First-instar larvae of Sitona lineatus L. (Coleoptera: Curculionidae) penetrate and feed on the nodules of Pisum sativum, which causes nitrogen fixation to stop. A model, based on experiments conducted at constant temperatures and the Sharpe and DeMichele formula, was derived to predict mean egg hatch times as a function of temperature. Variability was introduced through the use of the Weibull distribution around the mean. The model was validated in artificial conditions under naturally varying air temperatures. The fit between actual and predicted times was good. The data generated herein was compared with that of Andersen’s, which was collected 70 yr ago in the area of Munich, Germany. No biologically significant differences between the parameters derived from the two sets of data were identified. The model can be used to accurately predict egg hatch under natural conditions.

The migratory locust, Locusta migratoria L., has one to four generations per year in China, overwintering as eggs in the soil. In temperate Hebei province, this species has two generations per year, known as the summer and fall generations. In this study, locust populations occurring in different seasons were compared to investigate the adaptation of eggs to a cold environment. Large seasonal variations were observed in the supercooling point (SCP) and lower lethal temperature (Ltemp₅₀, the temperature that causes 50% mortality in a population) of locust eggs. Mean SCP values of the fall population were −26.0 ± 0.1°C, while those of the summer and postwinter populations were −22.0 ± 0.8 and −23.4 ± 0.7°C, respectively. The fall population also had significantly lower Ltemp₅₀ values (−14.2°) than the summer (−4.8°) and postwinter populations (−6.7°C). The survival ability of eggs at different development stages was also compared; 10-d-old eggs incubated at 25°C were more cold hardy than other stages. Prechilling at 5°C was effective in increasing the cold hardiness of eggs. These results confirm that eggs of the fall population are better conditioned for overwintering. The low mortality of overwintering eggs often leads to high population density and serious crop damage in the next season or following year.

Movement and survival of early instar clover root curculio, Sitona hispidulus (F.), and the development of root nodules in alfalfa, Medicago sativa L., were examined in relation to soil texture and moisture. Early instars were subjected to three soil textures (loamy sand, loam, and silty-clay loam) and two moisture potential regimes approximating very moist and slightly moist conditions, respectively. Survival of early instars was significantly higher in the slightly moist silty-clay loam (61%) and lowest in the slightly moist loamy sand (23%). These results suggest that cracks 1.0 mm or larger in the silty-clay loam increased access of the first instars to alfalfa root nodules. Production of root nodules was significantly greater in the loamy sand, yet clover root curculio survival in this soil type was lower, indicating that this soil deterred first instar access to critical nodule resources. We tested the ability of first instars to penetrate soils of three different textures and five moisture levels. First instars penetrated moist and slightly moist silty-clay loam and coarse sand significantly better than severely moist and saturated treatments, and also better than loamy sand at any moisture level. This was due to the presence of large cracks and/or pores in the drier silty-clay loam and coarse sand. This information will be useful for identifying soil conditions in alfalfa fields that influence the pest potential of this insect and hence assist in developing more effective integrated pest management strategies.

Adult parasitoids frequently require access to food and adequate microclimates to maximize host location and parasitization. Realized levels of parasitism in the field can be significantly influenced by the quantity and distribution of extra-host resources. Previous studies have demonstrated a significant effect of landscape structure on parasitism of the armyworm Pseudaletia unipuncta (Haworth) (Lepidoptera: Noctuidae). As a possible mechanism underlying this pattern, we investigated the effect of carbohydrate food sources on the longevity and fecundity of armyworm parasitoids under laboratory conditions of varying temperature, host availability, and mating status. Glyptapanteles militaris (Walsh) (Hymenoptera: Braconidae) adults lived significantly longer when provided with honey as food and when reared at 20°C versus 25°C. Meteorus communis (Cresson) (Hymenoptera: Braconidae) adults also lived significantly longer when provided with honey, although longevity was reduced when females were provided hosts. Honey-fed females of M. communis parasitized significantly more hosts because of their increased longevity, but did not differ in daily oviposition from females provided only water. Mating significantly increased parasitism by honey-fed M. communis, but not those provided water alone. These results indicate that the presence of both carbohydrate resources and moderated microclimates may significantly increase the life span and parasitism of these parasitoids. However, the greater longevity and lower daily rate of oviposition of M. communis suggest that food and microclimate resources are more critical for this species than for the shorter lived, gregarious G. militaris. These findings contribute to our understanding of how these two parasitoids respond to landscape complexity.

The cerambycid beetles Phoracantha recurva Newman and Phoracantha semipunctata F. were accidentally introduced into southern California where they have caused significant mortality to eucalyptus trees. In recent years, P. recurva populations have increased rapidly with a concomitant decrease in P. semipunctata numbers in their shared habitat in southern California. P. recurva has been collected in field surveys earlier in the season, suggesting that this species may be active over a broader range of temperatures and consequently have a longer seasonal activity period. We conducted lifetime fecundity studies to examine egg production, egg hatch, and adult longevity of beetles of both species subjected to temperatures typical of late fall and late winter/early spring in southern California. Overall, there were no differences in lifetime fecundity between P. recurva and P. semipunctata. P. recurva did not seem to reproduce over a larger range of temperatures than P. semipunctata, and there did not seem to be any substantial differences in their reproductive biologies. P. recurva eclosed slightly faster and lived slightly longer at reproductive temperatures than P. semipunctata, suggesting that P. recurva may have a slight reproductive advantage over P. semipunctata. However, it seems unlikely that such an advantage can account for the rapid increase in P. recurva populations and the simultaneous decrease in P. semipunctata populations in southern California.

Two flea beetles, Aphthona lacertosa Rosenheim and A. nigriscutis Foudras, have been introduced to control leafy spurge, Euphorbia esula L., in North America. We determined the effect of temperature on developmental rates of overwintered third instars to adult for each species. Developmental rates were determined by field collecting soil cores containing overwintering larvae and holding soil cores at constant temperatures of 12, 15, 18, 21, 22.5, and 26°C with 24-h light. Linear regression indicated that the lower developmental thresholds for A. lacertosa and A. nigriscutis were 7.5 and 9.3°C, respectively, and the median-required cumulative degree-days for emergence was 461 DD for A. lacertosa and 433 DD for A. nigriscutis. For each species, a three-parameter Weibull function was fit to a cumulative probability distribution of emergence. First emergence estimates for each species were calculated by multiplying the gamma (γ) parameter from the fit of the Weibull function with median-required degree-days from the linear model. First emergence for A. lacertosa and A. nigriscutis were predicted at 326 and 322 accumulated DD, respectively. Emergence models were validated with springtime field captures in Minnesota, Montana, and North Dakota. Results overall indicate a lack of bias in first emergence predictions for both species. However, there was a possible bias for predicting first emergence of A. nigirscutis in Montana, which was on average 15 d late. We speculate that different climatic and environmental conditions may have played a role.

