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We consider using non-host plants that express both a toxin and oviposition deterrence for to increase stability for insect resistance management. The two traits reinforce each other ecologically. We used a two-gene model to evaluate this combination of traits. When toxin resistance was recessive or partially recessive, even moderate levels of oviposition deterrence extended time to resistance. When sensitivity to oviposition deterrence started at a low frequency (0.001) selection pressure from the toxin caused the frequency of the gene for sensitivity to oviposition deterrence to increase and the time to resistance was extended beyond the 150-y timeline of the simulations. Even in the worst-case scenario, when toxin resistance was dominant, oviposition deterrence extended time to resistance up to 150 y. The genes for toxin and sensitivity to oviposition deterrence support each other ecologically to prevent resistance from developing to either trait. This creates a more stable insect resistance management strategy.

Entomopathogenic nematodes of the family Steinernematidae and their mutualistic bacteria (Xenorhabdus spp.) are lethal endoparasites of insects. We hypothesized that growth of the nematode’s mutualistic bacteria in the insect host may contribute to the production of cues used by the infective juveniles (IJs) in responding to potential hosts for infection. Specifically, we tested if patterns of bacterial growth could explain differences in CO2 production over the course of host infection. Growth of Xenorhabdus cabanillasii isolated from Steinernema riobrave exhibited the characteristic exponential and stationary growth phases. Other non-nematode symbiotic bacteria were also found in infected hosts and exhibited similar growth patterns to X. cabanillasii. Galleria mellonella larvae infected with S. riobrave produced two distinct peaks of CO2 occurring at 25.6–36 h and 105–161 h post-infection, whereas larvae injected with X. cabanillasii alone showed only one peak of CO2, occurring at 22.8–36.2 h post-injection. Tenebrio molitor larvae infected with S. riobrave or injected with bacteria alone exhibited only one peak of CO2 production, which occurred later during S. riobrave infection (41.4–64.4 h post-infection compared to 20.4–35.9 h post-injection). These results indicate a relationship between bacterial growth and the first peak of CO2 in both host species, but not for the second peak exhibited in G. mellonella.

Pheromone production in virgin females of Heliothis virescens (F.) (Lepidoptera: Noctuidae) peaked between the fourth and seventh hours of scotophase on the second, third, fourth and fifth days following eclosion. The highest peak (186 ng) occurred on day 3 after eclosion. Z-11-Hexadecenal comprised the highest proportion of seven components in the pheromone glands. Disproportionately higher amounts of hexadecanal and Z-11-hexadecenol occurred during photo-phase and other periods when low quantities of total pheromone were recorded. Mating suppressed pheromone production which remained low until 48 h after mating. Coupling females with males mated three times previously or with 6-day-old males was less effective in causing a drop in pheromone content which peaked again 24 h after mating. This suggests the transfer of a male factor, a pheromonostatic factor, that suppresses pheromone production in mated females and that the factor from older and previously mated males is less effective.

Capture of Rhyzopertha dominica in pheromone-baited traps located many kilometers away from grain storage suggests that this species may be exploiting non-grain food sources. To investigate the potential for survival of this species on alternative hosts in the absence of grain, we conducted no-choice feeding assays with twigs and seeds of trees, and seeds of grasses, forbs, and shrubs, commonly encountered on Kansas prairie landscapes where R. dominica has been captured. In addition, R. dominica development and progeny production were assessed on seeds that adults were able to survive on for at least two weeks. Adult survival was poor on grass and forb seeds, although 13.4% of individuals survived on Elymus canadensis, Canada wildrye, seeds after two weeks, compared with 80.3% on Triticum aestivum, wheat, and 0.0% survival in the absence of food. Beetles readily tunneled into twigs from a wide range of tree species, but survival was generally low. A few individuals survived up to four weeks on Gleditsia triacanthos, honey locust. In contrast, bioassays showed that R. dominica could survive and reproduce on damaged seeds (acorns) of six species of oak, but not on undamaged seeds. For example, survival was 95.8% on damaged Quercus muehlenbergii, chinquapin oak. A survey of acorns at the original field collection site showed that the majority of the acorns on the ground had been cracked or bored into by insects and small mammals. Furthermore, we recovered three R. dominica adults from acorns collected in the field and held in sealed containers in the laboratory. These findings suggest that R. dominica populations in Kansas can persist on wild acorns when grain is not available.

SUMMARYPotential hosts for infective juveniles of entomopathogenic nematodes can vary considerably in quality based on the characteristics of the host species/stage, physiological status (e.g. stress, feeding on toxins), and infection status (heterospecific or conspecific infection). In this study, we investigated responses of the entomopathogenic nematodeSteinernema riobraveto hosts (Galleria mellonellaorTenebrio molitor) that were previously parasitized with conspecifics or injected with the nematode-symbiotic bacterium,Xenorhabdussp., to determine if there is a preference for previously parasitized/injected hosts and when this preference might occur. In no-choice bioassays, the number of juveniles infecting both host species decreased with increasing time post-infection. However, infective juveniles continued to infect previously parasitized hosts up to 72 h. Significant preference was exhibited byS. riobravefor 24 h post-infectionG. mellonellalarvae over uninfected, and by 24 h post-injectionG.mellonellalarvae over 48 h post-injection larvae. No significant preference was exhibited byS. riobraveforT. molitorhosts previously parasitized with conspecifics or those injected with bacteria in any treatment combination. Such preference for, or continued infection of parasitized insects, has the potential to impact nematode efficacy.

Persistence of stored-product insects in hidden refugia and their subsequent movement into stored commodities resulting in product infestation contributes to their pest status and represents a potential target for biological control agents. Entomopathogenic nematodes have not been previously tested against stored-product insects in environments such as empty grain bins or food processing and warehouse facilities, but their eVectiveness at Wnding and infecting hosts in other cryptic habitats has been demonstrated. In laboratory bioassays, Steinernema riobrave reduced survival of red Xour beetle, Tribolium castaneum, larvae, pupae and adults from 77.9 § 3.2% in the controls to 27.4 § 2.5% in treatments. Temperature (25 and 30 °C) and relative humidity (43, 56–57, 75, and 100%) did not signiWcantly inXuence S. riobrave eYcacy in this experiment. Field trials simulating empty grain bin treatments were conducted using red Xour beetle and the Indian meal moth, Plodia interpunctella. Total survival of mixed stages (larvae, pupae and adults) of T. castaneum was 42% of that in the control and total survival of mixed stages of P. interpunctella was 27% of the control. Larval stages were the most susceptible to S. riobrave for both insect species with P. interpunctella larvae having 99% mortality and T. castaneum larvae having 80% mortality. S. riobrave shows promise as a biological control agent for stored-product insects, particularly Indian meal moth, but further studies looking at combinations of treatments may further enhance eYcacy. Published by Elsevier Inc.

