Diet-induced thermogenesis (DIT) is a concept that has been well known in one form or another for more than a century in vertebrate nutrition and physiological ecology. Yet, it is practically unknown in the physiology and nutritional ecology of insects. We suggest that DIT is a ubiquitous mechanism occurring in most if not all organisms and functions to maintain nutritional homeostasis by metabolically oxidizing excess energy intake to maintain a metabolic pool of nutrients that is balanced in both energy and nutrients. There is sufficient evidence to suggest the phenomenon exits in insects and should be considered as a viable hypothesis to enrich the paradigms of insect nutritional ecology and biological stoichiometry. We demonstrate evidence for DIT in the phytophagous spruce budworm (Choristoneura fumiferana [Clemens]). Budworm larvae with the highest dietary metabolizable energy/protein ratio and highest assimilated food are the least metabolically efficient and are apparently able to oxidize excess metabolizable energy intake (i.e., they exhibit diet-induced thermogenesis). Metabolic adaptations such as DIT would allow organisms to use foodstuffs that are high in energy but critically low or unbalanced in essential nutrients to maintain normal growth, survival, and reproduction. Understanding the role DIT plays in nutritional and elemental stoichiometric homeostasis of insects may be an important element in interpreting their nutritional ecology.

A previous study showed that feeding of adult banded cucumber beetle, Diabrotica balteata LeConte, and development of the female reproductive system were strongly inhibited by a diet of fresh Valmaine (Val) romaine lettuce, Lactuca sativa L., relative to Tall Guzmaine (TG). Leaf surface chemicals have been shown not to be involved in the resistance of Val. In this study, leaves of TG and Val were freeze-dried and incorporated into an artificial diet to evaluate whether the chemicals within the lettuce leaves were responsible for resistance to D. balteata feeding. The amount consumed and mature eggs produced were not significantly different when adults were given either a choice or no choice of TG or Val diets. However, latex from TG and Val strongly inhibited D. balteata feeding on a favorite food, lima bean leaves, when applied to leaf surfaces. Latex from Val turned brown faster than that from TG, and flowed for a longer period of time before ceasing. Localized induced resistance to feeding was found in Val but not in TG after plants were previously damaged for 48 h. Therefore, we propose that localized inducible resistance and physical defenses in latex may account for resistance in Val to D. balteata.

Laboratory studies were conducted to identify the sex pheromone of Tyta luctuosa (Denis and Schiffermuller), a Eurasian noctuid moth that has been imported and released to aid in control of field bindweed, Convolvulus arvensis L. Using gas chromatography-mass spectrometry, together with electroantennogram and windtunnel bioassays of male moths, two compounds, (Z)-9-tetradecenal and (Z)-11-hexadecenal, were identified as the major pheromone components. Whole-gland extracts contained these components, as well as two other major compounds, (Z)-9-tetradecanol and (Z)-11-hexadecanol. However, the two alcohols were not detected in airborne emissions of calling females. Ratios of Z9–14:ALD to Z11–16:ALD were markedly different for whole-gland extracts and airborne emissions (1:3 and 2:1, respectively). Also, although the total amount of the two compounds varied nearly eight-fold among individuals (22–167 ng, mean 75 ± 56 ng [SD]) in gland extracts, the Z9–14:ALD/Z11–16:ALD ratio was relatively constant (0.3 ± 0.15). On average, calling females released 94 ng of Z9–14:ALD and 45 ng Z11–16:ALD per hour, with a mean ratio of 2.2. In wind tunnel tests, 69% of males exhibited complete upwind flights and touched the stimulus source in response to a synthetic pheromone blend that mimicked the female-produced Z9–14:ALD/Z11–16:ALD airborne concentration and ratio, as compared with 82% and 50% in response to calling females and pheromone gland extracts, respectively. Tyta luctuosa adults are vagile, and both adults and larvae are cryptic in the field-factors that make recoveries of released insects unlikely. Therefore, our data will contribute to the development of a pheromone-based monitoring tool to help assess colonization and establishment of this potentially useful weed biological control agent.

