Several boll weevils, Anthonomus grandis Boheman, were captured in pheromone traps in 2004 near Tlahualilo, Durango, Mexico, an area where none had been reported for ≈10 yr. It is possible that they were from an endemic population normally too low in numbers to be detected but that increased in response to more favorable rainfall conditions in 2004. Alternatively, they may represent an influx of migrants or the immediate descendents of migrants. To identify the most likely origin of the boll weevils captured in this area, we characterized microsatellite variation of the Tlahualilo weevils and compared it with the variation from three other populations in northern Mexico and from one in southern Texas. Measures of gene flow and individual assignment tests suggest that the boll weevils captured near Tlahualilo were primarily from an endemic low-level population, but that this area also is receiving immigrants from a cotton growing region ≈200 km to the north, near Rosales, Chihuahua, which is currently under a boll weevil eradication program. Similarly, Rosales is receiving immigrants from Tlahualilo. This study shows that microsatellite markers and population assignment techniques will be practical tools for determining the most likely origins of boll weevils reintroduced to eradication zones in the United States and Mexico. Population assignment strategies based on genetic markers hold promise for replacing conventional, but spatially constrained, mark-recapture studies of insect dispersal. This relatively new and powerful analytical approach is widely used in conservation genetics and fisheries studies, but has been underused by entomologists.

An immunomarking system useful for determining insect movement patterns was developed that allows the marking of naturally occurring populations of insects within large areas with inexpensive and readily available proteins that can be applied using standard spray equipment. Enzyme-linked immunosorbent assay (ELISA) protocols were developed to detect chicken egg albumin (as egg whites), bovine casein (as cows’ milk), and soy protein (as soy milk) at levels ≤30 ppb. Field applications showed that all of the proteins were stable and detectable at high levels on apple leaves at least 19 d after application. When adult pear psylla (Cacopsylla pyricola Foerster, Homoptera: Psyllidae) walked across apple leaves with field-aged residues of the marker proteins plus either Sylgard 309, EDTA, or both, they acquired the mark over the 19-d test period an average of 78.9, 19.4, and 2.1% of the time for egg whites, milk, and soy milk, respectively. Two field applications of the three markers were applied to an apple orchard during the first generation flight of codling moth (Cydia pomonella L., Lepidoptera: Tortricidae). We found that 46.5% of moths captured within a 2.8-ha area (including 1.6-ha surrounding the treated areas) tested positive for at least one of the three proteins. The marker systems developed cost between $0.12 and $0.26liter versus older immunomarkers (using purified vertebrate IgG) that cost roughly $500/liter.

The energetic cost of a sublethal treatment with chlorpyrifos was estimated by use of direct microcalorimetry to measure metabolic heat in susceptible and resistant strains of the German cockroach Blattella germanica L. Moreover, one of the detoxification enzyme systems known to be involved in detoxification of chlorpyrifos, glutathione-S-transferase, was measured. Individual cockroaches were exposed for 20 min on a glass-surfaces treated with 1.14 μg/cm² of chlorpyrifos. There was no difference in glutathione-S-transferase activity of susceptible or resistant strains after the treatment. The heat production increased in the susceptible strain ≈30 min after exposure and declined again after ≈120 min to the basal level. The energetic cost of the exposure to the insecticide corresponds ≈5 h of normal metabolism. There were no significant differences in heat production after toxic treatment in any of the resistant strains. It was shown that measurement of heat production is a sensitive method to prove toxic reactions after exposure to a low dose of insecticide. The use of microcalorimetry as a promising biomarker technology was shown.

Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), has been classified as one of the most cold-tolerant pests of stored grain. In this study, the supercooling point (SCP) of field-collected, cold-acclimated fifth instars was determined as an index of cold hardiness. In addition, mortality of laboratory-reared and field-collected, cold-acclimated fifth instars exposed to −10°C was measured to understand the ability of P. interpunctella to survive winter conditions. Finally, the overwintering mortality of this species in southern Minnesota was measured in grain bins filled with shelled corn. The SCP of field-collected, cold-acclimated fifth instars was approximately −24°C before their release in grain bins. Mortality of laboratory-reared fifth instars exposed to −10°C reached 100% after only 12 h, whereas the same percentage was achieved after 312 h for field-collected, cold-acclimated individuals. Overwintering mortality of P. interpunctella under field conditions reached 100% in all locations inside the grain bins; however, depth within the grain mass, location inside the grain bin, and the duration of exposure to outdoor conditions significantly affected the rate of mortality. A mathematical model for the overwintering mortality of P. interpunctella is proposed as a first step to forecast early season infestations under field conditions.

The toxicity of spinosad and methoxyfenozide against neonates and fourth instars of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) was tested under laboratory conditions. According to LC₅₀ values, no significant differences were observed between spinosad (0.50 mg [AI]/kg diet) and methoxyfenozide (0.54 mg [AI] /kg diet) after 48 h of ingestion treatment on neonate larvae, based on the overlap of 95% CL. Similarly, on fourth instars, no significant differences were observed between LC₅₀ (2.98 and 5.17 mg [AI]/kg diet for spinosad and methoxyfenozide, respectively, at 96 h after ingestion of artificial diet) and LD₅₀ (4.74 and 2.68 μg [AI]/g larva for spinosad and methoxyfenozide, respectively, at 144 h after topical application). In addition, spinosad and methoxyfenozide significantly suppressed weight gain of neonates and fourth instars continuously fed with artificial diet containing the insecticides. The second part of this project was focused on the effects of methoxyfenozide on the reproduction of S. littoralis by determining the effect on oviposition in three different crosses and the pharmacokinetics pattern of (¹⁴C)-methoxyfenozide in the body tissues of female and male adults after topical application in their excrement and in the deposited eggs to test transport through the female and the male adult. Methoxyfenozide negatively affected the reproduction of adults regardless the treated sex, presumably because of its presence in the adult body, accumulation in the laid eggs, and slow excretion of the product. We conclude that spinosad and methoxyfenozide represent an important choice to be used in integrated pest management where S. littoralis is a major pest.