The flight activity of lesser grain borer, Rhyzopertha dominica F. (Coleoptera: Bostrichidae), was monitored at two Foundation seed wheat warehouses during the 2003 and 2004 field seasons, using pheromone-baited Lindgren funnel traps positioned indoors and outdoors. General stored-product insect activity was also monitored using unbaited sticky traps positioned inside the warehouses around overhead doors. Pheromone-baited traps were useful for monitoring R. dominica activity, however insect captures decreased when lures were not changed weekly. Flight peaks were documented in early May and again from September through October, and insect captures inside warehouses correlated with timing of outdoor captures. Multiple regression analyses showed that slightly more than half of the variability in R. dominica captures could be explained by mean ambient air temperature and wind speed during the 2 h preceding sunset. Stored-product Coleoptera captured on unbaited glue boards around overhead doors included Ahasverus advena, Cryptolestes ferrugineus, R. dominica, Sitophilus oryzae, Tribolium castaneum, Trogoderma variabile, and Typhaea stercorea. Door gaskets significantly reduced the number of insect captures on glue boards placed around the overhead doors, and generally restricted their entry to ground level. These studies demonstrated that outdoor pheromone-baited traps are effective monitoring tools for determining when grain-handling facilities are most susceptible to infestation and that exclusion may be an effective component of a pest management program.

Dispersal of the southwestern corn borer,Diatraea grandiosella Dyar, was examined by release and recapture of dye-marked adults and by capture of feral adults in and around 50-ha center pivot irrigated Þelds of Bacillus thuringiensis (Bt) maize. Pheromone and blacklight traps were used to capture the adults. In 1999, 2000, and 2001, a total of 177, 602, and 1,292 marked males, and 87, 231, and 1,045 marked females were released in four irrigated Bt maize Þelds, respectively. Recapture beyond release point was 2.13, 6.17, 3.16, and 17.91% for males and 0, 0, 2.23, and 4.18% for females in the four Þelds, respectively. One male was recaptured over native vegetation outside the Þeld perimeter, and one was caught in a neighboring maize Þeld, 457 m from the release point. An exponential decay function explained recapture of marked adults across the dispersal distance. More than 90% of adults were recaptured within 300 m of the release point. Large numbers of feral adults were captured throughout the study Þelds and over native vegetation between Þelds. The feral adult dispersal could be described with a linear model. Virgin females (38% marked and 14% feral) were captured throughout the study Þelds. The recapture of marked insects suggests that the dispersal was limited. However, capture of feral adults throughout Bt maize Þelds indicates that the actual dispersal may be more extensive than indicated by recapture of marked adults. Potential refuge sources for the feral adults were 587Ð1,387 m from the edge of the Þelds. There seems to be some dispersal of D. grandiosella from the nontransgenic "refuge" Þelds into the transgenic Þelds, which may allow for some genetic mixing of the Bt-resistant and -susceptible insects to help suppress potential evolution of pest resistance to transgenic maize. However, it is not clear whether the dispersal recorded in this study is sufÞcient to support the current resistance management strategy for corn borers.

Entomopathogenic nematodes (Nematoda: Heterorhabditidae and Steinernematidae) are commonly used biological control agents of insects in cryptic habitats, but their potential for suppressing stored-product insects in these habitats has not been explored previously. Here, we provide data from the first step in a program to evaluate entomopathogenic nematodes in the genus Steinernema as biological control agents of stored-product pests by determining their pathogenicity to some of the major stored-product pest species. When evaluated against larvae, pupae and adults of six pest species (Plodia interpunctella, Ephestia kuehniella, Oryzaephilus surinamensis, Tenebrio molitor, Tribolium castaneum, and Trogoderma variabile), and the adults of two additional pest species (Sitophilus oryzae and Rhyzopertha dominica), Steinernema riobrave was either the most pathogenic or of similar pathogenicity compared to S. carpocapsae and S. feltiae. A dose of 10 infective juveniles of S. riobrave caused 80% or higher mortality against larvae of P. interpunctella, E. kuehniella, T. castaneum, and O. surinamensis, pupae of T. castaneum and T. molitor, and adults of T. molitor and the two moth species. All stages of Trogoderma variabile exhibited 70% or higher mortality. Adults of S. oryzae and R. dominica exhibited low susceptibility with 15% and 35% mortality, respectively. On the basis of these results, S. riobrave was selected for further evaluation under more field-like conditions.

Feeding in codling moth caterpillars was induced by the general glutamate receptor activator monosodium glutamate (MSG) and by three different mGluR agonists known to specifically stimulate different classes of vertebrate metabotropic glutamate receptors, including: (1S,3R)-ACPD, which stimulates group I mGluRs (2R,4R)-APDC, which stimulates group II mGluRs and L-AP4, which stimulates some group III mGluRs. Experiments exposing larvae to combinations of specific mGluR agonists and specific signal transduction modulators suggest that each tested mGluR uses a different signaling pathway. First, feeding stimulatory effects of (1S,3R)-ACPD were abolished by phospholipase C inhibitor, U 73122, but remained unaffected by adenylate cyclase activator, NKH 477, or phosphodiesterase inhibitor, Rolipram. Second, (2R,4R)-APDC induced feeding in presence of U 73122 or Rolipram, but lost its feeding stimulatory effects in presence of NKH 477. Finally, L-AP4 did not induce feeding in presence of Rolipram, but maintained its feeding stimulatory effects in presence of U 73122 or NKH 477. The activity of the general glutamate receptor activator MSG was abolished by NKH 477, and Rolipram. U 73122 did not affect MSG-stimulated feeding. These results suggest that transduction of MSG taste in the codling moth caterpillar relies mostly on cAMP-dependent signaling pathways.

