Neem has been used as an effective postharvest protectant for many crops. Neem is especially effective against the cowpea weevil, Callosobruchus maculatus (F.), a major pest of cowpeas. Although it is well known that azadirachtin A breaks down rapidly at high temperatures, the efficacy of neem kernel extract previously exposed to high temperatures for protecting stored pulses has not been conclusively investigated. Effectiveness of these materials would allow West African farmers to make a neem extract at their convenience and store it for later use. We found that neem kernel extract continued to reduce infestations of C. maculatus, after the neem kernel extract had been stored at high temperatures, including 2 wk at 50°C followed by up to 5 mo storage at 28°C. Neem kernel extract analyzed with high performance liquid chromatography revealed that azadirachtin A present in unheated or fresh neem kernel extract dissipated when stored at 50°C for 2 wk. Neem kernel extract heated to 28°C or above also lost effectiveness as an oviposition deterrent. However, the number of neem kernel extract-treated eggs that survive to become adults was significantly reduced even when the neem kernel extract was exposed to 50°C for 2 wk. We attribute the mortality we observed, which was maintained even when azadirachtin A was absent in neem kernel extract, to physical effects of the oil properties of neem kernel extract. We conclude that neem kernel extract can be stored at high temperatures for at least 5 mo without significant reduction in overall effectiveness.

The lady beetle Coccinella septempunctata L. is an important predator of aphids in arable crops, but depends on noncrop landscape elements, such as hedgerows, for hibernation. We studied the effect of the shape, area, and fragmentation of noncrop landscape elements on the control of aphids by C. septempunctata using a spatially explicit simulation model. The model is based on a description of the phenology and population dynamics of aphids and C. septempunctata, as well as the predation dynamics and dispersal characteristics of C. septempunctata. The study compares biocontrol in 12 landscapes consisting of field crops and hedgerows that differ in the shape, proportion (1, 4, 9, and 16%), and fragmentation of the hedgerow elements (hedgerow area divided into 1, 4, or 16 elements) in the landscape. Linear hedgerow elements provided better control than square elements in 3 of the 12 simulated landscapes and resulted in similar levels of control in the other nine landscapes. The total area of hedgerow habitat was the key factor for the control of aphid populations. Landscapes with 9% and 16% noncrop habitat had large enough local populations of C. septempunctata to control aphid infestations, whereas landscapes with only 1% or 4% of hibernation area had no potential for improved aphid control. In landscapes with sufficient noncrop habitat, the best control was achieved when small hedgerow elements were evenly distributed over the landscape.

We measured significant variation in the instantaneous growth rates for varroa mites, Varroa destructor (Anderson & Trueman) from 1993 to 2002 in Baton Rouge, LA. Mite population growth was monitored in colonies of honey bees, Apis mellifera L., with queens from miscellaneous U.S. sources that had not been selectively bred for varroa resistance. Mite populations were measured at the beginning and end of short field tests that started in the late spring of each year. Analyses of multiple regression showed that only the first two of the following regressors were linear predictors of r, the instantaneous growth rate: 1) percentage of reproducing female mites, 2) proportion of total mites in capped brood, 3) mortality of mites in brood cells, 4) growth of the bee population, 5) capped brood area at the end of a test, and 6) duration of the test. Analysis of commonality indicated that the percentage of reproducing female mites explained ≈26% of the total variation in r, and the proportion of total mites in capped brood explained 6%. The joint expression of both variables accounted for another 4%. Thus, residual error reflected most of the total variation in r, which suggested possible climatic or environmental effects on mite growth. The lowest growth rates occurred in three consecutive years of drought in Louisiana. Measures of ambient temperature and relative humidity correlated to growth of mite populations among different years. Reduced growth rates were probably the result of diminished reproductive rates by varroa mites during periods of hot and dry weather.

Aedes albopictus (Skuse) was detected for the first time in Italy in 1990. Thanks to its high biological adaptability, it spread rapidly to colonize various urban areas in central and northern Italy. The purpose of this study was to examine the ecological niche occupied by Ae. albopictus and the role of competition with Culex pipiens L., which is a widespread indigenous species, in urban areas. The larval development cycle and competition for food between the two species was also studied under laboratory conditions. The study showed that both species can colonize any type of artificial water container. Ae. albopictus mainly occupies saucers under flower pots and other, usually smaller-sized, containers, whereas Cx. pipiens tends to develop more in large tanks (100–200 liters) used in residential gardens and other larger-sized containers. It would seem that the two species interact mainly in medium-sized containers (10–50 liters) such as manholes and tires. Laboratory studies showed that, at 25°C, the food-biomass conversion coefficient is significantly higher in Ae. albopictus than in Cx. pipiens, indicating that the new established species is more efficient in transforming food into biomass. As a consequence, it has a greater capacity to exploit food resources and therefore grow more rapidly than Cx. pipiens. In larval association where food was scarce, it was noted that competition between the two species takes place and is influenced by temperature: at 25 ± 2°C, Ae. albopictus prevails but is much less likely to do so at 20°C.