The aim of this study was to examine sex- and age-dependent changes in carbohydrate and lipid reserves throughout the fourth larval instar of Chironomus riparius Meigen. Individuals were sexed using genital discs and aged using phases of development defined through the observation of genital and thoracic imaginal discs. Glycogen concentration was measured in the eviscerated body (fat body, muscles, and cuticle), and the levels of glucose and trehalose were followed in the hemolymph, whereas the amounts of free glycerol and triglycerides were measured in both tissues. Compared with males, females had higher levels of body reserves, whereas the levels of sugars in the hemolymph were similar for both sexes, except for free glucose, which was slightly higher in males. The levels of energy-yielding substrates in both the eviscerated body and hemolymph varied significantly with the phase of development for both sexes, except for the concentration in free glycerol in the hemolymph. Analysis of variability indicated that selection of larvae for both the sex and phase of development significantly reduces uncertainty of biochemical measures. The results are discussed with respect to potential use of the levels of energy-yielding substrates as endpoints in toxicity tests with fourth-instar C. riparius larvae.

Acalymma vittatum (F.) is a cucurbit herbivore specialist and the vector of Erwinia tracheiphila (E. F. Smith) Holland, the causal agent of bacterial wilt in cucurbits. We determined the temperature-dependent development, survivorship, longevity, sex ratio, and fecundity of this vector. Egg-to adult development was modeled as y = e^{(0.225 × T)}−e^{[0.225 × 36.017 − (36.017 − T)/4.425]}, which suggests a maximum development rate of 4.29%/d at 32°C. Linear extrapolations suggest a lower threshold of 13°C and 432 DD needed for A. vittatum development. Survivorship of immature stages, which ranged from 60% at 27°C to 4% at 33°C, was strongly influenced by temperature, and no beetles survived to the adult stage at 36°C. Sex ratios did not deviate from 1:1. Adults were long-lived, with continuous egg production, which ranged from 0 to 4 eggs/female/d, after an 8-d preovipositional period at 27°C. Life table statistics were generated using these data. Together, these phenology models and life table information can be used to further develop integrated pest management programs for both A. vittatum and E. tracheiphila in cucurbits.

The cold-hardiness of fourth-fifth instars of the Japanese pine sawyer, Monochamus alternatus Hope, collected from 25 to 28 April in spring, 28 June to 1 July in summer, 29 October to 1 November in autumn, and 28 December to 1 January in winter in Anhui Province, China, was compared. Parameters compared were supercooling point (SCP), lethal temperature causing 50% mortality (LT₅₀), upper limit of cold injury zone above which temperature does not cause mortality even after an ecologically meaningful period of time (ULCIZ), sum of injurious temperature that is the duration of effective chilling that results in 50% mortality (SIT), and acclimation efficiency. The mean SCP values of summer, autumn, winter, and spring larvae were −6.2, −10.9, −15.4, and −12.3°C, respectively. The cold-hardiness of larvae collected in different seasons was consistent with seasonal air temperature in the wild. There was a significant positive correlation between SCP and LT₅₀ (r = 0.979, P < 0.05), between SCP and monthly mean air temperature (r = 0.990, P < 0.01), and between SCP and monthly mean absolute minimum air temperature (r = 0.995, P < 0.01). ULCIZ and SIT for autumn, winter, and spring larvae were 4.9, 9.7, and 4.7°C and 1.356, 16.142, and 5.323 DD, respectively. Autumn larvae displayed significant acclimation efficiency at 5 and 0°C; however, exposure to −5°C did not enhance the cold-hardiness of larvae from any season. Cold-hardiness of M. alternatus larvae seems to increase in autumn, peak in winter, and decline in spring. Results suggest that M. alternatus drops SCP through acclimation in autumn to avoid freezing and reduces ULCIZ or increase SIT to increase its chilling tolerance at low temperature in winter.

The potential and propensity in flight of Pectinophora gossypiella (Saunders) in the laboratory were measured using a 32-channel, computer-monitored flight-mill system. Females flew significantly farther within a 72-h flight period than did males. The mean accumulated flight distance and flight duration of 1-d-old female individuals in a tethered-flight test were 41.25 ± 7.76 km and 23.87 ± 2.55 h, respectively, whereas for male individuals, the same parameters were 23.46 ± 2.13 km and 14.12 ± 1.12 h. The flight ability of adults was significantly positively correlated with pupal weight. The flight activity of unmated pink bollworm moths increased daily from the time of eclosion, reaching a peak at 3≈5 d and reducing gradually. All the moths could fly normally at 16≈36°C; however, the optimum temperature for flight ranged from 24 to 28°C, whereas the optimum relative humidity ranged from 75 to 90%.

