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A bioassay to test the ovipositional responses of the generalist herbivore, Epiphyas postvittana, was developed, and various non-chemical factors that influenced the laying, and number of eggs laid, by females were tested. In choice experiments using various models, surface texture was found to be an important factor influencing ovipositional behaviour, with females preferring to lay on smoother rather than rougher surfaces. Another surface texture feature that influenced oviposition was a raised wax ridge on a smooth surface. The wax ridge stimulated more eggs to be laid within close proximity to the ridge. Observations of females showed that the increased numbers of eggs laid on models with a wax ridge resulted not from increased landing, time spent, or numbers of eggs laid per ovipositional bout, but rather through an increased probability of ovipositing after landing on models with a wax ridge compared to models without the ridge. Spatial features of the models were also found to influence egglaying by females. Females showed a tendency to lay on the upper rather than the lower surface of models, although this appeared to depend upon how stimulatory the upper surface of the model was. Females also laid more eggs on models with a dense array of leaves than on models with a more spread-out array.

The grain aphid, Sitobion avenae Fabricius (Hemiptera: Aphididae), is an important pest of cereal crops. Pesticides are the main method for control but carry the risk of selecting for resistance. In response to reports of reduced efficacy of pyrethroid sprays applied to S. avenae, field samples were collected and screened for mutations in the voltage-gated sodium channel, the primary target site for pyrethroids. Aphid mobility and mortality to lambda-cyhalothrin were measured in coated glass vial bioassays.A single amino acid substitution (L1014F) was identified in the domain IIS6 segment of the sodium channel from the S. avenae samples exhibiting reduced pyrethroid efficacy. Bioassays on aphids heterozygous for the kdr mutation (SR) or homozygous for the wild-type allele (SS) showed that those carrying the mutation had significantly lower susceptibility to lambda-cyhalothrin.The L1014F (kdr) mutation, known to confer pyrethroid resistance in many insect pests, has been identified for the first time in S. avenae. Clonal lines heterozygous for the mutation showed 35-40-fold resistance to lambda-cyhalothrin in laboratory bioassays, consistent with the reported effect of this mutation on pyrethroid sensitivity in other aphid species.

The aim of this study was to develop a method to cryopreserve the embryos of the pink bollworm moth, Pectinophora gossypiella (Saunders). Previously developed dipteran cryopreservation protocols were not directly adaptable to use with the embryos of this lepidopteran species. Physiochemical and electron microscope observations revealed substantial differences in the structure of the chorion, wax layer, and vitelline membrane complex when comparing the cryopreservable embryonic stages of P. gossypiella and dipteran embryos. Thus, the initial steps dealing with dechorionation and permeabilization were ineffective and had to be altered. Exposure to the sodium hypochlorite-based chorion removal step decreased P. gossypiella embryo viability to a very low level. Survival increased and permeability was evident when an alkane wash was used as the first step in the procedure. After the alkane treatment with a surfactant yielded the maximum exchange of cryoprotectant with water as evidenced by a significant lowering of the supercooling point of the cryoprotectant-loaded embryos. The remainder of the cryopreservation and storage recovery protocol for P. gossypiella was similar to those developed for dipteran embryos. Survival of recovered, hatched embryos to adulthood was approximately 7%.

The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) is amajor pest of agriculture worldwide that has proved to be particularly adept at evolving insecticide resistance. Several mechanisms that confer resistance to many insecticide types have been described in M. persicae. We measured the resistance status of nine multilocus genotypes (MLGs) of this aphid species collected in Chile. MLGs were identified using microsatellite markers, and these MLG clonal populations were measured for the presence of modified acetylcholinesterase (MACE), kdr and super kdr mutations, and enhanced carboxyl esterase activity. Toxicological bioassays were used to estimate aphid LC50 when treated with metamidophos (organophosphate), pirimicarb (dimethyl carbamate), cyfluthrin (pyrethroid), and imidacloprid (neonicotinoid). Two MLGs presented >20-fold resistance to pirimicarb, which was associated with the MACE mutation in the heterozygous condition. The kdr mutation was found in only four MLGs in the heterozygous condition and they showed resistance ratios (RR) to cyfluthrin of less than sevenfold. The super kdr mutation was not detected. Enhanced carboxyl esterase activity was predominantly found in the susceptible (S) to first level of resistance (R1) with RR to metamidophos less than eight-fold. Finally, RR to imidacloprid was also less than eight-fold in all MLGs tested. A few MLGs with resistance to pirimicarb were found, while susceptibility to cyfluthrin, metamidophos and imidacloprid was still predominant. A significant positive correlation between imidacloprid tolerance with pirimicarb resistance was detected, as well as between imidacloprid and metamidophos tolerance. With the increase in the use of neonicotinoid insecticides, better rotation of insecticides with different modes of action will be necessary to prevent further development of M. persicae insecticide resistance in Chile.

The survival of Myzus persicae (Sulzer) clones, representing the full range of the recognized levels of insecticide resistance, was measured after 3–4 week exposure to the winter climate in the field. Ten separate trials were carried out using known numbers of first/second instar nymphs on unsprayed oilseed rape and groundsel. These predominantly showed a negative association between resistance level and the proportion of aphids recovered alive after exposure. The strength of the relationship correlated closely with three meteorological variables: the length of time that aphids spent below 2°C, mean rainfall and mean windspeed. We conclude that selection for resistance to insecticides is subject to counteracting selection by cold, wet and windy conditions in the UK winter. Revertant clones, that had spontaneously lost extreme resistance to insecticides despite retaining resistance genes, survived no better than aphids that had kept their high resistance, indicating that overproduction of esterase was not the reason for poor survival.

Using a tracer–tracee approach, we fed 1-d-old virgin Heliothis virescens U- 13 C-glucose and analyzed the key labeled fatty acids, ( Z )-11-hexadecenoate, hexadecanoate and octadecanoate, known to be intermediates in pheromone biosynthesis, by mass isotopomer distribution analysis. This method allowed determination of enrichment, and fractional (FSR) and absolute (ASR) synthetic rates. As expected, FSRs and ASRs for all three moieties were greater in the scotophase than photophase. However, in whole gland extracts, FSRs and ASRs of ( Z )-11-hexadecenoate and hexadecanoate were much lower than those of the major pheromone component, ( Z )-11-hexadecenal, determined previously. Since pheromone is made via these acids, we postulated that pheromone was produced directly and very rapidly via a small pool of acyl CoA thioesters of these acids and that the pool of acids we analyzed in our whole gland extract was largely a ‘dead end’ pool of excess acids (i.e., not converted directly to pheromone) stored in glycerolipids. We tested this by fractionating the whole glandular extract and analyzing the glycerolipid fraction. FSRs and ASRs for the two acids in the glycerolipid fraction were similar to those for the whole gland extract, confirming our postulate. Thus, most acetate produced in the pheromone gland is converted rapidly and directly to pheromone, while excess fatty acids are stored in glycerolipids and remain relatively inaccessible for pheromone production, at least over the two periods studied. Precursor enrichment of octadecanoate was substantially lower than that determined for the two 16-carbon acids and pheromone component. This suggests that hexadecanoate is the principal product of the multi-enzyme complex fatty acid synthase in the gland, and that octadecanoate is formed by subsequent chain elongation of hexadecanoate.

