondary pests is facilitated by broken grain kernels, which resulted from either mechanical damage during harvesting and/or binning procedures, or the feeding activity of primary insect pests. Insect damaged kernels were more attractive to O. surinamensis, T. castaneum and T. confusum than whole kernels; in addition insect damaged kernels elicit more attractiveness than mechanically split kernels. The damage caused by primary pests, such as Rhyzopertha dominica (Fabricius) and Sitophilus oryzae (Linnaeus), on whole kernels may facilitate colonization by secondary pests, which continue damaging the cereals. O. surinamensis, T. castaneum and T. confusum utilize the grain volatile odours to distinguish whether the grain kernels of the stored cereals are damaged mechanically or by insects.
Diapause and polyphenism of life‐history of Lagria hirta
Authors: Zhou Hong‐Zhang , Topp Werner
Published: October 2003

This paper is focused on diapause and polyphenism of development of Lagria hirta L. and tries to unravel its mechanism of life‐history adaptation. Lagria hirta, distributed widely in Europe, has a strictly univoltine life cycle. The results showed that larval diapause and moulting polymorphism were the deciding factors that made L. hirta maintain its univoltinism and keep a flexible relation between seasonal changes and life‐history phases. In the laboratory, larvae of this species were not able to pupate if kept at constant temperatures of 5 °, 10 °, 15 °, 20 °, 25 ° or 30 °C combined with a photoperiod of either LD (L16:D8) or SD (L8:L16). Pupation only occurred if larvae were reared at 15 °–25 °C when intervened by a three‐month chilling at 5 °C in stages L3, L4, L5 or L6. A chilling treatment was shown to be obligatory for the termination of its larval diapause and had an accelerating and synchronizing effect on larval development. Larval diapause of L. hirta was characterized by no pupation and more moulting in advanced instars, longer duration of each single stage, and moulting desynchronization. Larval development was found to be variable with respect to the total number of instars: most larvae underwent a total of seven or eight moults; some larvae might even moult once or twice more, but they seldom pupated. It seemed that the choice for the 7‐instar or the 8‐instar development did not directly relate to any of the external conditions, such as temperature, photoperiod, and stages with chilling treatment. This polyphenism was observed in the same group under identical conditions and even in a single egg clutch. In L. hirta, overwintering in different stages of L3–L6, and choosing the 7‐ or 8‐instar pathway of development are two features that increase the plasticity and flexibility in coordinating its life cycle with seasonal change, that varies unpredictably from year to year.
Attract and kill: a new method for control of the codling moth Cydia pomonella
Authors: Charmillot P.‐J. , Hofer D. , Pasquier D.
Published: October 2003

The attract and kill technique has been formulated in a product under the trade name ‘Sirene CM®’. It consists of a viscous paste containing 0.16% codlemone to attract the male moths and 6.0% permethrin to kill them. The formulation is applied by hand twice per season using a specially developed system which can be calibrated for application of the paste to the host plant in small droplets of either 100 μl or 50 μl. Between 1995 and 1997, 15 trials on control of the codling moth were conducted in isolated orchards in the Lake Geneva region. In each plot, depending on tree size, two applications varying between 52 and 537 g ha−1 of Sirene CM were made. In 14 trials, the larval attack of the codling moth on fruit was below the economic threshold of 1% and the hibernating population stayed at a low level. One single plot (0.4 ha) had to be treated with a curative spray in 1995, because the initial population was much too high. According to the reductions in trap catch and of mating frequency measured by tethered codling moth females, efficiency of the attract and kill droplets lasted 5–7 weeks, after which it decreased slowly.
Physical and chemical cues influencing the oviposition behaviour of Aphidius ervi
Authors: Battaglia Donatella , Poppy Guy , Powell Wilf , Romano Antonio , Tranfaglia Antonio , Pennacchio Francesco
Published: October 2003