Whether sticky traps baited with ethyl (E, Z)-2,4-decadienoate (pear ester) can be used to accurately assess the mating status of female codling moth, Cydia pomonella L., was evaluated in a series of tests. The proportion female moths caught in these traps that were virgin was compared with catches using interception and light traps in two separate studies. The mean proportion of virgin female codling moths caught in pear ester–baited traps was significantly lower than caught with either interception or light traps. Results were similar in both untreated and sex pheromone–treated orchards. Cohorts of virgin and mated female codling moths were flown separately to a pear ester–baited trap placed overnight in a flight tunnel. The recapture rate of virgin moths was significantly lower than for mated moths. The relation of the mean proportion of females mated versus the density of female moths caught in pear ester–baited traps over the entire season was examined by grouping data from 180 traps into eight density classes from 1 to >20 female moths per trap per season. A significantly higher mean proportion of virgin females were caught in the lowest density class (one moth per trap) than in all other classes. Traps catching two female moths per season had a significantly higher proportion of virgin moths than traps catching 4–5, 9–15, and 16–20 moths. No significant differences in the proportion of virgin moths occurred among traps grouped into classes from 3 to >20 female moths caught per season. These data are consistent with action thresholds previously established for cumulative catch of female moths in pear ester–baited traps (at least one moth) and support the use of this kairomone to assess the potential efficacy of sex pheromone programs.

Female Homalodisca coagulata (Say) were collected from October 2001 to February 2005 from citrus at the University of California, Riverside. Between 5 and 20 females per sampling date were dissected, and each was assigned an ovarian rank: previtellogenic, vitellogenic, or postvitellogenic. Ovarian ranking was used to characterize H. coagulata reproductive activity. Results of these dissections revealed consistent annual patterns in the proportion of previtellogenic females present in this field population. These patterns indicate that there are two distinct generations annually, with an occasional third generation. A time-dependent model of H. coagulata vitellogenesis cycles in Riverside, CA, was developed, which makes it possible to predict the appearance of the subsequent generation based on previous observed peaks in the proportion of vitellogenic females.

We describe the biology and life stages of the birch bark beetle, Dryocoetes betulae Hopkins, and report its second known occurrence in Idaho. One annual generation was observed with broods overwintering as larvae and sexually immature adults. The species is polygamous with a ratio of 1.8 females per male. Two females (rarely three) joined a male after he entered the bark, and each female created a 3- to 4-cm-long egg gallery with short lateral spurs. Eggs were laid in niches along each side of the main gallery. Larvae have three instars. No hymenopterous parasitoid was found; however, two apparent predators, Rhizophagus dimidiatus Mannerheim, and a clerid, Thanasimus undatulus (Say), were present in galleries. Two mites, Histiostoma sp. and Proctolaelaps n. sp., also occurred in galleries, and a nematode of the Order Rhabditida occurred in the midgut of larvae and adult D. betulae. An ambrosia beetle, Trypodendron betulae Swaine, also infested the basal stems apart from D. betulae. Stems of infested trees were infected with a root rot fungus, Armillaria ostoyae (Romagnesi) Herink. Several generations of beetles infested the basal portion of stems of either decadent or recently dead paper birch. This behavior preserves a scarce host resource and is enhanced by a relatively low fecundity and ability to establish new galleries without flight dispersal.

Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) is a recently introduced non-native invasive species in North America that has the potential to destroy several tree species in urban and forest habitats. Adult survival, reproduction, and egg hatch of A. glabripennis from two populations (Ravenswood, Chicago, IL, and Bayside, Queens, NY) were evaluated at seven constant temperatures (5, 10, 15, 20, 25, 30, and 35°C), and adult survival was evaluated at −1°C. Nonlinear regressions were used to estimate the temperature optimum and thresholds for each life history parameter. The estimated optimum temperature for median longevity was 18°C, and upper and lower thresholds were 39 and −3°C for females and 38 and −2°C for males. The estimated upper and lower thresholds for fecundity were 35 and 11°C for the New York population and 34 and 14°C for the Illinois population. The estimated optimum temperature for maximum fecundity was 23 and 24°C for the New York and Illinois populations, respectively. Both longevity and fecundity declined as temperature increased or decreased from the optimum. Oviposition was arrested at temperatures ≤10 and ≥35°C, and either eggs did not mature or were reabsorbed by females that did not oviposit at the higher temperatures. Days to first oviposition approached infinity near 10°C and declined exponentially to a minimum of 16 d at 30°C. The lower threshold for egg hatch was estimated as 10°C and the upper threshold at 32°C, and eggs would be predicted to hatch the fastest at 29°C. Maximum percentage hatch was estimated to occur at 23°C, and the estimated upper and lower thresholds were 34 and 12°C, respectively. These results indicate that summer temperatures throughout most of the lower 48 United States should support beetle survival and reproduction, although oviposition may be suspended and adult survivorship would decline when summer temperatures are sustained for full a day or more at or above 30°C, and there are no cooler locations where the beetles can retreat. In addition, although beetles may survive into the fall, they may lay fewer eggs at lower temperatures, and those eggs may not hatch until spring. These responses of A. glabripennis to temperature can be used for predicting the potential geographical range of this species and in developing phenological models to predict the timing of egg hatch and adult mortality, which are important for management programs.

