Functional responses by Lysiphlebus testaceipes (Cresson), a common parasitoid of small grain aphids, on greenbug, Schizaphis graminum (Rondani), were measured at seven temperatures (14, 12, 10, 8, 6, 4, and 2°C) during a 24-h period (12-h light: 12-h dark). Oviposition by L. testaceipes ceased at temperatures <4°C. At all experimental temperatures, a type I, rather than a type II or type III, functional response was determined to be the best fit based on coefficient of determination (r²) values. L. testaceipes was observed to oviposit in greenbugs at temperatures below the developmental temperature of both the greenbug host (5.8°C) and the parasitoid itself (6.6°C). This ability to oviposit at subdevelopmental temperatures enables the parasitoid to increase the percentage of greenbugs that are parasitized while the greenbugs are unable to reproduce. The implications of these findings regarding population suppression of greenbugs are discussed.

Development and reproduction of Iphiseiodes quadripilis (Banks) were evaluated on single food diets of pollen (Malephora crocea Jacquin [ice plant] or Quercus sp. [oak]), spider mites, [Eutetranychus banksi (McGregor) or Panonychus citri (McGregor) (Acari: Tetranychidae)], or the citrus rust mite Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae). Experiments were conducted in an environmental chamber at 28° ± 1°C, 14:10 (L:D) daylength, and 45% RH. I. quadripilis completed development and laid viable eggs that subsequently hatched on diets of either ice plant or oak pollen or eggs and motile stages of E. banksi. P. citri was acceptable as prey, but survival of larvae to adults was only 36%, whereas survival on E. banksi, ice plant pollen, and oak pollen was 48, 60, and 68%, respectively. The webbing produced by P. citri seemed to inhibit foraging behavior of I. quadripilis larvae and nymphs. Larvae of I. quadripilis developed only to the second nymphal instar on a diet of P. oleivora alone or water alone. Starved I. quadripilis females and deutonymphs were observed preying on the pink citrus rust mite, Aculops pelekassi (Keifer) (Eriophyidae). During 4-min observation trials, two series of I. quadripilis fed on 1.8 ± 0.47 and 3.5 ± 0.45 A. pelekassi motile stages after being starved for 6 and 24 h, respectively. I. quadripilis females did not prey on P. oleivora in arenas containing both rust mite species.

The leaf beetle Diorhabda elongata Brullé subspecies deserticola Chen, collected in northwestern China, has been released in the western United States to control tamarisk (Tamarix spp.). While beetle establishment and saltcedar defoliation have been noted at northern study sites, this species has not established at latitudes south of the 38th parallel. Critical daylength for diapause induction was measured in the laboratory and ranged between 14 h 50 min to 15 h 08 min, depending on temperature, and adults were shown to cease reproduction and enter diapause at daylengths of 14 h 30 min or less. Critical daylength in the field was measured at ≈14 h 39 min and occurred 13 d before 50% of the population reached diapause. South of 36°20′ N, the longest days of the year are shorter than 14 h 39 min, making the beetles univoltine in the southern United States. North of 36°20′ N, a window of reproductive activity opens 13 d after the critical daylength is reached in the spring and closes 13 d after it is passed in the summer, allowing at least a partial second summer generation. It is predicted that south of the 38th parallel, premature diapause will increase mortality and disrupt synchrony between the life cycle of the beetle and host plant availability. This could hinder establishment and help explain the failure of this population south of the 38th parallel, providing a rationale for testing other populations of D. elongata in the southern range of Tamarix in North America.

The soybean aphid is an invasive pest in the midwest United States, with frequent population outbreaks. Previous work has shown that aphid population densities are higher on potassium-deficient soybean than on healthy soybean. The experiments reported here test the hypotheses that the potassium nutrition of the host plant affects the forms of phloem nitrogen available to soybean aphids, and subsequently, their abundance. In field surveys and an exclusion cage study when aphid populations were high, soybean plants with potassium deficiency symptoms had a higher density of soybean aphids than plants without deficiency symptoms. In clip cage experiments, this effect was caused by earlier aphid reproduction and higher numbers of aphid nymphs per mother on plants growing in lower-potassium soil. In phloem exudation samples, the percentage of asparagine, an important amino acid for aphid nutrition, increased with decreasing soil potassium, perhaps because of potassium’s role in the nitrogen use of the plant. Taken together, these results show that soybean potassium deficiency can lead to higher populations of soybean aphid through a bottom-up effect. A possible mechanism for this relationship is that soybean potassium deficiency improves the nitrogen nutrition of these N-limited insects. By releasing these herbivores from N limitation, host plant potassium deficiency may allow soybean aphid populations to reach higher levels more rapidly in the field.