Liriomyza huidobrensis Blanchard (Diptera: Agromyzidae) is an economically important pest around the world. The insect was first reported in China in 1993, and now has spread to >10 provinces, ranging from subtropical to temperate regions. Supercooling capacity and cold survival ability of pupal L. huidobrensis were investigated in eight populations along a latitudinal gradient: latitude 25°01′ N to latitude 42°16′ N. A northern distribution limit was proposed based on cold tolerance and the lowest monthly mean temperature of the year. The pattern of variation in cold tolerance with latitude differed for populations on different sides of the border. From the southernmost population in Kunming to the northern marginal population in Xi’an, cold tolerance of L. huidobrensis increased with latitude as measured by low lethal time (Ltime₅₀) at −5°C. Field populations can depress their supercooling point 3.6°C between the spring geographic populations at the two extremes. Cold tolerance also was enhanced significantly by prechilling of pupal L. huidobrensis at 0, 5, and 10°C. Both acclimation at 5 and 10°C for 8 d resulted in the maximum observed survival rate. Therefore, south of the distribution limit, L. huidobrensis can successfully overwinter and persist as a source population, continually supplying insects for further reinfestation or dispersal. However, populations beyond the northern border did not show the enhanced cold tolerance with increasing latitude. Most of the leafminers there survived severe winter condition by opportunistic exploitation of protected microhabitats. Our results may facilitate future predictions of range expansion and integrated management of this pest.

A simplified protocol for rearing the glassy-winged sharpshooter, Homalodisca coagulata (Say) (Homoptera: Cicadellidae), was tested on four genotypes of soybean, Glycine max (L.) Merrill. Growth and development of leafhoppers were examined on three glabrous isolines (D88-5320, D88-5328, and D90-9216) and one pubescent genotype (Hagood). All three glabrous isolines were adequate hosts producing an average of >100 adults from eight original mating pairs of leafhoppers. Pubescent Hagood produced significantly fewer adults with longer developmental times. Isoline D88-5328 produced 30% more adults than the other glabrous isolines. Genotype also had significant effects on total developmental times, developmental rates within instars, growth rates, and adult masses at eclosion with insect performance being enhanced on isoline D88-5328. All genotypes of G. max had similar xylem chemistry at the initiation of the rearing experiment (6-week-old plants), but as G. max matured (14–18 wk), isoline D88-5328 provided significantly more organic nitrogen. Chemical analyses of xylem fluid and developmental data support the hypothesis that young H. coagulata required balanced profiles of organic nitrogen for development but benefited from increased organic nitrogen as they approached maturation. Poor performance on pubescent Hagood was not related to xylem chemistry and was assumed to result from the inhibitory effect of trichomes. Xylem fluid analysis suggests that some plants may have eventually experienced nitrogen deprivation from high leafhopper loads; this, in turn, resulted in slow development and small body size at maturation for some insects. Although this protocol provides a simplified technique for rearing H. coagulata, it is likely that manipulation of xylem chemistry via fertilization would further maximize growth and developmental rates.

Timely insecticide application against the summer generation (first field generation) of the plum curculio, Conotrachelus nenuphar Herbst, is critical in the production of peach and other stone fruits in the southeastern United States. In the absence of monitoring tools that are effective during midseason when the adults of this generation emerge, a temperature-based emergence model would be useful as an alternative decision aid. In this study, we determined rates of larval development (from oviposition to peak emergence of larvae) and pupal development (from larval emergence to peak emergence of adults) for two populations of C. nenuphar in constant temperatures ranging from ≈11–37°C, developed linear regression models to describe the relationships between developmental rate and temperature for both stages, and estimated degree-day requirements for completing development from these models. The lower threshold temperature was 11.1 and 8.7°C for larval and pupal development, respectively. The thermal time requirement from oviposition to peak emergence of larvae was 215.5 DD, and peak emergence of adults occurred 442.4 DD later. For model validation, rearing experiments were carried out with both populations in fluctuating temperatures in the greenhouse and outdoors. Observed degree-day requirements were not significantly different from model-predicted values for larval emergence in the greenhouse and for adult emergence in the greenhouse and outdoors. For larval emergence outdoors, the model overestimated time to peak emergence by ≈35 DD (2–3 calendar d), most likely because these trials were carried out during relatively cool conditions in which overestimation by a linear model would not be unexpected. Aspects related to further validation of the model and its use in orchard conditions are discussed.

We studied four demes of the Chinese praying mantid, Tenodera aridifolia sinensis Saussure, in southwestern Virginia for periods ranging from one to six growing seasons to determine life history parameters and population dynamics of this introduced univoltine species. Survival from egg hatch to imago averaged 5%, but there was no significant relationship between initial and adult densities, both of which were highly variable within and among demes. The lowest survival rates (including two deme extinctions) occurred in years where precipitation during the first 2 mo after egg hatch was >50% below a 30-yr mean. Most mortality occurs during the juvenile stadia as a function of food limitation; therefore, dry conditions may have exacerbated this condition. Fecundity was not related to density of adults, but females that were food limited had lower fecundities than those not food limited. Replacement rate, R, averaged ≈1.0 but also was highly variable and was not a significant predictor of densities in successive years. Our results, combined with those from a Maryland study, indicate that deme extinction can be caused by extreme abiotic conditions: cool temperatures delay maturation and curtail reproduction before killing frost, and drought can reduce survival of nymphs to the imago, both of which adversely affect reproductive success. Intrinsic vagility is low, so metapopulation persistence of this and other species with similar life histories may be at risk if climate change increases the rate of deme extinction beyond interdeme dispersal rates.

Over a period of 2 yr, physiological and morphological traits related with nesting in two dominant dung beetle species in the Guadix-Baza Basin (Onitis ion [Ol.] and Onthophagus merdarius Chevr., Coleoptera: Scarabaeidae) were analyzed. The role of physiological conditions and resource availability for nesting as factors determining reproductive output in these species is discussed. Our results show that food does not seem to constrain sexual maturation. Both species reached sexual maturation and stored large amounts of reserves after a short period of nourishment. In addition, females were inseminated shortly after emergence, so they were ready to lay eggs only a few days after emergence. Although both species reached sexual maturation quickly, the number of nests dug by the females and the number of eggs laid were low, as indicated by the very low tibial wear and the low proportion of yellow bodies found. Although the rate of dung colonization was high, the number of beetles per dung pat was generally low. Therefore, aggregation of beetles does not seem to explain the low proportion of eggs laid by females of these species. Most dung pats in the study site were small, and only a small proportion (10.4%) was large enough to be suitable for nesting. In conclusion, both species were ready to reproduce soon after emergence, allowing beetles to increase their chances of reproductive success in a harsh environment in which high dung desiccation rates cause a low availability of suitable dung for nesting.