Dispersal of European corn borer, Ostrinia nubilalis Hubner was examined by release and recapture of the dye marked adults and by capture of the feral adults in and around the large 50 ha center pivot irrigated fields of Bacillus thuringiensis (Bt) maize. Pheromone and black light traps were used to catch the adults. In 1999, 15 094 marked males and 7993 marked females were released, and in 2001, 13 942 marked males and 9977 marked females were released. In 1999, maximum mean recapture beyond the release point was 1.95 and 1.67% for males and females, but in 2001, the recapture rate was 9.97 and 4.37% for males and females. Few males (3.8%) and females (2.07%) were recaptured in neighbourhood maize fields. An exponential decay function explained recapture of marked adults across the dispersal distance. More than 90% of marked adults were recaptured within 300 m of the release point. Large numbers of feral adults were captured throughout the study fields. Feral adult dispersal could be fitted to a linear model. Virgin females (20% marked and 8% feral) were captured throughout the study fields. The recapture of marked insects suggests that the dispersal was limited. However, capture of feral adults throughout Bt-maize fields indicate that the actual dispersal may be more extensive than indicated by recapture of marked adults. Potential refuge sources for the feral adults were 587-1387 m from the edge of the study fields. It is not clear if the dispersal recorded in this study is extensive enough to support the current resistance management strategy for corn borers. There appears to be some dispersal of corn borers from the non-transgenic refuge fields into the transgenic fields that allows some genetic mixing of the two populations.

Experiments were undertaken to determine the potential for using rubidium chloride (RbCl) or cesium chloride (CsCl) to mark southwestern corn borer, Diatraea grandiosella Dyar, for use in applied ecological studies. Maize, Zea mays L., plants were sprayed with aqueous solutions of RbCl or CsCl at rates of 100, 1000, or 10,000 μg/g and inoculated with D. grandiosella neonates. Rubidium and cesium were successfully absorbed and translocated in maize plants. There were only a few minor effects of the treatment on maize or on southwestern corn borers. Rb and Cs were detected in plants, but not in insects, by using flame atomic absorption spectrophotometry. Graphite furnace-atomic absorption spectrophotometry (GF-AAS) and neutron activation analysis (NAA) allowed identification of Rb and Cs in adults. Rb and Cs were detected by GF-AAS in feral unmarked adults, and they contained higher levels of Rb than Cs. Males and females contained similar amounts of Rb, but Cs levels were higher in males than in females. Adults recovered from field maize treated with 1000 μg/g Cs had higher levels of Cs than did those from untreated plants. Using NAA, neither Rb nor Cs was detected in adults recovered from greenhouse-grown untreated maize. Males and females recovered from maize treated with 1000 μg/g RbCl and CsCl contained similar amounts of Rb, but females contained more Rb than Cs. We conclude that application of 1000 μg/g RbCl or CsCl on plants is effective in marking adults of D. grandiosella with Rb or Cs and would be useful for mark–recapture dispersal studies.

Southwestern corn borers, Diatraea grandiosella Dyar, were reared on a control meridic diet and diets that incorporated rubidium chloride (RbCl) or cesium chloride (CsCl) at the rate of 1000 μg/g (1 g/liter of wet diet) to evaluate the effects on biology of D. grandiosella and to determine whether the resulting adults are marked with the rubidium (Rb) and cesium (Cs) physiological markers. The effects of RbCl and CsCl on survival, diet consumption, larval and pupal weight, developmental time, adult deformity, adult longevity, fecundity, and adult dry weight were generally minor and seldom reached statistically significant proportions. Males and females mated successfully when paired in different combinations across treatments. Graphite furnace atomic absorption spectrophotometer and neutron activation analysis were both effective in detecting Rb and Cs in male and female adults reared on RbCl and CsCl diets. Rb and Cs concentrations of males and females reared on RbCl and CsCl diets were above the background levels found in adults reared on the control diet. Rb and Cs can be used as physiological markers to mark D. grandiosella in dispersal experiments.

The mating behavior and developmental reproductive biology of the soybean stem borer Dectes texanus texanus LeConte were studied. Adults live for up to a month, but reach sexual maturity and are able to mate at 5 d of age. At hour-long observation times between 0900 and 1700 hours, no peak time of mating was observed. Females did, however, stridulate more often between 0900 and 1300 hours. Males approach females and tap the surface of the female’s elytra and thorax with their antennae. Subsequently, the male mounts the female, strokes her elytra with his palpi, bends his abdomen, and copulates. Male responses to solvent washes of females suggest the use of a contact sex pheromone. Mature eggs are first observed in virgin female ovarioles at 14 d of age, whereas mated females (8 d old) are able to oviposit just 4–8 d after mating.

The role of semiochemicals in host location by the parasitoid Pteromalus cerealellae (Boucek) was investigated in Y-tube and three-way olfactometers, by measuring responses to stimuli associated with the cowpea weevil, Callosobruchus maculatus. Orientation of mated parasitoid females was measured in response to five stimuli: live virgin female bruchid beetles, solvent extracts of whole body virgin female bruchids, solvent extracts of the oviposition marking pheromone from a glass substrate, previously infested cowpea seeds with adult emergence holes, and uninfested cowpea seeds. All stimuli elicited significantly better responses than those to blank controls. Female parasitoids that had previous exposure to live, virgin beetles and infested seeds exhibited shorter latency and response times to the stimuli than did naive females. Live, virgin female bruchids and whole body solvent extracts of virgin female bruchids elicited the strongest responses. Comparison of responses in a three-way olfactomet...

The courtship behavior of Cephalonomia tarsalis, a solitary semiectoparasitoid of Oryzaephilus surinamensis, was investigated in the laboratory. Courtship behavior includes a series of stereotypic movements. Males play the most active role, executing the majority of courtship action, and females respond with relatively limited observable behaviors. Males typically keep antennae still during encounters with females prior to mounting, which may be correlated with recognition of the female's sexual status. After mounting, males display a series of movements on females, such as antennae touching female's antennae, antennae or mouth touching female's head or thorax, and walking around on female, which may serve to stimulate females towards increased receptivity. Females signal receptivity by assuming a stereotypical posture of remaining stationary, with head down, and antennae still in front of the body. The male then inserts his aedeagus and the pair copulates. After an average of 40.4 s of copulation, females signal the end of copulation by waving the antennae and moving away from the copulation site. Males continue copulating for a short time after females start moving but dismount soon thereafter. After dismounting, the two wasps move away from each other immediately, and they typically begin grooming. Neither males nor females exhibit mating preference based on mate's mating status in both choice and no-choice tests. The male is polygynous and the mated female can mate multiple times within the first 3 days after starting oviposition. However, female mating frequency does not affect the production of female progeny.