Sex pheromone titers in females of two tortricid moths, Epiphyas postvittana and Planotortrix octo, did not significantly vary between the scotophase and photophase. Pheromone production in these two species is controlled by a factor located in the head of the respective females, probably the pheromone biosynthesis-activating neuropeptide (PBAN). Unlike that reported for the related tortricid, Argyrotaenia velutinana, the bursa copulatrix in female E. postvittana and P. octo does not appear to contain a factor that stimulates pheromone production. After mating, female E. postvittana permanently shut down pheromone production. In contrast, pheromone titer in mated P. octo females is reduced to a level approximately half that of similar-age virgins. While the abdominal nervous system is involved in the inactivation of pheromone production in mated E. postvittana females and probably acts to stop release of PBAN from the corpora cardiaca, the abdominal nervous system is not involved in effecting the decreased pheromone titers of mated P. octo females. It is possible that in the latter species, a humoral factor(s) is responsible for effecting the decreased pheromone titers, possibly through affecting the release of PBAN from the corpora cardiaca. Bioassaying head extracts allowed changes in PBAN titer in female E. postvittana to be inferred. PBAN titers remain roughly constant in virgins but increase after mating. This suggests that PBAN is biosynthesized throughout the life of an adult virgin female at approximately the same rate as it is released. Furthermore, it appears that the decline in pheromone titer observed in older E. postvittana females is probably due to a decline in competency of the gland to produce pheromone rather than to a decrease in PBAN titer in older females. © 1994 Wiley-Liss, Inc.

BACKGROUND: Parthenogenetic clones of the green peach aphid, Myzus persicae (Sulzer), and the cotton aphid, Aphis gossypii Glover, were tested with the anthranilic diamide insecticide cyantraniliprole (i.e. DuPont™ Cyazypyr™) in systemic-uptake bioassays to investigate potential for cross-resistance conferred by mechanisms of insecticide resistance to organophosphates, carbamates and pyrethroids and, in the case of M. persicae, reduced sensitivity to neonicotinoids. These data were compared with the response of field samples of M. persicae and A. gossypii collected from around Europe. RESULTS: Cyantraniliprole was not cross-resisted by any of the known insecticide resistance mechanisms present in M. persicae or A. gossypii. The compound was equally active against resistant and susceptible aphid strains. The responses of the M. persicae field samples were very consistent with a maximum response ratio of 2.9 compared with a standard laboratory clone. The responses of the A. gossypii field samples were more variable, although a majority of the responses were not statistically different. CONCLUSION: Cyantraniliprole is currently the only anthranilic diamide (IRAC MoA 28) insecticide targeting aphid species such as M. persicae and A. gossypii. There is no evidence to suggest that the performance of this compound is affected by commonly occurring mechanisms that confer resistance to other insecticide chemistries. Cyantraniliprole is therefore a valuable tool for managing insecticide resistance in these globally important pests. Copyright © 2011 Society of Chemical Industry

Activation of sex pheromone production in virgin female moths has been intensively studied over the last few years. In contrast, little is known about the reciprocal process, inactivation of pheromone production in mated females. In females of the lightbrown apple moth, Epiphyas postvittana, mating results in the permannent inactivation of pheromone production. Injection of mated female haemolymph or extracts of male accessory glands or whole reproductive tracts into virgins failed to induce this effect, suggesting that whatever elicits the inactivation is not transported humourally. When pairs were artificially forced apart during copulation, females without a spermatophore in their bursa copulatrix all produced levels of pheromone similar to virgins, while of the remales with a spermatophore in their bursa copulatrix, 47% produced levels similar to virgins and the remainder produced levels similar to mated females. This suggests that mechanical factors are not responsible for inducing inactivation of pheromone production. However, when the ventral nerve cord of females was transected before mating, the resultant mated females produced levels of pheromone similar to virgins, indicating that inactivation of pheromone production is induced by a neural signal, originating from the abdomen, which travels up the ventral nerve cord to a higher centre. Data are presented to support the hypothesis that the signal functions by switching off the release of pheromone biosynthesis-activating neuropeptide, or a like neuropeptide from the corpora cardiaca.

Wheat is the most widely cultivated plant in the world, providing more than 20 % of the food calories consumed [1]. The Hessian fly, Mayetiola destructor (Say), (Diptera: Cecidomyiidae), is one of the most destructive pests of wheat and is found in most of the major wheat-growing areas of the world [2]. Due to the feeding habit of the larva and the type of damage it produces, early infestations by Hessian fly are extremely difficult to detect or predict. Female Hessian flies are known to produce a sex pheromone that elicits upwind flight by males [3] and, given the widespread use of synthetic sex pheromones in pest management programs [4], it is very likely that this sex pheromone could find great utility in controlling this pest. As well as containing a large number of pest species, the family Cecidomyiidae is of evolutionary interest because of its rapid rate of species formation relative to a lesser rate of speciation in related families of Diptera [5]. We report here the first identification of a cecidomyiid sex pheromone, that of the Hessian fly, as (2S)(E)-10-tridecen-2-yl acetate (Fig. 1). The crude sex pheromone was obtained by dissecting the terminal segments of the ovipositors of female Hessian flies, and extracting them in pentane. The activity of extracts, fractions of extracts, and synthetic chemicals was determined

The aphid Myzus persicae is a globally significant crop pest that has evolved high levels of resistance to almost all classes of insecticide. To date, the neonicotinoids, an economically important class of insecticides that target nicotinic acetylcholine receptors (nAChRs), have remained an effective control measure; however, recent reports of resistance in M. persicae represent a threat to the long-term efficacy of this chemical class. In this study, the mechanisms underlying resistance to the neonicotinoid insecticides were investigated using biological, biochemical, and genomic approaches. Bioassays on a resistant M. persicae clone (5191A) suggested that P450-mediated detoxification plays a primary role in resistance, although additional mechanism(s) may also contribute. Microarray analysis, using an array populated with probes corresponding to all known detoxification genes in M. persicae, revealed constitutive over-expression (22-fold) of a single P450 gene (CYP6CY3); and quantitative PCR showed that the over-expression is due, at least in part, to gene amplification. This is the first report of a P450 gene amplification event associated with insecticide resistance in an agriculturally important insect pest. The microarray analysis also showed over-expression of several gene sequences that encode cuticular proteins (2–16-fold), and artificial feeding assays and in vivo penetration assays using radiolabeled insecticide provided direct evidence of a role for reduced cuticular penetration in neonicotinoid resistance. Conversely, receptor radioligand binding studies and nucleotide sequencing of nAChR subunit genes suggest that target-site changes are unlikely to contribute to resistance to neonicotinoid insecticides in M. persicae., Author Summary M. persicae is the most economically important aphid pest in many regions of the world due to its large host range and the damage it causes through direct feeding and through the transmission of plant viruses. This species has developed resistance to most classes of insecticide; and although, to date, the neonicotinoids have remained an effective control measure, recent reports of resistance in M. persicae represent a threat to the long-term effectiveness of this chemical class. Work on other insect species has shown that resistance can arise through increased production of metabolic enzymes (such as cytochrome P450s) that detoxify the insecticide. In this study we made use of recent advances in genomics to quantify the expression of all genes encoding detoxification enzymes in a resistant strain of M. persicae. We found resistance correlated with the over-expression of a single P450 gene, and we show that this is due to gene amplification. We also showed that over-expression of cuticular proteins and reduced penetration of insecticide through the cuticle may also play a role in resistance. These findings will influence the design and monitoring of management strategies that aim to slow or prevent the development of resistance.

