We explore the influence of egg mortality dynamics on the rate at which target pests evolve resistance to high-dose transgenic insecticidal crops. We develop a two-patch deterministic population genetic model in which pests can develop in either toxic or nontoxic (refuge) fields, and their eggs are subject to varying levels and forms of egg mortality. The three standard forms of egg mortality are studied: density independence (DI), positive density dependence (PDD), and inverse density dependence (IDD). Resistance is modeled as a single locus with a fully recessive allele that confers complete resistance with no fitness cost. Insect movement and oviposition is modeled as follows: males move panmictically before mating and females may either stay in their natal patch to oviposit or move after mating before oviposition. While our simulations show that both the magnitude and form of egg mortality can influence the rate of resistance evolution, important caveats apply. Higher levels of DI egg mortality can lead to substantial delays in resistance evolution, but this effect is dependent on the presence of intraspecific competition among larvae. The rate of resistance evolution is affected by the form of density dependence (DI versus PDD versus IDD), but these effects are dependent on at least some females ovipositing in their natal field. If this condition is met, the rate of resistance evolution is fastest when eggs are subject to PDD mortality and slowest when eggs are subject to IDD egg mortality. DI egg mortality produces intermediate rates of resistance evolution.

Age-specific life tables of the lettuce aphid, Nasonovia ribisnigri (Mosley), feeding on lettuce were determined at different constant temperatures under controlled conditions. Our results showed that the proportion of alates increased with increasing temperatures, remaining below 7% at 16°C and increasing to 40–57% at a temperature above 20°C. The longest developmental time of apterous aphids was obtained at 8°C (31.5 d), and the shortest was at 26°C (6.2 d), whereas the developmental time of alates was always 0.7–1.1 d longer than for apterous. Most aphids needed four instars to reach adult stage, but at 8, 26, and 28°C, many individuals passed through five or six molts. Age-specific survivorship (lx) was always above 90% at the temperature range of 16–24°C. Mortality rate (qx) was rather low but constant at 8°C. However, mortality was high at 28°C and occurred mainly in the last nymphal instars and adult stage. Unexpectedly, no nymphs were produced by the adult morphs at 28°C, but effective fecundity was high at 8°C. Fecundity for alates was always lower than for the apterous aphids at the same temperature. The largest intrinsic rate of natural increase (r_m), and the mean relative growth rate (RGR) occurred at 24°C, for both apterous and alate morphs, and the lowest at 8°C. Our results show that lettuce aphid is better adapted to survive and reproduce at low (8°C) than at high (28°C) temperatures, and its best performance occurred at 20–24°C.

Global warming is expected to increase nocturnal environmental temperatures. We determined how elevated nocturnal versus diurnal temperatures alter fitness components in the imported cabbageworm (Pieris rapae L.). Full-sib families of P. rapae caterpillars were split into control, increased nocturnal, and increased diurnal temperature treatments. We found significant variation among families for relative growth rate, development rate, and pupal mass. Some families had a positive correlation between pupal mass and development rate, whereas others had a negative correlation. On average, we found a faster development rate caused by the nocturnal treatment and a smaller pupal mass caused by the nocturnal and diurnal temperature treatments. We found no significant effect of the temperature treatments on relative growth rate. An exponential growth model suggests that, despite the decreased pupal mass associated with the increased nocturnal temperature regimen, the faster development rate would cause the nocturnal population to multiply more quickly than the control or diurnal populations.

The goal of this study was to characterize the cellulose-degrading microorganisms in the guts of wood-inhabiting beetles. We enriched for cellulose-degrading microorganisms by inoculating filter paper in liquid growth medium with macerated guts from larvae and adults of the wood-boring longhorned beetle, Saperda vestita, and the phloeophagous bark beetles, Ips pini and Dendroctonus frontalis. After incubation, microorganisms were isolated in pure culture and tested for their ability to digest carboxymethylcellulose (CMC). Isolates were identified based on their ribosomal RNA gene or intergenic region sequences. Bacteria and fungi from the gut of S. vestita degraded filter paper, whereas the microorganisms from the phloeophagous insects did not. The only bacterium detected that was able to degrade CMC is closely related to Sphingobium yanoikuyae, a member of the α-Proteobacteria class. We found this species in all field-collected S. vestita larvae in 2002 and 2003. Population densities of cellulolytic bacteria in S. vestita ranged from 2.4 × 10⁵ to 3.6 × 10⁶ CFU/gut. Bacteria isolated from the phloeophagous beetles I. pini and D. frontalis did not degrade CMC. Two fungi isolated from the gut of S. vestita adults had strong degradative activity. Sequences of the ITS1, 5.8S, and ITS2 rRNA regions indicated that these fungi are highly similar to Fusarium culmorum and Penicillium crustosum, respectively. This study provides the first description of the gut microbial community of S. vestita and the first documentation of association between cellulolytic microorganisms and a wood-boring beetle.

