The law of total effective temperature, which has been conventionally used by many researchers, and the thermodynamic model based on enzymatic reaction, which was presented by previously, are representative models used to express a relationship between temperature and the development rate of poikilotherms. The former is a very simple and highly descriptive linear model. In contrast, the latter is very complex because it is a nonlinear model, but it has fine descriptive power. In a previous paper, I discovered the existence of a common temperature (Tc) and a common duration (Dc) of development among closely related members of arthropods during the course of comparatively analyzing many estimated values of constants of the linear model and succeeded in explaining the significance of Tc−Dc in an evolutionary process. This study was focused on an extended application of Tc−Dc to the nonlinear thermodynamic model. One of the practical difficulties in using the nonlinear thermodynamic model results from the vexatious complication of estimating simultaneously the values of seven unknown constants. In particular, there were no means to estimate the values of the constants of reference temperature (T₀) and development rate (ρ) at T₀, which are defined in the nonlinear thermodynamic model. Here, I determine a suitable replacement of the constants T₀ and ρ by the common temperature (Tc) and inverse of the common duration (1/Dc), respectively, resulting in reasonably successful curve fitting for data. Therefore, Tc (=T₀) could be considered in principle to be common in the two models. I suggest that Tc and T₀ be conferred a new definitive concept, that is, the intrinsic optimum temperature for development that tends to be fixed for a taxon, and that they exhibit the minimum effects on enzyme inactivation at low and high temperatures.

We describe variation in wing length, head width, and color of the corn leafhopper, Dalbulus maidis (DeLong and Wolcott), in Mexico from 21 sites at nearctic and neotropical latitudes, from low (<700 m) and high (>700 m) elevations, and wet season (June) and irrigated dry season (October) maize habitats. Female and male D. maidis were collected from 21 sites located from 15.72° N to 25.48° N latitude and 2–1,203 m elevation. Females and males from the northern nearctic latitudes were larger and darker than leafhoppers from the southern Neotropical latitudes. Elevation did not affect the size or color of female or male leafhoppers. At an irrigated site where maize is cultivated all year (Colima), females and males collected in October had longer wings than leafhoppers collected in June. At a nonirrigated site (Zapopan) where maize is cultivated only in the wet season, females collected in June had longer wings, wider heads, and were darker than females collected in October. Compared with leafhoppers living in irrigated maize habitats, D. maidis from maize cultivated only in the wet season have significant variations in body size and color, suggesting D. maidis adapts to survive seasonal harsh environments.

Integrated pest management (IPM) programs for the bean leaf beetle, Cerotoma trifurcata (Förster), could benefit from an ability to forecast the magnitude and timing of early-season infestations. The objectives of this study were to examine the supercooling point (SCP) of adult C. trifurcata as an index of its cold hardiness, monitor overwintering survival, and revise an existing model used to predict the overwintering survival of this pest in wooded areas as a function of low-temperature accumulation. Within a year, the mean SCP of C. trifurcata ranged from −8.9 to −6.0°C. Soil temperatures dropped below the lowest mean SCP (i.e., −8.9°C) in only 2 of 11 yr (1994–2004). In-field survivorship studies showed that adult C. trifurcata successfully overwintered in Minnesota (34–59% survival). This species survived well in years when the existing model predicted zero or low survival. In contrast, our revised model predicted more closely the overwintering survival of this species in southern Minnesota. However, other overwintering mortality factors should be studied to improve our understanding of how well C. trifurcata overwinters in temperate regions.

The antiaggregation pheromone verbenone was operationally tested for 5 yr to deter mass attack by the mountain pine beetle on lodgepole pine in campgrounds and administrative areas surrounding Redfish and Little Redfish Lakes at the Sawtooth National Recreation Area in central Idaho. Each year, five-gram verbenone pouches were evenly distributed (≈10 m apart) within seven of 14 0.2-ha plots. During the first 2 yr of the study a median of 12% of the host trees >13 cm dbh were attacked and killed on the treated plots, whereas trees on the untreated plots incurred a median mortality of 59%. When ≈50% of the trees on the untreated plots were killed a detectable beetle response to verbenone on the treated plots dramatically declined. After 5 yr, mountain pine beetle had killed a median of 87% of the lodgepole pine trees >13 cm in untreated plots and 67% in plots containing verbenone pouches. Beetle pressure was higher on untreated plots in 2000 and 2001, nearly equal between treatments in 2002, higher on verbenone-treated plots in 2003, and similar between treatments in 2004. It is hypothesized that the lack of response to verbenone after 2 yr may be related to both population size and spatial scale, i.e., large numbers of vigorous beetles in a local area with a reduced number of preferred large-diameter trees become crowded and stressed, causing a decline in the response to verbenone. The 2-yr delay in widespread pine mortality caused by verbenone would have given land managers time to use other management tactics to deter catastrophic loss of trees caused by mountain pine beetle.