The effect of temperature on the duration of egg, larval, prepupal, and pupal development of the predator Laricobius nigrinus Fender was studied at six constant temperatures (6, 9, 12, 15, 18, and 21°C) where Adelges tsugae Annand was used as prey. Developmental time was inversely proportional to temperature between 6 and 18°C. Laricobius nigrinus did not complete development at 21°C. Significant positive linear relationships were observed between developmental rate and temperature for all life stages. Minimum developmental threshold temperatures were estimated at 5.4°C for eggs, 3.2°C for larvae, 2.9°C for prepupae, and 3.1°C for pupae. Median development times for eggs, larvae, prepupae, and pupae were 59.5, 208.3, 217.4, and 212.8 degree-days (DD) above minimum developmental temperatures, respectively. Development from oviposition to adult eclosion required a minimum temperature of 3.7°C and 666.7 DD. A degree-day model, developed in the laboratory for predicting egg hatch, predicted a degree-day value that was within 4 d of the median egg hatch observed at two field sites in 2000. This regression model is a useful predictor of egg hatch in Victoria, British Columbia, Canada. In addition, the lower development threshold from egg to adult for L. nigrinus (3.7°C) is similar to that for the A. tsugae progrediens (spring) generation from second instar to adult (3.9°C), indicating that L. nigrinus and A. tsugae are adapted to similar climatic regimes.

Wolbachia are endosymbiotic bacteria that commonly infect arthropods. These bacteria induce a number of phenotypes in their hosts, including cytoplasmic incompatibility, thelytokous parthenogenesis, feminization, and male killing. We surveyed native South American populations of the fire ant Solenopsis invicta Buren for Wolbachia infections by using a diagnostic polymerase chain reaction assay. In addition, we determined the fidelity of vertical transmission of the bacteria from mother to offspring in this species by assaying daughters in 24 simple-family (monogyne) colonies. Infections were common in many parts of the extensive native range of S. invicta. However, the proportion of individuals infected varied greatly among samples, ranging from zero in several populations from the northerly parts of the range to >90% in more southerly populations. Possible explanations for this variation in the prevalence of Wolbachia infections are discussed. A survey of the two social forms of S. invicta from four geographic areas showed that the prevalence of Wolbachia infections consistently was higher in the monogyne form (single queen per colony) than the sympatric polygyne form (multiple queens per colony). One likely explanation for this trend is that the selective regimes acting on Wolbachia in the two forms differ because of the dissimilar reproductive strategies used by each form. Finally, overall transmission efficiency was found to be very high (>99%), making it unlikely that imperfect transmission prevents the spread of the microbe to near fixation in native populations.

Laboratory studies on the temperature-dependent development of Sesamia nonagrioides (Lefebvre) were performed under five constant temperatures ranging from 20 to 30°C as well as under the corresponding alternating temperatures of 25:10, 27.5:12.5, 30:15, 32.5:17.5, and 35:20°C, at a photoperiod of 16:8 (L:D) h. Both linear and nonlinear (Lactin formula) models provided a reliable fit of developmental rates versus temperature for all immature stages either at constant or alternating temperatures. Developmental thresholds that were estimated by a linear model for eggs, larvae, or pupae were approximately the same and estimated to be 10.57, 8.89, and 10.75°C, respectively, at constant temperatures. Lower values were estimated when immature stages were exposed to the corresponding alternating temperatures (7.23, 6.20, and 6.50°C for eggs, larvae, and pupae). Therefore, the evaluation of the development of immature stages under constant temperatures resulted in an overestimation of the lower thresholds. The Lactin-2 model also was applied, and larval and egg developmental thresholds did not differ from those that were estimated by the linear model. Differences, however, occurred at the pupal stage. Nevertheless, the differences in the estimated values of the lower developmental thresholds of the immature stages under constant or alternating temperatures indicate that a model predicting phenology in the field should be based on fluctuating temperature.