The objective of this study was to evaluate the effect of temperature on survival, development, and reproduction of Copitarsia decolora. Both linear and nonlinear models were used to model temperature-dependent development and population growth for C. decolora reared on asparagus and artificial diet. We used @Risk Software to bootstrap model parameters so that variability in observations could be incorporated into model predictions. C. decolora eggs required ≈69 DD to complete development with a base temperature of 7.8°C. C. decolora developed through four to six instars depending on temperature and food source. Development of larvae from neonate through prepupa required 341.4 DD above a base of 7.3°C on asparagus, whereas 254.5 DD were needed on artificial diet, where the base temperature was 7.7°C. Pupae required ≈236 DD (base temperature 8.2–8.4°C) to develop when reared on asparagus or artificial diet. Female moths laid significantly more eggs at 14.6 and 20.1°C than at higher or lower temperatures. Survival of individuals to the adult stage increased from 71% at 9.7°C to 93% at 24.9°C. Survival fell off rapidly to 25% at 29.5°C. The generation time was the shortest at 29.5°C; however, only 25% of females survived to the adult stage, fecundity was low, and only 53% of the eggs hatched. The capacity for increase, r_c, was low at 9.7°C, peaked at 25.7°C, and declined as temperature increased. We estimated that populations on asparagus would not develop at temperatures >31.3°C or <6.9°C. We show the importance of estimating a range of values for base temperature and degree-days by conducting a preliminary pathway analysis that incorporates the effect of temperature on egg hatch.

In lower termites, the soldier is the only sterile caste. Through hormonal control, soldiers seem to promote caste differentiation of workers to the reproductive caste. However, little data exist on how hormonal levels change in soldiers and workers in the field and how this may tie into the seasonal reproductive formation. Our objective was to collect baseline data on hormonal changes in colonies of subterranean termites in the field. Over a 1-yr period, the seasonal variation of juvenile hormone III (JH) titers was determined for Coptotermes formosanus Shiraki soldiers and workers collected monthly from field colonies infesting isolated cypress trees (Taxodium distichum L. Rich.). A total of five colonies were evaluated. Soldier JH titers leveled from February through May, with peak values in June and July. JH titers in workers followed a similar trend. Both soldier and worker JH titers remained at low levels in the fall and winter. This is the first effort to correlate physiological and hormonal aspects with soldier production in the field. Seasonal changes in JH titers as an intrinsic mechanism for reproductive caste differentiation is also discussed.

Larval Protocalliphora Hough are obligate hematophagous parasites of nestling birds. While there is much interest in their effects on birds, little is known about the factors influencing their population sizes within nests. We experimentally increased temperature at nests of tree swallows (Tachycineta bicolor Vieillot) on two study areas and compared densities of larval Protocalliphora with control nests. We found that number of Protocalliphora varied in a curvilinear fashion with temperature, with population sizes highest in nests around 25°C and decreasing at both higher and lower temperatures. After controlling for temperature, we found differences between study areas in number of Protocalliphora in nests, and we hypothesize that these results are caused by differences in the size and dispersion of nests between the two areas. There was no seasonal variation in number of Protocalliphora in nests, but numbers increased significantly with the number of hosts in a nest, presumably because more resources were available for exploitation as host brood size increased. The cell-mediated immune responses of nestling tree swallows was positively correlated with number of Protocalliphora, and we suggest that these results are the consequence of the immune systems of nestlings in heavily parasitized nests being more sensitive to challenges by novel antigens or mitogens. To our knowledge, our study is the first to show variation in densities of larval Protocalliphora as a consequence of experimental manipulation of temperature and provides insight into important factors affecting population sizes of parasites in avian nests.