Male and female Monochamus clamator (LeConte) and M. scutellatus (Say) are able to detect bark beetle pheromone components electrophysiologically and are attracted to traps baited with blends of pheromone components of scolytid bark beetles. We investigated the effect of individual pheromone components (ipsenol, ipsdienol, 3-methyl-2-cyclohexen-1-one (MCH), frontalin, verbenone, cis- and trans-verbenol, and endo- and exo-brevicomin) on Monochamus Dejean trap catches. Only traps baited with ipsenol and/or ipsdienol together with the host volatiles ethanol and α-pinene caught significantly more male and female M. scutellatus and M. clamator than traps baited with host volatiles alone. Ipsenol and ipsdienol are aggregation pheromones of secondary bark beetles in the genus Ips DeGeer while the other components are pheromones of primary bark beetles in the genus Dendroctonus Erichson. The former should be the most reliable indicators of suitable host material because most Ips spp. attack weakened or moribund trees or trees already successfully under attack by primary bark beetles, and their pheromones may be more persistent in space and time than those of Dendroctonus spp. In two successive years in an operational (commercial) mass-trapping program, traps baited with ethanol, α-pinene, and ipsenol captured twice as many beetles as traps baited with host volatiles alone. These results suggest that operational monitoring or mass-trapping programs could be improved significantly by the inclusion of ipsenol in baits at a minimal cost.

Factors influencing pheromone production by the boll weevil, Anthonomus grandis Boheman, have been extensively studied, yet recent research using new methods suggests much remains unknown in this regard. The studies reported herein examined age-related changes in production and composition of pheromone at ages from 0 to 6 d, and at 3, 6, 9, and 12 d, respectively, and evaluated the association between accessory gland condition and pheromone production. Estimates of pheromone from extracted feces were near the upper values previously reported. However, ≈95% of the total pheromone was obtained from headspace collections. Based on feces extractions, pheromone production increased with age until the sixth day, while headspace collections indicated an increase in production until the ninth day of adulthood. The boll weevil pheromone is composed of two alcohols (components I and II) and two aldehydes (components III and IV), and ratios of these components changed with age. Component I was dominant for the first days of adult life, but the composition subsequently stabilized at ≈42.5:42.5:5:10 (I:II:III:IV). Also, high levels of pheromone production were associated with well-developed accessory glands, while weevils with small, transparent glands produced little or no pheromone. These results demonstrate production of pheromone in greater quantities, and at earlier ages, than was previously recognized. Additional study using the methods reported herein should provide improved understanding of the dynamics of boll weevil pheromone production that will facilitate ecological interpretation of field data and improvements in trapping systems.

Vegetative diversification with weeds can enhance natural enemy populations and suppress pest-related damage in various crops. Weedy and weed-free cotton (Gossypium hirsutum L.) plots were used to study the effects of weediness on selected herbivorous arthropod groups, including the boll weevil (Anthonomus grandis grandis Boheman), and natural enemies, boll weevil-induced injury to cotton squares, and cotton plant growth and yield in the Lower Rio Grande Valley of Texas, during 2000 and 2001. The presence of weeds was associated with greater populations of 9 of the 11 prey arthropod groups, and 9 of the 13 natural enemy arthropod groups counted in this study. These trends were mostly evident late in the season when weed biomass was greatest. Weed-free cotton harbored more cotton aphids (Aphis gossypii Glover), early in the season and silverleaf whiteflies (Bemisia argentifolii Bellows and Perring) later in the season than weedy cotton on some of the sampling dates. Diversity (Shannon’s index) within the selected arthropod groups counted in this study was significantly greater in dvac samples from the weed foliage than from weed-free cotton plants during both years, and diversity on weedy cotton plants was greater than on weed-free cotton plants during 2000. Boll weevil oviposition injury to squares was unaffected by weeds, but the higher weed-associated predator populations mainly occurred after most squares had become less vulnerable bolls. Weed competition resulted in lower lint yields of 89% and 32% in the 2 yr.

The effect of vegetation, intercropping, and Telenomus spp. egg parasitism during the vegetative stage of maize on Busseola fusca (Fuller) (Lepitoptera: Noctuidae) infestations and maize yields at harvest were studied during two consecutive cropping seasons, in the humid forest zone of Cameroon. Six locations grouped into three blocks, representing gradients in human population densities of 15–88 inhabitants/km² were chosen. The fields were located at 20–90 min walking distance from the next road. Differences between blocks in the measured variables were mostly not significant indicating that the population density gradient was not strong enough to affect length of fallow period and thereby vegetation, the population dynamics of pests and natural enemies, and maize yields in forest fields. Numbers of egg batches per plant but also egg parasitism by and sex ratio of Telenomus spp. were significantly higher during the second than the first season (66.9 versus 19.9% and 0.67 versus 0.21, respectively). As a result, the number of borers per plant was only 0.22 versus 0.73 during the first season. Similarly, total mortality of immature B. fusca was 60.5% during the first and 93.2% during the second season. The seasonal differences in unexplained mortality was probably because rainfall caused drowning of migrating first instars. High mean parasitoid mortality at the beginning of the first season was probably caused by high superparasitism promoted by low host density conditions. Across seasons, abundance of grasses in the surroundings of a field was negatively related to egg batch density. Likewise, numbers of B. fusca decreased with increasing density of the nonhost cassava in the field, indicating increasing mortality of migrating larvae. Egg numbers per plant was negatively and egg parasitism or parasitoid sex ratio was positively related to yield.