The oviposition behaviour of the aphid parasitoid Aphidius ervi Haliday is influenced by both chemical and physical cues. Oviposition attack responses were elicited by paint pigments sealed into the tip of a glass capillary tube. Parasitoids reacted to yellow pigments with repeated oviposition attack responses, but they did not react to green pigments. The spectrum of reflected light from the yellow pigments was very similar to that from the ‘green’ natural host Acyrthosiphon pisum (Harris), with a high proportion of the total radiation energy being emitted in the yellow‐orange wavebands (580–660 nm). Pea aphid cornicle secretion also elicited oviposition attack responses, which were not exclusively induced by its pale yellow‐green colour. In fact, the oviposition attack response to capillary tips coated with cornicle secretion remained evident under red light conditions, which, in contrast, nearly completely suppressed the response to yellow pigments. Chemical compounds from cornicle secretion do not appear to be involved in parasitoid orientation, even though they stimulate intense oviposition attack responses. Olfactometer experiments showed that the putative kairomone involved acts only at very short range or on contact. Host exuviae, which also elicited strong and persistent oviposition reactions from A. ervi females, appear to be a good alternative source of ovipositional kairomone(s). This work confirms the existence of an aphid cuticular kairomone.
Application of synthetic sex pheromone for management of diamondback moth, Plutella xylostella, in cabbage
Authors: Schroeder P.C. , Shelton A.M. , Ferguson C.S. , Hoffmann M.P. , Petzoldt C.H.
Published: October 2003

Over a 2‐year period field trials were conducted to assess the potential to disrupt mating ofPlutella xylostella (L.) using a commercial rope formulation of a 70:30 mixture of (Z)‐11‐hexadecenal and (Z)‐11‐hexadecenyl acetate, two components of the sex pheromone of the female. Screened field cages were placed into blocks of cabbage which were either treated with the pheromone or left untreated. Different densities of P. xylostella pupae were placed into each cage and then larval and pupal counts were made of the subsequent generation. In addition, sentinel females at mating stations were placed in each cage to assess the influence of the pheromone on the ability of males to locate and mate with females. Likewise, we used pheromone traps to assess whether the pheromone treatment influenced the ability of males to locate a pheromone source. In both years larval and pupal populations, produced as a result of the original inoculation, did not differ between pheromone‐treated and untreated fields. The effect of pheromone treatment on larval and pupal numbers did not change with changes in inoculated P. xylostella density, however, the density of P. xylostella released caused significant differences in the density of the subsequent generation. No significant differences were detected between the number of sentinel female adult P. xylostella that successfully mated in pheromone‐treated fields compared with untreated fields. Significant differences in the numbers of male P. xylostella caught in pheromone‐baited traps occurred between pheromone‐treated and untreated fields in the first trial of 1993, and in the first trial in 1994 but not in the second trial. Such differences are often thought of as indications of mating disruption, although our other data presented in this study and reports from other studies indicate this is not always the case. Previous studies on mating disruption of P. xylostella in larger scale field tests have been performed but the results have been variable and often ambiguous. Overall, our results indicate that mating disruption of P. xylostella with the present technology does not appear to work even under the very controlled situations which we utilized to eliminate insect movement between plots.
Synergism of imidacloprid and entomopathogenic nematodes against white grubs: the mechanism
Authors: Koppenhöfer Albrecht M. , Grewal Parwinder S. , Kaya Harry K.
Published: October 2003