A Fourier transform infrared (FTIR) spectroscopic method was developed to quantify ammonia (NH₃) and carbon dioxide (CO₂) to facilitate accurate determination of antennal sensitivity of adult Caribbean fruit flies, Anastrepha suspensa (Loew), to these compounds. Electroantennogram (EAG) recordings were made from antennae of flies that were exposed to known quantities of each of the pure gases and to mixtures of these gases. EAG response to volumetric dilutions of saturated vapor from a commercially available ammonium bicarbonate lure was determined, and FTIR analysis was used to measure the amount of NH₃ and CO₂ in the samples. Maximal EAG responses were elicited with doses ≥24 μg NH₃ and ≥57 μg CO₂. Mean female response was greater than male response to substrates that included CO₂. For both sexes, EAG response to NH₃ was greater than response to CO₂. When NH₃ and CO₂ were combined either as a mixture of pure gases or as vapor emitted from the lure, the EAG response was approximately equal to the sum of the individual responses to the two compounds. A polynomial regression was the best fit for describing antennal response to ammonia, carbon dioxide, and mixtures of these chemicals whether obtained from pure gas sources or from commercial lures.

The response of Diachasmimorpha longicaudata (Ashmead) females to mango fruit that were intact (healthy), mechanically damaged, or infested with Anastrepha ludens (Loew) larvae, and their respective hexanic and methanolic extracts, was studied using behavioral, electrophysiological, and chemical techniques. Female parasitoids significantly preferred to visit infested mangoes and their extracts over healthy and mechanically damaged mangoes in wind tunnel and field cage bioassays. This suggests that the presence of the larvae inside the fruit is of clear importance in the host location behavior performed by this species. Methanolic extracts of infested mangoes evoked a significant electroantennography (EAG) response in female antennae compared with the responses elicited by solvent, healthy, and mechanically damaged mango extracts, but EAG response to hexanic extracts of infested mangoes was only significant compared with solvent control. Most of the compounds found in infested mango hexanic extracts were commonly found in healthy and mechanically damaged mango hexanic extracts, except 2-phenylethyl acetate, which seems to be exclusively present in infested mangoes. Also, infested mango extracts contain several compounds in higher amounts compared with the other two types of mangoes, as do the methanolic extracts from infested mangos. These differences could explain why female parasitoids preferred to visit infested mangos, with their correspondent methanolic and hexanic extracts. Our results suggest that this species uses a complex mixture of compounds for host location.

Current ammonia-based lures vary considerably in their ability to attract Anastrepha fruit flies in the field. This report presents results from electroantennography (EAG) and behavioral bioassays that examined the effect of age on fly response to ammonia and carbon dioxide, two volatile chemicals released from commercial ammonium bicarbonate lures. EAG measurements from female Caribbean fruit flies, Anastrepha suspensa (Loew), showed that ammonia generated a greater EAG response in sexually immature females compared with mature females. Conversely, carbon dioxide elicited stronger EAG responses in sexually mature females. In flight tunnel bioassays, females from both age groups were captured in response to ammonia ranging from 60 to 3840 μg/h, but captures declined with increasing ammonia concentration. In bioassays with the two highest ammonia release rates, captures of immature females were significantly lower than captures of mature females. Carbon dioxide, ranging from 300 to 7200 μg/h, did not capture any flies when presented alone in the flight tunnel bioassay. However, for sexually mature flies, carbon dioxide in combination with ammonia was more attractive than ammonia alone. These age-related differences in response to ammonia and carbon dioxide may account for some of the variability observed in field tests with ammonium bicarbonate lures.

We conducted four behavioral choice tests in stands of mature lodgepole pine in British Columbia, from 1988 to 1991, to determine the dose-dependent responses of Orthotomicus latidens (LeConte) and Ips pini (Say) to their respective pheromones. Dose-dependent responses were exhibited by I. pini to (±)-ipsdienol and lanierone, with trap catches directly proportional to pheromone release rates. We found differences in sex ratio of I. pini in their responses to ipsdienol but not lanierone. There was no dose-dependent response exhibited by O. latidens to its pheromone, (±)-ipsenol, with or without the presence of the host kairomone, (−)-β-phellandrene. The bark beetle predator, Enoclerus lecontei (Wolcott), showed a dose-dependent response to lanierone. Thanasimus undatulus (Say) was attracted to ipsenol in a dose-dependent fashion only when traps were also baited with β-phellandrene. Neither T. undatulus nor E. sphegeus (F.) exhibited dose-dependent responses to ipsdienol.