BACKGROUND: Onion thrips, Thrips tabaci Lindeman, is a prevalent pest of glasshouse and field vegetables, such as leeks and salad onions. Pesticides are the main option for control, but this approach risks the evolution and spread of insecticide resistance. In the light of anecdotal reports in the United Kingdom of poor efficacy of pyrethroids against T. tabaci, thought to be primarily a consequence of resistance, the responses to deltamethrin of ten English samples of T. tabaci, collected from field leeks and salad onions in 2006, were measured to establish the level and prevalence of potential resistance to this compound. RESULTS: All the samples showed significant deltamethrin resistance that was comparable or slightly lower than the maximum level reported previously for T. tabaci from New Zealand. CONCLUSION: The mechanism(s) conferring deltamethrin resistance remain unknown at present but are likely to extend to other synthetic pyrethroids approved for use against this species. The findings suggest that these compounds are unlikely to give satisfactory control of T. tabaci in England and have stimulated the recommendation to use alternatives. Copyright © 2010 Society of Chemical Industry

1. Phenotypic diversity is the fuel that powers evolution. 2. Asexual organisms rely on mutation whereas sexual organisms combine mutation with recombination. 3. Few organisms provide examples of species that are both sexual and asexual, but aphids do. 4. To examine evolution on perceptible timescales requires strong evolutionary forces and, as Darwin noted, agricultural practices provide strong selection. In the case of aphids, insecticides provide a considerable force in the elimination of genotypes. 5. Insecticide resistance in Myzus persicae (Sulzer) has arisen independently through point mutation and gene amplification on a number of occasions and at different times. Resistance to organophosphates, pyrethroids, and pirimicarb (a dimethyl carbamate) is now widespread. 6. In this paper, we examine these three elements: sexual recombination, clonal expansion, and insecticide selection in the peach–potato aphid M. persicae in relation to the evolution of insecticide resistance and survival of the fittest clone.

In a controlled atmosphere of 0.4% O2, 5% CO2, previously found to rapidly kill the tortricid Epiphyas postvittana (Walker), the mortality responses of 3-d-old eggs and first, third, and fifth instars of three tortridd pests of New Zealand apples (two endemic species, Planotortrix octo Dugdale and Ctellopseustis ohliqualla [Walker], and an introduced species, Cydia pomollella [L.]), were detemlined at two different temperatures. At 20C, all three species showed a pattern of susceptibility of the different stages to the atmosphere similar to that found for E. postvittana (i.e., in order of decreasing estimated time for 99% mortality [LT99]: fifth instars (including both diapausing and nondiapausing larvae of Cydia pomonella ) > third instars ≥3-d-old eggs ≥ first instars. Responses of the four species showed a general trend of decreasing LT99s at 20°C in the following order: Cydia pomollella > E. postvittana ≈ P. octo ≈ Ctellopseustis ohliqualla . An increase in treatment temperature to 30°C resulted in significant decreases in LT99s for all stages of all three species by factors of between 1.8 and 9. The order of susceptibility of the four species at 30°C changed relative to that at 20°C, with smaller differences between Cydia pomonella and E. postvittana . Most noticeably, all stages of P. octo and Ctenopseustis obliquana had significantly lower LT99s than those of the corresponding stages of E. postvittana .

Work on the mortality responses of four lepidopteran pests of apples in New Zealand—Epiphyas postvittana (Walker), Cydia pomonella (L.), Planotortrix octo Dugdale, and Ctenopseustis obliquana (Walker)—to low O2/moderate CO2 atmospheres is reviewed and additional data are presented. For both E. postvittana and C. pomonella, reducing the O2 concentration and elevating the treatment temperature enhanced controlled atmosphere (CA) efficacy more than did increasing the CO2 concentration. Thus at 20°C, a 0.4% O2/5.0% CO2 CA gave the most rapid kill of the mixtures tested. The order of lifestage tolerance to this CA was similar for E. postvittana, C. pamonella, P. octo, and C. obliquana i.e., fifth instar > third instar > 3-day eggs > first instar. The four species exhibited a trend of tolerance of C. pomonella > E. postvittana = P. octo = C. obliquana. An increase in the temperature to 30°C decreased the time for high mortality for all four species. However, this decrease was much greater for P. octo a...

SUMMARY Long-distance, female-produced sex pheromones are widespread among moths. Larval feeding provides most of the nutrients for development of these insects but is not thought to influence the de novo production of the fatty-acid derived compounds used as pheromones by most species. Feeding on plant nectar (sugar) by adult moths is important for increasing female fitness and also for the pollination of many plant species. In this paper, I show that feeding on sucrose solution, as opposed to water, increases sex pheromone titre in mated, but not virgin, female Heliothis virescens. Mating caused a rapid decrease in haemolymph trehalose concentration, which was restored to near-virgin levels by sugar ingestion. When isolated mated female abdomens were cultured with different concentrations of trehalose, pheromone titre increased with increasing trehalose concentration. This effect was not observed when abdomens were cultured on saline containing the sugar rhamnose,which insects cannot metabolise to glucose. Virgins injected with the juvenile hormone (JH) analogue, methoprene, showed the same effects as mated females with respect to pheromone titre and haemolymph trehalose concentration. Thus,following mating increases in JH titre increase demand for, and lowering of,blood sugar to develop oocytes, which can be compensated for by sugar ingestion. Haemolymph trehalose concentration probably influences glycolysis in gland cells and, consequently, levels of cytosolic citrate and acetyl-CoA for pheromone biosynthesis. This increase in pheromone titre in sugar-fed,mated females may facilitate further mating and increased fecundity. Thus,exogenous sugar feeding is behaviourally and physiologically integrated with endogenous JH titre to maximise female fitness.

Variation in vulnerability to natural enemies, reproductive rate and insecticide resistance among phenotypes of Myzus persicae (Sulzer) has been shown to have the potential to disrupt biological control and IPM of this species, and movement of particularly troublesome phenotypes in international horticultural trade could be cause for concern. Three important components of fitness, vulnerability to parasitoids, reproduction and insecticide resistance were determined in three clones of M. persicae originating from prevalent phenotype populations on pepper crops in greenhouses in British Columbia, Canada. One of these phenotypes appeared to be consistently involved in outbreaks in commercial operations. These clones were also characterized for their DNA microsatellite genotype and compared with genotypes of M. persicae from Europe. The clone involved in outbreaks in commercial greenhouses showed reduced vulnerability to parasitoids, and a higher reproductive rate compared to the other two clones suggesting that these traits may have been involved in outbreaks. As in M. persicae European clones, a higher reproductive rate was correlated with a lack of esterase-based resistance (primarily to organophosphates and, to some extent, to carbamates and pyrethroids). However, microsatellite analysis demonstrated that the three clones investigated in British Columbia had unique genotypes, and therefore there was no evidence for their movement in international trade.