Parasitoids of the Cotesia flavipes complex (C. flavipes and Cotesia sesamiae) are natural enemies of stemboring lepidopteran pests in sub-Saharan Africa. The two species are difficult to differentiate using morphological markers, and a quick, reliable test was sought for their correct identification. After numerous, unsuccessful attempts at developing species-specific monoclonal antibodies that could differentiate between the two species, we were successful in using near-infrared spectroscopy to distinguish the cocoons of the two species with an accuracy of better than 85%. Calibrations were established using partial least squares analysis, enabling identification of cocoons of known species, cocoons from an alternative host, as well as in blind tests. This technology would greatly expedite identification of field-caught insects used to determine ecological parameters and parasitization rates of an individual species.

Male Cephalonomia tarsalis (Ashmead) compete with one another for mates. The behavioral interactions between males for mates occur both on and off females. Males winning the first copulation do not exhibit apparent postcopulatory mate-guarding behaviors, and females accept subsequent copulations with losing males soon after separation. The duration of copulation when a second male is present is shorter than when only one male is present. However, females receive sufficient sperm for their life-time female progeny production in copulations disrupted artificially at 10 s (∼1/5 of the regular copulation duration) under normal noncompetition situations. This suggests that shorter copulations because of male–male competition could still result in adequate sperm transfer. Larger males were not more successful in competition than small males, but male competitive ability decreased with age.

We studied effects of parasitism by two Tiphia species (Hymenoptera: Tiphiidae) on burrowing behavior of their respective scarabaeid hosts and tested the hypothesis that parasitoid alteration of host hormones accounts for the observed behavioral change. In turf field-plots, third-instar masked chafer grubs, Cyclocephala sp., parasitized by native Tiphia pygidialis Allen burrowed to depths of 12-16 cm within 21 d, whereas nonparasitized grubs remained in the upper 4 cm of soil. Grubs bearing an egg or early-instar Tiphia larva were found relatively close to the surface, whereas those with a fourth- or fifth-instar parasitoid were deeper. Experiments in soil-filled, vertical observation chambers confirmed downward movement by parasitized Cyclocephala, and similar response in third-instar Japanese beetle, Popillia japonica Newman, parasitized by Tiphia vernalis Rohwer. Removal of the Tiphia egg from masked chafers was followed by initial downward movement of grubs and then a gradual ascent, suggesting that host behavior is affected both by the venomous sting and feeding by the wasp larva. Significant but inconsistent differences were found in juvenile hormone-III (JH III) titers in hemolymph taken from nonparasitized grubs or grubs parasitized for 1 or 14 d. Topical application of JH III and methoprene acid resulted in grubs moving deeper into the soil, whereas injection of 20-hydroxyecdysone did not affect grub behavior. Failure to dig deeply enough in soil when sampling for parasitized scarab grubs or Tiphia cocoons likely will result in underestimation of parasitism rates.

Scanning and transmission electron microscopy were used to study the morphology and formation of the eggshell in the tarnished plant bug, Lygus lineolaris . Eggs are bean-shaped, with an operculum at the anterior end surrounded by a row of 36–40 respiratory horns. Three micropylar openings are on the operculum, and are sealed in oviposited eggs. The chorion consists of the chorion proper and the innermost chorionic layer. An air layer composed of colonnades is present in the chorion. The innermost chorionic layer is homogeneous and electron lucent. The follicle cells secrete electron dense materials that later coalesced into the reticulated vitelline membrane. This is followed by the deposition of the innermost chorionic layer by the follicle cells. After the primordial innermost chorionic layer is formed, follicle cells at the anterior pole of the oocyte secrete the scaffold for the colonnades in the air layer. Later, the primordial scaffold matrix is redistributed and localized at the lateral and posterior end of the oocyte where it becomes secondarily modified. At the end of choriogenesis, follicle cells at the anterior pole secrete the operculum and respiratory horns.

In vitro catabolism of juvenile hormone (JH) in haemolymph of adult female Cydia pomonella was ascribed mainly to juvenile hormone esterase (JHE) activity. No significant differences were noted between virgin and mated females 0-96 h post-emergence. Changes in JHE activity did not appear dependent upon fluctuations in JH titre; conversely, changes in JHE activity could not explain the changes in JH titres. Maximal JHE activity was recorded at 24 h (331.47 +/- 47.25 pmol/h/microl; 355.93 +/- 36.68 pmol/h/microl, virgin; mated insects, respectively) and preceded the peak in JH titres at 48 h. Topical application of JH II (10 ng-10 microg) or fenoxycarb (50 ng) enhanced JHE activity up to 640 and 56%, respectively. Treatment upon emergence with 10 microg JH II induced enzymic activity for less than 24 h, and when 10 microg JH II or 50 ng fenoxycarb were applied, circulating JH titres returned to control levels within 24 h. Oviposition was highly sensitive to exogenous JH and declined significantly with dosages >100 pg. To allow a degree of oocyte maturation before JH treatment, the hormone was administered at 6, 12, 24, or 48 h post-emergence and/or females were mated. Neither measure "protected" the system; oviposition declined immediately after JH application.

Reproductive characteristics of a northeastern Kansas population of the fritillary Speyeria idalia (Drury) were studied. Hemolymph juvenile hormone (JH) titers, ovarian development, and fat body utilization were monitored weekly in adult females over their entire 1997 flight period, which extended from mid-June to early October. Dissections of female reproductive systems revealed that S. idalia females mate just once, soon after they emerge in mid- to late June. Gas chromatographic-mass spectrometric determinations of juvenile hormone suggested that they undergo a reproductive diapause through mid-August related to the absence of or very low titers of juvenile hormone. Oogenesis and fat body depletion do not commence until late August/early September, soon after which oviposition occurs. The onset of oogenesis coincides with a rapid rise in hemolymph titers of JH I, JH II, and JH III. The predominant juvenile hormone homolog was JH II, but both JH I and JH III exhibited smaller, concomitant peaks. Four fundamentally different lepidopteran reproductive strategies have been recognized based on various reproductive characteristics and the type of gonadotropic hormones used to stimulate oogenesis. Speyeria idalia exhibits a type of reproductive strategy that has not been documented in Lepidoptera, typified by protandry, female monandry, long-lived (>8 wk) females that feed throughout their adult lives, greatly delayed oogenesis that occurs late in adult life, and apparent juvenile hormone control of gonadotropic processes. This reproductive strategy appears to be an adaptation to the phenology of larval host plants, namely coordinating the life cycle with that of the seasonally restricted violets on which larval survival of this monophagous species depends.