Studies evaluated blends of the pear-derived kairomone ethyl (E, Z)-2,4-decadienoate and codlemone, loaded in gray halobutyl septa, as attractants for adult codling moth, Cydia pomonella L. Studies were conducted in apple orchards, Malus domestica Borkhausen, treated with or without sex pheromone dispensers for mating disruption (MD). Septa were loaded with either one or both compounds at rates of 0.0, 0.3, and 3.0 mg pear ester and 0.0 and 3.0 mg codlemone in the first series of tests. Traps baited with a 3.0/3.0-mg blend caught significantly more males and total number of codling moths than traps baited with either compound alone in both types of orchards. Traps baited with two lures loaded individually with pear ester (3.0 mg) and codlemone (3.0 mg) caught significantly fewer males and total moths than traps baited with the dual lure (3.0/3.0 mg). The addition of 3.0 mg codlemone to pear ester did not significantly affect the capture of female moths. However, increasing the loading of pear ester from 0.3 to 3.0 mg in the dual lure significantly increased female moth catch in the untreated orchard but not in the sex pheromone MD orchard. Increasing the loading of pear ester to 20.0 mg in a dual lure with 3.0 mg codlemone significantly increased total codling moth catch compared with a 3.0 mg codlemone lure, but female catch was significantly lower compared with traps baited with a 3.0 mg pear ester lure. Adding a 3.0 mg pear ester lure to traps baited with a 42.0 mg sex pheromone lure significantly reduced male moth catch compared with the sex pheromone lure alone but did not reduce the catch of female moths compared with traps baited with a 3.0 mg pear ester lure alone.

Studies were conducted in apple, Malus domestica Borkhausen, orchards to evaluate the attractiveness of the kairomone, ethyl (E, Z)-2,4-decadienoate (pear ester), loaded at various rates into gray halobutyl septa, to adult codling moth, Cydia pomonella L. All studies were conducted in orchards treated with sex pheromone mating disruption. Lure loadings from 0.01 μg to 50.0 mg were evaluated in 12 orchard plots in 1999. Lures loaded with 1.0–50.0 and 0.1–50.0 mg caught significantly more male and female moths than the blank control, respectively. Field dose–response studies were repeated with five lure rates (0.1–40.0 mg) of pear ester during four periods during the 2000 season. Significant seasonal date and rate effects were found for the capture of males and female moths. The 0.1-mg lure caught significantly fewer males than the 1.0-, 3.0-, and 40.0-mg lures. The 40.0-mg lure caught significantly fewer female moths than the 1.0- and 3.0-mg lures. The 3.0-mg lure caught a higher proportion of virgin females than the 10.0- and 40.0-mg lures. The attractiveness of the 1.0 and 3.0 mg pear ester loadings were compared with a sex pheromone lure during a 10-wk trial in 2002. Both pear ester lures caught significantly fewer moths than the sex pheromone lure during the first 4 wk of the study and over the entire 10-wk period. However, no difference among lures occurred during week 5, and the 3.0-mg lure caught significantly more moths than the sex pheromone lure during week 6. The 3.0-mg lure caught a significantly higher proportion of female moths and a higher proportion of virgin female moths than the 1.0-mg lure. These studies suggest that the optimal loading of pear ester for capture of codling moth in mating disrupted apple orchards likely depends on the specific objectives of the monitoring program.

We evaluated the distribution and abundance of feral honey bee, Apis mellifera L., colonies in a coastal prairie landscape by examining nest site characteristics, population trends, and spatial and temporal patterns in cavity use. The colony densities of up to 12.5 colonies per km² were the highest reported in the literature for an area including both suitable and unsuitable patches of nesting habitat. The measured cavity attributes were similar to those reported from other areas. The time occupied and turnover indices provided useful information about cavity quality, although none of the measured cavity attributes were correlated with these indices. Unmeasurable cavity characteristics, such as cavity volume, may provide a better estimate of cavity quality. Spatial patterns existed in cavity use by the feral colonies, with the colonies showing an aggregated pattern of distribution throughout the study. Colony aggregations probably resulted from the distribution of resources, especially cavities. Two years after the arrival of Africanized honey bees, cavities used by Africanized and European colonies were aggregated in distribution. During what seemed to be a transition period, both Africanized and European colonies were randomly distributed. After that time, European colonies remained randomly distributed, whereas Africanized colonies were aggregated. Therefore, the invasion of Africanized honey bees seemed to fragment the existing European population, corresponding to a decrease in the overall number of European colonies in the study area.