Although Diabrotica pest species have been well studied in field corn, Zea mays L., relatively little is known about adult habitat use by pest and nonpest species at prairie-corn interfaces. Therefore, the objective of this work was to compare seasonal patterns of beetles of four Diabrotica species and their use of remnant prairie and adjacent field corn habitats in southeastern Nebraska. The study was conducted at five sites in 2001 and continued at three sites in 2002. The Diabrotica species included D. barberi Smith and Lawrence, D. cristata (Harris), D. virgifera virgifera LeConte, and D. undecimpunctata howardi Barber. Cucurbitacin vial traps were used to monitor Diabrotica populations. Available flowers and Diabrotica use of these flowers were also documented. The virgifera group species (D. barberi, D. cristata, and D. v. virgifera) were closely tied to a primary habitat, corn or prairie, but moved to secondary habitat if relative attractiveness of food sources in the primary habitat decreased; these three species had high initial population densities that decreased over the season. The one fucata group species (D. u. howardi) was found in various habitats, with low initial densities that increased over the season. Habitat type and contrasts in plant phenology seem to be key factors that influenced habitat choice by Diabrotica species; this especially affected the level of noncorn habitat use by pest species D. v. virgifera and D. barberi. Use of crop and noncrop parts of the agroecosystem by pest species suggests that a more holistic approach rather than a single field view may be appropriate when managing corn rootworms.

Reintroduction of fire and thinning have been suggested as the main practices to regain forest health in ponderosa pine forests of northern Arizona. Recent silvicultural programs and the occurrence of catastrophic wildfires have created a range of disturbance severities and a mosaic of forest conditions. Sixteen stands were randomly selected to create a completely randomized experimental design with four treatments, (1) unmanaged, (2) thinned, (3) thinned and burned, and (4) wildfire, with four replicates of each treatment. We assessed changes occurring in ground foraging ant functional groups at the stand scale as related to these treatments. A pitfall trapping scheme was implemented during the summer months of 2002 and 2003. A total of 18,009 specimens were collected representing 20 species from 10 genera. We found that traditional biodiversity measures, such as species richness, diversity, and dominance were a less satisfactory measure of treatment impact on ants than functional group analysis, which allowed us to consider the ecosystem role of each species. We found that different functional groups were dominant under different levels of disturbance severity and suppressed or excluded other functional groups that were less suited to the disturbance intensity. Maintaining a diversity of habitat types is suggested for supporting ecologically diverse ant functional groups and improve forest health.

We used pitfall traps to study the effects of fire and salvage logging on distribution of carabid beetles over a forest disturbance gradient ranging from salvaged (naturally burned and subsequently harvested) to unsalvaged (naturally burned and left standing). Significantly more carabids were caught in the salvaged forest and the overall catch decreased steadily through the edge and into the unsalvaged forest. We also noted a strong negative correlation between carabid abundance and percent vegetation cover. Beetle diversity as measured through rarefaction was significantly greater at the edge relative to both the unsalvaged and salvaged forest. This stand level study suggests that the amount of edge habitat created by salvage logging has significant implications for recovery of epigaeic beetle assemblages in burned forests by inflating the abundance of “open habitat” species in the initial communities. Carabid beetle responses to salvage logging can differ from responses to harvesting in unburned boreal forest suggesting that management of postfire forests requires special consideration.

This study investigated the influence of climate variables on insect establishment patterns by using discriminant analysis to classify the climatic preferences of two groups of polyphagous insect species that are intercepted at New Zealand’s border. One group of species is established in New Zealand, and the other group is comprised of species that are not established. The discriminant analysis classified the presence and absence of most species significantly better than chance. Late spring and early summer temperatures correctly classified a high proportion of sites containing the presence of both established and nonestablished species. Soil moisture and winter rainfall were less effective discriminating the presence of most of the species studied here. Cold winter air temperature was also a good classifier for the insect species that are not established in New Zealand. This study showed that multivariate statistical techniques such as discriminant analysis can help distinguish the climatic limits of insect distributions over large geographical scales.

Beetle biodiversity, particularly of leaf litter fauna, in the Sierran mixed-conifer ecosystem is poorly understood. This is a critical gap in our knowledge of this important group in one of the most heavily managed forest ecosystems in California. We used pitfall trapping to sample the litter beetles in a forest with a history of diverse management. We identified 287 species of beetles from our samples. Rarefaction curves and nonparametric richness extrapolations indicated that, despite intensive sampling, we undersampled total beetle richness by 32–63 species. We calculated alpha and beta diversity at two scales within our study area and found high heterogeneity between beetle assemblages at small spatial scales. A nonmetric multidimensional scaling ordination revealed a community that was not predictably structured and that showed only weak correlations with our measured habitat variables. These data show that Sierran mixed conifer forests harbor a diverse litter beetle fauna that is heterogeneous across small spatial scales. Managers should consider the impacts that forestry practices may have on this diverse leaf litter fauna and carefully consider results from experimental studies before applying stand-level treatments.