Entomopathogenic nematodes and the chloronicotinyl insecticide, imidacloprid, interact synergistically on the mortality of third‐instar white grubs (Coleoptera: Scarabaeidae). The degree of interaction, however, varies with nematode species, being synergistic for Steinernema glaseri (Steiner) and Heterorhabditis bacteriophora Poinar, but only additive for Steinernema kushidai Mamiya. The mechanism of the interaction between imidacloprid and these three entomopathogenic nematodes was studied in the laboratory. In vials with soil and grass, mortality, speed of kill, and nematode establishment were negatively affected by imidacloprid with S. kushidai but positively affected with S. glaseri and H. bacteriophora. In all other experiments, imidacloprid had a similar effect for all three nematode species on various factors important for the successful nematode infection in white grubs. Nematode attraction to grubs was not affected by imidacloprid treatment of the grubs. Establishment of intra‐hemocoelically injected nematodes was always higher in imidacloprid‐treated grubs but the differences were small and in most cases not significant. The major factor responsible for synergistic interactions between imidacloprid and entomopathogenic nematodes appears to be the general disruption of normal nerve function due to imidacloprid resulting in drastically reduced activity of the grubs. This sluggishness facilitates host attachment of infective juvenile nematodes. Grooming and evasive behavior in response to nematode attack was also reduced in imidacloprid‐treated grubs. The degree to which different white grub species responded to entomopathogenic nematode attack varied considerably. Untreated Popillia japonica Newman (Coleoptera: Scarabaeidae) grubs were the most responsive to nematode attack among the species tested. Untreated Cyclocephala borealis Arrow (Coleoptera: Scarabaeidae) grubs showed a weaker grooming and no evasion response, and untreated C. hirta LeConte (Coleoptera: Scarabaeidae) grubs showed no significant response. Chewing/biting behavior was significantly increased in the presence of nematodes in untreated P. japonica and C. borealis but not in C. hirta and imidacloprid‐treated P. japonica and C. borealis. Our observations, however, did not provide an explanation for the lack of synergism between imidacloprid and S. kushidai.
Surface films as mosquito larvicides: partitioning the mode of action
Authors: Corbet Sarah A. , Tiley Catherine , Moorhouse Tom , Giam Colin , Pursglove Stephanie , Raby Joanne , Rich Merynne
Published: October 2003

Oils and other surface films used against mosquito larvae may act by flooding the tracheal system with oil, by disrupting the surface forces that allow larvae to rest at the surface, by toxicity, or by eliciting chemosensory responses. In an attempt to identify diagnostic symptoms of these modes of action we treated fourth‐stage larvae of Culex pipiens L. form molestus Forskål (Diptera: Culicidae: Culicinae) with agents operating in a single mode (Ondina oil for flooding with oil, nicotine for toxicity, and the detergent Triton X‐100 for disruption of surface forces), in two modes (silicone oil) or in three (eucalyptus oil, citronellal, or caproic acid ethyl ester). We monitored the time course of flooding and immobilisation, used experiments to separate volatile toxicity from toxicity of the aqueous solution, and used video and The Observer software to analyse larval behaviour.

Larvae that experienced tracheal flooding applied their mouthparts to the siphon (tail nibbling), often losing contact with the surface while doing so and falling to the bottom. Nicotine immobilised larvae without interfering with surface forces, and the larvae remained immobile hanging from the air‐water interface for long periods. In detergent, larvae made repeated unsuccessful attempts to thrust the siphon through the surface. The behaviour‐modifying chemicals caproic acid ethyl ester, eucalyptus oil and citronellal all operated in more than one mode. They all decreased the proportion of time larvae spent at the surface, whereas Ondina oil and silicone fluid increased it.

Using this approach it should be possible to identify the modes of action of novel larvicidal agents. This could form a basis for rational design of larvicides giving an optimal compromise between efficacy against mosquito larvae and minimal damage to non‐target organisms.
Ability of a generalist insect, Schistocerca gregaria, to overcome thioglucoside defense in desert plants: tolerance or adaptation?
Authors: Mainguet A.M. , Louveaux A. , El Sayed G. , Rollin P.
Published: October 2003

Desert locusts, Schistocerca gregaria (Forskål) (Orthoptera, Acrididae), are generalist herbivores that, in the Sahara desert, may at times feed only on Schouwia purpurea (Forskål) (Brassicaceae), that is 10 times richer in thioglucosides than currently observed in other crucifers (>100 μmoles/g d.w.). Thioglucosides, when ingested, release products that are usually toxic to generalist insects.