Critical temperatures and the upper lethal limit (ULL) of field collected workers of Formosan subterranean, Coptotermes formosanus Shiraki, and eastern subterranean termites, Reticulitermes flavipes (Kollar), were measured monthly from September 2001 to August 2002. Monthly mean critical thermal maxima (CTMa), ULL, and critical thermal minimum (CTMin) fluctuated significantly throughout the year. Seasonal variations of CTMax and ULL of both species were slightly, but significantly, statistically correlated with seasonal variation of habitat soil temperatures at 15-cm depth. Regression analyses revealed a significant linear relationship between CTMin and habitat temperatures for both termites as well. The two termite species responded positively to temperature changes in a similar manner. The values of all three parameters were significantly greater for C. formosanus (CTMax: 44.8–45.9°C, ULL: 49.1–50.4°C, CTMin: 7.2–9.0°C) than R. flavipes (CTMax: 43.5–44.9°C, ULL: 46.9–48.3°C, CTMin: 1.0–4.9°C). R. flavipes had a wider range between the upper and lower critical temperatures than C. formosanus. The three thermal tolerance parameters were not correlated with worker body mass. The significance of the critical and lethal temperatures and comparisons with previous studies are discussed.

The response of the introduced red turpentine beetle, Dendroctonus valens LeConte, to host semiochemicals in Shanxi Province, China, was distinctly different from that reported in previous studies conducted in the western part of the native range of D. valens in the central Sierra Nevada, CA. This finding suggests either that there is regional variation in D. valens response to host volatiles in North America or that the species underwent rapid adaptation after its introduction into Asia. In the Chinese population of D. valens, ( )-3-carene was the most attractive host monoterpene tested in studies conducted in 2002 using multiple funnel traps suspended in a Pinus tabuliformis stand. It attracted significantly more beetles than did any other single semiochemical or any of the ternary or quaternary blends tested, including the standard D. valens blend used in North America [a 1:1:1 blend of ( )-α-pinene, (−)-β-pinene, and ( )-3-carene]. ( )-α-Pinene and (−)-β-pinene, presented individually, were not significantly more attractive than controls. Adding limonene to the standard lure decreased response of D. valens but not significantly. A new type of semiochemical release vial was tested using a range of release rates of a 1:1:1 blend of ( )-α-pinene, (−)-β-pinene, and ( )-3-carene. The rates ranged from 150 to 210 mg/d, and these were compared with the standard North American lure, which releases ≈110 mg/d. The most attractive of these vials, which released ≈150 mg/d, captured significantly more beetles than did the standard release device; however, increasing the release rate beyond 150 mg/d did not further increase trap catch. The implications of our results for the phylogenetic geography of D. valens and its management as an invasive species are discussed.

Six different attracticide formulations (LastCall OFM) were tested for attractiveness and toxicity to the Oriental fruit moth, Grapholita molesta (Busck). Oriental fruit moth pheromone was incorporated into the formulation at rates of 0.016, 0.16, and 1.6%, with and without the insecticide permethrin (6.0%), for a total of six different formulations. Formulations containing 0.016 and 0.16% pheromone were equally attractive to male moths, and both were significantly more attractive than formulations containing 1.6% pheromone. The presence of 6% permethrin in the formulations did not influence trap capture and there was no pheromone × insecticide interaction effect. Comparison of the most attractive formulations in a wind tunnel bioassay showed a significant effect of pheromone dose and a pheromone × insecticide interaction effect on the proportion of males that took off from the release device and contacted the attracticide droplet. There was no pheromone dose, insecticide, or pheromone × insecticide effect on the proportion of males that exhibited wing fanning, locking-on to the pheromone plume, and upwind-oriented flight behaviors in the wind tunnel. A second wind tunnel experiment revealed that a greater proportion of male Oriental fruit moths conducted all behaviors to calling virgin females compared with attracticide formulations containing 0.016 and 0.16% pheromone and 6% permethrin. Toxicity of the attracticide formulations was determined at 3 and 24 h after exposure in the laboratory and in the wind tunnel. Almost all of the males exposed to formulations in the laboratory bioassay and 66.4% of males exposed in the wind tunnel showed signs of pyrethroid poisoning by 3 h after exposure, and significant mortality was observed at 24 h after exposure. This research showed that attracticide formulations containing 0.016 and 0.16% pheromone and 6% permethrin were effective in attracting wild and laboratory-reared Oriental fruit moths and exposing them to insecticide through source contact. Further work is necessary to determine if LastCall OFM formulations are competitive with calling virgin females under field conditions and whether treatment with LastCall OFM will result in reduced mating frequency and ultimately population control.

The pine shoot beetle, Tomicus piniperda (Coleoptera: Scolytidae), is an exotic pest of pine in North America. We evaluated blends of semiochemical disruptants, which included nonhost volatiles and verbenone, for their ability to disrupt attraction of T. piniperda to traps baited with the attractant α-pinene and to Scots pine, Pinus sylvestris L., trap logs. In Michigan and in Ontario, Canada, a single blend of nonhost volatiles alone [comprised of 1-hexanol, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, 3-octanol, and 1-octen-3-ol] or the nonhost volatile blend combined with verbenone significantly reduced attraction of T. piniperda to attractant-baited traps by 68–77%. Similarly, verbenone plus the nonhost volatile blend or a similar blend without 1-octen-3-ol also significantly reduced attack density of T. piniperda on pine trap logs by 56–74% in both Michigan and Ontario. Although relative responses between the different blends were slightly different between Michigan and Ontario, the recommended operational disruptant consisted of 1-hexanol, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, 3-octanol, and verbenone.

Elachertus scutellatus Howard is a synovigenic, koinobionic ectoparasitoid that preys on the Brazilian skipper caterpillar, Calpodes ethlius (Stoll) (Lepidoptera: Hesperiidae). This wasp exhibits a rare combination of life history strategies, some associated with being a koinobiont and others with being ectoparasitic. The female wasp lays large, inflexible, anhydropic eggs that are passed externally down the ovipositor. This process is uncommon and is considered the morphological intermediate between the use of the ovipositor as an egg-laying device and a stinger. The average clutch size and the oviposition frequency of E. scutellatus females are comparable with other wasps in the Eulophidae. Female wasps were observed to be nonconcurrent host-feeders. The sex ratios of E. scutellatus broods were consistently female biased. Adult male wasps lived longer than female wasps, which may have been a result of host size or the rearing technique used. E. scutellatus has potential as a biocontrol agent because of its female-biased sex ratios, destructive host-feeding, and synovigeny.

Habitat loss is often—but not always—correlated with diminishing levels of biodiversity. When species diversity does not vary across a gradient of patch sizes, species replacement may still occur in which some species are lost from smaller habitat patches and replaced by other species. In particular, matrix-dwelling species may become disproportionately abundant in smaller patches. In this study, I tested the hypothesis that the abundance of four crop and pasture grass consumers (Lepidoptera: Crambidae, Noctuidae) would be higher in smaller forest fragments compared with larger woodland sites in two ecoregions of Ohio. The two ecoregions differed in the dominant habitat type within the surrounding matrix and in the two most abundant matrix-dwelling moth species that were found in forest patches. In both ecoregions, smaller forests contained a significantly higher abundance of matrix-dwelling moth species, and patch area explained between 50 and 78% of the total variation in moth abundance. Because the total abundance of moths did not vary across the gradient of patch sizes in each ecoregion, the invasion of small forest stands by matrix-dwelling species may offset a reduction in the abundance of forest-interior moth species. If so, regional moth species diversity is predicted to become increasingly impoverished as small forest fragments and agricultural habitats converge in species composition.