The objective of this study was to evaluate the suitability of killed house fly (Musca domestica L) pupae for production of two economically important pupal parasitoids. Two-day-old fly pupae were subjected to heat shock treatments of varying temperatures and durations in an oven at ≥70% RH; exposure to temperatures of 55°C or higher for 15 min or longer resulted in 100% mortality. Exposure to 50°C resulted in 40 and 91% mortality at 15 and 60 min, respectively. All (100%) pupae placed in a −80°C freezer were killed after 10-min exposure; exposure times of <5 min resulted in <21% mortality. Progeny production of Spalangia cameroni Perkins and Muscidifurax raptor Girault and Sanders (Hymeoptera: Pteromalidae) from pupae killed by heat shock or 50 kR of gamma radiation was not significantly different from production on live hosts on the day when pupae were killed. Freeze-killed pupae produced 16% fewer S. cameroni than live pupae and an equivalent amount of M. raptor progeny on the day when pupae were killed. When killed pupae were stored in freezer bags at 4°C for 4 mo, heat-killed, irradiated, and freeze-killed pupae remained as effective for production of M. raptor as live pupae. Production of S. cameroni on heat-killed and irradiated pupae was equal to parasitoid production on live pupae for up to 2 mo of storage, after which production on killed pupae declined to 63% of that observed with live pupae. Production of S. cameroni on freeze-killed pupae was 73–78% of production using live pupae during weeks 2–8 of storage and declined to 41 and 28% after 3 and 4 mo, respectively. Killing pupae by heat shock provides a simple and low-cost method for stockpiling high-quality hosts for mass-rearing both of these filth fly biological control agents.

The effect of nine constant temperatures (15, 17.5, 20, 22.5, 25, 27.5 30, 32.5, and 35°C) on the development of the stone leek leafminer, Liriomyza chinensis (Kato), on Japanese bunching onion, Allium fistulosum L., was studied in the laboratory. Developmental times for immature stages were inversely proportional to temperature between 15 and 30°C but increased at 32.5°C. Total developmental times from egg to adult emergence decreased from 69.6 to 17.1 d for temperatures from 15 to 30°C, with pupae requiring more time for development than the combined egg and larva stages. Both linear and nonlinear (Logan equation VI) models provided a reliable fit of development rates versus temperature for all immature stages. The lower developmental thresholds that were estimated from linear regression equations for the egg, first, second, and third instars, total larva, egg-larval, pupa, and total combined immature stages were 12.1, 10.6, 13.6, 8, 9.6, 11.3, 11.2, and 11.4°C, respectively. The degree-day accumulation was calculated as 312.5 DD for development from egg to adult emergence. By fitting the nonlinear models to the data, the upper and optimal temperatures for egg, larva, pupa, and total immature stages were calculated as 37.8 and 31.7, 34.9 and 30.1, 35.8 and 30.6, and 35.0 and 30.9°C, respectively. These data are useful for predicting population dynamics of L. chinensis under field conditions and determining the maximum proportion of susceptible individuals for facilitating improved timing of application of control measures.

The banana aphid, Pentalonia nigronervosa Coquerel, is present worldwide where banana (Musa spp.) is grown. It is the vector of Banana bunchy top virus (Nanoviridae, Babuvirus), the etiological agent of banana bunchy top disease, currently the most important constraint for banana producers in Hawaii. P. nigronervosa is not well studied, and effects of temperature on its growth and reproduction are unknown. We studied the longevity and fecundity of one clone of banana aphid on different types of plant materials to determine an effective method to study the insect in the laboratory. We found that insects performed better unconfined on plantlets, followed by leaf midrib cuttings. We also conducted complete life table studies with P. nigronervosa on banana leaf midrib cuttings at 20, 25, and 30°C, with a photoperiod of 12:12. Intrinsic rate of increase (r), net reproductive rate (R₀), doubling time (DT), nymphal mortality, and mean offspring per female all showed maximal rates at 25°C. Population growth was studied on whole banana plantlets as well, and growth rates were also highest at 25°C. We found r to be greater when aphids were reared on intact banana plantlets than on cuttings. Our results show the importance of comparing insect rearing methods for studies such as life tables.

Male Metamasius spinolae (Gylh.) produce several volatile compounds that are likely constituents of its aggregation pheromone. These compounds were identified by volatile collections and gas chromatography (GC), followed by coupled gas chromatography-mass spectrometry (GC-MS), as 2-methyl-4-heptanone [1], 6-methyl-2hepten-4-one [2], and 2-hydroxy-2-methyl-4-heptanone [3]. Preliminary field experiments using synthetic racemates of these compounds showed that significantly more adult cactus weevils were caught in traps baited with the major single compound three or the 2 3 binary combination than in unbaited control traps. However, highest trap efficacy occurred with the 1 2 binary combination and a blend of all three synthetic compounds plus prickly pear. Potential uses for the cactus weevil pheromone and possible ways to increase trap captures are discussed.