The feasibility of mating disruption in the oriental beetle, Anomala orientalis Waterhouse, with microencapsulated sprayable formulations of (Z)-7-tetradecen-2-one, the major sex pheromone component, was evaluated in turfgrass areas. The effect of the applications was measured by monitoring male A. orientalis captures in pheromone-baited traps throughout the flight period and estimating A. orientalis larval densities in September in soil/sod samples. Trap captures were 90–100% lower in the treated areas during the first 7–10 d after treatment, but started to increase thereafter. Therefore, applications were repeated after 14 d in most treatments. The formulation tested in 2002 and 2003 reduced trap captures by 87–88% with two applications of each 12.5 or 50 g pheromone/ha but only by 74% by a single application of 75 g pheromone/ha. Reductions of A. orientalis larval populations by 68–74% were not significant because of very high variability of larval densities in the nontreated areas. Two different formulations tested in 2004 were less effective. Significant amounts of the pheromone remained on grass foliage after application, but 51 and 73% of this residue were washed off the foliage with 3.2- and 6.4-mm post-treatment irrigation, respectively. Shoes walked at 1 day after treatment through pheromone-treated areas were sufficiently contaminated with pheromone to attract high numbers of A. orientalis males in nontreated areas. Mating disruption is a promising strategy for A. orientalis management in turfgrass. However, more persistent formulations need to be developed that have a lower potential to contaminate shoes and other clothing articles with pheromone.

The sex pheromone component muscalure [(Z)-9-tricosene] on the cuticles of female house flies (Musca domestica L.) was quantified using gas chromatography. Laboratory and wild-strain house fly colonies were derived from poultry and dairy farms and a horse-riding stable. Muscalure levels from strain MB females were highest after 13 and 23 generations in culture, but 30–70% of females from early generations (F8–F12) had no detectable levels of muscalure. Flies <2 d old from the MB laboratory colony (F23) had less muscalure than did older flies, and levels tended to increase as flies aged from 3 to 8 d. Of 10 wild house fly populations sampled at 3 d of age (72–96 h old) between F1 and F7 in culture, 1 had no detectable muscalure, and 8 of 10 averaged ≤218 ng of muscalure per female, comprising ≤1.6% of total cuticular hydrocarbons. In 6 of 10 field populations, ≥67% of females had no detectable muscalure. In contrast, two field strains had average levels of 559 and 1,113 ng muscalure/female (comprising 3.2 and 5.0% of total hydrocarbons), which was comparable to long-established laboratory strains such as the UCR strain (751 ng muscalure/female, comprising 3.0% of total hydrocarbons). More than 70% of females from those two field strains had muscalure. Flies from the Cooper laboratory strain also lacked detectable muscalure. Muscalure amounts were highly variable; it was rare or lacking in many field populations and thus does not seem to be essential for house fly reproduction.

The behavioral and electrophysiological responses of the obliquebanded leafroller, Choristoneura rosaceana (Harris), and the redbanded leafroller, Argyrotaenia velutinana (Walker), to crude extracts of Arctium lappa, Bifora radians, Humulus lupulus, Xanthium strumarium, and Verbascum spp. were studied under laboratory conditions. Plant materials were dried and ground before extraction with methanol. Plant extract residues were mixed in acetone to give 20% (wt:wt) suspensions after evaporation of excess methanol. All five plant extracts elicited significant electroantennogram (EAG) responses from both males and females of each species. EAG responses to X. strumarium were generally the highest for both species. The behavioral responses of male and female obliquebanded leafrollers to the plant extracts were compared with responses to pheromone [(Z)11–14:Ac] and a solvent control. Significantly more male and female obliquebanded leafrollers were attracted to X. strumarium compared with pheromone on filter paper, H. lupulus, Verbascum spp., and the control. Compared with the control, there was no significant attraction to pheromone on filter paper, A. lappa, H. lupulus, and Verbascum spp. The oviposition-deterring effect of plant extracts on female obliquebanded leafrollers was studied in dual-choice bioassays. B. radians elicited the highest oviposition deterring effect with no eggs laid on this treatment. A. lappa was also effective and reduced oviposition to 2.9% of that observed in the controls. The number of eggs laid on X. strumarium (14.4%) and Verbascum spp. (21.2%) treatments were not significantly reduced relative to the control; however, oviposition was reduced by three-fold by these two treatments. The results show that certain crude plant extracts induce behavioral effects on male and female obliquebanded leafrollers. Further studies are needed to determine the active ingredients and their potential use in pest management strategies aimed at managing these pest species in tree fruit production.

Feeding deterrent activity of some enantiomeric pairs of terpenoid lactones with the p-menthane system was tested against larval and adult Colorado potato beetle (Leptinotarsa decemlineata Say). The lactones were synthesized from optically pure isomers of pulegone and isopulegol. Monoterpene ketones and alcohols with the p-menthane system were weak antifeedants toward both Colorado potato beetle developmental stages. The introduction of the lactone moiety and an accessory functional group (hydroxy or ketone group) into the p-menthane skeleton increased feeding deterrent activity of the compounds. Our results show a correlation between chemical structure and antifeedant activity and indicated that the sensitivity of Colorado potato beetle to the tested lactones depends on the chiral centers configuration and the developmental stage of insects tested.