Subterranean termite activity was investigated using field monitoring stations placed around 16 public schools in the triparish New Orleans metropolitan area of Louisiana. With the exception of one school, monitoring stations revealed the presence of Formosan subterranean termites. Native subterranean termites were found in six of the schools. The number of attacked monitoring stations varied significantly with light conditions at different directional aspects and termite species. For example, >50% of first-time attacked monitors by subterranean termites were at east with shade, north with shade, and south with shade placements. Formosan subterranean termites attacked a higher percentage of monitoring stations that were located in east with direct sun, east with shade, and north with direct sun. Native subterranean termites attacked a higher percentage of monitoring stations placed on south with direct sun, south with shade, and north with shade locations. Directional aspects at attacked monitoring stations by termites and corresponding average temperature at a depth of 10.2 cm from the foundation were not significantly correlated. Soil temperature readings 10.2 cm from the foundation did significantly affect seasonal foraging activity of subterranean termites.

Since 1996, the numbers of migrating monarch butterflies stopping over at Peninsula Point, Michigan, have been monitored by volunteers during the fall migration with standardized daily counts. In this study, we describe this project and examine: 1) general patterns of migration and stopover of monarchs at this site, and 2) how environmental conditions influence monarch stopover frequency. We tested for yearly, seasonal, and diurnal variation in monarch counts within each season. We further combined these data with basic weather information recorded at the time of each count to explore the effects of wind direction and speed, temperature, and cloud cover on monarch stopover abundance. A total of 22,539 monarchs was counted over 7 yr, with yearly totals ranging from 757 in 1998 to 6,638 in 1997. Over the 7-yr period, an average of 29 monarchs was recorded per count at Peninsula Point. Interestingly, in the migration season immediately following a major population decline at overwintering sites in Mexico, the total number of monarchs counted at Peninsula Point was not significantly different from long-term average counts. The timing of the peak of migration was not consistent from year to year, and there were few consistent temporal trends within seasons. More monarchs were counted with walking transects during the day than with a roost count in the early morning. Furthermore, more monarchs were counted earlier in the season than later. Of the environmental variables we examined, wind direction had a significant influence on the number of monarchs recorded on each count with higher counts during north winds. Cloud cover also influenced monarch counts, so that the number of monarchs observed increased with temperature and decreased with cloud cover. Based on the large numbers of monarchs that stop there each fall, we suggest that Peninsula Point represents an important monarch stopover site, and thus has the potential to increase our knowledge of monarch migration and stopover ecology greatly.

Using 49 yr of rangeland grasshopper (Orthoptera: Acrididae) survey data for Wyoming digitized into a spatially explicit format, we constructed a two-state (infested or uninfested) Markov chain model to evaluate the probabilities of population changes between states at the scale of 1 km². Our analyses revealed that only very limited areas of Wyoming are likely to support multiyear infestations of rangeland grasshoppers. Across the state, 91% of the land has a >50% probability of a transition from infested to uninfested conditions from one year to the next. Considering only the land that has ever been infested by grasshoppers, 55% of this area was found to have a >90% probability of becoming uninfested in the year after an infestation. The life expectancy of a grasshopper infestation in Wyoming is generally <2 yr, and large portions of the state can expect infestations to persist for <1 yr. Although rangeland grasshopper infestations are unlikely to persist for >1–2 yr, uninfested conditions are also unlikely to last. Of the land that has ever been infested, uninfested conditions are expected to persist for ≤10 yr on 36% of the area. Thus, rangeland grasshopper outbreaks are highly erratic events, with either infested or uninfested conditions lasting for short periods. Contrary to previous analyses at much coarser spatial scales, the probability of rangeland grasshopper infestations persisting for multiple years appears to be quite low. As such, for most of Wyoming there is little basis for prorating the benefits of control beyond the year of treatment.

Colonization of potato (Solanum tuberosum [L.]) fields by Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), has often been recognized as a process that initially results in an edge-biased spatial pattern. We modeled this spatial process by measuring distance of immigration for individual overwintered adults. Distance was measured to the nearest field edge or to the field edge along a radial vector from the field center. The frequency of beetles captured within 1-m distance intervals was modeled as an exponential decay function of distance from the edge for both measurement methods. Expression of the results as a cumulative frequency has management implications for spatial deployment of control measures against immigrating beetles and applicability for spatially explicit simulation of the within-field population dynamics of the beetle. Managers might use such models to estimate the proportion of immigrating adults that would be affected by border treatments of a plant systemic or transgenic insecticide as a function of the width of the treatment.

Field studies were conducted in 1992 and 1993 in Hermiston, Oregon, to evaluate nontarget impacts of transgenic Bt potato (Newleaf) expressing Cry3Aa protein derived from Bacillus thuringiensis (Bt) Berliner subsp. tenebrionis and conventional insecticides for control of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say). Pitfall traps were used to estimate the abundance of nontarget ground-dwelling arthropods in different treatment plots. There were no significant differences in the trap captures of major ground-dwelling coleopteran predators such as carabids (Coleoptera: Carabidae) and staphylinids (Coleoptera: Staphylinidae) among Bt and non-Bt potato fields treated with weekly sprays of a microbial Bt-based formulation containing Cry3Aa, biweekly applications of permethrin, early and mid season in-furrow applications of systemic insecticides (phorate and disulfoton), or no insecticides. While weekly sprays of permethrin significantly reduced the trap capture of ground-dwelling spiders (Araneae), there were no significant differences in the capture of spiders between Bt and non-Bt-potato fields treated with Bt sprays, systemic insecticides, or no insecticides. Significantly more springtails (Collembola: Entomobryidae and Hypogastruridae) were captured in potato fields treated with permethrin than with any other CPB control regime (transgenic Bt potato alone, microbial Bt formulation containing Cry3Aa, applications of systemic insecticides, or no action controls), among which there were no significant differences. The relevance of these findings to field evaluation of nontarget impacts of transgenic Bt crops is discussed.

Previous studies suggest grain sorghum, Sorghum bicolor (L.) Moench, acts as an early-season predator source for nearby cotton, Gossypium hirsutum L., in areas where their growing seasons overlap. However, few data exist on predator movement in this system, and proposed causes of movement have not been tested. Field studies in 2001 and 2002 addressed both issues. Predator marking with rubidium was employed to measure predator movement between equal-sized areas of cotton and grain sorghum at three stages of grain sorghum phenology. Concurrent manipulative experiments in field cages tested for effects of phenology and aphid levels on movement by Hippodamia convergens Guérin-Méneville, a common predator in this system. Results from 2001 showed cotton gained 2.7 predators for every one lost to adjacent grain sorghum but that the collective movement of predators was similar among the three periods examined. The coccinellids H. convergens and Scymnus loweii Mulsant moved preferentially into cotton and seemed responsible for the overall pattern of predator movement between crops. For predators moving from grain sorghum into cotton, estimated rates of dispersal (15.8–19.9 m/d) were found to be similar among all taxa studied. Cage experiments suggested both crop phenology and abundance of aphid prey in cotton and grain sorghum cause predator movement, but only the effect of phenology was consistent between years. These results support the idea that grain sorghum is a source of predators during cotton’s early growth stages and suggest that grain sorghum may continue to contribute to natural enemy populations during later stages of cotton growth.