The female-produced sex pheromone of the Hessian fly,Mayetiola destructor (Say) (Diptera: Cecidomyiidae), has been identified as (10E)-tridecen-2-yl acetate. A flexible synthetic route was developed which allowed access to the chiral and racemic forms of the pheromone, and to the 10Z stereoisomer of the pheromone. The natural compound was determined to have the 2S configuration by hydrolysis of the acetate function, derivatization of the resulting alcohol with (2S)-2-acetoxypropionyl chloride, and capillary gas Chromatographic comparison of the derivative with the corresponding derivatives prepared from the synthetic enantiomers. Trace amounts of the 10Z isomer of the pheromone have also been detected in extracts of female Hessian fly ovipositors, along with (10E)-tridecen-2-ol and 2-tridecanyl acetate. Due to the small quantities of these compounds available from ovipositor extracts, the chirality of the trace components has not yet been determined.

In a wind-tunnel, male Hessian flies flying toward a source of the female-produced sex pheromone exhibited flight maneuvers very similar to those described for male moths. Upwind flight, consisting of zigzagging and straight flight upwind, was initiated within seconds after flies were placed in the odor plume. This upwind flight was sometimes interrupted by casting, which consisted of wide excursions in the horizontal plane ranging 10-35 cm across the central zone of the tunnel. Comparison of the flight maneuvers of males exposed to ten female equivalents of a hexane extract of female ovipositors and males exposed to 20 ng of (2S)-(E)10-tridecen-2-yl acetate (SE10-13:OAc), which has been identified as a component of the Hessian fly sex pheromone, indicated that the sex pheromone probably contains additional components. However, SE10-13: OAc elicited upwind flight and source location by a significant number of males, even at dosages as low as 2 ng on filter paper. At the highest dosage of SE10-13:OAc tested (200 ng on filter paper), there was a significant decrease in net flight velocity and a slight, but not significant, reduction in the number of males contacting the odor source. The addition of increasing amounts of the R enantiomer to the S enantiomer resulted in increased inhibition of upwind flight and source contact by males.

First-instar light brown apple moths, Epiphyas postvittana (Walker), were exposed to various controlled-atmosphere treatments at different temperatures. The time required for 99% mortality (LT••) was highly dependent on the concentration of 0, and temperature; insects died more rapidly with lower concentrations of O, and with higher temperatures. The effect of different concentrations of CO, on mortality of first instars was less pronounced. At 2O°C and an 0, concentration of 0.4%, a CO, concentration of 5.0% resulted in lowest LT•• (mean of 22.5 h) of all of the CO, concentrations tested. Using this atmosphere (i.e., 0.4% O2 5.0% CO2), we determined mortality of third instars, fifth instars, and eggs of E. postvtttana at 20 and 30°c. At both temperatures, LT99s decreased in the following order: fifth instar > third instar ≈ eggs > first instar. An experiment testing this atmosphere at 40°C on fifth instars gave a mean LT99 of 4.2 h.

Virgin female Hessian flies biosynthesize sex phermone in a cyclical fashion throughout their lifetime. Pheromone titre is relatively high early in the photophase, coinciding with the period of sexual activity, and decreases to a low level some 8 h later in the photophase. Mating results in the cessation of pheromone biosynthesis. Injection of male abdomen extract into virgin females suggested that this is due to the transfer of a chemical factor from the male to the female during mating. Decapitated female Hessian flies did not biosynthesize sex pheromone. However, injection of female head extract into these decapitated females resulted in the biosynthesis of sex pheromone, indicating that pheromone biosynthesis is initiated by a factor located in the female head. Injection of synthetic pheromone biosynthesis activating neuropeptide of Heliothis zea into Hessian fly females also initiated some pheromone biosynthesis, and it is believed that this neuropeptide or a related neuropeptide is responsible for initiation of pheromone biosynthesis. Analysis of the fatty acyl groups present in the pheromone gland of virgin female Hessian flies revealed the unusual compound (E)-9-dodecenoate. This compound may be an intermediate in the biosynthesis of the pheromone component (2S)-(E)-10-tridecen-2-yl acetate.

Coupled gas chromatographic (GC)-electroantennographic detection (EAD) analyses of ovipositor extract of calling Hessian fly, Mayetiola destructor, females revealed that seven compounds elicited responses from male antennae. Four of the compounds-(2S)-tridec-2-yl acetate, (2S,10Z)-10-tridecen-2-yl acetate, (2S,10E)-10-tridecen-2-yl acetate, and (2S,10E)-10-tridecen-2-ol-were identified previously in female extracts. Two new EAD-active compounds, (2S,8Z,10E)-8,10-tridecadien-2-yl acetate and (2S,8E,10E)-8,10-tridecadien-2-yl acetate, were identified by GC-mass spectroscopy (MS) and the use of synthetic reference samples. In a Y-tube bioassay, a five-component blend (1 ng (2S)-tridec-2-yl acetate, 10 ng (2S,10E)-10-tridecen-2-yl acetate, 1 ng (2S,10E)-10-tridecen-2-ol, 1 ng (2S,8Z,10E)-8,10-tridecadien-2-yl acetate, and 1 ng (2S,8E,10E)-8,10-tridecadien-2-yl acetate) was as attractive to male Hessian flies as a similar amount of female extract (with respect to the main compound, (2S,10E)-10-tridecen-2-yl acetate). The five-component blend was more attractive to male flies than a three-component blend lacking the two dienes. Furthermore, the five-component blend was more attractive than a blend with the same compounds but that contained one tenth the concentration of (2S,8E,10E)-8,10-tridecadien-2-yl acetate (more accurately mimicking the ratios found in female extract). This suggests that the ratios emitted by females might deviate from those in gland extracts. In a field-trapping experiment, the five-component blend applied to polyethylene cap dispensers in a 100:10 microg ratio between the main component and each of the other blend components attracted a significant number of male Hessian flies. Also, a small-plot field test demonstrated the attractiveness of the five-component blend to male Hessian flies and suggests that this pheromone blend may be useful for monitoring and predicting Hessian fly outbreaks in agricultural systems.

Two amino acid substitutions (L1014F and M918T) in the voltage-gated sodium channel confer target-site resistance to pyrethroid insecticides in the peach potato aphid, Myzus persicae . Pyrethroid-resistant and -susceptible M. persicae clones with various combinations of these mutations were crossed under laboratory conditions, and the genotypes of aphid progeny were analysed by direct DNA sequencing of the IIS4–S6 region of the sodium channel gene. Segregation patterns showed that in aphids heterozygous for both L1014F and M918T, both mutations were present in the same resistance allele. Despite these mutations appearing largely recessive in other pest species, such aphids exhibited strong resistance to pyrethroids in leaf-dip bioassays. These results have important implications for the spread and management of pyrethroid resistance in field populations.