We evaluated the responses of male and female Monochamus alternatus Hope (Coleoptera: Cerambycidae) to various terpenes commonly associated with host trees. Electroantennogram (EAG) tests were conducted with 12 plant volatile compounds and ethanol. Antennae of both sexes were highly sensitive to (R)-( )-α-pinene, ( )-3-carene, (−)-β-pinene, and terpinolene. Both sexes of M. alternatus were attracted by traps baited with ( )-α-pinene, (−)-β-pinene, ( )-3-carene, or terpinolene. Our results support the first of the three-stage hypothesis posed by Ginzel and Hanks that suggests that location of stressed trees by cerambycids involves three stages: (1) both sexes locate larval hosts by using plant volatiles as kairomones; (2) males produces sex pheromones to attract females after both sexes land on the larval hosts; (3) males and female recognize each other by contract pheromones in their epicuticular wax layer. Males and females showed differences in their EAG responses to several compounds, including (R)-( )-α-pinene, (−)-β-pinene, myrcene, ( )-3-carene, (R)-( )-limonene, terpinolene, and trans-caryophyllene. In all cases, males exhibited greater sensitivity than females. In laboratory assays, male M. alternatus showed strong preference for 1% ( )-α-pinene and 1% (−)-β-pinene over other compounds. In field assays, traps baited with ( )-α-pinene, (−)-β-pinene, ( )-3-carene, or terpinolene caught more beetles than control traps. We found strong male bias in beetle catches in baited traps and those captured on the stem of stressed trees despite a strong female bias in emerging beetles in 2004. We hypothesize that male M. alternatus are more responsive than females to plant volatiles and that males have more capacity than females in finding mating locations.

Mycophagy by bark beetles is widespread. However, little is known regarding which developmental stages of bark beetles actually feed on fungi. To study this question, we sampled fungi associated with Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae) throughout development in naturally attacked trees. Isolations of fungi were made from phloem adjacent to brood and from brood exoskeletons and guts. Overall, the incidence of fungi with individual brood increased as brood development progressed. Grosmannia clavigera (Robinson-Jeffrey and Davidson) Zipfel, de Beer and Wingf. and Ophiostoma montium (Rumbold) von Arx exhibited generally opposing trends in prevalence. G. clavigera was most likely to be found in phloem adjacent to prewintering third- and postwintering fourth-instar larvae. O. montium was most likely to be found in phloem adjacent to eggs, first-instar larvae, pupae, and teneral adults. In contrast to isolations made from phloem, fungi isolated from brood guts and exoskeletons were not observed to shift in prevalence. First- and third-instar larvae were often observed migrating to older portions of their galleries, indicating that they do not spend all of their time feeding at, and extending, the apex of the gallery. Our results suggest that not only are D. ponderosae brood in contact with and feeding on fungi throughout development, but also, that during development, contact of brood with a particular fungus is likely to change. Such temporal shifts in fungal symbionts may be environmentally driven and have important implications in how these fungi interact with their hosts within and across generations.

The tropical root weevil, Diaprepes abbreviatus (L.), has been a pest of citrus and ornamental plants since its introduction into Lake County, FL, in 1964. Since then, it has colonized the Florida peninsula to the south of its point of introduction but has not expanded its range to the north. A lower threshold for oviposition by D. abbreviatus was estimated as 14.9°C. Eggs were highly susceptible to cold, with 95% mortality (LTime₉₅) occurring in 4.2 d at 12°C. Relative susceptibility of life stages to cold was eggs > pupae > larvae > adults. Archived weather data from Florida were examined to guide a mapping exercise using the lower developmental threshold for larvae (12°C) and the lower threshold for oviposition (15°C) as critical temperatures for mapping the distribution of D. abbreviatus and the potential for establishment of egg parasitoids. Probability maps using the last 10 yr of weather data examined the frequency of at least 10, 15, 20, 25, or 30 d per winter when soil temperature was ≤12°C. The geographic area that experienced between 15 and 20 d per winter with mean daily soil temperature ≤12°C closely approximated the northern limit of D. abbreviatus in Florida. Homologous maps of Arizona, California, and Texas predict the areas where soil temperatures favor establishment of D. abbreviatus. Successful establishment of egg parasitoids in Florida seems to be limited to southern Florida, where mean daily air temperatures fall below 15°C <25 d/yr. By this measure, we predict that egg parasitoids will not establish in Arizona, California, or Texas.

We studied the effects of maternal age on fitness of progeny in the rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae). Five-, 20-, and 50-d-old female rice weevils were used to study the effects of maternal age on the lifetime fecundity and longevity of their daughters. In addition, we determined the effects of maternal age on the weight and survivorship of daughters’ progeny. Daughters of 5- and 20-d-old weevils lived longer, and the numbers and weights of the progeny of these daughters were higher than for daughters of 50-d-old weevils. Survivorship of immature grand-offspring of 5-, 20-, and 50-d-old female weevils was similar. None of the fitness characteristics of the daughters and grand-offspring of 5- and 20-d-old weevils that were measured differed significantly. We believe maternal age effects on rice weevil progeny fitness may at least partly be acting through maternal age effect on egg size. Individuals that developed from younger 5- and 20-d-old weevils had a greater fitness than those produced by older 50-d-old females. Our study shows maternal age is impacting life history parameters that influence population dynamics across generations. Therefore, maternal age could significantly affect population development and have far reaching implications for pest management and simulation modeling of rice weevil populations.