Although many species of tumbling flower beetles (Coleoptera: Mordellidae) are common and abundant, little is known of their life histories. Larvae of most species seem to be phytophagous, and acts of predation are considered rare and accidental. In this study, we dissected host plants of the endophytic mordellid Mordellistena aethiops Smith and subjected plant and insect samples to stable isotope analysis to determine trophic position. Dissections indicated that M. aethiops is a predator of the gall former Antistrophus rufus Gillette (Hymenoptera: Cynipidae) and possibly its parasitoids. Ratios of stable isotopes of nitrogen confirmed that prey constitute a significant proportion of the diet of the mordellid larvae but also revealed that some insects species and/or life stages, particularly hymenopteran parasitoids, may not enrich nitrogen isotopes as predicted by stable isotope theory, which currently is based primarily on predators.

In this research, we determined: 1) the insect guilds visiting the flower heads of five Asteraceae species (Eupatorium petiolare Mociño ex De Candolle, Senecio praecox [Cavanilles] De Candolle, Dahlia coccinea Cavanilles, Tagetes lunulata Ortega, and Verbesina virgata Cavanilles); 2) the role of floral phenology and floral morphology on species composition and frequency of visits of different insect order; and 3) the diurnal schedules of anthophilous visitors and their relationship to temperature and relative humidity. Collections and observations of floral visitors for each species were made over 24 h per day. The five Asteraceae were visited by 137 Diptera, Hymenoptera, Coleoptera, and Lepidoptera species. Tagetes lunulata had the highest species richness of floral visitors (41 species), while V. virgata had the lowest (23 species). Apis mellifera L. (Hymenoptera) was the only visitor found visiting all five species. Species composition of insect visitors was closely related to plant phenology. Order-level frequency of visits was closely related to floral morphology. Two separate principal component analyses based on frequency of visits and floral morphology showed similar plant species groupings. Two groups of insects (Formicidae and Coleoptera) and two floral traits (ligulae length and presence of a cylindrical-campanulate involucre), respectively, were the variables determining these groupings. The highest frequency of anthophilous visitors coincided with the highest temperatures and the lowest relative humidity levels on flowers of all species, except S. praecox. The combination of diurnal activity and guild visitor analyses in this study showed the importance of including both characteristics in pollination studies.

Vitis grapevines are the native host of the grape berry moth, Endopiza viteana Clemens (Lepidoptera: Tortricidae), and are found in uncultivated habitats throughout eastern North America. Levels of infestation by grape berry moth larvae at vineyard borders and interiors were compared among vineyards adjacent to four types of uncultivated habitats: deciduous woods, coniferous woods, a single row of trees, and grasses. Adult male moths were monitored at these same positions and inside uncultivated habitats using sex pheromone-baited traps. Wild grapevines were surveyed at each site for their presence or absence, abundance, and whether they bore fruit. Infestation of grape clusters at vineyard borders was greater when adjacent to deciduous woods than grasses, but infestation near grasses was not significantly different from infestation near coniferous woods. Captures of moths inside vineyards were similar irrespective of nearby uncultivated habitat type. In uncultivated habitats, significantly fewer moths were trapped in grasses than in habitats with trees. Depending on habitat type, wild grapevines were found in 71–100% of the adjacent habitat sites, and although vine presence did not vary with habitat type, the proportion fruiting was significantly greater in deciduous woods than the other habitats. Significant, but weak positive correlations were found between larval infestation in vineyards and the abundance of wild grapevines and occurrence of fruit in adjacent uncultivated habitats. Results indicate that the presence of wild hosts within adjacent habitats and their likelihood of fruiting are important determinants of risk from grape berry moth infestation in a vineyard. The implications of these findings for cultural approaches to management of grape berry moth are discussed.

Resumé Les vignes Vitis (Vitaceae) sont les hôtes originaires de la tordeuse de la vigne, Endopiza viteana Clemens (Lepidoptera: Tortricidae), et se trouvent dans les habitats non-cultivés de l’Amérique du Nord. Nous avons comparé les niveaux d’infestation par larves à l’intérieur et au bord de vignobles commerciaux côtoyés par quatre genres d’habitats non-cultivés: bois de décidées, bois de conifères, une seule ligne d’arbres parallèle au vignoble, et des herbes. Les mâles adultes ont été échantillonnés à l’aide de pièges à phéromone placés à ces mêmes positions et aussi dedans les habitats non-cultivés. À chaque endroit étudié nous avons fait le levé de la présence de vignes sauvages, de la présence de grappes de raisins sur celles-ci, et de l’abondance de vignes. L’infestation par larves de E. viteana était plus intense aux bords des vignobles quand ils étaient côtoyés par des bois de décidées que par des herbes; seulement, les niveaux d’infestation dans les vignobles côtoyant des herbes n’étaient pas différents de ceux présents près des bois de conifères. L’abondance de mâles dans les vignobles était similaire, sans importer quel genre d’habitat les côtoyait. Dedans les habitats non-cultivés, nous avons attrapé significativement moins de mâles dans les herbes que dans les habitats possédant des arbres. Il y avait des vignes sauvages dans le 71–100% des habitats non-cultivés, mais la possibilité de trouver des grappes de raisins sauvages était majeure dans les bois de décidées où les vignes étaient plus abondantes. Des corrélations significatives entre les niveaux d’infestation par larves de ces vignobles et l’abondance de vignes sauvages dans l’habitat contigu, et aussi de l’occurrence de grappes sauvages étaient positives mais faibles. Ces résultats indiquent que l’abondance de Vitis spp. (et de grappes) dans les habitats contigus est une donnée importante pour le risque d’infestation par E. viteana dans un vignoble. Les implications de ces résultats sur comment manager la tordeuse de la vigne sont discutées.

Recent advances in weed control technology have changed how vegetational diversity can be managed in agroecosystems. This 2-yr study assessed the impact of altering the timing of herbicide application in herbicide-resistant field corn on the European corn borer, Ostrinia nubilalis (Hübner), and on the beneficial insects that prey on O. nubilalis egg masses. Treatments in this study were intended to allow weed presence in the field for varying periods of time, but control the weeds before crop yield was negatively impacted. Effects on O. nubilalis oviposition were assessed directly by counting egg masses and indirectly by assessing damage to corn stalks resulting from O. nubilalis infestations. The impact of weeds on the main generalist predators in this system was quantified through direct counts and predation trials on sentinel egg masses. In this study, altering the timing of herbicide application in herbicide-resistant field corn did not appear to affect the oviposition preference of O. nubilalis or the beneficial insects that prey on its egg masses. End-of-season stalk comparisons showed no differences in O. nubilalis infestation levels among the treatments. Predation on sentinel egg masses showed few significant differences among treatments, and predator densities were only rarely significantly different by treatment and showed no evident trends. Thus, our data suggest that under the conditions of this experiment, manipulating herbicide applications to minimize O. nubilalis damage is not a viable management technique in field corn.