The wolf spider, Pardosa agrestis Westring (Araneae: Lycosidae), is a dominant arthropod predator in central European agricultural areas. Recent studies have indicated that this spider has a unique phenology among Pardosa species. Three years of systematic field monitoring of a P. agrestis population in Hungary confirmed that an early summer peak (P1) of adults typical of the Pardosa genus is followed by a second late summer peak (P2) that does not occur among congenerics. Rearing experiments conducted outdoors revealed that offspring from P1 can reach maturity in ≈2 mo time, well before the end of summer. Thus, P2 adults represent a second generation of the species, with a chance for a potentially successful reproduction. However, the speed of development was variable among P1 offspring; individuals, which proved to be slower developers, did not mature during P2; rather they overwintered as juveniles and matured during the following year P1 period. Thus, members of the P1 cohort followed different developmental pathways; this corresponds to a cohort-splitting strategy. Splitting occurred even among spiderlings originating from the same clutch (cocoon) at the beginning of P1. In contrast, spiderlings born at the end of P1 uniformly matured by next spring. Splitting among offspring spreads the mother’s reproductive success between risk averse slow-developing and risk prone fast-developing offspring. The facultative bivoltine life cycle arising through cohort splitting may allow P. agrestis to adapt to predictably ephemeral agricultural habitats by flexibly producing the most dispersive juvenile stages in synchrony with the appearance of vacated habitats.

Field studies at sites with two contrasting soil types investigated effects from the presence of yellow foxtail [Setaria pumila (Poir.) Roem. and Schult.], established in bands parallel to corn rows, on western corn rootworm (Diabrotica virgifera virgifera LeConte) survival, corn root injury, lodging, biomass production, and yield. Results suggested that the presence of foxtail as an alternate host influenced the degree and progression of corn rootworm damage and adult emergence in a given locality. Rootworm adults emerged later from foxtail band areas and had smaller head capsule size than did individuals from areas without foxtail, consistent with earlier findings that foxtail in the diet of western corn rootworm was a poor nutritional substitute for corn. Lodging was reduced in the presence of yellow foxtail in some cases, but corn stover biomass and yield also were lower. Influences, if any, of soil type on rootworm survival were unclear because of differences in planting date between the two sites. Foxtail may function as a buffer to reduce rootworm damage to corn and serves as an alternate host that should be considered in the development of resistance management strategies for transgenic corn modified for rootworm resistance.

The spider fauna of vineyards in northern parts of North America are completely unknown, even though spiders represent important natural enemies to phytophagous insects occurring in vineyards. Weekly pitfall trapping in 1998 and 1999 in two vineyards in southern Quebec yielded over 4,600 spiders belonging to 97 species and 16 families. Spider assemblages (diversity and community composition) were similar between the two vineyards independent of environmental differences. However, some species-specific patterns were noted when the two vineyards were compared. High landscape diversity, including fallow fields and adjacent apple orchards, is hypothesized to account for a higher abundance of certain agrobiont species in one of the vineyards. Phenological data shows the most abundant linyphiid species, Tennesseellum formicum (Emerton), exhibits high phenotypic variation, and its multivoltine life cycles may be of adaptive importance for vineyards that are frequently disturbed. We also note several other species exhibiting period of peak activity in the spring [e.g., the wolf spiders Pardosa moesta Banks and Trochosa ruricola (De Geer)] or autumn [e.g., the funnel-web spider Agelenopsis potteri (Blackwall)]. Species turnover was high between sample dates, and data on activity and species richness of two guilds (web-building spiders and hunting spiders) indicate that many species that differ in foraging mode are active during all months of the growing season. The diverse ground-dwelling spider fauna in vineyards is therefore well positioned to prey on phyotophagous pests, and their populations should be conserved in these agroecosystems.

Microarthropod densities within late-successional coniferous forests thinned 16–41 yr before sampling were compared with adjacent unthinned stands to identify longer term effects of thinning on this community. Soil and forest floor layers were sampled separately on eight paired sites. Within the forest floor oribatid, mesostigmatid, and to a marginal extent, prostigmatid mites, were reduced in thinned stands compared with unthinned stands. No differences were found for Collembola in the forest floor or for any mite suborder within the soil. Family level examination of mesostigmatid and prostigmatid mites revealed significant differences between stand types for both horizons. At the species level, thinning influenced numerous oribatid mites and Collembola. For oribatid mites, significant or marginally significant differences were found for seven of 15 common species in the forest floor and five of 16 common species in soil. Collembola were affected less, with differences found for one of 11 common species in the forest floor and three of 13 common species in soil. Multivariate analysis of variance and ordination indicated that forest thinning had little influence on the composition of oribatid mite and collembolan communities within either the forest floor or soil. Differences in microclimate or in the accumulation of organic matter on the forest floor were likely most responsible for the observed patterns of abundance. Considering the role that microarthropods play in nutrient cycling, determining the functional response of a wide range of taxa to thinning may be important to effective ecosystem management.