The prevalence of insecticide resistance mechanisms in populations of Myzus persicae on potatoes in New Zealand was determined in five parthenogenetic aphid lineages raised from individuals collected from Pukekohe in the North Island, and 66 from Canterbury and one from the West Coast in the South Island during mid-summer (January) to early autumn (March) 2005. For each lineage, the genotypes, determined using four microsatellite loci, were compared with the presence or absence of resistance mechanisms assessed using a combination of biochemical tests, polymerase chain reaction-based allelic discrimination and diagnostic dose bioassays. The 72 lineages comprised 23 genotypes (defined using microsatellite markers), with 60% containing one or more mechanisms that confer resistance to between one and three of any of four insecticide classes. In all, 38% contained high or extreme elevated carboxylesterases (E-Carb-R2 and -R3) that confer resistance primarily to organophosphates, and some resistance to carbamates and pyrethroids; 19% contained modified acetylcholinesterase (MACE) that gives strong resistance to the di-methyl carbamates, pirimicarb and triazamate; 54% contained a mutation in a voltage-gated sodium channel gene, called knockdown resistance (kdr), that confers resistance to pyrethroids; and 36% contained a second mutation of the gene (super-kdr) that gives enhanced resistance to pyrethroids. In all, 10% of the lineages also showed low-level resistance to neonicotinoids, as shown in imidacloprid diagnostic dose bioassays. Most of the microsatellite genotypes appeared to disclose cycles of sexual reproduction, the clones of which were susceptible to all classes of insecticide chemistry, except two that had acquired MACE possibly by breeding with an invasive MACE genotype or an individual carrying a locally derived MACE mutation. However, lineages carrying multiple resistance mechanisms belonged to two resistant genotypes that formed widely distributed clones. Behavioural bioassays on selected lineages from New Zealand and Europe showed that M. persicae clones from both regions carried E-Carb R3, or kdr/s-kdr, and showed consistently low responses to the aphid alarm pheromone (E)-β-farnesene. Methods are discussed for exploiting such putative fitness costs of resistance traits in M. persicae aphids to minimise the development of resistance and restore efficacy to insecticide programmes.

Video recordings were used to obtain a detailed description of the mating behavior of seaweed flies. The roles of wings, antennae, and legs were inferred from ablation and masking experiments. There is no apparent interaction between flies over a distance of more than 1–2 cm. After mounting the prothoracic legs of the male are located in the region of the female's antennae and interactions between these structures appear to facilitate successful mating. There follows either a female rejection response or a voluntary dismount by the male, or mating proceeds to insemination. When triplets of one female and two males were observed, larger males often displaced small males and were themselves less frequently displaced. The observed opportunities for female choice, male choice, and male-male competition are discussed in the light of previous reports of differential male mating success and of assortative mating with respect to size and genotypes.

Peach-potato aphids, Myzus persicae (Sulzer), collected in Scotland in the years 1995 and 2002–2004 were characterized using four microsatellite loci and three insecticide resistance mechanisms. From 868 samples, 14 multilocus genotypes were defined (designated clones A–N). Five of these (denoted A, B, H, M and N) carried modified acetylcholinesterase (MACE) resistance, the most recent resistance mechanism to have evolved in M. persicae. The current paper shows that the continued presence of MACE aphids is due to turnover, as clones A and B were replaced in field samples by clones H, M and N in later seasons. Thus, insecticide-resistant populations in Scotland can be attributed to multiple waves of rapid clone colonisations and not to the continued presence of stable resistant clones or mutation or sexual recombination in local populations. The MACE clones carried varying levels of the other insecticide resistance mechanisms, kdr and esterase. The presence of these mechanisms could alter the clones success in the field depending on insecticide spraying (positive selection) and resistance fitness costs (negative selection).

Myzus persicae (Sulzer) collected in Scotland were characterized for four microsatellite loci, intergenic spacer fingerprints and the resistance mechanisms modified acetylcholinesterase (MACE), overproduced carboxylesterase and knockdown resistance (kdr). Microsatellite polymorphisms were used to define a limited number of clones that were either fully susceptible to insecticides or possessed characteristic combinations of resistance mechanisms. Within these clones, intergenic spacer fingerprints could either be very consistent or variable, with the latter indicating ongoing evolution within lineages, most likely derived from the same zygote. Two clones (termed A and B) possessed all three resistance mechanisms and predominated at sites treated with insecticides. Their appearance on seed potatoes and oilseed rape in Scotland in 2001 coincided with extensive insecticide use and severe control failures. Clones C, I and J, with no or fewer resistance mechanisms, were found in samples from 1995 and were dominant at untreated sites in 2001. A comparison of Scottish collections with those from other UK and non-UK sites provides insight into the likely origins, distribution and dynamics of M. persicae clones in a region where asexual (anholocyclic) reproduction predominates, but is vulnerable to migration by novel genotypes from areas of Europe where sexual (holocyclic) reproduction occurs.

The sex pheromone of the painted apple moth, Teia anartoides (Lymantriidae) was investigated using GC-EAD and GC-MS analysis, derivatization, TLC analysis, and field cage and field trapping bioassays. The major sex pheromone components were identified as (6Z,9Z)-henicosa-6,9-dien-11-one and (6Z,9Z)-henicosa-6,9-diene. Other minor components of pheromone gland extracts included (6Z)-9R,10S-epoxyeicos-6-ene, (6Z)-9R,10S-epoxyhenicos-6-ene, (6Z,9Z)-henicosa-6,9-dien-11-ol, (6Z)-henicos-6-en-11-one, and (6Z, 8E)-henicosa-6,8-dien-11-one, but the roles of these minor components remain equivocal. In field cage and field experiments, a blend of all seven identified components [(6Z,9Z)-henicosa-6,9-dien-11-one (relative amount 100), (6Z,9Z)-henicosa-6,9-diene (100), (6Z)-9R,10S-epoxyeicos-6-ene (5), (6Z)-9R,10S-epoxyhenicos-6-ene (10), (6Z,9Z)-henicosa-6,9-dien-11-ol (5), (6Z)-henicos-6-en-11-one (1), and (6Z,8E)-henicosa-6,8-dien-11-one (25)] was as attractive to males as calling females, but tests with blends of the major component(s) with subsets of the minor components did not produce consistent results that unequivocally showed the various minor components to be critical components of the active blend. (6Z,9Z)-henicosa-6,9-dien-11-one is thermally labile and rearranges to (6Z,8E)-henicosa-6,8-dien-11-one and other products at ambient temperature, rendering the synthetic pheromone lure inactive after two days of field exposure.