The commercial release of transgenic maize with resistance to rootworms incorporated with glyphosate tolerance has become a reality, and questions have arisen regarding the impact of grassy weed phenology on the biology of the western corn rootworm, Diabrotica virgifera virgifera LeConte. A study to determine the impact of host plant phenology on the survivorship (percentage larval recovery), growth (dry-weight gain), and development (change in head capsule width) of western corn rootworm larvae was conducted in a split-split-plot randomized complete block design experiment under greenhouse conditions. Six host species were evaluated under eight weekly infestations of 15 neonate western corn rootworm larvae that were sampled for larval recovery after 7, 14, and 21 d, each with five replications. Percentage larval recovery, change in head capsule width and weight gain were significantly impacted by infestation time and host species. Other than from maize, Zea mays L., larval survivorship was highest in large crabgrass, Digitaria sanguinalis L. Scop, followed by giant foxtail, Setaria faberi R. A. W. Herrm, witchgrass, Panicum capillare L., woolly cupgrass, Eriochloa gracilis, and green foxtail, Setaria viridis L. P. Beauv. Infestation in weeks 4, 5, and 6 supported western corn rootworm survivorship, growth, and development better than infestation at later times. Alternate host phenology may be an important larval movement factor between grassy weeds and transgenic rootworm-resistant maize.

Gypsy moth management is divided into three components: eradication, suppression, and transition zone management. All three components require knowledge of the boundaries that delimit these areas. Additional interest is also placed on the relationship between population spread and defoliation to prepare for the gypsy moth advance in new areas and minimize its impact. We developed relationships between advancing population boundaries, which were estimated using an algorithm implemented under the USDA Forest Service Gypsy Moth Slow-the-Spread Project and defoliation records collected by State and Federal agencies. We used current data from Wisconsin, West Virginia, and Virginia and historical data from the lower peninsula of Michigan. We observed that in West Virginia, Virginia, and Michigan, defoliation generally occurred in areas where moth abundance exceeded 300 male moths per pheromone-baited trap (i.e., the 300-moth population boundary), whereas in Wisconsin, it generally occurred between the 100- and 300-moth population boundaries. We also detected temporal changes in Michigan in the relationship between boundaries and defoliation, where the transition time between the 10-moth population boundary and defoliation was 4–5 yr. Recent data from Wisconsin suggest a similar transitional time, whereas recent data from West Virginia and Virginia do not seem to contradict an earlier study suggesting a transition time of roughly 8 yr.

The soybean aphid, Aphis glycines Matsumura, is a serious pest in Midwestern soybean, Glycine max L. Merrill, and has the potential to colonize a large geographic range throughout a single growing season. Our objectives were to describe colonization patterns on a statewide spatial and temporal scale, examine the changing proportion of winged forms throughout a season, and assess photoperiod as a potential trigger for alate production. In Minnesota, we define initial colonization as the period of time during the early vegetative growth when alates were present and alatoid nymphs were absent on soybean. Initial colonization during 2002 and 2003 was ∼2 wk. On average across Minnesota, summer migrants were first produced when most fields were at the initial flowering stages in 2002. In 2003, an outbreak year, initial detection of summer migrants occurred earlier during vegetative stages before flowering. The significant increase in the proportion of all potential migratory forms (i.e., alatoid nymphs and adults) occurred during the beginning of seed set for both years. During seed set, the mean proportion of alate A. glycines was 0.15 ± 0.04 (SE) in 2002 and 0.16 ± 0.06 in 2003. The mean proportion of alatoid nymph A. glycines was 0.14 ± 0.04 in 2002 and 0.29 ± 0.04 in 2003 during seed set. The total mean proportion of migratory forms was higher when the critical L:D photoperiod was 14.5:9.5 h/d. A regression analysis also indicated the proportion of winged A. glycines increased with decreasing photoperiod.

We used the aquatic communities living in the purple pitcher plant (Sarracenia purpurea L., Sarraceniaceae) to determine if patterns produced by trophic interactions at the local scale can be detected at larger spatial scales. Mosquitoes (Wyeomyia smithii Coq., Diptera: Culicidae) are known to have a negative effect on the aquatic microfauna within leaves. We compared the abundance of two microfaunal taxa, Bodo (Kinetoplastea: Bodonidae) and Habrotrocha rosa Donner (Rotifera: Bdelloidea), in bogs with and without pitcher plant mosquitoes. Bogs containing pitcher plant mosquitoes had lower densities of bacteria through the study period. However, within these bogs, leaves with mosquitoes did not have lower bacterial densities. We found that the pattern for Bodo was similar at the leaf and bog spatial scales. Abundance of Bodo was closely linked to bacterial densities and the presence of mosquitoes strengthened that relationship, because of greater predator impacts when bacteria were scarce. In contrast, different patterns emerged at the two scales for H. rosa. At the leaf scale, a predator effect was seen only for low bacterial densities (as for Bodo), but at the bog scale, H. rosa was less abundant in mosquito bogs, and abundance was not associated with bacterial levels. We suggest that differences in life history characteristics (population growth rate and average abundance) may influence the relative influence of local interactions and regional processes such as colonization.