Because the viability of a population may depend on whether individuals can disperse, it is important for conservation planning to understand how landscape structure affects movement behavior. Some species occur in a wide range of landscapes differing greatly in structure, and the question arises of whether these species are particularly versatile in their dispersal or whether they are composed of genetically distinct populations adapted to contrasting landscapes. We performed a capture-mark-resight experiment to study movement patterns of the flightless bush cricket Pholidoptera griseoaptera (De Geer 1773) in two contrasting agricultural landscapes in France and Switzerland. The mean daily movement of P. griseoaptera was significantly higher in the landscape with patchily distributed habitat (Switzerland) than in the landscape with greater habitat connectivity (France). Net displacement rate did not differ between the two landscapes, which we attributed to the presence of more linear elements in the connected landscape, resulting in a more directed pattern of movement by P. griseoaptera. Significant differences in the movement patterns between landscapes with contrasting structure suggest important effects of landscape structure on movement and dispersal success. The possibility of varying dispersal ability within the same species needs to be studied in more detail because this may provide important information for sustainable landscape planning aimed at maintaining viable metapopulations, especially in formerly well-connected landscapes.

It is known that substantial boll weevil, Anthonomus grandis grandis Boheman, individuals can survive mild subtropical winters in some habitats, such as citrus orchards. Our study shows that endocarp of the fruit from prickly pear cactus, Opuntia engelmannii Salm-Dyck ex. Engel.; orange, Citrus sinensis L. Osbeck.; and grapefruit, Citrus paradisi Macfad., can sustain newly emerged adult boll weevils for >5 mo, which is the duration of the cotton-free season in the subtropical Lower Rio Grande Valley of Texas and other cotton-growing areas in the Western Hemisphere. Cotton, Gossypium hirsutum L., and the boll weevil occur in the same areas with one or all three plant species (or other citrus and Opuntia species that might also nourish boll weevils) from south Texas to Argentina. Although adult boll weevils did not produce eggs when fed exclusively on the endocarps of prickly pear, orange, or grapefruit, these plants make it possible for boll weevils to survive from one cotton growing season to the next, which could pose challenges to eradication efforts.

Myrmica rubra L. was introduced into New England in the early 20th century, and at present, has a patchy distribution in parts of northeastern North America, including records from 31 communities in Maine. M. rubra is highly polygynous, and colonies reproduce vegetatively, forming dense local populations where conditions are favorable. Using mobile nests and baited arenas in a series of field aggression bioassays, we tested patterns of internest tolerance within and among local populations on Mt. Desert Island, ME. We found that foragers originating from fragments of the same colony or from neighboring nests retained a high level of intraspecific tolerance over several months, whereas significant intercolony aggression among workers was present between colonies within the same local patch separated by ≈10 m. Within populations, aggression score values were found to increase linearly with internest distance within a site. Aggression was highest between colonies from spatially different populations on the island and was higher still when nests were assayed against colonies at an off-island site 70 km away in Castine, ME. These data strongly suggest a multicolonial organization within and among local populations of M. rubra in parts of its introduced range. These findings contradict the loss of intraspecific aggression and unicolonial social structure over large geographic areas that have previously been observed in other invasive ant species, particularly Linepithema humile Mayr.

Sphaeropsis sapinea (Fr.:Fr.) Dyko and Sutton, is among the most common and widely distributed pathogens of conifers worldwide. S. sapinea is disseminated over short distances by rain splash and moist wind, but significant knowledge gaps regarding long-range dispersal remain. Our objective was to determine whether or not the pine engraver beetle, Ips pini Say, is a vector of the pathogen onto Austrian pines (Pinus nigra Arnold). In 2004 and 2005, individuals of I. pini were collected with pheromone traps at two locations in central Ohio (197 and 1,017 individuals for 2004 and 2005, respectively) and screened for the presence of S. sapinea. In the field, fresh logs of Austrian pine were baited with pheromone lures, mechanically wounded, or left undisturbed. After 2 mo, logs were evaluated for insect feeding and the presence of S. sapinea along beetle galleries. Fresh logs were also inoculated in the greenhouse with adult I. pini that were either artificially infested or uninfested with S. sapinea spores to determine vectoring potential. Phoresy rates for individual collections ranged from 0 to 4.1%; average rates were 1.5 and 2.0% for 2004 and 2005, respectively. Isolation frequencies of S. sapinea from baited (15 ± 5%) and unbaited logs (3 ± 1%) differed significantly (P = 0.009). I. pini was also capable of transmitting the pathogen under controlled conditions. Based on phoresy rates, association, and artificial inoculation studies, we conclude that I. pini is able to transmit S. sapinea to Austrian pine stems.