We studied the short‐term (8 days) and long‐term (21–26 days) consequences of a Schouwia‐only diet on the digestion of these insects. The response was compared to the effects of a diet of Brassica oleracea, a crucifer well consumed in laboratory rearing conditions (7 μmoles/g glucosinolates d.w.).

We found that the production of a myrosinase was induced in the midgut as early as 8 days following exposure to glucosinolates. No negative short‐term effects were observed on the growth of the insect, but the activity of β‐glucosidases decreased in the midgut. The long‐term exposure to the Schouwia diet affected activities of β‐glucosidases and β‐galactosidases, growth and assimilation efficiency. The limited adaptation of the desert locust to plant glucosides is compensated by an ability to tolerate high concentrations of allelochemicals for a short period.
Change in response of Rhopalosiphum padi spring migrants to the repellent winter host component methyl salicylate
Authors: Glinwood Robert T. , Pettersson Jan
Published: October 2003

Olfactometry showed that the response of spring migrants of the bird cherry‐oat aphid, Rhopalosiphum padi (L.) (Homoptera: Aphididae), to the repellent winter host volatile methyl salicylate changes with age of the adult aphid. Between three and four days after becoming adult, and having left the winter host Prunus padus L., aphids lost their negative response to the chemical. The change in response was not associated with contact with a summer host, oats. In a settling choice bioassay, migrants avoided oats which had been exposed to volatile methyl salicylate. Aphids with removed antennal tips did not avoid the exposed plant, indicating that plant choice was influenced by cues from the plant surface. The results are discussed in relation to the use of methyl salicylate in integrated control.
Inheritance of resistance against biotype 2 of the Asian rice gall midge, Orseolia oryzae
Authors: Pani J. , Sahu S.C.
Published: October 2003

The inheritance of resistance in the rice cultivars Phalguna, ARC5984, ARC 5158, Veluthacheera, and T1477 to the Asian rice gall midge biotype 2 was studied under both natural and artificial infestation conditions against the susceptible cultivars Jaya and IR20. A single recessive gene in Veluthacheera and two recessive complementary genes in T1477 control resistance. Phalguna and ARC5984 possess a single dominant gene while ARC5158 has a single dominant and a single recessive gene for resistance. Allelism studies showed that genes for resistance in Veluthacheera and T1477 are allelic but non‐allelic to the resistance genes in Phalguna and ARC5984, which are allelic to each other. Genes for resistance in ARC5158 are allelic to resistance genes of the other four donors. There was no cytoplasmic inhibition of resistance by the susceptible parents.
Long‐term effects of soybean protease inhibitors on digestive enzymes, survival and learning abilities of honeybees
Authors: Pham‐Delègue Minh‐Hà , Girard Cécile , Le Métayer Martine , Picard‐Nizou Anne‐Lorraine , Hennequet Christelle , Pons Odile , Jouanin Lise
Published: October 2003

We have investigated the effects of long‐term ingestion of two serine proteinase inhibitors (PIs), the Kunitz Soybean trypsin inhibitor (SBTI) and the Bowman‐Birk inhibitor (BBI) on survival, learning abilities involved in the foraging behaviour, and digestive physiology of the honeybee (Apis mellifera L., Hymenoptera). A threshold‐dose was established, above which adverse effects of long‐term ingestion of the PIs tested are to be expected. The experiments reported herein could be extended to other PIs or gene products used to confer insect resistance, and be part of a general procedure used to assess the innocuousness of transgenic melliferous plants to honeybees.
Feeding behaviour and reproductive biology of Colorado potato beetle adults fed transgenic potatoes expressing the Bacillus thuringiensis Cry3B endotoxin
Authors: Arpaia Salvatore , De Marzo Luigi , Di Leo Grazia M. , Santoro Maria E. , Mennella Giuseppe , van Loon Joop J.A.
Published: October 2003