The degree of shift in stable isotope ratios between trophic levels, known as trophic shift, can help elucidate trophic interactions in systems not amenable to conventional analyses. Gall wasp communities have long been a model system for community ecologists, yet much remains to be explored concerning trophic interactions between hosts, herbivores, and natural enemies. Before stable isotopes can be successfully applied to trophic interactions within gall communities, quality estimates of trophic shift between community members are required. In this study, we document the degree of trophic shift in carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes within a simple cynipid gall wasp community, Neuroterus sp. (Cynipidae), in Quercus turbinella Greene (Fagaceae). The trophic shift in δ¹⁵N between Neuroterus sp. and Q. turbinella was much lower than values reported for Cecidomyiid gallers, whereas the shift in δ¹⁵N between Neuroterus sp. and its parasitoid, Omyrus sp., was similar to that reported for parasitoids. The trophic shift in δ¹³C was considerably greater in Neuroterus sp. than previous estimates from other types of herbivores, whereas Omyrus sp. exhibited a trophic shift in δ¹³C similar to other biological systems. The unusual trophic shift in δ¹³C in Neuroterus sp. is likely a result of metabolic differences between host and gall tissues. We discuss commonalities in the observed trophic shift of δ¹³C and δ¹⁵N in the Neuroterus sp. community to other biological systems and postulate physiological mechanisms for deviations from reported estimates of trophic shift.

Conservation of biodiversity recently has focused on the importance of pollinator services for the preservation of threatened plant species in fragmented landscapes such as the tallgrass prairie biome. In this study, we assessed the influence of local and landscape floral resource diversity and abundance on bumble bee (Bombus Latreille) diversity and abundance at eight tallgrass prairie sites in Iowa. We calculated a landscape floral resource index (LRI) for areas within 500- and 700-m radii of each site based on the density and diversity of flowering plant species in polygons of different landscape elements. LRI values, areas of each landscape habitat type, and the diversity and abundance of bumble bee–used flowering ramets at each site were compared with bumble bee diversity and abundance at the site. Bumble bee diversity was best predicted by a model including the LRI of grasslands surrounding sites at 500 m, which explained most of the variance, and the abundance of bumble bee–visited plants at the site. Bumble bee abundance was best predicted by a model including the percent of the landscape in grasslands at the 700-m radius, which explained most of the variance, and the abundance of bumble bee–visited plants at the site. Our results reveal that bumble bee diversity at tallgrass prairie patches is influenced by the availability of resources in the landscape, particularly in grasslands, and to a lesser extent by site characteristics, indicating the importance of spatial scale for creating successful pollinator management plans in fragmented landscapes.

Effects of the antiparasitic drug ivermectin on the dung-breeding flies and beetles Liatongus minutus (Motschulsky) were studied in laboratory and field experiments in Hokkaido, Japan. Ivermectin was detected in dung from 1 to 21 d after treatment, with a peak at the first day after treatment in two pour-on administrations (500 μg/kg). Laboratory bioassays were performed on the flies Musca bezzii Patton and Cragg and Scatophaga stercoraria L. and on the beetle Liatongus minutus. Dung from treated cattle inhibited larval development of M. bezzii from 1 to 14 d and pupation rate was reduced 21 d after treatment. In S. stercoraria, pupation and emergence rates were reduced for up to 14 and 28 d, respectively. In laboratory experiments of the dung beetle L. minutus, no significant difference was found in numbers of brood balls constructed per female between dung from treated and control cattle, whereas in field experiments, numbers of brood balls recovered in treatment were more abundant than that of control at 14 d after treatment. However, emergence rates of L. minutus were significantly reduced in dung from treated cattle for up to 14 d after treatment in both laboratory and field experiments. In a field experiment using emergence traps, numbers of flies emerged were 10,494 (18 families) in dung from untreated control cattle and 9,348 (17 families) in dung from treated cattle. Emergence of Paregle cinerella (Fallén), Neomyia cornicina (Fabricius), Ravinia striata (Fabricius), Sepsis latiforceps Duda, Sepsis duplicata Haliday, Sphaeroceridae spp., and Empididae spp. was reduced severely in dung from treated cattle. Conversely, numbers of Ceratopogonidae and Psychodidae increased in dung from treated cattle. Total dry weights of flies emerged from 48 dung pats in field experiments was 5,849.7 mg in dung from control cattle and 1,268.2 mg in dung from treated cattle, showing a 79.3% reduction in treated dung.