Widespread planting of transgenic insecticidal (TI) crops for pest control has raised concerns about potential harm to nontarget arthropods. Because the first generation of TI crops produce single Bacillus thuringiensis (Bt) toxins causing little or no harm to most nontarget arthropods, they are not likely to cause such negative effects. However, varieties of transgenic crops with multiple Bt toxins or novel toxins might be more harmful to nontarget arthropods. Field studies assessing nontarget effects typically compare the relative abundance of nontarget arthropods in TI crop fields to non-TI crop fields. However, for nontarget arthropods that are killed by TI crops, such analyses may miss important effects. Results from simulations of a spatially explicit population dynamics model show that large-scale planting of TI crops could cause three types of negative effects on nontarget arthropods that suffer mortality caused by TI crops: (1) lower abundance in TI fields than non-TI fields with little or no effect on abundance in non-TI fields, (2) lower abundance in TI fields than non-TI fields and decreased abundance in non-TI fields, and (3) loss of the arthropod from TI and non-TI fields. Simulation results show that factors increasing the potential for negative effects of TI crops on nontarget arthropods in non-TI fields are low reproduction, high emigration, high adoption of TI crops, high mortality in TI fields, insecticide sprays, and rotation of TI and non-TI fields. The results suggest that risk assessment should consider the regional distribution of transgenic crops and the life history traits of nontarget arthropods to identify the most vulnerable regions and nontarget species.

Saproxylic succession in fire-killed black spruce [Picea mariana (Mill.) B.S.P.] coarse woody debris (CWD) in northern Quebec is estimated in this study using a 29-yr postfire chronosequence. Sampling was performed using both trunk-window traps and rearing from snag and log sections. A total of 37,312 arthropods (>220 taxa) were collected from both sampling methods. Two distinct colonization waves were identified. The onset of initial colonization occurs the year of the fire, whereas the second colonization phase begins only once debris falls to the ground. The initial colonization step is influenced by fire-associated species including subcortical predators, xylophages, and ascomycetes feeders. Abundance of most early colonizer species decline with time since fire with the disappearance of subcortical habitat. No noticeable species turnover occurred in snags thereafter. Lack of succession in snags is related to very low decomposition rates for postfire CWD because this substrate is unsuitable for species associated with highly decayed wood. Snag falling triggers fungal growth and concomitant saproxylic succession toward micro- and saprophagous species and increases accessibility for soil-dwelling organisms. Because the position of woody debris greatly influences overall physical properties of dead wood, the fall of burned CWD plays a major role in saproxylic community shift after fire.

The relative effects of visual and olfactory stimuli on host plant detection in immature and adult Homalodisca coagulata Say (Homoptera: Cicadellidae) were studied using a novel olfactometer and factorial experimental designs. Colored, gray, and white cards were used as visual targets. Each card was attached to a glass thistle tube from which host-plant odor (from Vigna unguiculata L.) or blank, humidified air was dispensed. Visual odor stimuli combinations were presented in no-choice tests. Nymphs were released onto a perch stick downwind from the target. Nymph response to color odor treatments was measured by the duration of orientation behavior, residence time on the perch, and percentage of individuals that jumped to the target. The assay was modified so that adults crawled from the perch onto the target. Adult response was measured by the duration of individual behaviors (e.g., foraging) and by their position and residence time on the target. Both main effects and interactive effects of the stimuli were observed. Nymphs showed a decrease in orientation and residence times in the colored target host odor treatments and increased jumping response in the gray host odor treatment. When adults were exposed to host odor, the duration of foraging behavior increased, whereas crawling and phototactic behaviors decreased. Although nymphs and adults responded to visual stimuli blank air treatments, host odor enhanced their responses. The primary effect of host odor on host detection behavior may be to enhance H. coagulata responsiveness to visual cues.

We studied and modeled damage caused by Helicoverpa armigera larvae on cotton with the aim of developing a coupled crop pest model. Two damage components were studied: the voracity (quantity of fresh matter and number of organs consumed) and feeding preferences (type of organ infested). The laboratory no-choice study of voracity on excised squares and bolls revealed that an H. armigera larva consumes 2,856 mg of fresh matter throughout its larval life, with the sixth instar consuming 86% of this quantity. This consumption rate corresponded to 23.6 squares, or 7.8 bolls. We developed equations to predict the quantity of fresh matter uptake from an individual plant organ, according to the organ mass and the larval instar. The field study of feeding preference confirmed previous findings that larvae prefer squares to bolls, with this preference decreasing as the larval age increases. However, no significant relationship was noted between the age of larvae and the size of infested organs within each organ class (square or boll). We developed a logistic model to predict the probability of a larva infesting a boll rather than a square. According to this model, the relative organ availability in the field and the larval instar were found to be significant factors.