Corn engineered to produce the Cry3Bb1 protein from Bacillus thuringiensis Berliner (Bt) has provided unprecedented control for corn rootworm (Diabrotica virgifera virgifera Le Conte). However, accumulation and persistence of plant-produced Bt protein in soils may occur where Bt crops are repeatedly grown and residues of the crop plants are incorporated into the soil. If Bt protein is released into the soil rhizosphere, it may affect soil organisms. Studies were conducted to determine the effect of Bt or non-Bt corn roots and biomass on the weight and mortality of the earthworm, Lumbricus terrestris L. with different exposure methods and times. Enzyme-linked immunosorbent assay (ELISA) was conducted to determine if the Cry3Bb1 protein was present in the soil from the gut and excreta of earthworms. Results of these studies showed that there were no significant differences in weight and percent mortality of earthworms in soil planted or not planted with Bt and non-Bt corn or in soil containing ground air-dried biomass of Bt and non-Bt plants. Cry3Bb1 protein was detected in the soil from pots and the gut and excreta of earthworms exposed to Bt roots or biomass, whereas it was absent in soil from pot, the gut and excreta of earthworms exposed to roots or biomass of non-Bt corn. There was no significant difference in the amount of the protein recovered from pots or the gut or excreta of earthworms exposed to soils containing Bt roots or biomass for 12 or 33 d.

Producers in many North American sugarbeet (Beta vulgaris L.) growing areas rely heavily on organophosphate insecticides to manage the sugarbeet root maggot, Tetanops myopaeformis Röder. The threat of losing organophosphate options because of the potential for development of resistant root maggot strains or regulatory action has prompted a search for alternative control tools. American Type Culture Collection (ATCC) accession no. 62176, a strain of the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin, was studied in field trials as a bioinsecticidal option for control of T. myopaeformis larvae because of shown virulence in preliminary laboratory testing. The fungus was evaluated at four field sites during 2001 and 2002 as a planting-time granule, an aqueous postemergence spray, or a combination of both. Three rates of M. anisopliae conidia, 4 × 10¹² (1×), 8 × 10¹² (2×), and 1.6 × 10¹³/ha (4×) were applied as granules, and the spray was tested at the 1× rate. A significant linear response in sucrose yield in relation to M. anisopliae granule application rate confirmed its entomopathogenic capacity under field conditions. Each multiple of M. anisopliae granules applied affected a yield increase of ≈171 kg sucrose/ha. The fungus was less effective than conventional insecticides at preventing stand loss from high root maggot infestations early in the season. It is concluded that, with additional research, mycoinsecticides could potentially be incorporated into management systems to complement chemical control tactics such as insecticidal seed treatments, soil insecticides (possibly at reduced rates), or postemergence materials for integrated control of T. myopaeformis adults or larvae.

The behavior of adult Colorado potato beetles (Leptinotarsa decemlineata) in the presence of Beauveria bassiana sporulating on cadavers was studied to determine the likelihood of disease infection as beetles emerge from the soil and colonize host plants. In 2001, the movement of single adult Colorado potato beetles was monitored in arenas containing infective cadavers in differing spatial patterns between four potato plants. In 2002, a similar design was used, but was under the more natural conditions of a potato field. In both experiments, direction, time, and directness of beetle travel was not significantly affected by the presence or absence of infective cadavers, showing no avoidance of these cadavers by adult Colorado potato beetles. The likelihood that emerging adults would contact infective cadavers on the soil surface was quantified at different cadaver densities. A curvilinear relationship (y = 4.8313x^0.4459) best describes the frequency of encounters of adults as a factor of increasing density of cadavers on the soil surface. Mortality of adults and production of conidia on cadavers after encounters with increasing densities of infective cadavers had similar relationships that show the decreased susceptibility of adults to B. bassiana compared with prepupae. These relationships were used to model horizontal infection to emerging adults in the summer months, subsequent to a conidial spray targeted at larvae. The model indicates that horizontal infection of adults may potentially be significant (30–70% of horizontal infection), and that simulated early sprays targeted at first-instar larvae resulted in the maximum levels of predicted horizontal infection.

The membracid Aconophora compressa Walker, a biological control agent released in 1995 to control Lantana camara (Verbenaceae) in Australia, has since been collected on several nontarget plant species. Our survey suggests that sustained populations of A. compressa are found only on the introduced nontarget ornamental Citharexylum spinosum (Verbenaceae) and the target weed L. camara. It is found on other nontarget plant species only when populations on C. spinosum and L. camara are high, suggesting that the presence of populations on nontarget species may be a spill-over effect. Some of the incidence and abundance on nontarget plants could have been anticipated from host specificity studies done on this agent before release, whereas others could not. This raises important issues about predicting risks posed by weed biological control agents and the need for long-term postintroduction monitoring on nontarget species.

Classical biological control is a practice to control alien invasive weeds, but many introduced biological control agents exhibit only a weak negative impact on their targets. One reason is that prerelease impact studies in the natural environment are often difficult to carry out. Heracleum mantegazzianum Sommier and Levier (Apiaceae), which is native to the Caucasus, is a perennial noxious weed introduced into Europe and North America. We examined the impact and host size preference of different endophagous insect guilds in the weed’s native range. Instead of the commonly used insect exclosure approach, we estimated plant vigor before and after herbivore attack under natural conditions. Endophagous herbivores were dominated by the weevil species Lixus iridis Olivier, Nastus fausti Reitter, and Otiorhynchus tatarchani Reitter (Coleoptera: Curculionidae), the fly Melanagromyza heracleana Zlobin (Diptera: Agromyzidae), and an unidentified root-boring agromyzid fly species. Most observed insect species exhibited a strong preference for either big or small plants, but none of them caused serious damage within the study period. Occurrence of root-feeding weevils was associated with weak plants, but because of their long larval development, it was not possible to assign this relationship clearly to either feeding damage or host size preference. A comparison with other studies indicated that mature H. mantegazzianum plants are quite tolerant to herbivory. Insects belonging to the feeding guilds studied here will probably not guarantee successful biological control. Further research should focus on earlier stages in the weed’s life cycle.