Host range is a fundamental aspect of host-pathogen population dynamics and is a vital determinant of the risks associated with the use of a pathogen for biological control. Yet even for widely studied baculoviruses we often do not know which hosts they infect under natural conditions. Baculoviruses are primarily pathogens of Lepidoptera and Hymenoptera and exhibit great variation in host range. Some are apparently monospecific, whereas others are able to infect numerous hosts from diverse families. In this report, I review host range data, concentrating on two generalist viruses, Autographa californica (Speyer) multicapsid nucleopolyhedrovirus (AcMNPV) and Mamestra brassicae L. multicapsid NPV (MbMNPV). To my knowledge, 145 and 78 host species have been assayed with AcMNPV and MbMNPV, respectively. I examined susceptibility of these species according to various life history parameters using a phylogenetic analysis. Host susceptibility was poorly predicted by taxonomic relationships. Host susceptibility was correlated with some life history traits; of the species tested, a significantly higher proportion of polyphagous species and pest species were susceptible to AcMNPV compared with mono- or oligophagous species or nonpest species, respectively. A higher proportion of multivoltine species were susceptible to MbMNPV compared with univoltine species, although the opposite trend was shown for AcMNPV. Providing convincing explanations for these patterns is problematic and highlights the inadequacies in our understanding of the ecology of baculoviruses. Some possible explanations are discussed. I suggest that current patterns of host susceptibility may, in part, reflect an ongoing evolutionary arms race between numerous host species and each baculovirus, in which the virus repeatedly colonizes new host populations and new species while others evolve resistance.

Local dispersal of the diamondback moth (Plutella xylostella [L.]) was studied using the mark-recapture technique in commercial cauliflower and broccoli crops in the northern Adelaide plains. Moths were marked with fluorescent powder and released at one or more points within the experimental fields. Recaptures of the marked moths were made with pheromone traps and yellow sticky buckets, the latter being used to study the dispersal of both males and females. Four indices of dispersal ranges were estimated from the recapture data, the average dispersal distance and the distances from the release point within which 95, 99, and 99.9% of the released moths were expected to remain. Separate estimates were obtained for recapture data of males from the pheromone traps, recapture data of males from the yellow sticky buckets, and recapture data of females from the yellow sticky buckets. Overall, the estimated average dispersal distance ranged 14 to 35 m and the 95, 99, and 99.9% distances ranged 40 to 106 m, 63 to 177 m, and 113 to 300 m, respectively. Longer dispersal distances were obtained from the pheromone traps than from the yellow sticky buckets. Data from the yellow sticky buckets revealed similar dispersal ranges of the males and the females. The positions of recapture centers of the two sexes were also largely similar. While the distance ranges of recaptures increased gradually during the experiments, the recapture centers stayed within close vicinity of the release points. Temperature and wind did not appear to influence the dispersal ranges or directions. Implications of the results in the management of diamondback moth are discussed.

The effect of soil moisture on entomopathogenic nematode virulence was examined in the laboratory. Objectives were to determine the virulence of several species and isolates of entomopathogenic nematodes at various soil moisture contents and temperatures, and after fluctuations in soil moisture. Studies included up to five isolates of entomopathogenic nematodes: Heterorhabditis bacteriophora Poinar (Oswego and Tuscarora strains), Steinernema glaseri (Steiner) (NC1 strain), S. feltiae (Filipjev) (Biosys 369 strain), and S. carpocapsae (Weiser) (NY001 strain). Nematodes were applied to sandy loam soils ranging in soil moisture content from below the permanent wilting point of plants to near saturation. In all experiments, a rainfall or irrigation event was simulated by adding water to rehydrate soils to high moisture levels (near saturation). Nematode virulence was evaluated periodically by measuring insect mortality in Galleria mellonella (L.) larval bioassays, before and after rehydration. Nematode virulence increased with soil moisture content for all species and isolates tested. Our studies demonstrated that the virulence of entomopathogenic nematodes in low moisture conditions could be restored by rehydrating the soil. Insect mortality was generally low in low-moisture, nematode-infested soils before rehydration, but increased to high levels posthydration. Moisture effects were evident from the onset of each experiment, whereas the effect of soil temperature on nematode-induced insect mortality was delayed and nonsignificant until 14 wk after the initiation of the third experiment.