Tamarix ramosissima Ledebour (Tamaricaceae) is an invasive shrubby tree naturalized in riparian areas throughout the western United States. Biomasses of arthropod taxa on T. ramosissima branches were quantified as dry mass per plant dry mass on three trees at each of three sites near surface water at Las Vegas Wash, NV, during 2002 and 2003. Biomass of two phytophagous-arthropod taxa, Opsius stactogalus Fieber (Homoptera: Cicadellidae) and Chionaspis spp. (Homoptera: Diaspididae), comprised 97.7% of arthropod biomass and varied among sites and among trees within sites. Their biomass was positively related to percent water of branches. Biomass of O. stactogalus was strongly associated with those of its parasites, Polynema saga (Girault) (Hymenoptera: Mymaridae) and Gonatopus sp. (Hymenoptera: Dryinidae), and predatory Dictynidae (Araneae) and weakly associated with those of omnivorous Attalus spp. (Coleoptera: Melyridae) and Formica xerophila M. Smith (Hymenoptera: Formicidae). Biomass of Chionaspis spp. was only associated with biomass of predatory Cybocephalus californicus Horn (Coleoptera: Nitidulidae). Biomass of predatory Salticidae (Araneae) was not associated with that of either phytophagous arthropod taxon. Low percentage of secondary-consumer biomass and large fluctuations in biomasses of O. stactogalus and Chionaspis spp. between years suggest populations of phytophagous arthropods on T. ramosissima are not regulated by natural enemies. T. ramosissima branches offer vertebrates arthropod prey with low diversity and highly variable biomass.

Competitive interactions among two specialist predators, Laricobius nigrinus Fender and Sasajiscymnus (Pseudoscymnus) tsugae Sasaji and McClure, and a generalist predator, Harmonia axyridis Pallas, of hemlock woolly adelgid, Adelges tsugae Annand, were studied in the laboratory. The two specialist predators are part of a biological control program that has been initiated for A. tsugae, and the potential for competition among these species and polyphagous established predators is unknown. Laboratory assays were evaluated in environmental chambers at two conditions: (1) early spring, 9:5°C (D:N), 12:12 (L:D) h, and 50–75% RH; and (2) late spring, 18:10°C (D:N), 16:8 (L:D) h, and 75–90% RH. Predator feeding trials using conspecific and heterospecific eggs showed that L. nigrinus and S. tsugae eggs were consumed by all species, and predation was decreased with increased A. tsugae density. Eggs of H. axyridis were eaten almost exclusively by conspecifics, at high rates, regardless of A. tsugae density. Survival, feeding on A. tsugae, and net egg production of single predators and groups of three conspecifics and heterospecifics were also examined. Survival for all species was not significantly affected by the presence of additional predators. In conspecific groupings, only H. axyridis showed significant reductions in feeding on A. tsugae, whereas all species had significantly reduced net egg production with conspecifics. In heterospecific groupings, no significant effects on A. tsugae predation or net egg production were detected. The only significant negative competitive interactions detected in these assays were among conspecifics, whereas heterospecific combinations showed noninterference.

The Indianmeal moth, Plodia interpunctella (Hübner), is a cosmopolitan pest of stored products, infesting most commodities in warehouses and grain bins. We studied the susceptibility of Indianmeal moth adults and larvae to seven entomopathogenic nematode species and strains. The nematodes studied were Heterorhabditis bacteriophora Poinar (HP88, Lewiston, and Oswego strains); H. indica Poinar, Karunakar, and David (Homl strain); H. marelatus Liu and Berry (Point Reyes strain); H. megidis Poinar, Jackson, and Klein (UK211 strain); and H. zealandica Poinar (NZH3 strain). Overall, the nematodes that had the highest virulence to larvae and adults of Indianmeal moth were H. indica, H. megidis, and H. marelatus. Adult Indianmeal moths seemed to be more susceptible to the nematodes than the larvae, and egg laying was significantly reduced by at least 44% in Indianmeal moths adults that survived exposure to the nematode strains. We conclude that H. indica, H. megidis, and H. marelatus should be studied further as potential biocontrol agents of Indianmeal moth in stored grains and processed commodities.