Relationships between host density and mortality of house fly, Musca domestica L., and stable fly, Stomoxys calcitrans (L.), caused by Muscidifurax raptor Girault & Sanders, Muscidifurax zaraptor Kogan & Legner, Muscidifurax raptorellus Kogan & Legner, and Trichomalopsis sarcophagae Gahan were determined. Host mortality varied with host density and was highest when pupae were exposed to M. zaraptor followed by M. raptor, M. raptorellus, and T. sarcophagae. The relationship between host density and mortality was unaffected by host species for M. raptor and M. zaraptor; however, M. raptorellus killed a higher percentage of stable fly pupae and T. sarcophagae killed a higher percentage of house fly pupae. Residual mortality was higher on stable fly pupae than house fly pupae for M. zaraptor and M. raptorellus. The percentage of pupae with parasitoid emergence was reduced on stable fly pupae only for M. zaraptorand T. sarcophagae compared with house fly pupae. The gregarious species M. raptorellus and T. sarcophagae superparasitized pupae at low host densities and produced high numbers of progeny per female even at low host densities. Progeny production by T. sarcophagae was low on stable fly pupae compared with house fly pupae. The proportion female showed either no change or a small increase as host density increased for Muscidifurax species; however, T. sarcophagae had a greatly reduced proportion female at low host densities on house fly pupae. The number of female progeny per female parasitoid increased with host density for all parasitoid species except for T. sarcophagae parasitizing stable fly pupae. The reduced sex ratio of T. sarcophagae and low host mortality at low host densities suggested this species offers no advantage in terms of rearing efficiency, whereas the Muscidifurax species would be more efficient for rearing and release.

We determined the prevalence of natural field infections of the fire ant pathogen Thelohania solenopsae Knell, Allen, and Hazard in the monogyne and polygyne social forms of the red imported fire ant, Solenopsis invicta Buren, in three pastures in Florida. Social form was determined by examining the genotype of ants at the Gp-9 locus. The monogyne form contains a single fertilized queen per colony, and colony members have a genotype of Gp-9^BB. In contrast, the polygyne form contains many fertilized queens per colony, and all three genotypes of Gp-9^BB, Gp-9^Bb, or Gp-9^bb can be present within a colony. Among the study sites, ratios of monogyne:polygyne colonies ranged from 3:55–28:22, and infections rates were 42–78% when both social forms were included in the samples from each site. However, T. solenopsae infections were restricted to colonies of the polygynous social form. While T. solenopsae was only detected in polygynous colonies in the field, T. solenopsae infections were found in ants with the monogyne genotype. Ants from four colonies reared from field-collected, newly mated queens that were naturally infected with T. solenopsae were found to exhibit this genotype. T. solenopsae also was detected in individual alate female reproductives possessing the monogyne genotype, which were collected from polygynous colonies. Polygynous colonies can contain individual ants that possess either the polygyne or monogyne genotype. Thus, T. solenopsae infections can occur in fire ants with genotypes of either social form. Because making genotypic determinations of S. invicta social forms may be impractical in the field, we compared visual and genotypic determinations of polygyny and monogyny. Visual determinations, based mainly on the relative preponderance of major workers, corresponded to 85% of the genotypic determinations.

Biological control of waterhyacinth [Eichhornia crassipes (Mart.) Solms.] by waterhyacinth weevils [Neochetina bruchi (Hustache)] and [Neochetina eichhorniae (Warner)] varies according to field environment, season, and plant stress levels. Plants at four field sites were sampled to determine if leaf scarring caused by adult weevil feeding was associated with plant biomass, biochemical and population measures, and insect densities. Leaf scar densities were consistently higher on plants from two sites at which root and dead plant part biomass were high. Scarring was correlated to root and dead biomass across all sites. Scarring was not associated with weevil densities summed across all life stages or larval gallery density. Soluble protein contents were lower in plants from the two sites with high scarring than at two other sites in Spring 2002, and scarring was negatively correlated to protein content across all sites. Protein was usually highest in immature furled leaves. Activities of soluble peroxidase enzymes were highest in old leaves. Scar densities were not associated with canopy height and shoot density. At one site, high scar densities occurred on plants with small leaf areas, which were likely growing slowly under the influence of multiple abiotic and biotic stress factors. Mechanical and natural plant removal and regrowth may have facilitated plant compensation for weevil feeding at the other site with high scarring. Temporally and spatially dynamic physical and biochemical plant traits and growth environments could limit biological control of waterhyacinth.

Galerucella calmariensis L. is a leaf-feeding beetle introduced into North America for biological control of purple loosestrife, Lythrum salicaria L. It is well known that existing natural enemy communities can reduce herbivore establishment and limit their impacts as weed biocontrol agents. Although such biotic interference can often initially be avoided through inundative releases or use of exclusion cages, successful biological control of L. salicaria will ultimately rest on natural colonization of new host patches. The objectives of this study were: 1) identify potential arthropod predators in Michigan wetlands; 2) test predator propensity to attack G. calmariensis; and 3) assess importance of biotic interference by simulating G. calmariensis colonization in wetland habitats. Field surveys showed that Coleomegilla maculata De Geer, Coccinella septempunctata L., and Harmonia axyridis L. (Coleoptera: Coccinellidae) were most abundant potential predators of G. calmariensis, followed by Pterostichus melanarius Illiger (Coleoptera: Carabidae) and Podisus maculiventris Say (Hemiptera: Pentatomidae). In laboratory tests, 24-h attack rates on eggs and larvae ranged from 10 to 100%, with C. maculata and Forficula auricularia L. consuming the greatest number of G. calmariensis. Increasingly realistic laboratory trials demonstrated that several predators effectively located and consumed immature stages of G. calmariensis under more complex conditions. In the field study, predator abundance and attack rates were low, ranging from 0.63 to 1.63 egg masses consumed (10–27%). Survival of individuals to the adult stage in caged (53–90%) versus open treatments (24–42%) revealed a significant effect of predation. However, even the lowest survival rate observed is probably adequate to ensure effective colonization. We conclude that predation can significantly reduce G. calmariensis population increase in the field, but is unlikely to prevent establishment and spread under the conditions studied.

In solitary parasitoid species, superparasitism incurs a high cost because only one individual can emerge per host. While avoiding already-parasitized hosts seems advantageous, it requires an ability to discriminate between parasitized and unparasitized hosts. The ability to discriminate can be based on physical or chemical cues or signal associated either internally or externally with a given host. The type of stimuli used to recognize parasitized hosts generally depends on the features of these hosts but also on costs and benefits associated with reusing them. Some local factors such as mortality rate of females, host availability, and competition level can influence this trade-off. In species that occupy a large geographic range, local conditions may favor either external or internal mechanisms of host discrimination. We describe the behaviors associated with host discrimination in Pachycrepoideus vindemmiae Rondani (Hymenoptera: Pteromalidae), a solitary pupal parasitoid of cyclorraphous dipteran species. To detect potential intraspecific variability in their host discrimination behavior, we compared two P. vindemmiae populations originating from different geographical areas in France. Our results revealed different host discrimination strategies in both populations and indicated a potential trade-off between the speed and the accuracy of host discrimination. One population discriminated hosts externally (faster but less accurately), whereas the other discriminated internally (more slowly but more accurately). In our experimental conditions, these two strategies resulted in differences in the fitness gains of both populations. The ecological conditions that could have selected for such differences in the host discrimination and oviposition strategies of the two populations remain to be investigated.