Coexistence of the wolf spiders (Araneae: Lycosidae) Hogna helluo (Walckenaer) and Pardosa milvina Hentz in soybean fields is partially driven by a trade-off in competitive ability and colonization success. H. helluo can out-compete P. milvina, but its population densities are limited by its colonization ability. However, even after repeated additions in soybean habitats, H. helluo seldom sustains high population densities. Our research focuses on whether emigration might explain this pattern. Relying on mark-recapture techniques, we tested the role of habitat quality and presence of heterospecifics as factors initiating emigration of H. helluo and P. milvina from suitable habitat patches. We assessed emigration by trapping spiders (with pitfall traps) at the outer edge of an unfavorable habitat (tilled soybean field) surrounding either no-till or mulched habitats (i.e., addition of straw), the latter representing an increase in habitat quality. Spiders were added to enclosures with con- or heterospecifics. Experiments were conducted twice, and ran for 4 d, at which time captures of marked spiders were low. Results showed H. helluo emigration was influenced by habitat quality because it was captured leaving no-till habitat significantly more often than exiting mulched habitats. In contrast, P. milvina activity was not driven by changes in habitat, and as such has more habitat versatility than H. helluo. The presence of con- or heterospecifics did not alter the propensity of either species to leave experimental units. H. helluo population densities are therefore limited by both its ability to colonize soybean fields and by its propensity to emigrate if suitable habitat is not available.

The pinewood nematode (Bursaphelenchus xylophilus) is known to be the causative agent of pine wilt disease, which is transmitted from wilt-killed to healthy pine trees by the insect vector Monochamus alternatus. The second-stage propagative juvenile develops into third-stage dispersal (J_III) or propagative juveniles. The J_III develops into the fourth-stage dispersal juvenile (J_IV), a special stage for transportation, then the J_IV enters the tracheal system of adult beetles in pupal chambers in the xylem. To determine the differences in some life history parameters related to transmission between a virulent and an avirulent isolate of B. xylophilus, progression to the different life stages was investigated using two nematode isolates of different virulence, M. alternatus larvae, and pine bolts with an artificial pupal chamber. The numbers of J_IIIs and J_IVs produced around the pupal chamber by the time of beetle emergence were much smaller in the avirulent isolate than in the virulent one. The proportion of J_IIIs produced in a population around the pupal chamber (the J_III and J_IV number/the total population) and the probability of J_IIIs developing into J_IVs (the J_IV number/the J_III and J_IV number) were also smaller in the avirulent isolate. Although the probability of J_IVs boarding beetles (the initial nematode load/the J_IV number) was equal between the two isolates, the mean initial nematode load was much smaller in the avirulent isolate. The smaller initial nematode load of the avirulent isolate was ascribed to its smaller rate of reproduction and to lower production rates of J_III and J_IV. A trade-off between the virulence and transmission rate of B. xylophilus is discussed herein, taking into account the effect of the initial nematode load on the vector’s longevity and flight performance.

Field and laboratory studies evaluated the influence of selected crop hosts on Helicoverpa zea (Boddie) population dynamics in relation to genetically engineered Bt (Bollgard) and non-Bt cottons. Host specific H. zea colonies were initiated with a colony originally collected from sweet corn. The colony was allowed to complete one generation on meridic diet then split into cohorts and allowed to complete one generation on field corn, grain sorghum, soybean, cotton, or meridic diet in individual 29.5 ml plastic cups. During the first part of the study, larval developmental times, pupal weights, and survival were measured. H. zea survival was higher on meridic diet and grain sorghum than on soybean and cotton. Development of H. zea larvae was faster on field corn than all other larval diets. Also, H. zea required a longer period of time to complete development on cotton than on the other hosts. Pupal weights were higher on meridic diet than the plant hosts. Pupal weights of H. zea that completed larval stadia on cotton were lower than on the other larval diets. Neonates (F₁) from each of the host specific colonies (200 per colony) were exposed to Bt and non-Bt cottons. Mortality of second generation H. zea on non-Bt and Bt cottons was measured at 96 h. H. zea larvae from the cotton colony had higher mortality on non-Bt cotton than the other host specific colonies except the grain sorghum colony. On Bt cotton, larvae from the corn colony had a higher level of mortality than larvae from the soybean and grain sorghum colonies. These data provide valuable information for evaluating the contribution of cultivated hosts as additional, alternative refugia in Bt cotton resistance management plans.