We evaluated the family-level richness and abundance of aquatic and terrestrial arthropods in marine supralittoral habitats and related arthropod assemblages to the presence and composition of supralittoral vegetation. Using pan traps, we collected 12,226 arthropods in 24 taxa. Collembolans (Entomobryomorpha, Hypogastruridae), amphipods (Talitridae), and midges (Chironomidae) were the most abundant taxa. Regardless of habitat associations, arthropod abundance was higher in sites with supralittoral vegetation than in the site where vegetation had been removed for townhouse development. This was true for both aquatic and terrestrial arthropods. Our results suggest that removal of supralittoral vegetation may have cascading effects on supralittoral arthropod communities and may adversely affect the productivity of both aquatic and terrestrial arthropods.

Landscape-level geographic analysis was used to examine the occurrence of Dendroctonus pseudotsugae Hopkins (Coleoptera: Scolytidae) in association with geology (rock type) and forest stand types on the Panhandle National Forests of northern Idaho and northeastern Washington from 1996 to 1999. Beetle infestations occurred most often in mature stands comprised primarily of trees ≥23 cm in diameter at breast height (≈1.4 m), in habitat types likely to contain Douglas-fir. Douglas-fir stands growing on Prichard and lower Wallace formation metasedimentary rocks and intrusive dikes and sills were significantly more likely than Douglas-fir stands growing on other rock types to harbor beetle populations during nonoutbreak years early in the study period. By 1999 (when outbreak populations of Douglas-fir beetle were present), beetle infestations occurred across all rock types at rates proportional to the amount of stand area on those rocks, indicating a decrease in infestation rates for stands on particular rock types when beetle populations were large. Although the biological mechanisms influencing beetle preferences were not examined, information derived in this study could be useful in developing quantitative hazard-rating models for Douglas-fir beetle, and, subsequently, in designing silvicultural practices to reduce the amount of beetle-susceptible Douglas-fir stands on particular rock types.

Eighteen 200-ha study plots were established in the Monongahela National Forest, West Virginia, and in the George Washington National Forest, Virginia. The overall purpose of the study was to determine nontarget effects of biological insecticides used to control gypsy moth, Lymantria dispar (L.). From 1995 through 1998 blacklight traps, foliage pruning, and canvas bands were used to collect lepidopteran adults and larvae to determine population abundance 2 yr before and during two consecutive years of treatment applications. During 1997 and 1998, six plots were each aerially treated with nucleopolyhedrosis virus Gypchek (GC) (US Forest Service, Ansonia, CT) and Bacillus thuringiensis variety kurstaki (Btk). The remaining six plots were left untreated (control). Counts of adults and larvae of 19 species from five families were tallied to assess treatment effects. Both spring- and summer-defoliating larvae were sampled. Analysis of variance indicated a significant interaction between pretreatment/treatment years and the three treatment groups for the adults of two species and the larvae of three species. Fewer larvae were collected from Btk plots than from GC and control plots during treatment years, but not during pretreatment years. Gypchek was not determined to adversely affect nontarget species. Adults of 10 species and larvae of four species were more numerous during treatment years than pretreatment years. Adults of four species and larvae of five species were more numerous during pretreatment years than during treatment years.

Ataenius spretulus (Haldeman) (Coleoptera: Scarabaeidae) is more abundant and causes greater damage to golf course fairways than roughs. An inverse relationship between the density of predatory insects and the density of A. spretulus grubs on golf courses was previously reported. Here we investigate if the most abundant predators found on golf courses consume A. spretulus eggs and grubs. Eight of the most common species of carabids and staphylinids were individually placed into petri dishes containing insect eggs and A. spretulus grubs. Most carabids and staphylinids except Apocellus sphaericollis (Say) consumed immature A. spretulus. Harpalus affinus (Schrank) adults and Philonthus sp. larvae consumed 100% of available A. spretulus grubs in all replicates. Natural predation was measured by the release and recovery of A. spretulus grubs in the field. In 1999, more grubs were naturally removed from soil cores in the rough compared with the fairway. In 2000, more grubs were naturally removed from unrestricted soil cores compared with soil cores covered to exclude surface predators. In a separate field experiment in 2000, the density of carabid and staphylinid adults was manipulated using directional barriers around field plots. Simple decrease of adult predators did not lead to an increase in grub infestation. More work is needed to evaluate the significance of predation on A. spretulus eggs and grubs by carabid and staphylinid larvae.