Water chestnut (Trapa natans) is an annual floating aquatic plant native to Asia but invasive throughout northeastern North America. Information about the range of T. natans in Asia suggests that the plant has not reached its potential range in North America. We studied whether herbivory by the water lily leaf beetle, Galerucella nymphaeae, which has adopted T. natans as a new host in North America, can contribute to reductions in plant performance. We released 0, 10, 20, and 50 G. nymphaeae first-instar larvae on developing T. natans rosettes and measured larval survival, larval development time, plant growth, plant biomass, and reproductive output. The larval densities we chose in our experiment represent the range of densities we frequently observe in the field, with the highest density exceeding field attack rates. Larval mortality was particularly high for first instars (50% within 1 wk) and not associated with treatment or lack of food. Overall, larval survival was extremely low, with survival rates of 5.1% in the highest (50 larvae) to 11.3% in the lowest (10 larvae) herbivore treatment after 4 wk. We found no significant differences among plants exposed to different herbivore treatments for the number of leaves, rosette diameter, biomass, or reproductive output. In central New York, it seems that G. nymphaeae has no impact on water chestnut performance at the herbivore levels we see in the field and chose in our experiments. Water chestnut is a poor (but abundant) food plant for G. nymphaeae in the northeastern United States, but it is unlikely that the leaf beetle can contribute to local or regional control of water chestnut or reduce its spread.

The response of field-collected Hylastinus obscurus Marsham (Coleoptera: Scolytidae) to volatiles from Trifolium pratense L. of different ages was studied in a four-arm olfactometer. Volatiles from 1.5-, 2-, and 2.5-yr-old plants were more attractive than volatiles from 1-, 3-, and 3.5-yr-old plants. Two-year-old plants were preferred during winter, spring, and summer. One-year-old plants were not preferred in their early stages, but preference increased as they aged. Volatiles from 3-yr-old plants were never preferred. The essential oils obtained from 2-yr-old T. pratense elicited an attraction response from H. obscurus. Beetle response is discussed in relation to host-locating behavior.

Male Oriental fruit moths, Grapholita molesta (Busck), were briefly preexposed in a wind tunnel to plumes from a rubber septum lure releasing a three-component, optimally attractive pheromone blend for this species or to plumes generated by Isomate-M Rosso pheromone dispensers. The objectives were to determine how brief preexposures to low- and high-dosage pheromone dispensers affect initiation of anemotaxis, duration of sustained anemotactic flight, and peripheral sensitivity 15 min and 24 h after exposure. A greater proportion of G. molesta males took flight and successfully oriented toward a lure 15 min after briefly orienting in plumes generated by an identical lure compared with unexposed, naïve moths or control moths preexposed to clean air. In addition, the proportion of males contacting a lure or orienting to the lure without source contact 24 h after a preexposure was not significantly different from the proportions of naïve or control moths completing these behaviors. However, the mean duration of sustained flights of lure-preexposed male G. molesta in plumes generated by a lure was significantly shorter 15 min and 24 h after preexposure compared with that of naïve moths. The proportion of male G. molesta contacting lures 15 min and 24 h after preexposure to ropes was not statistically different from the proportions of naïve or control moths contacting the lure or orienting without source contact. However, as observed with moths preexposed to a lure, the mean duration of sustained flights of male G. molesta preexposed to an Isomate-M Rosso dispenser was significantly shorter than that of naïve moths 15 min and 24 h after preexposure. Mean durations of sustained flights of male G. molesta preexposed to a lure or rope were significantly longer after 24 h compared with 15 min after the exposure treatment, indicating that the effect of pheromone preexposure decayed over time. Electroantennograms recorded 15 min and 24 h after preexposures to lures or Isomate-M Rosso dispensers in the flight tunnel were indistinguishable from those recorded from unexposed moths. We suggest that false-plume following by naïve male G. molesta combined with decreases in duration of subsequent anemotactic orientations after previous bouts of false-plume following may explain why Isomate-M Rosso dispensers are effective in mating disruption experiments with G. molesta.