The purpose of this study was to characterize the behavior of black vine weevil larvae, Otiorhynchus sulcatus (F.), in the presence of two possible control options: the synthetic pyrethroid bifenthrin and the entomopathogenic fungus Metarhizium anisopliae (Metch.) Sorokin. Five third-instar black vine weevil were placed in two-choice soil olfactometers that allowed larvae to infest one of two pots. Larvae were allowed to choose between M. anisopliae (1 × 10⁶ spores/g dry media) and untreated media, bifenthrin (25 ppm) and untreated media, as well as M. anisopliae– and bifenthrin-treated media. For all comparisons, experiments were conducted without plants in the system to test for innate responses, as well as with plants to test host–plant influence. Larvae were significantly deterred by bifenthrin without plants present in the system. No significant effect on larval preference was observed when M. anisopliae was present in media for trials without plants. M. anisopliae–treated media was preferred by black vine weevil larvae over bifenthrin without plants present in the two-choice soil olfactometer. When plants were included, a significant attraction to M. anisopliae–treated media was observed over untreated media. Unlike comparisons without plants, larvae were not repelled by bifenthrin when plants were included in the two-choice soil olfactometer. The attraction of black vine weevil larvae to pots containing plants and fungus indicates the operation of a previously undescribed tritrophic interaction. This behavior may be useful in the development of more effective biological control programs.

The invasive red turpentine beetle, Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed >6 million pines in recent years. There is a need to understand the basic biology and ecology of the beetle to develop an effective monitoring and management strategy. Combining field observation with experiments in the laboratory, we tested red turpentine beetle attacking behavior under artificial conditions and examined its behavioral responses to volatiles from holes bored. Our research proved that (1) an red turpentine beetle male adult cannot successfully bore into a pine without a preexisting tunnel that has been bored by a female, whereas an red turpentine beetle female can successfully bore into the tree without the presence of a male; (2) nearly all red turpentine beetle females who made tunnels were joined by red turpentine beetle males, and an red turpentine beetle male always joined a female’s tunnel ≈5 h after she had built it; (3) both red turpentine beetle male and female adults had similar rhythms for boring into the bark, namely, both preferred to bore in the early morning (0300–0800 hours) and evening (1600–2300 hours); (4) red turpentine beetle males and females had different sensitivities to volatiles: the males were sensitive to dust from holes bored by single females, and the females were more sensitive to dust from holes bored by paired male and female adults. Our research suggested some pheromones in this species mediate tree colonization. The significance of this research for red turpentine beetle management is discussed.

Red imported fire ant, Solenopsis invicta Buren, is a serious pest in the southeastern United States. It has caused economic losses in agricultural products, stings can cause anaphylactic shock, and it has reduced biodiversity. S. invicta has displaced native ant species throughout its range, presumably by competitive exclusion. In 1998, S. invicta populations were confirmed in southern New Mexico, resulting in a quarantine of Doña Ana County. Although large populations of the native southern fire ant, S. xyloni McCook, are common in the Mesilla Valley, only two small populations of S. invicta have been found since the initial quarantine. It is unclear why these populations have not become more dominant. This research studied the influence of the fire ant parasitoid Pseudacteon tricuspis Borgmeier (Phoridae), low humidity, and competition with S. xyloni on the survival and fitness of S. invicta. Competitive and noncompetitive foraging experiments with and without parasitoids were conducted in the laboratory to evaluate food retrieval and worker activity of each species. Overall, S. invicta was able to retrieve more food than S. xyloni. Pseudacteon flies reduced foraging and worker activity of S. invicta under low humidity. S. invicta dominated at high and low humidity in the absence of P. tricuspis. However, S. xyloni dominated at high humidity and coexisted with S. invicta at low humidity when P. tricuspis was present. This may help explain the lack of establishment and spread of S. invicta in the southwestern United States and encourage the use of Pseudacteon flies as a control option in arid environments.

In Illinois and Indiana, the western corn rootworm, Diabrotica virgifera virgifera LeConte, circumvents crop rotation as a control measure by ovipositing in soybean (Glycine max L. Merr.) fields and in other crops in rotation with corn (Zea mays L.). A means of distinguishing between rotation-resistant and wild-type behavioral phenotypes is the first step in determining the genetic basis of rotation resistance. The time between release into and departure from a bioassay arena was used as a measure of beetle activity to distinguish between behavioral phenotypes. Results from these assays indicate that D. v. virgifera females from regions where crop rotation is no longer effective are more active than females from regions where rotation remains effective. The geographic source of the beetle population was a main significant effect in trials done in both 2004 and 2005. Behavioral differences were more easily observed in a cornfield rather than in the laboratory. Results were consistent with the hypothesis that a loss of fidelity to corn rather than any particular attractant is the cause of rotation resistance. Behavioral differences between populations of beetles in similar environments suggest that there is a genetic difference between rotation-resistant and wild-type D. v. virgifera, although no specific gene or genes have yet been identified.