Vitellogenin (Vg) concentration was determined in pupal hemolymph of female southwestern corn borer, Diatraea grandiosella (Dyar). Vitellogenin concentration increased significantly with pupal age. Vitellogenin level reached 7 mg/ml on day 7 after pupation. The vitellogenin was separable into 2 apoproteins on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), with molecular weights of 145,000 for apoVg-I and 38,000 for apoVg-II. SDS-PAGE analysis revealed that vitellogenin polypetides in female pupal hemolymph appeared to be identical to those from eggs, but were absent in male and early female pupal hemolymph. A method to quantify vitellogenin by indirect ELISA is described. Results from this study and those of a previous study suggest that juvenile hormone does not have a role in vitellogenesis but does so in choriogenesis.

Rearing of Callosobruchus subinnotatus (Pic) under crowded condition at 30°C and 80% RH produced active males and females. The active individuals emerged later than normal individuals and were lighter in weight. The responses of normal and active males of C. subinnotatus to sex pheromone were compared in electroantennogram (EAG) and olfactometry bioassays. The olfactometry bioassay involved observing males in Y-tubes containing blends of the components of the sex pheromone in one arm and a blank filter paper in the other. Behavioral characteristics of males were analyzed as they walked upwind in the tubes. The latency periods were shorter in active than in normal males. More normal males reached the source and spent more time on the source compared with active males. The normal males clearly demonstrated preference for 2 blends of the sex pheromone containing the (E)-3-methyl-2-heptenoic acid (E32C7) and (Z)-3-methyl-2-heptenoic acid (Z32C7) isomers in the ratio of 75%:25% and 50%:50%, whereas active males showed preference for blends comprising >50% of the Z isomer. The EAG bioassay showed that responses of normal males to female pheromone extracts were twice those of active males.

Laboratory rearing and an enzyme-linked immunosorbent assay (ELISA) were used to identify tobacco budworm, Heliothis virescens (F), and bollworm, Helicoverpa zea (Boddie), eggs collected from cotton fields in Mississippi. Identification of eggs by enzyme-linked immunosorbent assay (ELISA) was consistent with that by laboratory rearing. Significant relationships were detected between percentage eggs identified by rearing and by ELISA for H. virescens ( R 2 = 0.87) and for H. zea ( R 2 = 0.89). Percentage of H. virescens or H. zea detected in the field in pheromone traps was consistent with those detected using rearing and ELISA in late July but different from those in late August. This study shows that the monoclonal antibody-based ELISA provides a reliable, simple, and convenient way to determine the proportion of H. virescens and H. zea eggs collected from cotton fields.

Sex pheromone produced by Callosobruchus subinnotatus females stimulates conspecific males to walk upwind toward the source. Gas chromatographic and mass spectrometric analyses of sex pheromone components and their hydrogenated derivatives suggested that the sex pheromone consisted of two short-chain fatty acids, (E)-3-methyl-2-heptenoic acid (E32C7) and (Z)-3-methyl-2-heptenoic acid (Z32C7). The composition of the sex pheromone was confirmed by electrophysiological and behavioral bioassays with synthetic compounds. A mixture of 5 ng E32C7 and 5 ng Z32C7 elicited a 2.1-mV male EAG response, whereas the solvent control elicited 0.1 mV. Mixtures of the two compounds at various ratios were attractive to males in Y-tube bioassays. A pitfall-type trap equipped with a lure impregnated with 1 ng E32C7 and 1 ng Z32C7 was effective in trapping males. Traps baited with the lure caught 80% of males in a glass aquarium during nighttime and 50% during daytime, whereas control traps (solvent treated) in a separate aquarium caught 20% and 10%, respectively.

The effect of anesthetizing with carbon dioxide, nitrogen, or low temperature on the reproductive behavior and fecundity of Callosobruchus subinnotatus was investigated. Males and females anesthetized with N 2 as virgins had shorter recovery time, copulated earlier, and had shorter mating time than those subjected to CO 2 or low temperature. Exposure of males and females to 2.0 ± 0.5 °C for 10 min had the most profound effect on the recovery periods, copulation time, and duration of mating. Adults anesthetized with CO 2 and low temperature laid fewer eggs than those anesthetized with N 2 . Females were more affected than males by the treatments, except when males were chilled for 10 min, and this prolonged the time for commencement of mating. The mode of anesthesia could affect egg production because vitellogenesis and choriogenesis take place in the imago stage of bruchids.

Factors affecting sex pheromone production and male responses in the bruchid beetle, Callosobruchus subinnotatus (Pic), were studied using electroantennogram (EAG) and behavior assays. Virgin females at emergence already had produced a significant amount of putative sex pheromone. As females grew older, sex pheromone production reached a maximum at age 2 d. Virgin females emitted pheromone throughout the day, but they emitted slightly less during the 2nd half of photophase. Immediately after mating, females produced significantly less sex pheromone than did virgin females of the same age, but older mated females produced similar amounts of pheromone to those of virgin females of the same age. The pygidium is the likely site of sex pheromone production, because extracts of pygidium elicited highest male EAG responses among the extracts of various dissected body parts of newly emerged females. Male EAG responses increased with the male age.

Two monoclonal antibodies (MAbs) specific to tobacco budworm, Heliothis virescens (F), and bollworm, Helicoverpa zea (Boddie), eggs were established. These MAbs were tested against all tobacco budworm or bollworm life stages by enzyme-linked immunosobent assay (ELISA). The MAb for tobacco budworm is specific only to budworm egg and adult female antigens, and the MAb for bollworm is specific only to bollworm egg antigen. Eggs of other lepidopterous species tested by ELISA did not react to the species-specific bollworm or budworm MAbs. Eggs from feral insect populations were tested to determine specificity of MAbs, and no cross-reactivity was observed between bollworm and budworm eggs. This highly species-specific characteristic of MAb for bollworm or budworm eggs can be used to distinguish each of these 2 important pests and, thus, help in insecticide selection decisions and insecticide resistance management.