Widespread management practices such as transgenic insecticidal crops influence the distribution and density of targeted pest species across the agricultural landscape. Natural enemies must cope with this altered distribution, and their response potentially influences the rate of resistance evolution in the pest. The purpose of this study was to examine spatial patterns of parasitism by the specialist parasitoid Macrocentrus grandii Goidanich (Hymenoptera: Braconidae) in response to the density of its host, the European corn borer (Ostrinia nubilalis Hübner [Lepidoptera: Crambidae]). When we manipulated host distribution and observed resulting patterns of wasp density and parasitism, we found that the smallest host aggregations had the lowest parasitism, but only when not associated with larger host aggregations. A subsequent field experiment confirmed that proximity to large host aggregations increased parasitism in small host aggregations. Theory indicates that such positive density-dependent parasitism should accelerate the evolution of toxin resistance in pest species, but our study suggests that close spatial proximity between insecticidal crops and refuges may help equalize M. grandii parasitism and that simple management techniques such as in-field refuges could potentially increase the complementarity of transgenic and biological control of European corn borer in this system. Further research is needed, however, before extrapolating the results of our small-scale study to field-level patterns and concluding that M. grandii will necessarily hasten resistance evolution in the European corn borer.

Entomopathogenic nematodes are important biological control agents for a variety of soil- and litter-dwelling insect pests. A major drawback to their use against pest species is their low level of persistence in many agricultural systems. While a number of studies have examined the persistence of these biological control agents over periods of days and/or weeks, the longer-term survival of these nematodes has received less attention. We report the results of a year-long field experiment testing the long-term survival of infective juveniles (IJs) of the entomopathogenic nematode Heterorhabditis marelatus (Liu and Berry), under a range of initial densities. We buried mesh-covered tubes containing raw field soil with varying densities of H. marelatus IJs in a coastal prairie containing naturally occurring populations of this nematode and then destructively sampled subsets of the tubes for nematode presence five times over 1 yr. H. marelatus IJs lived a surprisingly long time in the absence of prey: some nematodes from the initial cohort were viable after a year in the field. Survival over the year-long course of the experiment was independent of the starting IJ density, suggesting that H. marelatus does not aggregate at high densities to reduce desiccation risk. Our results highlight the fact that IJs vary greatly in their long-term survival; selecting entomopathogenic nematode isolates for persistence as well as virulence could enhance this biological control agent’s long-term effectiveness in agricultural systems.

Anastrepha spp. (Diptera: Tephritidae) larval behavior on the ground was quantified, and biotic and abiotic mortality factors were identified from the moment larvae exit fruit until they secure pupation sites in the soil in four environments that differed in climate, soil structure, and fruit tree composition in tropical Mexico (State of Veracruz). Distribution of pupae was influenced by fruit position on the ground but not by shade, litter depth, average soil temperature, soil pH, vegetation cover, and number of predacious insects per surface unit. At all sites, most larvae (90%) entered the soil after exiting the fruit within 10 min, but only at one site did larvae die because of sun exposure during the hottest part of the day. The most important biotic mortality factor at all sites was predation by ants, which in turn was influenced by temperature, humidity, and soil dampness, and varied significantly among host trees within a site. Ants commonly attacked larvae within 5 min of exit from fruit at all but one site. In laboratory experiments, larvae exposed to ant attack pupated at greater depths than larvae exposed to ants but that were not attacked (which in turn pupated at greater depths than larvae not exposed to ants).

To predict Lygus hesperus Knight population dynamics in the field, a quantitative understanding of dispersal is needed. L. hesperus is a major pest of cotton and other seed crops in the San Joaquin Valley. Mark recapture experiments were performed that measured movement and abundance of L. hesperus in cotton (Gossypium hirsutum L.), alfalfa (Medicago sativa L.), and blackeye bean (Vigna sinensis L.). Male L. hesperus moved farther than females (4.6 versus 3.6 m/d). Movement was greater in the east-west axis than the north-south axis (7.0 versus 2.4 m/d). Calculations based on mark–recapture data suggest that a random walk model describes L. hesperus dispersal well. Diffusion estimates predict 98% movement radiuses in cotton, alfalfa, and bean as 15.6, 14.4, and 7.3 m/d, respectively. Estimates of absolute L. hesperus abundance were 45,000/ha in alfalfa during the August peak, approximately five times those in cotton. The results suggest that management of L. hesperus may be affected by greater dispersal along the east-west axis and the strong male bias in sweep-net samples.

Studies were conducted to examine the behavioral response of fifth-instar and adult Lygus hesperus Knight (Heteroptera: Miridae) to odors associated with a host plant (alfalfa) when presented singly or in combination with a visual plant cue (530 nm, green light-emitting diode [LED]). Bioassays were conducted in a modified Y-tube olfactometer, where incoming air was filtered and humidified before passing through chambers that held plant/conspecific treatments. A LED, placed behind an organdy screen at the end of one arm of the Y-tube, simulated a visual plant cue. In agreement with our previous findings, fifth-instar and adult female L. hesperus were attracted to plant/conspecific odor combinations, but adult males were not. Independently, the LED also was attractive to immature and adult female L. hesperus, and for all life stages, a much larger percentage of the bugs walked to the extreme end of the Y-tube when the visual cue was present. When visual and volatile cues were presented simultaneously, responses by both immature and adult (male and female) L. hesperus were significantly enhanced. Plant/conspecific treatments that had been marginally acceptable when only volatile stimuli were available showed the greatest enhancement in response with the addition of the visual cue. Presentation of visual and volatile cues together led to a mean increase in the percentage of bugs that walked to the extreme end of the Y-tube (nymphs, 36.6%; females, 23.4%; males, 26.1%). Results are discussed in terms of stage-specific responses and how these behavioral differences will likely play a role in developing effective trapping and monitoring systems for this important pest.