A computer model developed to simulate the interaction between the pathogenic fungus, Entomophaga maimaiga, and the gypsy moth, Lymantria dispar, was used to investigate airborne dispersal of fungal conidial spores. The model used data on egg mass density gathered from 32 sites in an area of Connecticut and information on fungal prevalence, gypsy moth abundance, fungus resting spore load in the soil, and detailed weather records from six intensively sampled plots in the same area. It calculated seasonal survival rates of gypsy moths at the six plots using a variety of dispersal distributions, or kernels, for the conidia. Distributions ranged from normal densities to the exponential, a Bessel and power distribution, along with a “kinked” linear distribution, which had two parts. All kernels gave good fits to the data so long as the dispersion parameter caused each standardized distribution to have an abscissa value near 0.05 at a distance of 1.25 km from the source. However, significant dispersal beyond 10 km only occurred for the kinked linear and power distributions. Thus, mechanisms for short-range dispersal may be different from those for long-distance dispersal. The model was also used to investigate the potential for dispersal of E. maimaiga in the northeastern United States just after it was known to be established in 1989. For the weather conditions prevalent in 1989 and 1990, and assuming a kinked linear dispersal kernel, I predicted that the fungus would spread rapidly, which did indeed happen. Furthermore, in these years rainfall and other weather conditions were very favorable for fungus development, so even if relatively few conidia dispersed long distances, they might easily have initiated viable infections.

This study evaluated the agricultural impacts of organic and integrated pest management (IPM) orchards in Québec, Canada on the carabids Pterostichus melanarius Illiger (Coleoptera, Carabidae), with two biomonitors, population density and fluctuating asymmetry (FA) of morphologic and meristic characters. The carabids were trapped between May and August 1999 and 2000 in 20 pitfall traps on four organically certified orchards and five IPM farmlands located in two farming communities 100 km apart. Numbers of P. melanarius and total trap catch were assessed for each year. We measured the length of two segments of the right and left antennae, the length of first tarsae, and the number of tibiae spines on the mesothoracic leg of 50–100 individuals per site/yr. These measurements were used to calculate two fluctuating asymmetry indices to evaluate individual developmental stability. No differences in fluctuating asymmetry were found between organic and IPM orchards although total catch of P. melanarius was higher in IPM orchards in 1999. The use of fluctuating asymmetry analysis in these fields seem inadequate to assess the impact of pesticides. Density analysis give a slightly response in the opposite of the predictions because IPM orchards seem to be a more adequate habitat for this carabid species. There is a need for evaluating the impacts of natural products used in the organic cultures.

The boll weevil, Anthonomus grandis Boheman, enters a diapause state to survive winters in temperate regions and subsequently emerges from overwintering habitats to infest squaring cotton in the spring. Previous research has found that boll weevil overwintering emergence is closely associated with climatic patterns of temperature and precipitation. The objectives of this study were to determine the effects of temperature, humidity, and other meteorological factors on the temporal pattern of boll weevil emergence, and to compare the physiological and morphological conditions of emerged and trapped weevils. Emergence cages were infested with diapausing weevils in the fall. Daily emergence and microclimatic conditions of the leaf litter and air were monitored until the subsequent summer. Air temperature and relative humidity, incident solar radiation, and precipitation were significantly greater on emergence dates than on dates with no emergence. Emerged and trapped weevils were dissected to assess their morphology. Emerged weevils tended to exhibit greater fat body development, a higher frequency of testicular atrophy, and less ovary development than trapped weevils. None of the emerged weevils were rated extra lean and no trapped weevils were rated fat. These results are consistent with previously-reported effects of climatic factors on weevil emergence in other areas of the Cotton Belt, and add new information about the physiological and morphological characteristics of emerged weevils. This information on the dynamics and mechanisms of overwintering provides insight that should be helpful in formulating improved predictive models, risk assessments, and management strategies for the boll weevil.

The melon fly, Bactrocera cucurbitae (Coquillett) is a serious pest of cucurbit crops. Although melon fly females oviposit in cucurbit crops, both males and females are frequently associated with a range of nonhost plants, including both crops such as corn (Zea mays C. Linnaeus) and wild plants such as castor bean (Ricinus communis C. Linnaeus) that occur within the cropping area or along the crop borders. This association with nonhost plants has been used for control purposes through the technique of spraying protein baits incorporating a toxicant on these nonhost plants. Association of melon flies to corn has not been reported to be tied to any phenological stage of corn. We report field studies that show that melon flies, as well as oriental fruit flies, B. dorsalis (Hendel), may show increased population levels in corn at the time of, and subsequent to, flowering and pollen shed and suggest that this population increase may be tied to pollen consumption. Before this, pollen had not been reported to be an important food source for the tropical Bactrocera spp.