Colorado potato beetle (Leptinotarsa decemlineata Say) adult longevity and fecundity were studied on transgenic potato clones expressing a Cry3B endotoxin of Bacillus thuringiensis (Bt). Adult longevity and fitness were studied for the first 3 weeks after emergence. Beetle reproductive biology on highly resistant clones, intermediary resistant clones and control potato plants was monitored by dissecting females after 7–15 days of feeding and also by analysing haemolymph protein content after 3 days of feeding. Feeding behaviour on transgenic plants expressing high toxin concentrations and on control plants was monitored individually for 36 newly emerged adult beetles feeding on leaf disks during the first two meals. Lethal Time50 for adult beetles feeding on transgenic clones as the sole source of food was not significantly shorter than for beetles on control clones reared in a growth chamber. Differences tended to be larger when the experiment was conducted in a greenhouse with a less optimal temperature range (LT50= 9.52 and 10.45 days for two transgenic clones and 13.86 for control). In contrast, female egg production on transgenic plants was almost totally inhibited. Dissection studies indicated that adult males living on high‐level Bt‐expressing transgenic potatoes were still able to mate and produce mobile sperm, but the females were impaired in their reproductive ability since their ovaries were generally not fully developed. An examination of the haemolymph revealed the protein concentration in females living on transgenic plants to be dramatically reduced (≅ 50%), and electrophoresis showed a reduced content of vitellogenin in these samples.

Feeding behaviour of adult Colorado potato beetles was not affected by the different food plants; this indicates that transgenic potato plants were readily accepted as host plants by beetles. The effects of these findings on the use of transgenic plants as a means of L. decemlineata control are discussed.
Movement behaviour of the pine weevil Hylobius abietis in relation to soil type: an arena experiment
Authors: Kindvall Oskar , Nordlander Göran , Nordenhem Henrik
Published: October 2003

Pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae), movement behaviour on different substrates was studied in an indoor arena using a video camera and digital image processing technique. We analysed individual variation in movement characteristics, i.e. turning angles, movement directions, and distance moved per unit time on the bare and level arena surface which consisted of mineral soil (sand) and/or humus sections in various spatial configurations. Pine weevils on humus did not turn back when they came to the border with the sand. However, most individuals moved faster on sand than on humus. Thus, the results suggest that interactions between substrate differences and individual movement behaviour may to some extent explain why pine weevils have been observed to feed less frequently on coniferous seedlings planted on mineral soil than on those planted on humus.
Catching Ariadne by her thread: how a parasitoid exploits the herbivore's marking trails to locate its host
Authors: Hoffmeister Thomas S. , Roitberg Bernard D. , Lalonde Robert G.
Published: October 2003

Chemical signals that can be associated with the presence of a host insect often work as arrestants in close range host location by parasitoids, leading to longer searching times on patches where such signals are present. Our current view of parasitoid host location is that by prolonging the search times in patches, randomly searching parasitoids enhance their chance of detecting host insects. However, prolonged search times are not necessarily the only modification in parasitoid behaviour. In this study, we examine the exploitation of host‐fruit marking pheromone of rose‐hip flies, Rhagoletis basiola Osten‐Sacken (Diptera: Tephritidae) by the specialized egg‐larval parasitoid Halticoptera rosae Burks (Hymenoptera: Pteromalidae). We provide evidence that the instantaneous probability that a host egg will be located by a searching parasitoid wasp differs markedly between pheromone‐marked and unmarked fruits. The arresting response to the marking pheromone, i.e., the prolonged time a wasp is willing to search on marked fruits, can only account for a small fraction of the difference in successful host location on marked and unmarked fruits. We further demonstrate that the time wasps require to locate the host egg is independent of the size of the rose‐hip harbouring the fly egg, and thus is independent of the area the wasp potentially has to search. A comparison of our findings with results of different search algorithms for parasitoid wasps suggests that wasps use the fly's pheromone marking trail as a guide way to the fly's oviposition site and thus the host egg.
The temperature‐dependent duration of development and parasitism of three cereal aphid parasitoids, Aphidius ervi, A. rhopalosiphi, and Praon volucre
Authors: Sigsgaard Lene
Published: October 2003