Various surgical treatments were used to determine the role of the brain, ventral nerve cord (VNC), and corpora cardiaca- corpora allata complex in the reproductive behavior of Heliothis virescens (F.). VNC-transected females mated successfully and exhibited increased egg production after mating, suggesting that an intact VNC is not required for calling, sex pheromone emission, mating, or mating-induced oogenesis. The patterns of increase in egg production in decapitated, virgin females and mated, decapitated females were similar. Allatectomized females called less overall than did the others, but all females called and were able to mate with males. The allatectomized, virgin females produced

Studies were undertaken to determine whether adult males of Heliothis virescens transfer juvenile hormone (JH) to females during copulation, and an in vitro radiochemical assay was used to determine whether mating causes an allatotropic effect, i.e., stimulation of JH biosynthesis by corpora allata (CA). In vitro, CA from 3-day-old mated females synthesized and released approximately 2.5 times total JH as that of CA from comparably aged virgin females. Of the homologues, JH II exhibited significant increase in mated females; JH I also increased but not significantly. JH III remained similar to that of virgin females. This is the first demonstration of an allatotropic effect of mating in moths. In contrast to the female, CA of virgin males did not produce any JH, but accessory sex glands (ASG) in 3-day-old males synthesized small amounts of JH. Immediately after adult emergence, male ASG contained approximately 1.5 ng JH I and II, which increased by 12 h after emergence and remained at this high level up to 54 h after emergence. JH III was barely detected in ASG. JH in ASG of mated male immediately after uncoupling was depleted almost completely, and 24 h later recovered to levels comparable to that of 54-h-old virgin male. Virgin female bursa copulatrix did not contain any JH, but mated female bursa, immediately after uncoupling, had JH at levels comparable to that observed in virgin male ASG. By 6 h after uncoupling, JH levels decreased dramatically in mated female bursa. These data suggest the transfer of JH to females by the male.

A unique chordotonal structure in the fore coxae of adult male and female bruchid beetles, Callosobruchus maculatus (F.) and C. subinnotatus (Pic), is described. The structure is a heavily sclerotized cuticular cone that is recessed within an opening in the medial surface of the coxa. Perpendicular to the cuticular cone is a pair of scolopidial sensilla with bipolar neurons, cap cells, scolopale sheath, and accessory cells. Unlike scolopidia described from other insects, these sensilla have a free distal tip that opens into a crotch in the distal inside surface of the coxa.

Juvenile hormones I, II and III were monitored in hemolymph of pupal and adult stages of various ages of Diatraea grandiosella females. JH III was the predominant homologue followed by JH II, and JH I was rarely detectable. At day 5 after pupation, no JH was detectable. JH titers increased from 7.5 days after pupation to a peak of 24.8 ng ml −1 JH II and 26 ng ml −1 JH III at adult emergence and then declined to low levels by 24 h after emergence. Ovarian development in D. grandiosella parallels changes in hemolymph JH titers, but the role of JH in vitellogenesis is unclear since the time of vitellogenesis initiation has yet to be determined. No apparent vitellogenin deposition was observed in eggs 5 days after pupation. Some oocytes were partially vitellogenic by 7.5 days after pupation and oocytes continued to grow afterwards, but no oocytes were chorionated during the pupal stage. Chorionated oocytes were observed in 24-h-old female moths. Juvenile hormone is essential for chorion formation in this species, because decapitated pupae treated with 10 μ g JH III in corn oil developed chorionated oocytes while decapitated pupae treated with corn oil did not.

The sensilla on the antennae, maxillary and labial palpi, tarsi and ovipositor of adult Callosobruchus maculatus (F.) and C. subinnotatus (Pic) were examined using light and scanning electron microscopy. Six types of antennal sensilla occur in both species. Type 1 are long and have longitudinal ridges and a conspicuous basal socket. These sensilla occur in rings at the distal margin of each antennal segment; the terminal segment bears 2 such rings. Type 2 sensilla are found on all segments and have a well developed basal socket and less conspicuous cuticular ridges. Type 3 sensilla are numerous and found only on flagellar segments. Type 4 sensilla are medium in length and stout. Types 5 and 6 sensilla are short, few, and are found along with type 4 sensilla in groups distally on the distal antennal segments. Types 1 and 2 are sensilla chaetica, type 3 are trichodea, and types 4, 5, and 6 are sensilla basiconica. Sexual dimorphism in numbers of antennal sensilla is observed. Maxillary and labial palps in both species have 3 types of sensilla. Two subtypes in type 3, fluted (3a) and blunt (3b), sensilla are observed in females of both species. Tarsi and ovipositor of both species have 3 types of sensilla each.

Mating and oviposition behaviors were studied inCallosobruchus subinnotatus. Copulation was most frequent during the late scotophase, 2–3 h before onset of photophase. The females were less willing to mate during photophase, which increased the time to initiate mating while decreasing the duration of mating. Females exhibited increased movement prior to mating, resting immediately after mating, and remained stationary for 6 h when oviposition commenced. Multiple mating by both males and females affected the number of eggs laid, duration of mating, and uncoupling time at the end of mating. Females that mated two or three times laid more eggs than females that mated once or more than three times. Females that remainedin copula for less than 18 min showed greater readiness to remate than those that remainedin copula longer. There was a gradual decrease in the number of eggs females could lay with an increase in the number of previous matings by males.

The characteristics of vitellogenin (Vg) and the relationship between Vg production and egg production in the tobacco budworm, Heliothis virescens, were studied. The relationship between Vg production and juvenile hormone (JH) and the impact of mating on Vg and egg production were also investigated. Vg appears in the hemolymph of H. virescens about 6 h after moth eclosion. Vg may be separated into two apoproteins (ApoVg-I and ApoVg-II) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weights were calculated to be 156,065 ± 800 for ApoVg-I and 39,887 ± 323 for ApoVg-II. SDS-PAGE analysis revealed that the female hemolymph Vg polypeptides appear to be identical to those from eggs but are absent in male hemolymph. Vg concentration was significantly higher in mated females than in virgin females of the same age at 48 h after emergence. Rates of egg production increased as Vg production increased; rates of egg production in mated females were significantly higher than those of virgin females at 48, 72, 96, and 120 h postemergence. Vg production is dependent on JH, because hemolymph from decapitated females lacked Vg while that of decapitated females treated with synthetic JH had Vg at levels comparable to similarly aged, normal H. virescens females. Hemolymph JH titers in mated females were significantly higher compared with those in virgin females at all sampling periods. The high JH level in mated females may explain the high Vg and egg production in mated H. virescens. Arch. Insect Biochem. Physiol. 34:287–300, 1997. © 1997 Wiley-Liss, Inc.