Experiments and models are described that quantify the functional responses of the larval and adult stages of the sevenspot ladybeetle, Coccinella septempunctata L. toward mixed stage populations of the cotton aphid, Aphis gossypii Glover, in cotton. In the laboratory, functional responses were measured for five beetle stages and three size groups of prey at five temperatures (15 to 35°C). The 75 resulting functional responses were each characterized by a search rate (cm²/predator/d) and a handling rate (prey/predator/d). Both search and handling rates increased with predator stage. Search rates increased, while handling rates decreased, with prey size. Search rate increased linearly with temperature, while handling rate showed an optimum response to temperature. Field cage studies were conducted to verify whether the search rates determined in the laboratory were valid under field conditions. Search rates of predators derived from observations in field cages yielded parameter estimates that were similar to those found in the laboratory. A comprehensive model, allowing for effects of temperature, stage distribution of the aphid population, and plant leaf area on predation rate, was then constructed to calculate predation by larvae and adults of C. septempunctata on multi stage populations of prey. This model gave good correspondence to the cage observations if two-sided leaf area was input into the model as search substrate for the predator. The model appears suitable for calculating predation rates of C. septempunctata on A. gossypii under field conditions. A sensitivity analysis of the functional response model shows the crucial effect of crop leaf area on predation.

The effect of mixing Brussels sprouts with potato plants on the foraging behavior of two parasitoid species was examined within the tritrophic system of Brassica oleraceae, the herbivore Pieris rapae L. (Lepidoptera: Pieridae), and two parasitoids, Cotesia glomerata L. (Hymenoptera: Braconiadae) and Cotesia rubecula Marshall (Hymenoptera: Braconidae). The two parasitoids differ in the spectrum of host used: C. glomerata has a wider host range, and C. rubecula has narrower host range, with P. rapae being its preferred host. The experimental design consisted of a completely crossed multifactorial design with the following factors: (1) plant diversity (monoculture and diculture), (2) species of parasitoid (C. glomerata and C. rubecula), and (3) level of experience (naive and experienced individuals). Results indicated that the effect of plant diversity was different for the two parasitoids. Naive C. glomerata, the parasitoid with the wider host range, were less efficient in the diculture than in the monoculture, but this difference disappeared after experience. In contrast, naive C. rubecula were more efficient in the diculture than in the monoculture with experience having no effect. Response level increased for both species after oviposition experience, with C. glomerata exhibiting a high degree of behavioral plasticity. Data indicates that the negative effect of polyculture on the foraging efficiency of C. glomerata is a result of an attraction to the nonhost plant (potatoes).

This study aims to infer the proportion of queens and workers of the hornet Vespa analis parasitized by the strepsipterous parasite Xenos moutoni in overwintered females from morphological data collected for three years. It is known that both worker and queen hornets parasitized by strepsipterous insects overwinter. The parasitized queens cannot reproduce in the next season and thus the level of parasitism potentially affects the number of colonies to be established in the population. Thus, estimation of the ratio of parasitized queens to the total of parasitized females would be useful for understanding the population dynamics of the hornet. K-means cluster analysis demonstrated that 50 to 85% of individuals were workers in the total of parasitized females during the period. From 8 to 15% of total queens were thought to be sterilized by X. moutoni, a level that would not be expected to have a serious effect on the population dynamics of V. analis. Forced hibernation of workers might be considered to be a result of manipulation of the diapause system of the host by the parasite to increase its reproductive success.

We evaluated preferences of the parasitoid Glyptapanteles militaris (Walsh) among various host-diet complexes in an effort to understand the abundance of the parasitoid in Azorean pastures. We also examined effects of host diet on the quality of the parasitoid as a biological control agent. The larvae of Pseudaletia unipuncta (Haworth) were reared on three different diets (Zea mays L., Lolium perenne L., and artificial diet) and were exposed to G. militaris. The percentage of parasitized larvae (yielding parasitoid cocoons), of host mortality unrelated to successful parasitism (host death without cocoon formation) and of pupating hosts did not differ significantly among diet treatments. Also, the total number of parasitoid larvae per host and the mean number of cocoons yielded per host did not differ significantly when hosts were fed on different diets. Time from egg to cocoon formation (16.1 and 18.6 d, respectively), pupal period (8.0 and 8.5 d, respectively), and total developmental time (24.1 and 26.9 d, respectively) for G. militaris were significantly shorter (at 22°C) when hosts were reared on L. perenne compared with artificial diet. Rate of adult parasitoid emergence from cocoons was significantly lower when hosts were fed artificial diet (82.5%) than when fed L. perenne (91.2%) or Z. mays (91.1%). The longevity of the adults of G. militaris ranged from 5.1 to 7.2 d among treatments differed significantly for the three types of diets and between sexes. When adults of G. militaris could choose among hosts reared on Z. mays, L. perenne, or artificial diet, they preferred the hosts fed L. perenne leaves. These results suggest that the parasitoid may be well adapted to the Azorean agricultural ecosystems, characterized by the prevalence of L. perenne throughout the year. Results show that hosts fed fresh leaves of L. perenne are the most suitable for the mass rearing of G. militaris.