Scarab beetles colonizing vertebrate feces are considered polyphagous insects, because they often use dung of several species. However, recent works have provided evidence for strong feeding preferences in some dung beetle species. The influence of dung odors in the process of resource selection by beetles has not received attention. The objective of this study was to investigate trophic preferences in Mediterranean dung beetles colonizing cattle and horse dung. The pattern of resource use by insects was studied using series of pitfall traps baited with cattle or horse dung in three different sites of south-central France. A total of 4,276 insects belonging to 39 species were captured. Cattle dung attracted more insects than horse feces (2,570 versus 1,706 individuals). Twenty-four of the 39 beetle species collected had clear feeding preferences for cattle dung (13 species) or horse dung (11 species). None of these species seemed linked exclusively to one kind of dung. The behavioral responses of seven scarab beetles to volatile compounds emitted by cattle and horse dung were compared in laboratory olfactometer bioassays. Three insect species (Aphodius erraticus, A. scrutator, Onthophagus vacca) were more attracted to volatile compounds from cattle dung. Two other species (Euonthophagus amyntas, Bubas bubalus) orientated preferentially toward horse dung volatiles. Except for two species, beetles were thus attracted to volatiles from the dung type they preferred in the field. The reasons why coprophagous beetles show local feeding preferences for particular dung types are discussed.

Experiments were designed to examine the effects of the IGRs tebufenozide and diflubenzuron on Pavlovian conditioning of harnessed foragers. In one set of experiments, animals learned a simple task in which they associated a conditioned stimulus with feeding. A second set of experiments required the animal to learn a complex discrimination task. Within each experiment, separate groups of bees were pretreated with the insecticide, whereas others received the insecticide imbedded in the sucrose solution used as the unconditioned stimulus. Results indicated that exposure to both tebufenozide and diflubenzuron influence the performance of honey bees. Bees pretreated with 10 μl of tebufenozide, 10 min before learning a simple Pavlovian task, produced lower levels of acquisition when the concentrations were administered in dosages equivalent to 0.22, 0.29, and 1.0 liter/ha. When animals were given a series of 1-μl droplets of diflubenzuron over the course of 12 training trials, the effect on acquisition and extinction was even more pronounced. No such effects were seen when tebufenozide was used. Discrimination learning was also influenced in bees pretreated with the insecticides or having the insecticides imbedded in the unconditioned stimulus.

We evaluated responses of plum curculio, Conotrachelus nenuphar (Herbst), to baited and unbaited black pyramid and Plexiglas panel traps in mark-release-recapture experiments to determine whether presence of host apple trees diminishes trap effectiveness. Identical experiments were conducted in an open field (little competition present) and in an unsprayed apple orchard (presence of competition from natural host apple trees). Results of mark-release-recapture experiments were successful; we recaptured 21.0 and 2.9% in the field and orchard, respectively. Plum curculio response to traps was influenced by presence of apple trees, because significantly more recaptures were recorded in the field compared with the orchard. Pyramid traps recaptured more plum curculio in the field compared with the orchard and recaptured significantly more plum curculio compared with panel traps. Female plum curculio responded in significantly greater numbers to pyramid traps baited with benzaldehyde compared with unbaited traps in the field, but not under orchard deployment. Combined data indicate that positioning traps in proximity to host apple trees diminishes both trap and bait effectiveness either by direct competition from host tree stimuli or by physical obstruction of trap-related visual stimuli and/or volatile release. We conclude that an effective trap-based monitoring system for plum curculio will require better odor baits, trapping mechanisms, and/or deployment strategies that can overcome visual and olfactory interference presented by host apple trees.

The use of pheromone trap catches to reliably predict damage by the Nantucket pine tip moth, Rhyacionia frustrana (Comstock), in loblolly pine (Pinus taeda L.) plantations would provide forest managers with a valuable integrated pest management tool. At 17 sites throughout four states in the southern United States, in areas where R. frustrana has four annual generations, adult moths were monitored throughout the year (2002) using two types of pheromone traps, and subsequent infestation levels were determined for each tip moth generation. Cumulative wing trap catch tallies up to published spray dates for three of four adult emergence periods were highly predictive of top whorl damage during the subsequent generation using linear regression models. Multiple linear regression that included initial average tree height as a covariate did not significantly improve model efficacy. Cumulative delta trap catch tallies up to the spray date were not predictive of subsequent damage levels for any tip moth generation using linear regression models. Although multiple linear regression incorporating tree height as a covariate did greatly improve delta trap model efficacy, the power and significance of these models remained insufficient. Wing traps seem to be much more sensitive to tip moth population change than delta traps; however, both are useful for monitoring seasonal activity and initiation of spray timing models.

The lingonberry fruitworm, Grapholita libertina Heinrich, is a tortricid moth whose larvae infest wild lingonberry (Vaccinium vitis-idaea L. variety minus Lodd) fields in Newfoundland, Canada. This study investigated the potential for predicting G. libertina larval damage by using adult pheromone trap captures. Spatial patterns of capture were studied in relation to subsequent larval and damaged berry distributions in four wild lingonberry fields during 1998, 1999 and 2000. A model was tested that incorporated the effects of resource availability and coincident plant composition on insect distribution. In 1998 and 2000, the mean adult capture/trap correlated well with larval (R² = 0.38–0.63) and damaged berry (R² = 0.41–0.59) density within grids at each site. In 1999, larval and damaged berry densities were not significantly correlated to adult distributions, and were more dependant on a limited host berry distribution (R² = 0.54 and 0.47, respectively). The results of this study suggest that correlation between adult trapping of G. libertina and subsequent larval distributions is dependant on a minimal host berry population. Other factors that may contribute variability are also discussed.

Four methods (light traps, foliage samples, canvas bands, and gypsy moth egg mass surveys) that are used to study the population dynamics of foliage-feeding Lepidoptera were compared for 10 species, including gypsy moth, Lymantria dispar L. Samples were collected weekly at 12 sites during a 15-wk period in 1995–2001. For each non–gypsy moth species, light trap and canvas band estimates were regressed against foliage sample to determine how well they predict population abundance. Gypsy moth estimates obtained from foliage and under canvas bands were compared with counts of egg masses using a similar linear model. All comparisons were made on three spatial scales: plot (200 ha), forest (2,000–3,000 ha), and study site (200,000 ha). Abundance of moths collected by light traps were good predictors of population size compared with counts of larvae on foliage, whereas mixed results were obtained for canvas bands. Both foliage samples and canvas band samples proved to be good predictors of gypsy moth population size on the plot and forest scale, although only foliage samples provided good estimates at the study site scale. For all comparisons, predictability of light traps and canvas bands increased with increasing spatial scale.