Studies were conducted in 0.07- to 0.18-ha peach and apple plots to determine the effects of pheromone trap and hand-applied emulsified wax pheromone dispenser application heights on captures of Grapholita molesta in traps baited with pheromone lures or virgin females. Traps and pheromone dispensers were placed either low (1.2–1.8 m) or high (2.7–4 m) within tree canopies. In the majority of cases, equivalent numbers of male G. molesta were caught in traps placed at the low and high positions in both pheromone-treated and untreated plots. Furthermore, pheromone dispensers placed at the low and high positions equally disrupted orientation of male G. molesta to pheromone traps placed at either height and to virgin female traps placed at 1.2–1.8 m within canopies season-long at most sites. Our results indicate that for trees ≤3.5 m tall, dispensers with release rates ≥18 mg/ha/h placed at 1.5–2.0 m (heights easily reached from the ground) should effectively disrupt mating of G. molesta throughout tree canopies. In trees between 3.5 and 4.5 m tall, the dispensers should be moved to ≈1.5 m from the top of the canopy. For trees taller than 4.5 m, we recommend hanging dispensers both in the top and bottom thirds of tree canopies. Most commercial Michigan peach and apple trees are <3.5 m tall. Eliminating the need to apply dispensers high in the canopy in most orchards will enable growers to reduce application costs, thereby facilitating increased adoption of mating disruption for G. molesta control by growers.

We studied the effect of UV-blocked greenhouses made from netting and plastics on the movement and pest status of three important pest of tomatoes: whitefly (Bemisia tabaci), thrips (Ceratothripoides claratris), and aphid (Aphis gossypii). Under UV-blocked greenhouses, fewer whiteflies, aphids, and thrips entered the greenhouse compared with the ones having more UV intensity. Similarly, significantly fewer alate aphids and adult B. tabaci/leaf were counted in greenhouses with low UV intensity. Although thrips were the most abundant pest, they also were significantly less abundant in greenhouses with lower UV intensity. Consequently, significantly lower levels of leaf infestation were recorded under these greenhouse conditions. During open gates experiments, virus infection levels reached 96–100% under UV nonblocking greenhouses compared with 6–10% infection levels in greenhouses where UV irradiation was blocked. In addition, the appearance of virus symptoms was considerably delayed under greenhouses made from the UV-blocking roof material, although the majority of the plants tested positive for the tospovirus, capsicum chlorosis virus (CaCV; AIT isolate). The results are discussed in context of improved management of sucking insect pests of tomatoes in the humid tropics.

Native wasps were sampled from 33 lowbush blueberry (Vaccinium angustifolium) fields and adjacent forests in eastern Maine during the summers of 1997 and 1998. Sampling was conducted along a horizontal transect that bisected the field/forest interface using two methods: window-pane traps suspended at varying heights (1, 7, and 14 m above the ground) and ground-level malaise traps. The objectives of this study were to assess (1) the spatial distributions of wasp species assemblages associated with the two distinct habitats and (2) the potential interactions of wasp species assemblages across the blueberry/forest landscape. Wasp samples from the two trap types collected different wasp species assemblages, each of which were consistent across the 2 yr. Both methods documented lower abundances of wasps in blueberry fields in comparison with adjacent forests. Window pane traps at varying heights identified statistically significant but remarkably minor differences in height even at the highest traps in the middle of blueberry fields in both years of the study. The malaise traps detected distinct species assemblages whose horizontal distributions differed substantially from each other. Distributions ranged from those that were trapped exclusively in the forest, through those that were evenly distributed across the landscape, to taxa that were almost exclusively found in the blueberry field centers. Our results suggest that forest and edge habitats may be important refugia for wasp species assemblages that contribute to regulation of blueberry insect pest populations. Detailed knowledge of specific taxa should assist in the management of the blueberry/forest landscape for the conservation and enhancement of beneficial insects.

Rice plants are vulnerable to the yellow stem borer, Scirpophaga incertulas (Walker), during the booting phase, when infestations cause the greatest yield loss. Although the moth is ubiquitous in rice-growing regions, S. incertulas feeding patterns on booting plants have been poorly characterized. We studied the early-instar feeding patterns of S. incertulas on wild and cultivated rice accessions to determine where larvae feed and if feeding route influences larval survival and development. Three cultivated (Taichung Native 1, IR64, and IR72) and three wild rice accessions (two accessions of Oryza nivara and one accession of O. rufipogon) were chosen for the study. Larvae were introduced onto booting plants and sampled after 6 h, 1 d, 2 d, 4 d, and 7 d. Approximately 25% more larvae survived on cultivated accessions than on wild accessions. Larvae were also 15% more likely to feed on the panicle of cultivated accessions than wild accessions, and panicle-feeding improved larval survival and development. Stem borer feeding route depended on plant phenology; larvae were more likely to feed on the panicle than on vegetative structures on booting, heading, and flowering tillers. Because all stems were cut by the seventh day if larvae fed on the panicle, resistance during the booting phase may be effective if it reduces the likelihood of panicle feeding or if strong antibiotic resistance can be found in the panicle.

Ten self-fertile commercial sunflowers cultivars were evaluated for seed set with and without exposure to bees. In the first planting, the number of foraging honey bees was smaller than in the second, and seed set for most cultivars did not differ between those bagged to exclude bees and ones that were open pollinated. In the second planting, however, a majority of cultivars had significantly greater seed set when capitula were exposed to bees compared with when they were not. The weight of seeds from open-pollinated capitula was greater than from those where bees were excluded. Environmental conditions also played a role in seed set as evidenced by differences between plantings in set on bagged capitula. In the first planting, average maximum and minimum temperatures were significantly higher than in the second, and overall seed set was significantly lower in capitula where bees were excluded compared with the second planting. Under the high temperature conditions, however, some cultivars set four times more seed on open-pollinated capitula compared with those that were bagged. These results suggest that foraging activity and cross-pollination by bees might mitigate reductions in seed set caused by high temperatures.