The pecan weevil, Curculio caryae (Horn), is a major pest of pecans in the Southeastern United States. Entomopathogenic nematodes and fungi are potential alternatives to chemical insecticides for C. caryae control. Our objective was to survey pecan orchards in the southeastern United States for entomopathogenic nematodes and fungi and determine the virulence of the new isolates to C. caryae larvae. Soil was collected from 105 sites in 21 orchards in Arkansas, Georgia, Louisiana, and Mississippi. Entomopathogens were isolated by exposing soil to C. caryae and greater wax moth larvae, Galleria mellonella, (L.). We isolated entomopathogenic fungi and nematodes from 16 and 6 of the 21 orchards surveyed, respectively. The entomopathogenic fungi included Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin, and nematodes included Heterorhabditis bacteriophora Poinar, Steinernema carpocapsae (Weiser), Steinernema glaseri (Steiner), and Steinernema rarum (Doucet). This is the first report of Steinernema rarum in the United States. Soil characteristics in orchards were analyzed for pH, organic matter, and nutrients; we detected a negative relationship between fungal occurrence and manganese levels in soil and a positive relationship between M. anisopliae occurrence and calcium or magnesium levels. In laboratory assays, virulence of 15 nematode and 22 fungal isolates to C. caryae larvae was tested in small plastic cups containing soil. Results indicated poor susceptibility of the C. caryae larvae to entomopathogenic nematodes. Several fungal isolates that caused significantly higher mortality in C. caryae larvae than other strains (including a commercial strain of B. bassiana) should be investigated further as potential control agents of C. caryae.

Susceptibility of the generalist predator, the lacewing Chrysoperla carnea (Stephens), to the insect growth regulators azadirachtin, diflubenzuron, pyriproxyfen, and tebufenozide was tested in the laboratory. Third instars were topically treated with different doses of formulated materials of each compound by direct topical exposure. At maximum field-recommended dose, pyriproxyfen and tebufenozide were harmless to C. carnea, whereas azadirachtin and diflubenzuron were harmful (respective LD₉₀s were 24.5 and 6.9 ng active ingredient [AI] per insect). At sublethal doses of azadirachtin and diflubenzuron, females laid fertile eggs, but azadirachtin caused a slight negative effect on oviposition. Pyriproxyfen and tebufenozide had no effect on oviposition and egg fertility. As a second approach of this study, toxicity data are discussed in relation to the rate of penetration and excretion after topical application. One hour after administration, ≈80% of pyriproxyfen had penetrated; whereas for diflubenzuron and tebufenozide, only percentages of 10–20% were recorded in the same time interval. However, although pyriproxyfen penetration was fast and high, most of the compound was also quickly eliminated via excretion. Our data suggest that the use of azadirachtin and diflubenzuron in combination with C. carnea in integrated pest management (IPM) programs should be carefully evaluated. Pyriproxyfen and tebufenozide are considered to be safe for C. carnea.

Colony size and reproductive status of Solenopsis invicta (Buren), red imported fire ants, is measured by a rating system developed by Harlan et al. (1981). Because this rating system is commonly used to evaluate chemical controls, especially insect growth regulators, and biological controls such as Thelohania spp., we evaluated the environmental conditions that would affect mound ratings in Louisiana. Increases in relative humidity and mound height were associated with population rating increases. Brood presence in the above ground portion of the nest (mound) was strongly associated with mound temperature. Brood was only found in mounds that had soil temperatures between 25–30°C although mound temperatures may fall below 25°C in the early morning and reached 40°C by early afternoon during the summer in Louisiana. Researchers in warm climates such as Louisiana may consider monitoring mound temperature during sampling and excavating nests below ground surface to ensure that assessments of mound ratings are accurate.