Reproduction in moths and butterflies is a dynamic process that is influenced by various endogenous physiological processes and exogenous factors. The Lepidoptera may be divided into four distinct groups based on their gonadotropic hormones and other reproductive and biological characteristics, regardless of phylogenetic relationships. Some species have integrated their reproduction tightly with the endocrine events of metamorphosis, the waxing or waning ecdysteroid levels. Other species rely instead on juvenile hormone (JH), in part or solely. Species of Lepidoptera that rely on JH as the gonadotropic signal also exhibit polyandry. Several mechanisms have been suggested for the occurrence of polyandry, including availability of male-transferred nutrients (gonadotrophic effect), need for additional sperm, and increased genetic variability. We propose an additional reason for polyandry observed in some lepidopterans. If a female remains a virgin, her endogenous gonadotropic signal diminishes, and eggs that have been produced already may be resorbed to increase longevity. During copulation, the male may trigger a neural/humoral response in the female, thus stimulating release of her endogenous gonadotropic signal, JH, and/or inhibiting degradation of the same, whence she matures new eggs. The mating effect appears to act humorally on the cephalic structures in several species. Whether this change in JH titer is due to an effect on synthesis and release by corpora allata only or occurs in conjunction with inhibition of JH degradation is unknown. Arch. Insect Biochem. Physiol. 35:539–558, 1997. © 1997 Wiley-Liss, Inc.

The mechanism involved in bringing about post-coital suppression of pheromone production, pheromonostasis, was studied in the noctuid moth Heliothis virescens. Mating results in a transient suppression in pheromone production, the signal for which appears to originate in the testes and other components of the male's reproductive system. The mating-induced pheromonostasis is due to an ascending signal via the central nervous system that appears to inhibit the release of the pheromonotropin, pheromone biosynthesis activating neuropeptide (PBAN), or other potential pheromonotropic substances, and is not due to a refractoriness in response of the sex pheromone glands to PBAN in the female. A similar mechanism is operative in several species of moths where post-coital pheromonostasis has been observed. Sperm quality is not important for pheromonostasis in H. virescens, because males with apyrene or eupyrene sperm elicit similar pheromonostatic responses. The pheromonostatic activity of the ecdysteroid 20-OH-ecdysone appears to be the result of a direct effect on the sex pheromone glands. © 1996 Wiley-Liss, Inc.

Behavioral and electroantennogram (EAG) assays were used to determine rhythmicity and dynamics of the sex pheromone biology of the bruchid beetle, Callosobruchus maculatus (F.). Beetles were sexually active throughout the photophase. Virgin females entrained to a 16:8 L:D light cycle emitted more sex pheromone during the first half of photophase than during the second half of photophase or during scotophase. Sex pheromone production increased from day 0 to day 3 of adult life, and then decreased as females grew older. Availability of garbonzo beans, one of the larval food and adult oviposition hosts, to females did not stimulate sex pheromone production. Mating resulted in a reduction in post-coital sex pheromone production. Mated females, however, regained attractiveness to males and this attractiveness increased from day 1 to day 3 after first mating when females had been mated at day 0 after emergence. (Z)-3-Methyl-2-heptenoic acid (Z32A) and (Z)-3-methyl-3-heptenoic acid (Z33A), two compounds implicated as sex pheromone components for C. maculatus, both elicited male EAG and behavioral responses in the beetles; however, Z33A elicited larger responses than Z32A. Binary mixtures of the two compounds were more effective than either compound alone.

In intact animal assays, 2-day-old females of Helicoverpa zea injected with 2 pmol synthetic H. zea-pheromone biosynthesis activating neuropeptide (Hez-PBAN) exhibited significant stimulation of pheromone production. In contrast, octopamine did not stimulate pheromone production when injected 30 min before lights off. Additionally, females injected with PBAN and mianserin (an octopamine antagonist) or reserpine, produced significant amounts of pheromone. These results suggest that octopamine may not be involved in regulation of pheromone production in H. zea. In abdomen incubation assays, synthetic Hez-PBAN stimulated pheromone production at doses as low as 10 fmol. Additionally, one female equivalent of hemolymph or serum from scotophase females exhibited pheromonotropic activity that was comparable to activity elicited by 10 fmol synthetic Hez-PBAN. High pressure liquid Chromatographic (HPLC) fractionation of scotophase H. zea hemolymph serum filtrates, obtained after filtration through molecular weight filters, suggested the presence of a pheromonotropic fraction with molecular weight that appears to be less than 3000.

Several biological and physical factors were manipulated to determine if they interfere with the ability of females of Callosobruchus subinnotatus (Pic) to discriminate against seeds bearing conspecific eggs. Egg-laden seeds were found to be effective in deterring ovipositing females throughout the trial period of 6 weeks. Scraping off eggs from seeds caused the deterrent effect of the oviposition marker to dissipate after 4 weeks. Females were able to distinguish between egg-laden and pristine seeds under various regimes of temperature, humidity, and light. Age of females did not affect their ability to distinguish between egg-laden and pristine seeds. It is speculated that both contact and olfactory cues are necessary for the avoidance of egg-laden seeds.

Transmission and scanning electron microscopy methods were used to study the ultrastructure of integumentary glandular cells that may be involved in the production of sex pheromones and other semiochemicals in Callosobruchus subinnotatus and C. maculatus (Coleoptera : Bruchidae). Additionally, we measured electroantennogram (EAG) responses of male and female antennae to solvent extracts and glassadsorbed volatiles from both sexes of C. maculatus in order to localize the source of the putative sex pheromone. Both species have numerous cuticular pores on the abdomen and thorax. These pores open via an epicuticular duct into a single type 3 secretory cell. Solvent extracts of the pygidium from the female elicit the highest EAG responses from male antennae, suggesting this area of the abdomen to be the source of the putative sex pheromone in C. maculatus .