Temperature dependencies were established for the egg‐to‐mummy and mummy‐to‐adult phases, for mummy mortality, and for parasitism of Aphidius ervi Haliday, Aphidius rhopalosiphi De Stefani‐Perez, and Praon volucre (Haliday) (Hymenoptera, Aphidiidae), three parasitoids of Sitobion avenae (Fabricius) (Homoptera, Aphididae), at 8 °C, 12 °C, 16 °C, 20 °C, and 25 °C on winter wheat (cv. Haven). A physiological model described temperature‐dependent development over the full temperature range, whereas a linear model was fitted for data above 8 °C and used to estimate the lower temperature thresholds and day‐degrees (° D) required for development. The thresholds for A. ervi were 2.2 °C for egg‐mummy development and 6.6 °C for mummy‐adult development, those for A. rhopalosiphi were 4.5 °C and 7.2 °C, and those for P. volucre were 3.8 °C and 5.5 °C. The time to develop into mummies and adults differed significantly between the three species: A. ervi development into mummies required an average of 159 ° D, while development into adults took an average of 73 ° D. The corresponding average times required for A. rhopalosiphi and P. volucre to develop mummies were 124° D and 126° D, while their development into adults required an average of 70° D and 150° D, respectively. Mummy mortality was 25–35% at 8 °C and less at the higher temperatures tested, but began to increase again at 25 °C, showing a quadratic relationship between mortality and temperature. Parasitization was very low or, in the case of P. volucre, absent up to 12 °C and thereafter increased with increasing temperature. The relationship between parasitization, recorded as percent aphids mummified, and temperature was linear at the temperatures tested and depended on species. A. ervi superparasitized 11.1% aphids at 20 °C and 16.6% aphids at 25 °C, whereas superparasitism was low in A. rhopalosiphi and absent in P. volucre. From 16 °C to 25 °C the P. volucre sex ratio increased. For A. ervi and A. rhopalosiphi there was no trend with temperature, but at 20 °C and 25 °C it was close to even. Field data for 1996 and 1997 allowed for a comparison of actual and expected emergence of overwintering mummies. In both years, parasitoids were predicted to have emerged from overwintering mummies well in advance of the onset of aphid infestation, and more than a month earlier than the first parasitized aphids were found in winter wheat. Observations from trap plants in other crops supported the predictions of the models. Other factors that can affect biological control by cereal aphid parasitoids are discussed.
Serratia marcescens as a rapid indicator of Microctonus hyperodae oviposition activity in Listronotus maculicollis and potential application of the technique to host‐specificity testing
Authors: McNeill Mark R. , Vittum Patricia J. , Jackson Trevor A.
Published: October 2003