The synthetic pheromone (Z,Z)-3,13-octadecadien-1-yl acetate was tested in two trap types and at different loads for trapping the Douglas-fir pitch moth, Synanthedon novaroensis (Henry Edwards) (Lepidoptera: Sesiidae), in a lodgepole pine, Pinus contorta Douglas ex Loudon variety latifolia Engelmann, provenance trial at the Prince George Tree Improvement Station, Prince George, British Columbia. This moth causes considerable problems in lodgepole pine seed orchards at this location. No significant differences in trap catches were found between wing traps and Unitraps in two experiments. There were no significant differences between catches in Unitraps baited with 50, 100, or 200 μg of the pheromone loaded on red rubber septa. In a second experiment, Unitraps baited with four rubber septa, each loaded with 200 μg for a total load of 800 μg, captured significantly more Douglas-fir pitch moths than those baited with one septum (200 μg) or two septa (400 μg) of the pheromone. All pheromone loads caught significantly more moths than unbaited control traps. Based on trap catches in these trap bioassays, and catches in monitoring traps in four lodgepole pine seed orchards, 1996 through 2000, the flight period of S. novaroensis in north central British Columbia normally starts in early June, and lasts for 4–7 wk.

To effectively monitor forest tent caterpillar (Malacosoma disstria Hübner) populations, the use of synthetic sex pheromones to trap adults was evaluated in outbreak and nonoutbreak population levels. Three pheromone blends were field-tested, consisting of 1) (Z,E)-5,7-dodecadienal, 2) 100:1 (Z,E)-5,7-dodecadienal: (Z,Z)-5,7-dodecadienal and 3) 100:1:10 (Z,E)-5,7-dodecadienal: (Z,Z)-5,7-dodecadienal: (Z)-7- dodecanal. The tertiary blend (3) was superior for capturing forest tent caterpillar moths, and was best able to resolve population density levels. Lures dosed with 11 μg or less of either the binary (2) or tertiary blends failed to capture moths at nonoutbreak population levels, while lures dosed at 390 μg gave the highest mean trap catch and the lowest rate of zero-captures.

In choice tests, beet armyworm (BAW), Spodoptera exigua, larvae feed preferentially on leaves from peanut plants, Arachis hypogaea L., previously infected by the white mold fungus, Sclerotium rolfsii Saccodes (mitosporic fungi) (Cardoza et al. 2002). In this study we determined that third instar BAW caterpillars allowed to feed on S. rolfsii-infected plants had significantly higher survival, produced significantly heavier pupae, and had shorter time to pupation than those allowed to feed on healthy plants. Leaf tissue from white mold infected peanut plants contained similar levels of soluble and insoluble protein, but significantly higher levels of soluble sugars. In addition, white mold-infected plants had significantly lower starch content and total soluble phenolics compared with leaves from healthy plants. Levels of jasmonic acid were similar in plants attacked by either the fungus or BAW, but were significantly higher in plants that were infected by the fungus and then fed on by BAW. Salicylic acid (SA) levels in fungus-infected plants were not significantly different from those of control plants. However, levels of SA in plants damaged by BAW alone were significantly lower than those of plants under simultaneous attack by the fungus and BAW.

Basic biology and rearing methods were determined for Timandra griseata Peterson (Lepidoptera: Geometridae) and Homorosoma chinensis Wagner (Coleoptera: Curculionidae), two potential biological control agents of mile-a-minute weed (Polygonum perfoliatum L., Polygonaceae). Both species also were tested for their ability to feed and develop on crop plants in the family Polygonaceae. T. griseata defoliated potted mile-a-minute weed, developing from egg to adult in ≈26 d. However, T. griseata also fed and developed on common buckwheat (Fagopyrum esculentum Moench) and tartary buckwheat (Fagopyrum tartaricum Gaertn), and accepted these species and mile-a-minute weed equally in choice tests. Thus, the host range of T. griseata appears to be too broad for it to be considered for release in the United States. Homorosoma chinensis had a relatively high reproductive rate and short generation time on potted mile-a-minute weed. Internal feeding by H. chinensis larvae caused mortality of entire stems. Adult weevils fed on foliage of common buckwheat and rhubarb (Rheum rhabarbarum L.) when given no choice during an 8-wk test period, but laid no eggs on these hosts. In the same test, an average of over 130 eggs per female was laid on mile-a-minute weed. Newly emerged H. chinensis adults strongly preferred mile-a-minute weed to buckwheat and rhubarb in a choice test, and neonate larvae placed on buckwheat and rhubarb all died within 24 h. Thus, H. chinensis may be host specific to mile-a-minute weed, but further testing must be conducted on other potential host plants before release in the United States can be recommended.