Response to the alarm pheromone, (E)-β-farnesene, produced by many species of aphids, was assessed in laboratory bioassays using an aphid pest,Myzus persicae(Sulzer), and its primary endoparasitoid,Diaeretiella rapae(McIntosh). This was done in three separate studies, the first investigating responses of a large number ofM. persicaeclones carrying different combinations of metabolic (carboxylesterase) and target site (kdr) insecticide resistance mechanisms, and the other two investigating the responses of young virgin female adult parasitoids. InM. persicae, both insecticide resistance mechanisms were associated with reduced repellence suggesting that each has a pleiotropic effect on aphid behaviour. In contrast,D. rapaefemales were attracted to the alarm pheromone source. The implications of this apparent fitness trade-off for the evolution and dynamics of insecticide resistance, and the potential for using beneficial insects to combat resistance development are discussed.

We show that single-point mutations conferring target-site resistance (kdr) to pyrethroids and DDT in aphids and houseflies, and gene amplification conferring metabolic resistance (carboxylesterase) to organophosphates and carbamates in aphids, can have deleterious pleiotropic effects on fitness. Behavioural studies on peach–potato aphids showed that a reduced response to alarm pheromone was associated with both gene amplification and the kdr target-site mutation. In this species, gene amplification was also associated with a decreased propensity to move from senescing leaves to fresh leaves at low temperature. Housefly genotypes possessing the identical kdr mutation were also shown to exhibit behavioural differences in comparison with susceptible insects. In this species, resistant individuals showed no positional preference along a temperature gradient while susceptible genotypes exhibited a strong preference for warmer temperatures.&nbsp

Laboratory bioassays applying the neonicotinoid insecticides imidacloprid, acetamiprid and nitenpyram against clones of the peach-potato aphid Myzus persicae (Sulzer) demonstrated that these compounds effectively circumvent the known carboxylesterase, modified acetylcholinesterase (MACE) and knock-down (kdr) insecticide resistance mechanisms in this species. However, some clones showed cross-tolerance (up to 18-fold) of these compounds relative to susceptible standards. A survey assessing the frequency of neonicotinoid tolerance in M persicae in the UK, based on samples collected from the field and glasshouses between 199711 and 2000, showed that such tolerance is still rare. Experiments on neonicotinoid-susceptible and -tolerant populations of M persicae under simulated field conditions in the laboratory showed that, although the latter were well controlled by imidacloprid applied at recommended application rates, they were more likely to survive and reproduce when this compound was applied at lower concentrations. Such conditions are probably periodically present in imidacloprid-treated field and glasshouse crops. Selection favouring tolerant forms of M persicae could lead to increases in their frequency and the evolution of more potent resistance to neonicotinoids. (C) 2003 Society of Chemical Industry.

Advances in understanding insecticide resistance in the peach-potato aphid, Myzus persicae (Sulzer), at the genotypic, biochemical and molecular levels have led to rapid and precise methods for the detection of several resistance mechanisms (elevated carboxylesterase, modified acetylcholinesterase or MACE, and knockdown resistance or kdr) in individual insects, and for monitoring their frequencies over space and time. This paper summarises the results of two long-term surveys of resistance dynamics in M persicae in England, based on samples collected directly from field and glasshouse crops or from four 12.2-m suction traps. The study showed marked fluctuations in resistance frequencies that probably reflect the counteracting forces of selection imposed by insecticides for aphids possessing more copies of esterase resistance genes, and selection against these forms when insecticide use is relaxed. There is growing evidence that several different resistance mechanisms in M persicae have associated fitness costs. In the case of esterase and MACE, these costs are apparently strong enough to effect a decline in resistance frequency over winter, and a more prolonged decline over successive cropping seasons when aphid numbers are insufficient to trigger intensive chemical applications. Changes in the overall frequency of resistance genotypes may also be influenced by the predominance of year-round parthenogenesis in M persicae in the UK, leading to non-random associations between mechanisms and selection operating on clonal lineages rather than individual genotypes.

The voltage-gated sodium channel is the primary target site of DDT and pyrethroid insecticides, and point mutations in the domain II region of the channel protein have been implicated in the knockdown resistant (kdr ) phenotype of several insect species. Here, we report that one of these mutations, a leucine-to-phenylalanine replacement in transmembrane segment IIS6, is also found in certain insecticide-resistant clones of the peach-potato aphid, Myzus persicae. The mutation was present in four clones with amplified E4 esterase genes, but was absent from both susceptible clones and those with amplified FE4 genes. The inferred presence of kdr-type resistance in the four E4 clones was subsequently confirmed by bioassays that showed this to be the primary mechanism of resistance to deltamethrin and DDT, although the esterase-based mechanism also contributes to the overall level of deltamethrin resistance. The kdr mutation on its own conferred 35-fold resistance to deltamethrin and this was enhanced up to 540-fold when it was present in a high (E4) esterase background. The esterase (FE4) mechanism was far less effective without the kdr mutation, conferring just 3-4-fold resistance to deltamethrin. These findings, and the linkage disequilibrium of the kdr mutation within clones overproducing the E4 esterase, have important implications for the evolution of resistance in this insect and for the use of pyrethroid sprays in the management of M. persicae populations in the field.

Termites were sampled using randomized soil pits in 64 cropping plots, each 25 x 25 m, forming an experimental agrisilvicultural system in both a 6- and an 18-year-oldTerminalia ivorensisplantation, in which canopy cover, crop, cropping system and land preparation were the principal treatment variables. The treatments were established in April 1995 and sampling was carried out in November 1995, February 1996 and July 1996. A total of 82 termite species were found, of which 67 were soil-feeders. Overall termite abundance and the abundance of soil-feeders increased between November 1995 and July 1996, reaching a mean of nearly 6000 m-2. Pooling termite data from these sampling dates, in the old plantation, the high canopy cover treatment (192 stems ha-1) had a greater abundance of termites, compared with the low canopy cover treatment (64 stems ha-1) and this effect was independent of crop type (plantain or cocoyam), cropping system (single stands or mixed crops) and land preparation (mulch retained or burned, plantain only). The young tree plantation (same tree densities as in the old plantation) showed no significant difference in termite abundance between high and low canopy (levels of tree foliage) densities, though the high canopy sheltered a greater number of termites. Analysis of covariance showed that crop yield (both plantain and cocoyam) was not directly linked to the abundance of all termite populations, but that the cocoyam yield was positively correlated with the abundance of soil-feeding termites (the majority in the assemblage) in the young plantation. This may be due to the beneficial conditioning of soil resulting from the foraging and construction activities of soil-feeders.

The well-established carboxylesterase-based resistance to insecticides in Myzus persicae Sulzer has recently been accentuated by the appearance of aphids with a modified acetylcholinesterase (MACE) insensitive to pirimicarb and the novel aphicide, triazamate. This target site resistance mechanism was found in M. persicae from crops in the UK for the first time in 1996, together with especially large proportions of aphids with R2 and R3 levels of carboxylesterases, a combination that was associated with serious insecticide failures. This paper describes the incidence of both mechanisms and discusses the implications for future recommendations for aphid control in the UK.