Gall-inducing insects require close phenological synchrony with their host plants. It has been hypothesized, but seldom shown, that this is because, to induce galls the insects require physiologically active plant tissue, which exists only during a limited stage of plant development, forming a phenological window for gall induction. We examined this hypothesis in the system of a shrub, Aucuba japonica Thunberg, and its specialist fruit gall midge Asphondylia aucubae Yukawa et Ohsaki. Female midges lay eggs into young host fruit and stimulate the integument, a reactive tissue in the fruit, to induce galls. Our results showed that the lifetime of the integument defines the end point of the phenological window. The integument was rapidly degenerated as fruit matured, and eventually disappeared. The degeneration of the integument began simultaneously with the adult emergence season of the midge, and was greatly accelerated in the latter half of the adult midge season, forming an apparent end point of the window. We experimentally caged host infructescences to keep them free from midge oviposition, and released one field collected ovipositing female into each cage. When the treatment was performed before the end point of the window, gall induction success of the midge was much higher. The integument, however, does not define the start point of the window because gall induction success was not lower when the midge was released very early in the adult emergence season. We suggest that the start point is defined by another factor, likely the hard endocarp of the fruit.

Impact of the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), feeding injury on chlorophyll content and photosystem II (PSII) photochemistry in heads of wheat, Triticum aestivum L., at the grain-filling developmental stage was evaluated by biochemically assessing the total chlorophyll, chlorophyll a (Chla), chlorophyll b (Chlb), chlorophyll a/b ratio (Chla/b), and carotenoid concentrations in the glumes in combination with a chlorophyll a fluorescence test. C. cinctus–infested stems had altered head glume pigment composition and photochemistry. Chlorophyll content, Chla, Chlb, Chla/b, and total chlorophyll, and the photochemical efficiency of PSII were greater for glumes of heads developing on infested stems. Chlorophyll a fluorescence was also affected by C. cinctus. In this study, wheat plants in a controlled environment were able to compensate for injury imposed by C. cinctus. The mechanism underlying the compensatory processes seems to involve the alteration of wheat head physiology. Based on our results, either the photochemical efficiency of heads on infested stems was greatly improved or their senescence was delayed.

Laboratory toxicity studies were conducted to determine the subacute effects of Bt Cry1Ab corn leaf material on nontarget soil organisms. Survival and growth were measured for an earthworm, Eisenia fetida Savigny, and survival and reproduction were measured for a springtail, Folsomia candida Willem. The organisms were provided leaf material of two Bt11 corn varieties, two Mon810 corn varieties, and the isolines of each, in a soil system and monitored for 28 d. An assay control treatment of an optimal food and a reference control treatment, using the herbicide pendimethalin, were used to provide a context for the observed results. Basic nutritional data of protein, fat, and sugar content were analyzed for each food type. Greater growth was observed for E. fetida in two Bt varieties, Bt11 90-d and Mon810 108-d, compared with their isolines. F. candida receiving Bt11 90-d isoline material had more offspring compared with those in the corresponding Bt line, but no other pairs were different. Time to reproduction of F. candida was only affected by the reference control treatment. Both protein and sugar content were found to correlate significantly with growth for E. fetida, but the nutritional parameters were not found to correlate with the effects observed for F. candida. These results indicate that there is little direct hazard from Bt corn leaf material to E. fetida and F. candida but that differences in nutritional parameters of the Bt lines and the isolines may lead to differences in the effects on nontarget organisms.

Laboratory feeding experiments using rice plants containing a synthetic cry1Ab gene derived from Bacillus thuringiensis Berliner (Bt) were carried out to study the effects of Bt rice-fed prey on the predator Propylea japonica (Thunberg). Plants were obtained from two homozygous transgenic Bt-cry1Ab expressing rice lines, Kemingdao 1 (KMD1) and Kemingdao 2 (KMD2), and their untransformed parental variety Xiushui 11 (XS11). The herbivorous prey species tested was the brown planthopper, Nilaparvata lugens Stål, one of most serious insect pests of rice and not targeted by KMD1 or KMD2. The concentrations of Cry1Ab toxin expressed in KMD1 and KMD2 plants and that of the toxin transferred to N. lugens feeding on these plants were determined by enzyme immunosorbent assay technique. Development parameters of P. japonica reared on KMD1- or KMD2-fed N. lugens were assessed in the laboratory. The results showed that the concentration of Cry1Ab in rice leaves and stems significantly increased from the booting to grain filling stage and subsequently decreased as the plants matured. Cry1Ab could be detected in nymphs and adults of N. lugens feeding on the Bt rice plants. Development time, pupation, adult eclosion, pupal and adult weight, and male-adult locomotive activity of P. japonica that had preyed on KMD1- or KMD2-fed N. lugens nymphs as larvae were not significantly different from those that preyed on XS11-fed nymphs. In short, our results indicate that the nontarget insect N. lugens and its predator P. japonica are exposed to Cry1Ab toxin from transgenic cry1Ab rice, but development of this predator was not affected by the toxin through tritrophic interactions.