Studies were conducted with codling moth, Cydia pomonella L., to evaluate the mating status of male and female moths in apple, Malus domestica (Borkhausen), orchards treated with and without sex pheromone dispensers. Laboratory studies first examined the effect of multiple mating of male and female moths on female fecundity and egg fertility. Females that had mated three times had a significantly higher fecundity than singly mated moths. Sequential mating by male moths had no effect on the fecundity of female moths or egg fertility. However, male moth age did impact female fecundity, with significantly fewer eggs laid after mating with virgin 1- versus 3-d-old males. The mean size of the first spermatophore transferred by males was significantly larger than all subsequent spermatophores. Classifying spermatophores based on size was used in field sampling to categorize the mating status of the female’s partner. The proportion of mated females with small spermatophores (partner had previously mated) was significantly higher in treated versus untreated orchards. The proportion of female moths caught in traps baited with pear ester that were virgin was low (≤0.26) in both treated and untreated orchards. The proportion of females with more than one spermatophore was low (≤0.06) in treated orchards all season and during first moth flight in untreated orchards (0.11). Nearly one third of female moths, however, had more than a single spermatophore in untreated orchards during the second moth flight. The potential impacts of multiple mating and delayed mating by male and female codling moth on the effectiveness of sex pheromones are discussed.

A chamber to monitor mole cricket behavior was designed using two different soil-filled containers and photosensors constructed from infrared emitters and detectors. Mole crickets (Scapteriscus spp.) were introduced into a center tube that allowed them to choose whether to enter and tunnel in untreated soil or soil treated with Beauveria bassiana (Balsamo) Vuillemin. Each time the cricket passed through the photosensor located near the entrance of soil-filled containers, the infrared light was blocked and the exact moment that this occurred was logged onto a computer using custom-written software. Data examined included the first photosensor trigger, total number of sensor triggers, presence of tunneling, and final location of the cricket after 18 h. These behaviors were analyzed to discern differences in mole cricket behavior in the presence of different treatments and to elucidate the mechanism that mole crickets use to detect fungal pathogens. The first study examined substrate selection and tunneling behavior of the southern mole cricket, Scapteriscus borellii Giglio-Tos, to the presence of five strains of B. bassiana relative to a control. There were no differences between the first sensor trigger and total number of triggers, indicating the mole crickets are not capable of detecting B. bassiana at a distance of 8 cm. Changes in mole cricket tunneling and residence time in treated soil occurred for some strains of B. bassiana but not others. One of the strains associated with behavioral changes in the southern mole cricket was used in a second experiment testing behavioral responses of the tawny mole cricket, S. vicinus Scudder. In addition to the formulated product of this strain, the two separate components of that product (conidia and carrier) and bifenthrin, an insecticide commonly used to control mole crickets, were tested. There were no differences in mole cricket behavior between treatments in this study. The differences in behavioral responses between the two species could suggest a more sensitive chemosensory recognition system for southern mole crickets.

Trophallaxis and feeding relationships in the eastern subterranean termite, Reticulitermes flavipes (Kollar), were examined using a novel marking technique, rabbit IgG protein coupled with an enzyme linked immunosorbent assay (ELISA) to detect the marker. Transfer experiments in small dishes evaluated the trophallactic transfer of the marker from donor workers fed IgG-treated paper to recipient workers or larvae. Worker donors rapidly acquired the marker, and 100% of donors tested positive within 24 h. Trophallactic transfer from donors to recipients was relatively inefficient, and 51 ± 2% of recipient workers and 31 ± 2% of recipient larvae tested positive at 72 h. Based on the mean optical density counts, ≈27% of marker ingested by the donors was passed on to the recipient workers in the first 24 h, 14% to recipient larvae, and 26% to recipient soldiers. The ability of soldiers to feed independently of workers was examined in dish assays. Soldiers showed no significant uptake of the marker when isolated from the workers, and uptake increased significantly when workers were present. The distribution of the marker was further studied in larger colony fragments composed of workers, soldiers, nymphs, and larvae. Marker acquisition by the different castes/developmental stages was highly variable, with workers and nymphs acquiring the marker at a faster rate than soldiers and larvae. The results of this study contribute to our understanding of the foraging ecology and social behavior in R. flavipes. In addition, they may help design improved control programs for subterranean termites based on baits.

Reproductive boll weevil populations are typically identified by the presence of a frass seal and protuberance at the oviposition site in cotton squares. However, despite the occurrence of other oviposition puncture seal types and their use in previous fecundity studies, the relationship of these respective puncture seal types and oviposition has not been clearly examined. In this study, newly eclosed females (≤24 h old, but mated at 4 d of age) were fed fresh squares daily for 8 d to determine oviposition frequency in relation to individual puncture seal types. Puncture seal types were classified as unsealed; puncture with frass seal; puncture with wax seal; and puncture with wax seal and partially covered with frass. Overall, no significant associations were detected between the types of sealed punctures, and the frequency of oviposition in sealed punctures ranged from 64.6 (wax-seal with frass) to 72.9% (frass-sealed) during 2001 and 53.4 (wax-sealed) to 55.2% (wax-seal with frass) during 2002. Examination of individual trials revealed considerable variability in oviposition associated with all sealed puncture types. Oviposition also occurred in unsealed punctures by mated females in all trials. Because of the high degree of oviposition observed in punctures not normally associated as oviposition sites (i.e., wax-seal with frass, wax-seal), this study clearly shows the need to consider other puncture types as potential indicators of reproductive weevil populations. These results will be critical in boll weevil management programs where accurate detection of reproductive weevil populations is crucial for continued pest suppression.