The effect of barometric pressure changes on flight initiation of female Trichogramma evanescens Riley and Trichogramma pretiosum Westwood (Hymenoptera: Trichogrammatidae) was studied in a flight chamber over a 6-h period. Six different barometric pressure regimens were tested for their impact on flight initiation of both species: constant 975 and 1,025 mbar (stable regimens), and 50 mbar increase or decrease in pressure between 975 and 1,025 mbar either within 1 (rapid increase or decrease) or 6 h (slow increase or decrease). Both Trichogramma species did not respond to stable or slow changes in barometric pressure, but rapid barometric changes significantly reduced the flight initiation of females. The effect of rapid barometric pressure changes was almost immediate and independent of its direction, whether it was increasing or decreasing. The reduction in flight initiation was lifted rapidly when the barometric pressure became stable again, immediately for T. pretiosum and 1 h later for T. evanescens. These results are in agreement with the hypothesis of an adaptive response to rapidly changing climatic conditions and associated higher risks of mortality during flight for small insects like Trichogramma. The higher flight initiation observed for T. evanescens females also agrees with field results where they displayed higher dispersal capacity than T. pretiosum females under adverse climatic conditions. The effects of barometric pressure on parasitoid foraging behavior deserve more attention because this climatic variable may play a significant role in their population dynamics.

The European corn borer, Ostrinia nubilalis (Hübner), is a serious pest of commercial maize throughout the U.S. Corn Belt. Adults in the central and eastern Corn Belt aggregate in grassy areas around and within the cornfield where they spend the daylight hours resting and where mating activity occurs at night. Mated females leave the aggregation sites at night to oviposit in cornfields, thus using the grass as a staging area. Flush samples were taken in borrow ditches in central Iowa during the first (spring) flight of moths in 2003 and 2004 to determine if cropping patterns and crop phenology influence moth distribution across the landscape. Significantly more moths were present in ditches with an adjacent cornfield on at least one side of the road than in those with no corn on either side. In contrast, effects of corn stubble from the previous year’s crop, tillage, and corn phenology were weak or not detectable. Evidence suggests that some moths emerging from corn stubble may aggregate in adjacent grass but that they redistribute themselves in the landscape within a short time. Thus, the presence or absence of adjacent corn was the overwhelming factor affecting spatial distribution of first-flight European corn borer moths among grassy roadside ditches.

Lindgren multiple funnel traps and Japanese beetle traps captured more lesser grain borers, Rhyzopertha dominica F. (Coleoptera: Bostrichidae), than did Pherocon II sticky traps or bucket traps when all were baited with the same aggregation pheromones. Bucket traps captured six-fold fewer beetles than Lindgren four-unit traps. Retentions of captured R. dominica were not significantly different in traps with soapy water or dry insecticide as killing agents for either trap design but were significantly higher than those retained in traps lacking a killing agent. Lindgren eight-unit funnel traps captured a similar number of R. dominica compared with the four-unit funnel traps. More beetles were captured near grain storage facilities than in forests or in open fields. Trap height (1, 2, or 4 m above the ground) had no detectable effect across habitat but significantly interacted with habitat. Traps placed 1 or 2 m high near grain elevators and in open fields captured similar numbers of beetles and yielded higher catches of R. dominica than traps placed 4 m high in these habitats. The reverse was true in forest habitats. Captured R. dominica were similarly female-biased in all trap designs, and the proportion of females to males did not differ among trap heights or habitats in which they were trapped.

A 2-yr field study conducted in Texas to evaluate the effect of several management strategies on the Mexican rice borer, Eoreuma loftini (Dyar), in sugarcane, Saccharum spp. hybrids, showed that irrigation reduced injury in both susceptible (LCP 85–384) and resistant (HoCP 85–845) cultivars by 2.5-fold. Cultivar LCP 85–384 was more susceptible than HoCP 85–845 based both on injury and moth production. Irrigation, host plant resistance, and insecticide applications of tebufenozide decreased injury from 70% bored internodes to <10% during both years. The use of multiple control tactics was substantially better at suppressing E. loftini in sugarcane than solely relying on insecticide applications. In addition to accumulations of proline, several free amino acids (histidine and isoleucine) essential for insect growth and development were increased in sugarcane leaves by drought stressed conditions, which exacerbated E. loftini infestations. Modifying the suitability of the crop by reducing water deficit stress makes rational irrigation input a key component in the integrated pest management of E. loftini, in addition to other tactics such as cultivar resistance and insecticide application.