Pheromone biosynthesis in many species of moths requires a pheromonotropic neurosecretion, the pheromone biosynthesis activating neuropeptide (PBAN), from the brain-subesophageal ganglion-corpora cardiaca complex. Some investigators suggest that PBAN is released into the hemolymph and acts directly on sex pheromone glands (SPG) via a Ca++/calmodulin-dependent adenylate cyclase. Others suggest, however, that PBAN acts via octopamine that is released by nerves from the terminal abdominal ganglion innervating the SPG. These findings suggest that there are controversies on the mode of action of PBAN and other pheromonotropic factors, sometimes even within the same species. Mating in many insects results in temporary or permanent suppression of pheromone production and/or receptivity. Such a suppression may result from physical blockage of the gonopore or deposition of pheromonostatic factor(s) by the male during copulation that result in suppressed pheromone production and/or receptivity in females either directly or by a primer effect. In several species of insects, including moths, a pheromonostatic factor is transferred in the seminal fluid of males. Similar to the controversies associated with the pheromonotropic activity of PBAN, sometimes even within the same species, there appear to be controversies in pheromonostasis in heliothines as well. This paper reviews these conflicting findings and presents some data on pheromonostatic and pheromonotropic activity in Heliothis virescens that support and conflict with current information, raising further questions. Answers to some of the questions are partly available; however, they remain to be answered unequivocally. © 1994 Wiley-Liss, Inc.

Microplitis croceipes (Cresson) females were observed between 06:00 and 20:00 hours in cages containing spring host plants infested withHeliothis virescens (F.), tobacco budworm, larvae, Cages containedGeranium dissectum L. andTrifolium incarnatum L. in plantings of equal area, each infested with 50H. virescens larvae. A time budget for the various behaviors exhibited by the wasps was obtained. In order of decreasing time spent,M. croceipes females were observed to exhibit standing still, searching on plant surface, preening, oriented flight, general flight, and walking. The proportion of time spent preening increased over the day. Oriented flight, general flight, searching, and walking peaked in the morning between 09:00 and 12:00 hours. Oriented flight, general flight, and walking showed minor increases in the afternoon.Microplitis croceipes females spent significantly more time preening, orienting to, and walking and searching on clover than on geranium. However, there was no difference in time spent standing still on geranium or clover. Significance of these findings for development of effective augmentative release strategies is discussed.

Mating in the redbanded leafroller moth, Argyrotaenia velutinana, causes a permanent decline in pheromone titers. Three hours following the termination of mating, phermone titers were significantly decreased from premating levels, and titers remained low for at least four days after mating. Pheromone titers were similar in females that had been decapitated or mated for twenty-four hours. In the redbanded leafroller moth, two peptides control pheromone production. The pheromone biosynthesis activating neuropeptide is produced in the brain and the pheromonotropic bursa peptide is produced in the corpus bursae. Both peptides stimulated pheromone biosynthesis in mated females and extracts prepared from brains and bursae of mated females contained pheromonotropic activity. However, severing the ventral nerve cord before mating prevented the decline in pheromone titer that occurred in mated females. Hemolymph collected during scotophase from mated females did not have pheromonotropic activity, whereas hemolymph collected during scotophase from virgin females contained activity. These results indicate that mating produces a signal sent by the ventral nerve cord to the brain to stop the release of pheromone biosynthesis activating neuropeptide. © 1993 Wiley-Liss, Inc.

Some compounds that are bitter-tasting to humans, both alkaloidal (quinine, quinidine, atropine, caffeine) and non-alkaloidal (denatonium benzoate, sucrose octaacetate, naringin), deterred feeding and oviposition by Heliothis virescens (F.) in laboratory and field cage experiments. Preliminary electrophysiological studies of gustatory sensilla on the ovipositor of H. virescens provided evidence of 3 neurons, one of which is responsive to sucrose. Preliminary indications are that responses of this neuron may be inhibited by quinine and denatonium benzoate.

Flight responses of the parasitoid, Microplitis croceipes (Cresson) (Hymenoptera: Braconidae) to two phenological stages of spring host plants (crimson clover, Trifolium incarnatum L., hairy vetch, Vicia villosa Corbiere, and cutleaf geranium, Geranium dissectum L.) and summer host plants (cotton, Gossypium hirsutum L., sorghum, Sorghum bicolor L., and soybean Glycine max (L.) Merr.) of Heliothis virescens (F.), were measured in a dual choice situation in a wind tunnel. Preflowering clover was more attractive than preflowering geranium, followed by preflowering vetch. Clover was preferred over geranium in flowering stages as well. No within species differences were detected for the two phenological stages. Preflowering and flowering cotton and soybean were preferred over preflowering and flowering sorghum. The findings could be important in pre-determining release sites for M. croceipes in the field.

Structure, color, growth habit, and pubescence of plants, in addition to chemical characteristics, affect acceptability of plants as potential food, refuge, or oviposition sites for insects; however, the impact of physical characteristics of plants on egglaying by the tobacco budworm moth, Heliothis virescens (F.), is poorly understood. This study was undertaken to determine the physical attributes, especially trichome types and growth habit, that may influence oviposition by gravid H. virescens females on several species of plants. The types and densities of trichomes found on the leaves of eight plant species, pigeonpea [Cajanus cajan (L.) Huth], crimson clover (Trifodium incarnatum L.), Texas bluebonnet (Lupinus texensis Hooker), cotton (Gossypium hirsutum L.), velvetleaf (Abuliton theophrasti Medikus), rose-scented geranium (Pelargonium graveolens L'Her.), tobacco (Nicotiana tabacum L.), and groundcherry (Physalis angulata L.) were investigated using light and scanning electron microscopy

Neonate larvae of codling moth, Cydia pomonella (L.), modify their behavior in the presence of saccharin, monosodium glutamate (MSG), or L(+)-2-amino-4-phosphonobutyric acid (L-AP4) by commencing their feeding earlier. Previously published pharmacological analysis demonstrated that phagostimulatory effects of MSG and L-AP4 (which elicit umami taste sensation in humans) are reversed by adenylate cyclase activator and phosphodiesterase inhibitor. In this study, by measuring the time needed to start ingestion of foliage treated with mixtures of phagostimulants and signal transduction modulators, we show that phagostimulatory effects of l-aspartate (the third hallmark umami substance) are also abolished by both adenylate cyclase activator and phosphodiesterase inhibitor, but not by phospholipase C inhibitor. However, stimulatory effects of hemicalcium saccharin were affected only by phospholipase C inhibitor. The results suggest that codling moth neonates use different transduction pathways for perception of hemicalcium saccharin and umami.