Listronotus maculicollis (Dietz) (Coleoptera: Curculionidae) is a potential novel host of the braconid parasitoid Microctonus hyperodae Loan, but initial studies have shown that levels of parasitism are lower than in the natural host L. bonariensis (Kuschel). A novel bacterial indicator test was used to determine whether the lower level of parasitism was due to behavioural factors, lack of oviposition, or host resistance. The incidence of ovipositor penetration by the parasitoid M. hyperodae into adult L. maculicollis was measured by immersing the ovipositor of the parasitoid in the facultative pathogen, Serratia marcescens Bizio. Adult weevils were then exposed to parasitoids for up to 72 h and rapid mortality used as an indicator of oviposition penetration. Survival was assessed after six days and surviving weevils were dissected and examined for parasitoid larvae. Mortality among L. maculicolis exposed to parasitoids treated with S. marcescens was significantly higher (P<0.001) than the controls but significantly lower (P<0.001) than in the natural host, L. bonariensis. Dissection of weevils exposed to uncontaminated parasitoids revealed that parasitism in L. maculicolis was significantly (P<0.001) less than parasitism in L. bonariensis. Serratia marcescens‐induced mortality plus parasitism of surviving weevils in the parasitoid plus bacteria treatments produced a similar overall effect. Application of bacteria to the parasitoid ovipositor provided a rapid, simple test for ovipositor penetration, which shows potential for separation of behavioural and physiological defence mechanisms in parasitoid/host range studies.
Toxicity of insecticides to obliquebanded leafroller, Choristoneura rosaceana, larvae and adults exposed previously to neem seed oil
Authors: Lowery D. Thomas , Smirle Michael J.
Published: October 2003

Adult and sixth instar obliquebanded leafroller, Choristoneura rosaceana (Harris), exposed previously as fifth instar larvae to sub‐lethal concentrations of neem, Azadirachta indica A. Juss., seed oil contained in artificial diet were more susceptible to topically applied pyrethroid, carbamate and organophosphate insecticides than C. rosaceana reared on control diets. Increased susceptibility to insecticides did not result from reduced vigour, as measured by reductions in adult or larval weights, but is instead correlated with previously demonstrated reductions in detoxication enzyme activities. The modest increases in susceptibilities, not exceeding ca. 4.5‐fold, for C. rosaceana exposed to neem were achieved with subjects from a susceptible laboratory colony; a larger response could be expected for resistant field populations having elevated detoxication enzyme levels. Neem‐based insecticides could be useful tools for the management of orchard pests that have developed resistance to synthetic neurotoxins. These findings also contribute to a better understanding of the numerous physiological changes that occur in larval Lepidoptera following exposure to neem extracts.
Geographic variation in the field response of male European pine sawflies, Neodiprion sertifer, to different pheromone stereoisomers and esters
Authors: Anderbrant O. , Löfqvist J. , Högberg H.‐E. , Hedenström E. , Baldassari N. , Baronio P. , Kolmakova G. , Lyons B. , Naito T. , Odinokov V. , Simandl J. , Supatashvili A. , Tai A. , Tourianov R.
Published: October 2003

The European pine sawfly, Neodiprion sertifer (Geoffroy) (Hymenoptera: Diprionidae), is a widespread and economically important forest insect. The sex pheromone communication system of this species has been previously investigated in North America, Japan and Europe, with the acetate or propionate of the alcohol (2S,3S,7S)‐3,7‐dimethyl‐2‐pentadecanol (diprionol) shown to be the main pheromone component. In some locations, male attraction either increased or decreased by the addition of the (2S,3R,7R)‐diprionyl acetate isomer. However, these studies were made with different batches of synthetic pheromones, with different types of traps and according to different procedures, so the observed differences might not reflect true geographic variation. Here we investigate the geographic pattern of male sawfly response by using identical chemicals, traps and experimental procedures at eight field sites ranging from Japan in the east to Canada in the west. We found an increased inhibitory effect of the (2S,3R,7R)‐isomer from Japan and Siberia to Europe. At the eastern sites, increasing amounts of the (2S,3R,7R)‐isomer up to and equal to the amount of the (2S,3S,7S )‐isomer, did not influence the trap catch, whereas at sites in Europe, as little as 1% of the (2S,3R,7R)‐isomer almost completely inhibited the attraction. The response of the North American population was intermediate. The only site in which the (2S,3R,7R)‐isomer was essential for the attraction of males was in Siberia. A similar pattern was found for the (2S,3R,7S)‐isomer. Both the acetate and the propionate form of the (2S,3S,7S)‐isomer were attractive by themselves in Japan, Europe and North America, and neither the (2S,3R,7S)‐isomer nor the (2S,3R,7R)‐isomer alone were attractive, in the acetate or propionate form. We discuss the significance of our findings for the development of more efficient monitoring schemes and for the causes of population divergence and speciation in the European pine sawfly.
Host stage preference and sex allocation in Aenasius vexans, an encyrtid parasitoid of the cassava mealybug
Authors: Bertschy Catherine , Turlings Ted C.J. , Bellotti Anthony , Dorn Silvia
Published: October 2003