The growing emphasis on including invertebrates in global biodiversity conservation efforts has prompted an increase in the study of invertebrate assemblages. Invertebrate sampling designs and the bias of individual methods, nevertheless, remain poorly understood for a variety of habitats. We used a structured inventory approach to sampling ants in five upland ecosystems in Florida. We evaluated the efficiency of quantitative and nonquantitative methods for sampling ants. We also evaluated the performance of four species richness estimators. A total of 3,774 species occurrences were distributed among 1,732 samples that contained 94 species from 31 genera. Twenty unique species and 10 duplicate species were collected. Compared with a comprehensive species list for Florida, sampling captured ≈66% of the regional fauna and ≈70–90% of species within the ecosystems studied. Combinations of sampling methods were much more effective for assessing species richness. Individual methods were complementary and sampled only part of the entire assemblage. Nonparametric estimators (an incidence-based coverage estimator [ICE] and a jackknife estimator [Jack2]) performed better than lognormal fitting, and Michaelis-Menten curve extrapolation. However, none of the estimators was stable, and their estimates should be viewed with skepticism. The results of this study provide support for the use of the Ants of the Leaf Litter (ALL) protocol for thoroughly sampling ant assemblages in temperate and subtropical ecosystems. Furthermore, our results indicate that even in relatively species-poor (compared with the tropics) temperate and subtropical regions, a large sampling effort that includes multiple sampling methods is the most effective manner of thoroughly sampling an ant assemblage. Therefore, we suggest that structured inventory should be adopted for a wider variety of terrestrial invertebrate studies.

A resurgence of the wheat stem sawfly, historically the most important pest of wheat in the northern Great Plains, has been observed in western Canada over the past decade. Host plant resistance in the form of solid-stemmed cultivars remains the primary management strategy for this pest. The objectives of this study were to determine the effects of wheat cultivar on wheat stem sawfly fitness and sex ratio. The cultivars studied varied with respect to stem diameter and pith expression and included representatives of the red seed, solid-stemmed spring and red seed, hollow-stemmed common and durum wheat classes. We present results from a primary study conducted in southern Alberta from 2001 to 2003 and a similar smaller study conducted in 1987 and 1991. All of the solid-stemmed cultivars (AC Eatonia, AC Abbey, Lancer, Leader) reduced female weights, size, fecundity, and in some cases, larval survivorship in the cut stubs and delayed date of adult emergence in the laboratory. Males were less responsive to this aspect of host quality. The hollow-stemmed durum cultivar AC Navigator had similar negative effects and deserves further study. A number of other hollow-stemmed wheats (McKenzie, AC Intrepid, Katepwa, and the durum AC Avonlea) had intermediate but inconsistent negative effects on sawfly fitness. The varieties that maximized sawfly fitness were AC Cadillac, CDC Teal, and Kyle (durum). Sawfly sex ratios were affected by stub diameter in our current and historical cultivar studies. Larger diameter stubs produced significantly more females and smaller diameter stubs produced more males. Furthermore, stubs that failed to produce adults had significantly smaller diameters than those that produced females but similar to those that produced males. The effect of the solid stem trait on sex ratio was inconsistent. Only Lancer had a male-biased sex ratio, whereas the other varieties had no consistent pattern. These results, however, are similar to other published reports that have noted inconsistent effects of the solid trait on sex ratio. Planting a solid-stemmed cultivar in a rotation that includes broad-leaved crops is recommended to reduce sawfly damage and future populations.

Interest in native bees as alternative pollinators of agricultural crops has greatly increased in recent years. These bees do not produce honey but are often excellent pollinators, not aggressive, and not subject to a multitude of pest and regulatory problems. Herein we report the results of a 2-yr study of the eastern subspecies of Osmia lignaria Say, a univoltine, early-spring, mason bee. Our objective was to determine pollen choice of a wild population of O. lignaria lignaria Say throughout the period of nest construction and relate this to the phenology of local floral resources. Artificial nesting sites were provided and pollen provisions were sampled from nest cells constructed over a 7-wk period. Pollen was identified and quantified with scanning electron microscopy. Approximately 20 types of pollen were found in bee nest provisions, selected from 80 flowering species. Pollen choice changed over time in accord with flower phenology and pollen availability. Eastern redbud (Cercis canadensis L.) pollen was the most abundant (28%) in nest provisions, and bloom was coincident with initial spring nest construction. Nest provisions had 11% oak (Quercus sp.), 10% boxelder (Acer negundo L.), 10% mustard (Brassicaceae), 8% willow (Salix sp.), 7% ash (Fraxinus sp.), 6% blackberry (Rubus sp.), 4% black gum (Nyssa sylvatica Marsh), and 4% poison ivy (Toxicodendron radicans L. Kuntze) pollen. Maximum nest cell construction coincided with apple bloom and continued for several additional weeks. Floral resources were identified that could be used by eastern orchardists to attract and enhance local populations of O. lignaria lignaria.