Unbaited sticky traps were placed on ropes in the four cardinal directions and at different heights on the outside of commercial steel bins containing stored wheat. Weekly trap catches of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), were examined. The number of traps per steel bin varied due to differences in dimensions, and three height classes were established, but there was no significant difference in trap catches of C. ferrugineus among height classes. Significant yearly and between-steel bin variation was found, and these effects were removed before using a response surface regression analysis to determine how well two time variables (daylength and day number) and three weather variables (minimum and maximum temperature and precipitation) could explain the seasonal variation in C. ferrugineus flight activity. These variables were used in separate analyses of C. ferrugineus trap catches in the four cardinal directions and from the three height classes (12 separate analyses). The most robust model fit was obtained when using a subset representing 208 C. ferrugineus trap catches from the northern side at height class 3 (traps s placed at least three-quarters of bin height). The full model of the two time variables and three weather variables explained 48% of the variance in this subset of trap catches, whereas a model based on weekly means of daylength and minimum and maximum air temperatures explained 40% of the total variance in C. ferrugineus trap catches. The relative trap catch response to daylength and minimum and maximum air temperatures was evaluated. High beetle flight activity around grain bins may indicate a high risk of insect infestation of stored wheat, and the presented model can therefore be used to determine time periods with high risk of beetle immigration into commercial steel bins.

We studied dispersal and spatiotemporal dynamics of the Asian longhorned beetle, Anoplophora glabripennis Motschulsky, in Gansu Province of north central China. We used mass mark–recapture methods and observed that 98% of beetles were recaptured within 920 m from a release point, whereas the median dispersal rate for all recaptured adults was 30 m/d. Dispersal potential within the course of a season for males and gravid females was 2,394 and 2,644 m, respectively; however, more work is needed to evaluate the potential of long-distance dispersal events to initiate new colonies outside current U.S. quarantine boundary guidelines. We observed that tree size and number of existing emergence holes on a tree were significant positive predictors of new emergence holes, but we did not measure a significant effect of tree size, number of existing emergence holes, and number of new emergence holes on adult beetle abundance. Implications of these findings within the context of host quality are discussed, but more research is needed to identify key factors in the multiyear host colonization process. Peak population abundance of unmarked beetles (i.e., background populations) in both 1999 and 2000 occurred between 800 and 900 degree-days (base threshold = 10°C) from 1 January. Background populations exhibited local spatial autocorrelation during peak abundance, with ranges of spatial dependence of 229–543 m. The implications of this study are discussed in reference to the role that A. glabripennis population biology plays in the current eradication effort.

Understanding the critical host plant factors that determine oviposition behavior and survival of boll weevil, Anthonomus grandis grandis Boheman, on cotton, Gossypium hirsutum L., is important for developing successful pest management strategies. However, published information is both conflicting and limited regarding how different cotton fruit sizes affect boll weevil oviposition choices and subsequent larval survival to adulthood. Consequently, we used a standard based on fruit size diameter to evaluate boll weevil feeding and oviposition punctures, and survival to adulthood on 10 different cotton fruit sizes: squares of diameter 1.5–2.0 (pinhead), 3.0–3.5 (matchhead), 5–6, 7–8, or 9–10 mm; candle; and bolls of diameter 10–15, 15–20, 20–30, or >30 mm. Oviposition and feeding punctures were significantly affected by cotton fruit size. Females did not oviposit in pinhead squares. The fewest eggs were oviposited in boll sizes >30 mm. The highest number of eggs was recorded in square sizes of 5–6 and 7–8 mm. Boll weevil survival to adulthood was highest on square sizes of 7–8 or 9–10 mm (58.6–59.7%). No survival occurred in matchhead squares or bolls >30 mm. Duration of development was longest on boll sizes of 15–20 and 20–30 mm (18.2–18.8 d). The growth index (percentage immature survival divided by immature developmental time) of female boll weevils was 2.8-fold higher in 7–8- or 9–10-mm diameter squares than in 20–30-mm diameter bolls. This study will improve our capacity to develop methods to predict fruit losses and changes in boll weevil populations in the field, given a starting density of fruit suitable for oviposition, and a corresponding initial population density of weevils.

Several studies have addressed plant primary physiological responses (gas exchange responses) to insect herbivory. However, relatively few plant species have been examined. It is unknown whether responses to leaf-mass removal by insects vary among plant families and species. Within the legumes, only alfalfa, Medicago sativa L., and soybean, Glycine max (L.) Merrill, have been examined. The goal of this study was to test the hypothesis that gas exchange responses to leaf-mass consumption in a broad range of cultivated legumes do not differ from those of soybean and alfalfa. The species and cultivars used were M. sativa Cimarron, Medicago scutellata (L.) Sava, Medicago truncatula Gaertner Paraggio, Melilotus officinalis (L.) Pallas, Trifolium hybridum L., and Trifolium pratense L. Twelve greenhouse experiments were conducted and each legume species was used in a separate experiment. Depending on the experiment, there were either two or three treatments (control, simulated insect injury, and actual insect injury). For simulated and actual insect defoliation, injury was limited to a single leaf per plant. Simulated insect injury treatments were imposed by removing leaf tissue on each leaflet with scissors. For the actual insect defoliation treatment, fall armyworm larvae, Spodoptera frugiperda (J.E. Smith), were used. Defoliation of single leaves on the six species resulted in similar responses. Plant gas exchange variables (photosynthesis, stomatal conductance, intercellular CO₂, and transpiration) were not significantly affected by either simulated or actual insect defoliation. Our results support the hypothesis that there is a generalized primary physiological response to leaf-mass consumption injury among the cultivated legumes. More generally, the results from this experiment support that there is a generalized plant gas exchange response to leaf-mass consumption injury.

An understanding of boll weevil (Anthonomus grandis Boheman) dispersal behavior is essential to characterizing and responding to the threat of migration into eradication zones. Genetic variation in boll weevil mitochondrial DNA (mtDNA) was sampled and analyzed to make inferences on the magnitude and geographic pattern of genetic differentiation among weevil populations from 20 locations across eight U.S. states and northeast Mexico. Polymerase chain reaction (PCR)-restriction fragment length polymorphisms (RFLPs) analysis was conducted on a 12.4-kb amplicon of mtDNA from each of 419 individuals. A total of 28 distinct mtDNA haplotypes, 17 of which were unique to single locations, were identified from restriction reactions of 10 informative endonucleases. Haplotype and nucleotide diversity was generally greater in southern than northern populations and was greater in the east than the west among northern populations. Genetic differentiation between eastern and western populations was pronounced, and phylogenetic analyses revealed two major clades corresponding to these regions. These results are consistent with historical boll weevil range expansion into the southeastern United States from Mexico and a secondary colonization of the High Plains. Evidence suggests that gene flow is limited between eastern and western populations but is relatively high among populations within the eastern region. In addition, estimates of gene flow indicate that migration between locations separated by <300 km is frequent.