A single herbicide (Trimec® or Strike 3™) application in early season (March or April) was made to marginal areas around fields in 23-km² test sites of the Mississippi Delta in 1999, 2000, and 2001. The herbicide was used to kill broadleaf weeds in the marginal areas that served as hosts for tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois). The herbicide treatment caused a significant reduction in wild host densities in the treated test sites in all 3 yr. Tarnished plant bug populations in treated test sites did not increase significantly in the treated marginal areas during April and May after treatment of the margins in the first 2 wk of March in 2000 and 2001. The herbicide application was made in the first 2 wk of April 1999, and plant bug populations increased in treated marginal areas in this year. The increase was thought to be caused by plant bugs moving to Italian ryegrass, Lolium multiflorum Lamarck, a previously unreported plant bug host, which was not affected by the herbicide. Laboratory tests showed that plant bugs would oviposit in flowering or nonflowering ryegrass when caged on ryegrass for a 6-d period. Newly emerged nymphs developed into adults (56%) when reared on floral spikelets of ryegrass, but no adults were obtained when they were reared on ryegrass stems and leaves. Rearing on floral spikelets beginning with third-instar nymphs resulted in 92% adults, whereas third-instar nymphs reared on stems and leaves produced no adults. These results showed that ryegrass could serve as a reproductive host for plant bugs when it flowered during late April and May. Application of the herbicide in March, when ryegrass was not in flower, resulted in no significant increases in plant bug populations on wild hosts (mainly ryegrass) during April and May in 2 yr of the field study.

Probe traps are sensitive tools for detecting populations of beetles in stored grain, but their use for estimating insect density in concrete silos has not been established. Populations of grain beetles infesting wheat in concrete silos at two commercial storage facilities in north central Oklahoma were sampled using probe traps and grain probe samples over a 17-wk period. Grain temperature and quality parameters were collected during the study. Thirteen insect species were detected using probe traps, whereas eight species were detected with the grain samples; Cryptolestes ferrugineus and Rhyzopertha dominca were the most common insects collected in the grain samples. Across dates, there were no differences in mean number of insects recovered by species near the grain surface and 1 m below in either probe traps or grain samples. Comparison of slopes (insects recovered in grain samples regressed on insects in probe traps) showed that there were significant differences by trap position for C. ferrugineus but not R. dominica. Multiple regression models, developed to predict insect population estimates using number of insects captured in probe traps and a temperature component, indicated that more variability in the data were explained using traps positioned 1 m below the grain surface (R² = 0.70) than near the surface (R² = 0.21) for C. ferrugineus. About one-half (R² = 0.53) of the variability in insect density was described for R. dominca. These regression models show the potential for methodical use of grain probe traps in pest management decision-making.

The impact of wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), on the photosynthetic capacity and primary metabolism of wheat, Triticum aestivum L., was evaluated in three different environments: environmental growth chamber, greenhouse, and field. C. cinctus elicited different photosynthetic responses in different environments. Wheat gas exchange parameters, such as photosynthesis, stomatal conductance, intercellular CO₂, and transpiration in the growth chamber environment were negatively affected by C. cinctus feeding. Conversely, the same gas exchange responses were not observed under greenhouse and field conditions. This study shows the important role of environmental variables, such as ambient CO₂ concentrations and light intensity, on plant responses to herbivores.

We report on laboratory hybridization between the indigenous Chrysoperla nipponensis and its close relative, C. carnea, which has been imported since 2001 from Germany to Japan as a biological control agent. Interspecific hybrids were obtained, and fully viable and fertile F1 and F2 generations were produced. Crosses between C. carnea females and C. nipponensis males showed 41.3% fertility, but the reciprocal cross showed only 9.5% fertility. Despite the low fertility of interspecific crosses, most F1 hybrids were fertile and were successfully backcrossed to both parental species. However, F1 males from C. carnea females × C. nipponensis males showed low fertility (zero except for 20% in one case) when crossed with any females (F1 or backcross). In the one combination resulting in 20% fertility, an extremely long preoviposition period was observed, caused presumably by a mating delay. The absence of change in hatchability, adult emergence rate, total developmental period, or deviation from the 50:50 sex ratio from parents to the F2 generation of hybrids suggests that there is no genetic incompatibility between C. carnea and C. nipponensis resulting from hybrid breakdown. Because the courtship songs of the introduced C. carnea and the indigenous C. nipponensis are quite different, interspecific mating between the two close relatives may not occur under natural conditions. It will be necessary to monitor the establishment of the introduced C. carnea and its possible hybrids with the indigenous C. nipponensis in the wild to minimize any irreversible ecological risks, such as loss of genetic identity.