▪ Abstract We discuss methods using stimuli to manipulate behavior of a pest for the purpose of protecting a valued resource. The methods are divided into two categories: those that manipulate behavior over a long distance, e.g. volatile chemicals, visual, and auditory stimuli, and those that manipulate behavior at a short distance (>1 cm), e.g. involatile chemicals. Particular emphasis is placed on methods that have been developed through studies of pest behavior and on combining stimuli to increase efficacy. Future prospects for behavioral manipulation methods in pest management are discussed.

Most evolutionary processes, particularly those involved in speciation, are difficult to observe in nature because, in many cases, they probably occur over a time period that is not conducive to direct observation, and also because one usually knows little about the process of the change to be able to recognize that it is actually occurring. Thus, most evolutionary processes are usually studied by identifying closely related taxa, characterizing their differences and their genetic bases and attempting to construct some plausible explanation as to the process of change from one taxon to another.

Apterous aphids need to move from ageing to younger leaves in order to survive UK winters. This behaviour was studied at low temperatures in field and laboratory trials using Myzus persicae (Sulzer) clones representing all five recognized categories of esterase-based insecticide resistance found in UK populations. Both studies showed that the tendency of aphids to move from deteriorating leaves was inversely related to their insecticide resistance level. This maladaptive behaviour associated with greater insecticide resistance could lead to increased risks of aphids becoming separated from plants after leaf fall, and subsequent death from starvation when adverse cold and wet conditions prevent return. Revertant clones, that had spontaneously lost extreme resistance to insecticides by ceasing to express their amplified esterase genes, tended to show similar behaviour to aphids that had retained their high resistance phenotypes. This implies that rates of movement were not related directly to esterase production.

Chemicals are involved in mediating a wide range of insect behaviors, from communication between conspecific individuals to the recognition of specific features of the environment, such as a food source. Anyone who has observed the effect of a chemical on the behavior of an insect cannot fail to be impressed by the apparent power of the chemical. Metcalf and Metcalf (1992) related how their interest in chemical ecology was stimulated upon observing the extraordinary response of the oriental fruit fly to the plant kairomone methyl eugenol. “We vividly recall walking into our bedroom where a handkerchief with a trace of methyl eugenol was left, to find a screened window several meters away literally black with bemused Dacus dorsalis males.”

Background Myzus persicae is a globally important aphid pest with a history of developing resistance to insecticides. Unusually, neonicotinoids have remained highly effective as control agents despite nearly two decades of steadily increasing use. In this study, a clone of M. persicae collected from southern France was found, for the first time, to exhibit sufficiently strong resistance to result in loss of the field effectiveness of neonicotinoids. Results Bioassays, metabolism and gene expression studies implied the presence of two resistance mechanisms in the resistant clone, one based on enhanced detoxification by cytochrome P450 monooxygenases, and another unaffected by a synergist that inhibits detoxifying enzymes. Binding of radiolabeled imidacloprid (a neonicotinoid) to whole body membrane preparations showed that the high affinity [3H]-imidacloprid binding site present in susceptible M. persicae is lost in the resistant clone and the remaining lower affinity site is altered compared to susceptible clones. This confers a significant overall reduction in binding affinity to the neonicotinoid target: the nicotinic acetylcholine receptor (nAChR). Comparison of the nucleotide sequence of six nAChR subunit (Mpα1-5 and Mpβ1) genes from resistant and susceptible aphid clones revealed a single point mutation in the loop D region of the nAChR β1 subunit of the resistant clone, causing an arginine to threonine substitution (R81T). Conclusion Previous studies have shown that the amino acid at this position within loop D is a key determinant of neonicotinoid binding to nAChRs and this amino acid change confers a vertebrate-like character to the insect nAChR receptor and results in reduced sensitivity to neonicotinoids. The discovery of the mutation at this position and its association with the reduced affinity of the nAChR for imidacloprid is the first example of field-evolved target-site resistance to neonicotinoid insecticides and also provides further validation of exisiting models of neonicotinoid binding and selectivity for insect nAChRs.

More than twice the number of mated female Hessian flies,Mayetiola destructor (Say) entered a zone within 1 cm of a paper strip treated with one plant equivalent (PE) of a chloroform extract of wheat foliar waxes compared to a strip treated with solvent only; females also stayed six times longer and laid 10 times more eggs on the strip treated with the wheat extract. Column chromatographic fractionation of the wheat extract and application of these fractions onto filter paper strips showed four fractions elicited significant numbers of eggs to be laid. Single, binary, and tertiary combinations of three of these fractions (two of the four fractions apparently contained similar compounds) were tested. The greatest numbers of eggs were laid on strips treated with the tertiary combination or the binary combination conaining the two most active fractions (3 and 6); three times the number of eggs were laid on strips treated with this binary combination than the sum of eggs laid on strips treated with these two fractions separately. A comparison of grasses and their extracts showed female Hessian flies laid greater numbers of eggs on wheat or rye than on barley or oat. Fractionated barley and oat extracts were tested for activity as for wheat, and a similar pattern was observed, i.e., the greatest numbers of eggs were laid on fractions 3 and 6. Dose-response tests, using these two fractions of wheat, barley, or oat showed the same threshold of activity for fraction 3 for all three extracts, i.e., 2 PE. In contrast, fraction 6 of wheat was active at the lowest dosage tested, 0.25 PE, while the same fraction of either barley or oat was not active until tested at a dosage of 2 PE. It appears that (at least) two chemicals in the foliar waxes of these grasses influence ovipositional behavior of female Hessian flies. Furthermore, given the similar foliar chemistry of these grasses and the strong synergistic interaction between fractions 3 and 6 shown for wheat extract, it is likely that the ovipositional preferences exhibited by female Hessian flies towards these grasses may be explained by quantitative differences in the amount(s) of the active chemical(s) in their respective fraction 6 (most polar fraction tested).

Wheat is the most widely cultivated plant in the world, providing more than 20 % of the food calories consumed [1]. The Hessian fly, Mayetiola destructor (Say), (Diptera: Cecidomyiidae), is one of the most destructive pests of wheat and is found in most of the major wheat-growing areas of the world [2]. Due to the feeding habit of the larva and the type of damage it produces, early infestations by Hessian fly are extremely difficult to detect or predict. Female Hessian flies are known to produce a sex pheromone that elicits upwind flight by males [3] and, given the widespread use of synthetic sex pheromones in pest management programs [4], it is very likely that this sex pheromone could find great utility in controlling this pest. As well as containing a large number of pest species, the family Cecidomyiidae is of evolutionary interest because of its rapid rate of species formation relative to a lesser rate of speciation in related families of Diptera [5]. We report here the first identification of a cecidomyiid sex pheromone, that of the Hessian fly, as (2S)(E)-10-tridecen-2-yl acetate (Fig. 1). The crude sex pheromone was obtained by dissecting the terminal segments of the ovipositors of female Hessian flies, and extracting them in pentane. The activity of extracts, fractions of extracts, and synthetic chemicals was determined

Biosynthesis of the major sex pheromone components of the obliquebanded leafroller, (Z)- and (E)-11-tetradecenyl acetates, is shown to proceed by Δ11 desaturation of myristate as in the related redbanded leafroller. A comparison between the amounts of deuterium label incorporated into the pheromone components from labelled myristic, palmitic and stearic acids gave a higher level of incorporation for the shorter chain acids, suggesting that Δ11 desaturation is a faster process than 2 carbon chain-shortening by β-oxidation.