The solitary endoparasitoid Aenasius vexans Kerrich (Hymenoptera: Encyrtidae) is used for augmentative releases against the cassava mealybug, Phenacoccus herreni Cox & Williams (Sternorrhyncha: Pseudococcidae), an important pest on cassava in South America. In light of the need for large numbers of high quality females, experiments were conducted on host stage suitability and sex allocation. In choice and no‐choice experiments, individual female wasps were offered second and third instar, as well as adult, hosts. During the first five days after emergence, the wasps showed a steady increase in the number of hosts they successfully parasitised per day, but the respective secondary sex ratio for each instar remained constant. Parasitism was highest for third instar hosts in no‐choice tests, while in choice tests parasitism was highest in both third instars and adults. The later the developmental stage of the host at oviposition, the faster the parasitoids developed and emerged, and for each host stage, the development time of males was shorter than for females. The sex ratio of the wasps emerging from hosts that were parasitised as second instars was strongly male‐biased, while the apparently preferred later stages yielded significantly more females than males. Female and male A. vexans emerging from hosts parasitised at the third instar were significantly larger than for the other stages. This may explain the preference for the third instar as well as the female‐biased sex ratio, as size is usually positively correlated with higher fitness, especially in females. The results suggest that third instar hosts are the most suitable for rearing high numbers of large females.
Searching and oviposition behavior of a mymarid egg parasitoid, Anagrus nigriventris, on five host plant species of its leafhopper host, Circulifer tenellus
Authors: Al‐Wahaibi A.K. , Walker G.P.
Published: October 2003

Searching and oviposition behavior and parasitization ability of Anagrus nigriventris Girault (Hymenoptera: Mymaridae), an egg parasitoid of beet leafhopper, Circulifer tenellus (Baker) (Homoptera: Cicadellidae), were examined on five host plant species of beet leafhopper: sugar beet (Beta vulgaris L.), red stem filaree (Erodium cicutarium[L.]), peppergrass (Lepidium nitidum Nuttall), desert plantain (Plantago ovata Forsskal), and London rocket (Sisymbrium irio L.). Beet leafhopper embeds its eggs in the tissues of these plant species. For each plant species, A. nigriventris behavior was examined on plants with and without beet leafhopper eggs. Experimental design was a 5 (plant species) by 2 (host eggs present/absent) factorial. Additionally within each treatment, parasitoid behavior was observed over a 22‐h period at five different observation periods: t=0, 3, 6, 9, and 22 h where t=0 h represents initial exposure of the insect with the plant. The behavioral events observed were: ‘fast walking’ (general searching), ‘slow walking’ (intensive searching), ovipositor probing, grooming, feeding, and resting. Significant differences (α=0.05) among plant species in time spent on the plant, percentage of host eggs parasitized, and behavioral variables associated with intensive searching and oviposition all indicated that the plant species fell into two groups: ‘preferred’ plants (sugar beet, London rocket, and peppergrass), and ‘unpreferred’ plants (filaree and plantago). These variables also indicated that the parasitoids spent more time on, searched more, probed more, and oviposited more in plants with host eggs than plants without host eggs. Consistent effects of time (over the observation periods from t=0 to t=22 h) generally were detected only in the preferred plant species that had host eggs present. In these cases, intensive searching and probing decreased as time advanced, while variables related to general searching (‘fast walking’) and abandoning host egg patches (leaving the plant) tended to increase over time.