Hybrid poplar clones show varying levels of attack by Cryptorhynchus lapathi (L.), a wood-boring weevil. We studied differences in olfactory and feeding behavior among four different hybrid poplars in a series of laboratory bioassays. Weevils did not discriminate between resistant and susceptible clones based on olfaction in pitfall bioassays or antennal responses but did discriminate against the most resistant hybrid, NM 6 (P. nigra L. × P. maximowiczii Henry), in choice and no-choice paired-twig feeding bioassays. In addition, the susceptible hybrid, TN 302–9 (P. trichocarpa Torrey and Gray × P. nigra), was preferred for feeding over Salix scouleriana Barratt ex Hooker, a preferred host in the wild. We conclude that resistance among hybrid poplars is in part based on antixenotic cues before oviposition.

Changes of the uptake function of rice roots to nitrogen (N), phosphorus (P), and potassium (K) in a hydroponics culture solution were studied in three experiments: a single factor experiment involving rice leaffolder, Cnaphalocrocis medinalis, larval infestations or simulated damages (cutting of leaves); paired combinations of two factors (leaf and root cuts); and combination of three factors (Nilaparvata lugens infestation and leaf and root removal). In the single-factor experiment, both C. medinalis feeding and leaf cutting significantly reduced the uptake of N by rice roots compared with the control. There were no significant differences in N concentration in hydroponics culture solution between treatments of one, two, and four larvae per hill, but there were significant differences between two rates of leaf cutting. Also, C. medinalis feeding and the cutting of leaves reduced the uptake of P by roots significantly but did not affect K uptake except when two-thirds of the leaf area was removed. In the two-factor experiment, root removal promoted the uptake of N by roots and there was a significant interaction between leaf and root cutting treatments. In contrast, leaf and root removal significantly decreased the P uptake but did not affect uptake of K. In the three-factor experiment, the effect by which cuts to the root system promoted the uptake of N by roots was counteracted by N. lugens infestation, and there were significant interactive effects on the uptake of N between the N. lugens infestation and the cuts in the leaf and root system. Also in the three-factor experiment, N. lugens infestation and leaf cutting reduced significantly the uptake of P and K by roots. The removal of rice roots had no significant impact on the uptake of P and K.

The ability of the transgenic corn rootworm resistant corn (Zea mays L.) hybrid, MON 863, to affect the predator Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) through the consumption of corn-fed aphid (Rhopalosiphum maidis, Homoptera: Aphididae) prey was examined in the laboratory. Aphid weight was used as an index of prey quality. Larvae of C. maculata were reared to pupation on aphids that had consumed transgenic or nontransgenic (susceptible) corn plants. Larval duration, survivorship to pupation, postmortem adult dry weight (taken at 30 d after eclosion), adult mobility, and fecundity were compared for C. maculata between treatments. Fitness parameters of C. maculata were similar between transgenic and susceptible treatments, despite a 33% reduction in the weight of aphid prey reared on MON 863. Using immunostrip tests, Cry3Bb1 was detectable in the leaves of MON 863 but not in the susceptible plant, aphids, or C. maculata that were fed aphids. We conclude that transgenic corn that expresses Cry3Bb1 does not inflict acute or chronic degradations in fitness on individual C. maculata through aphid prey, but these results do not necessarily apply to other natural enemies, herbivores, or insect-resistant corn hybrids.

Most transgenic corn seed is now treated with systemic neonicotinoid insecticides. To address potential direct nontarget effects of these combined technologies, 16 Carabidae species from 10 genera (Agonum, Amara, Anisodactylus, Bembidion, Chlaenius, Harpalus, Patrobus, Poecilus, Pterostichus, and Scarites) field-collected from corn were directly exposed to Bacillus thuringiensis (Bt) Cry toxin-laden pollens and seed treatments in feeding and defined-dose bioassays. All adults readily fed on field or sweet corn pollens that expressed coleopteran-specific Cry3Bb1 or lepidopteran-targeting Cry1Ab/c, and no significant toxicity was observed. Adult survivorship ranged from 47 d for the predator Pterostichus melanarius (Illiger) to a year for the more omnivorous Scarites quadriceps Chaudoir, feeding solely on pollen containing 30–90 μg Cry3Bb1/g and water. In contrast, commercial doses of neonicotinoid seed treatments (imidacloprid, thiamethoxam, or clothianidin) elicited nearly complete mortality for 18 carabid species in 4-d bioassays containing corn seedlings. Carabid consumption of fungicide-only (fludioxonil plus mefenoxam) seed treatments was generally observed within 1 d, compared with a 2-d latency on neonicotinoid treatments, suggesting an antifeedant effect of the insecticide. In microcosm bioassays containing a corn seedling and five prey, clothianidin seed treatments killed adult western corn rootworm, Diabrotica virgifera virgifera LeConte and S. quadriceps, although the smaller Harpalus pensylvanicus (DeGeer) was more tolerant. We conclude that the neonicotinoid/fungicide seed treatments, and not Cry3Bb1 or CryIAb/c, are a major direct mortality factor for ground beetles. Field studies are needed to determine population and community level effects on Carabidae when these transgenic and seed-treatment technologies are combined.