A 3-yr field study was conducted at commercial grape farms to evaluate cutting wild grapevines as a cultural control strategy for grape berry moth, Paralobesia viteana (Clemens). At each farm, wild grapevines were cut in the woods adjacent to one vineyard for control of P. viteana, whereas the comparison vineyard received no such cutting. Both vineyards received a standard broad-spectrum insecticide program for control of P. viteana and other vineyard insect pests. Monitoring with pheromone traps showed no differences between treatments in the total number of male moths trapped in both woods and vineyards. Egglaying by P. viteana was similar between the two wild grape cutting treatments in all 3 yr. During weekly samples of crop infestation by P. viteana, no differences were observed between programs in the percent of clusters infested by P. viteana larvae. Berries infested by P. viteana were collected from vineyard borders during the second and third P. viteana generations and held under controlled conditions. In all but one sample, survival of P. viteana larvae was similar between the two wild grape cutting treatments, parasitism of P. viteana larvae within vineyards was similar between the two wild grape cutting treatments on all sample dates, and similar captures of natural enemies were found on yellow sticky traps in the two treatments throughout the study. The opportunities and benefits of cutting wild grapevines as a cultural control in grape integrated pest management programs in eastern North America are discussed.

Plant tolerance to herbivory is a key approach for managing pests. In alfalfa, Medicago sativa, the potato leafhopper, Empoasca fabae, is a major pest as a result of the cascade of plant responses to piercing-sucking injury. To identify tolerance to its injury based on alfalfa physiology, experiments were conducted in the field and greenhouse. In our comparison of the response of field-grown alfalfa cultivars to standardized leafhopper densities, net photosynthesis and transpiration rates of ‘Geneva’ leaves were reduced by 18 and 21%, respectively, by leafhopper presence compared with a rate change of <1% of resistant ‘EverGreen’ leaves. Under greenhouse conditions, alfalfa clones varied in their level of gas exchange (net photosynthesis and transpiration) and stem elongation responses to leafhopper injury. For example, in the comparison of seven clones, net photosynthesis declined an average of 40.7% with leafhopper injury, although individual clones varied from 26.6 to 74.3% reduction. Internode elongation after 2 d was 60.3% less on injured stems compared with healthy stems, but again, the individual clones varied from 17.3 to 91.9%. In a time-course study of selected clones, clones varied in their level of injury just after and 3 d after insect removal. Gas exchange responses of all clones recovered by 7 d after cessation of injury. In a choice test, leafhoppers spent similar amounts of time on the susceptible clone and the most tolerant clone; however, their precise feeding behaviors were not measured. Thus, the variable response of clones to injury may be either true physiological tolerance or antixenosis from a change in feeding behavior. This study showed putative tolerance to leafhopper injury among alfalfa genotypes, suggesting that tolerance could be the basis for crop protection in alfalfa from potato leafhopper injury.

Populations of Dalbulus maidis (DeLong and Wolcott) from the northeastern and central-southern regions of Brazil differ morphologically, suggesting that they could be genetically isolated. Here we used the random amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR) technique to estimate genetic structuring of this leafhopper species among five geographically distant localities across those regions and to estimate gene flow between populations. Ten specimens were sampled per population and genotyped with RAPD markers generated from amplification with nine oligonucleotides. The percentage of polymorphic loci was 78% in relation to the total number of amplified loci, and genetic similarity either between or within populations was higher than 0.72. Cluster analysis grouped specimens from the northeastern population (Mossoró/RN) into a single group, whereas central-southern specimens were not grouped in relation to their places of origin. Overall, the genetic subdivision index (Fst) was low (≤0.113), whereas the gene flow estimate (Nm) was high (up to 8.53) between populations, except between the Mossoró/RN population and those of the central-southern region (Fst ≥ 0.192 and Nm ≤ 1.05). The relatively high rates of gene flow between central-southern populations suggest the occurrence of migration within that region, whereas the Mossoró/RN population seems to be genetically isolated.