Toutes les liaisons Ge-Ge et Ge-H sont clivees dans les reactions des polygermanes ou des silylgermanes avec Co 2 (CO) 8 . Ge 2 H 6 donne (μ 4 -Ge)[Co 2 (CO) 7 ] 2 et Ge 2 Co 6 (CO) 20 . Me 2 Si(GeH 3 ) 2 donne Ge 2 Co 6 (CO) 20 avec un rendement eleve. Etude RX de Ge 2 Co 6 (CO) 19

The olfactory response from male pheromone sensitive sensilla was investigated in the endemic New Zealand brownheaded leafrollers Ctenopseustis obliquana (Walker) and C. sp. ‘ropeana' (Lepidoptera, Tortricidae). The responses from 281 sensilla from the parental strains and from both the reciprocal crosses, including F1, F2 and maternal and paternal backcrosses were recorded, and statistically analysed using a multivariate analysis. In males of both the parental strains, a large amplitude cell responded to the main pheromone component of the conspecific female, in C. obliquana (Z)‐8‐tetradecenyl acetate (Z8–14:OAc) and in C. sp ‘ropeana' (Z)‐5‐tetradecenyl acetate (Z5–14:OAc). Both male types also possessed a small amplitude cell, which in C. obliquana responded weakly to Z5–14: OAc and tetradecyl acetate (14: OAc), and in C. sp ‘ropeana' responded to Z8–14: OAc. The responses from the different types of hybrid males were more variable than the responses from parental males. A main pattern could, however be seen, corresponding with the expected pattern in a sex‐linked inheritance on the Z‐chromosome of a C. sp ‘ropeana' type dominant genetic factor. The more pronounced variation in the hybrids could not be explained by this model, and might be due to the involvement of additional genes. Liaison avec le chromosome Z de l'heredite des reponses olfactives a la composition de la pheromone sexuelle chez deux tordeuses: Ctenopseustis obliquana et C. sp. ‘ropeana' Les reactions olfactives des sensilles mâles sensibles aux pheromones ont ete examinees par enregistrement de l'extremite de la sensille chez les tordeuses C. obliquana Walker et C. sp. ‘ropeana'. Les enregistrements ont porte sur 281 sensilles des lignees parentales et des croisements reciproques de F1, F2 et de croisements en retour maternel et paternel. Les resultats des enregistrements d'une sensille ont ete soumis a une analyse en composantes principales. Chez les mâles de chaque lignee parentale un seul type physiologique de sensille a ete decouvert; une cellule repond par un pic grand au principal constituant de la pheromone femelle conspecifique. (Z)‐8‐acetate tetradecenyl (Z8–14:OAc) pour C. obliquana, et (Z)‐5‐acetate tetradecenyl (Z5–14:OAc) pour C. sp. ‘ropeana'. Une seconde type de cellule dans les sensilles des deux especes de mâles presente un pic petit pour Z5–14: OAc et pour l'acetate tetradecyl (14: OAc) chez C. obliquana, et pour C. sp. ‘ropeana' au Z8–14:OAc. Les reponses des sensilles des differents types de mâles hybrides sont plus heterogenes que celles des sensilles de leurs peres. Un schema general pourrait cependant etre decele, correspondant au schema prevu avec une heredite d'un facteur dominant liee au sexe sur le chromosome Z de C. sp. ‘ropeana’. La variation plus accentuee chez les hybrides ne peut etre expliquee par ce modele, et pourrait impliquer des genes additionnels. 1989 The Netherlands Entomological Society (Less)

GeMe 2 H 2 reacts under mild conditions with [{Co 2 (CO) 7 } 2 Ge] to replace one bridging CO and give [Co 4 (CO) 13 Ge(GeMe 2 )]. GeH 4 similarly yields a trace of [Co 6 (CO) 20 Ge 2 ], which may be made in high yield from [Co 2 (CO) 8 ] and Ge 2 H 6 or Me 2 Si(GeH 3 ) 2 . Spectroscopic evidence suggests structures of linked GeCo 2 triangles.

(Z)-5-Tetradecenyl acetate and tetradecyl acetate were identified as sex pheromone components of an unnamedPlanotortrix leafroller moth species found onAvicennia resinifera (mangrove). An equal mixture of the two compounds used as bait gave field trap catches at least as good as those baited with caged virgin females. Traps baited with the two chemicals caught malePlanotortrix moths in a mangrove swamp not previously found to host the unnamedPlanotortrix species. Adults of the unnamedPlanotortrix species and of the greenheaded leafroller,Planotortrix excessana are morphologically indistinguishable. The sex pheromone ofP. excessana has been found previously to be a mixture of (Z)-S-tetradecenyl acetate and tetradecyl acetate, and this means that the two species may now be distinguished by sex pheromone differences.

Ctenopseustis obliquana females collected from Christchurch were found to produce a mixture of (Z)-5-tetradecenyl acetate and tetradecyl acetate in their sex pheromone gland, in contrast toC. obliquana from Auckland which produce an 80∶20 mixture of (Z)-8-tetradecenyl acetate and (Z)-5-tetradecenyl acetate. This identification has been made on the basis of instrumental and chemical analyses. Antennae of maleC. obliquana from Christchurch gave a maximal electroantennogram response to (Z)-5-tetradecenyl acetate. A field trapping program in Christchurch using combinations of synthetic (Z)-5-tetradecenyl acetate and tetradecyl acetate caughtCtenopseustis males equally well if the latter chemical was present or absent. No males were caught in traps baited with the Auckland-type pheromone. In Alexandra,Ctenopseustis males were caught in traps baited with Auckland-type pheromone and not in traps baited with Christchurch-type pheromone. This phenomenon is ascribed to the existence of sibling species within the describedC. obliquana.

Experiments were done on commercial potato crops in the UK to investigate the effect of different insecticide sequences on the control and insecticide resistance status of Myzus persicae (Sulzer). The work was done to provide field validation of similar laboratory studies done in ‘field simulators’. To ensure adequate aphid populations and to influence the initial resistance status of the aphid population, cultured M. persicae from a clone of known resistance status (esterase R1, kdr heterozygote, non-MACE (modified acetylcholinesterase)) were inoculated into both experiments. Two-spray programmes starting with λ-cyhalothrin (a pyrethroid insecticide) gave poor control in comparison with programmes starting with pirimicarb (a carbamate insecticide) or pirimicarb-containing mixtures. This concurred closely with the results obtained from single applications in field simulator studies. Treatment sequences containing pymetrozine (a pyridine azomethine insecticide) were also effective, though slower-acting. This again concurs with field simulator studies. The proportions of aphids carrying different resistance mechanisms were largely unaffected by treatment in these experiments. The implications of these results for field control strategies are discussed. Copyright © 2006 Society of Chemical Industry