RESUMO Populações de Dalbulus maidis (DeLong and Wolcott) das regiões Nordeste e Centro-Sul do Brasil diferem morfologicamente, sugerindo que as mesmas são geneticamente isoladas. Nós usamos a técnica de RAPD-PCR para estimar a estrutura genética dessa espécie de cigarrinha de cinco localidades geograficamente distantes dentro dessas regiões, e para estimar o fluxo gênico entre populações. Dez espécimes amostrados por população foram genotipados com marcadores RAPD gerados a partir da amplificação com cinco oligonucleotídeos. A porcentagem de locos polimórficos foi de 78% em relação ao total de locos amplificados, sendo que a similaridade tanto entre como dentro das populações foi superior a 0,72. A análise de agrupamentos reuniu os espécimes da população do Nordeste (Mossoró/RN) em um único grupo, enquanto que os espécimes do Centro-Sul não se agruparam em relação aos locais de origem. Em geral, o índice de subdivisão genética (Fst) foi baixo (<0,113), ao passo que o de fluxo gênico (Nm) foi alto (até 8,53) entre as populações, exceto entre a população de Mossoró/RN e as do Centro-Sul (Fst ≥ 0,192 e Nm ≤ 1,05). As taxas relativamente altas de fluxo gênico entre as populações do Centro-Sul sugerem a ocorrência de migração dentro daquela região, enquanto que a população de Mossoró/RN parece estar geneticamente isolada.

The environmental impact of genetically modified (GM) plants in experimental fields has been examined in several ways, in particular with respect to the dynamics of specific nontarget organisms. The approach of sampling for biodiversity in agroecosystems to compare complex patterns could also be useful in studying potential disruptions caused by GM crops. In this study, we set up replicated field plots of Bt-expressing eggplants and near isogenic untransformed eggplants as a control. We monitored the presence and abundance of herbivore and predator arthropods in weekly visual samplings of the plant canopy for three growing seasons (2001–2003). Insect species were pooled in organismal taxonomic units (OTUs); three multivariate methods were used to compare species assemblage as an estimate of insect biodiversity. This multistep statistical approach proved to be efficient in recognizing association patterns, as evidenced by the data for the target species Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) clearly showing a significant association with the control plots. All the analyses indicate a comparable species assemblage between transgenic and near isogenic eggplant areas. Our results suggest that some taxa may warrant more specific study. For example, Alticinae beetles (Coleoptera: Chrysomelidae) were alternatively more abundant in either of the two treatments, and their overall abundance was significantly higher on transgenic eggplants. In light of these results and because of their taxonomic proximity to the target species, these herbivores may represent an important nontarget group to be further studied. Moreover, some sap feeders (e.g., Homoptera: Cicadellidae) were more abundant on Bt-expressing plants in some samples in all 3 yr.

Decreased larval feeding and weight of the monarch butterfly, Danaus plexippus L., have been detected after 4 d of exposure in the laboratory to a high density of Bacillus thuringiensis (Bt)-expressing anthers. One hypothesis is that larvae exposed to Bt anthers exhibit increased wandering, resulting in less feeding and lower weight gain. To test this hypothesis, 2-d-old monarch butterfly larvae exposed to milkweed leaf disks with no anthers, anthers that express Bt (Cry1Ab, event MON810), or other non-Bt anthers were observed using a video-tracking system. As had been shown in previous studies, larvae exposed to Bt anthers fed less and gained less weight than larvae exposed to non-Bt or no anthers, yet there was no evidence of feeding on anthers. Total distance moved, maximum displacement from release point, percentage of time spent moving or near anthers, or mean turn angle did not differ across treatments. However, larvae exposed to Bt anthers spent more time off milkweed leaf disks than those exposed to no anthers and were more likely to move off the leaf than larvae exposed to non-Bt anthers. Results suggest that larvae exposed to Bt anthers behave differently and that ingestion may not be the only way Bt can affect nontarget insects like the monarch butterfly.

Many ecological studies have focused on the effects of transgenes in field crops, but few have considered multiple transgenes in diversified vegetable systems. We compared the epigeal, or soil surface-dwelling, communities of Coleoptera and Formicidae between transgenic and isoline vegetable systems consisting of sweet corn, potato, and acorn squash, with transgenic cultivars expressing Cry1(A)b, Cry3, or viral coat proteins. Vegetables were grown in replicated split plots over 2 yr with integrated pest management (IPM) standards defining insecticide use patterns. More than 77.6% of 11,925 insects from 1,512 pitfall traps were identified to species, and activity density was used to compare dominance distribution, species richness, and community composition. Measures of epigeal biodiversity were always equal in transgenic vegetables, which required fewer insecticide applications than their near isolines. There were no differences in species richness between transgenic and isoline treatments at the farm system and individual crop level. Dominance distributions were also similar between transgenic and isoline farming systems. Crop type, and not genotype, had a significant influence on Carabidae and Staphylinidae community composition in the first year, but there were no treatment effects in the second year, possibly because of homogenizing effects of crop rotations. Communities were more influenced by crop type, and possibly crop rotation, than by genotype. The heterogeneity of crops and rotations in diversified vegetable farms seems to aid in preserving epigeal biodiversity, which may be supplemented by reductions in insecticide use associated with transgenic cultivars.