We report the results of a 2-yr survey that determined some of the host plant and parasitoid associations of Anastrepha fruit flies (Diptera: Tephritidae) in the “Montes Azules” tropical rainforest biosphere reserve (State of Chiapas, Mexico). We collected a total of 57.38 kg of fruit representing 47 native species from 23 plant families. Of these, 13 plant species from eight plant families were found to be native hosts of 9 species of Anastrepha. The following Anastrepha host associations were observed: Bellucia pentamera Naudin (Melastomataceae) with A. coronilli Carrejo y González; Malmea gaumeri (Greenm.) Lundell (Annonaceae) with A. bahiensis Lima; Tabernamontana alba Mill. (Apocynaceae) with A. cordata Aldrich; Quararibea yunckeri Standl. (Bombacaceae) with A. crebra Stone; Ampelocera hottlei (Standl.) Standl. (Ulmaceae) with A. obliqua (Macquart) and A. fraterculus (Wiedemann); Zuelania guidonia Britton and Millsp. and Casearia tremula (Griseb.) Griseb. ex C. Wright (Flacourtaceae) with A. zuelaniae Stone; Psidium sartorianum (O. Berg.) Nied (Myrtaceae) with A. fraterculus; Psidium guajava L. and P. sartorianum (Myrtaceae) with A. striata Schiner; and Manilkara zapota (L.) Van Royen, Pouteria sp., Bumelia sebolana Lundell, and Calocarpum mammosum (L.) Pierre (Sapotaceae) with A. serpentina (Wiedemann). The following are new host plant records: Malmea gaumeri for A. bahiensis; Quararibea yunckeri for A. crebra; Ampelocera hottlei for A. fraterculus and A. obliqua; Bumelia sebolana for A. serpentina; and Casearia tremula for A. zuelaniae. A. coronilli is reported for the first time in Mexico. Infestation levels were variable and ranged between 0 and 1.63 larvae/g of fruit depending on host species. Larvae of eight species of Anastrepha on nine plant species from six plant families were found to be parasitized by Doryctobracon areolatus Szepligeti, D. crawfordi Viereck, D. zeteki Musebeck (new report for Mexico and northernmost record for the species), Opius hirtus Fisher, Utetes anastrephae Viereck (all Hymenoptera: Braconidae), and Aganaspis pelleranoi Brethes (Hymenoptera: Figitidae). Percent parasitism ranged from 0 to 76.5%. We discuss our findings in light of their practical (e.g., biological control) and theoretical (e.g., species radiation) implications and highlight the importance of these types of studies given the rampant deforestation of tropical forests in Latin America and the risk of extinction of rare fruit fly species that could shed light on the evolution of host plant and parasitoid associations within the genus Anastrepha.

The current study was undertaken to investigate the role of the chemical and tactile cues in host–plant selection by Spodoptera frugiperda (Smith). Adult female S. frugiperda seemed not to depend on plant volatiles for orientation to host plants. In general, females oviposited more on control areas than on areas treated with leaf extracts of corn, cotton, and tomato. This outcome was independent of extraction duration (1 or 60 min) or solvent (hexane or methanol). The hexane extract of corn inhibited oviposition at doses of 1 and 0.2 g/ml but not at 0.005 and 0.001 g/ml. The methanolic leaf extract decreased oviposition at dosages of 1, 0.2, and 0.005 g/ml but not at a dosage of 0.001 g/ml. S. frugiperda females deposited more eggs on grooved or pitted surfaces than on smooth surfaces. Tactile cues seemed to be highly important during oviposition and could neutralize the deterrent effect of the corn leaf extracts; females oviposited on grooved surfaces independently of the presence or absence of leaf extracts.

Potato aphid, Macrosiphum euphorbiae (Thomas); green peach aphid, Myzus persicae (Sulzer); and buckthorn aphid, Aphis nasturtii Kaltenbach are polyphagous herbivores that commonly colonize potato plants, Solanum tuberosum L., in the northeastern United States and Canada. Their movement influences spatial and temporal patterns of viral spread within potato fields. We investigated aphid movement between potato plants early in the season, with a particular focus on their ability to walk over bare soil. On average, aphids survived 1.16 ± 0.04 d (mean ± SE) on the surface of bare soil; all of them dying within 3 d. Wingless aphids did not leave potato plants that were adequate as a food supply. When forcibly removed from the host plant and released on the soil surface, all three species colonized the nearest plant within 1 h. However, when given no other choice, a significant proportion of aphids was fully capable of colonizing potato plants as far as 180 cm away from the point of release. Potato aphid, which is the largest, was the most mobile of the three species. The green peach aphid was intermediately mobile, and the buckthorn aphid was the least mobile species.

The effect of prey species on plant feeding behavior by Geocoris punctipes (Say) females was determined by observing prey and plant feeding behavior on cotton plants for three prey treatments: 1) corn earworm, Helicoverpa zea (Boddie), eggs, 2) H. zea first instars, and 3) cotton aphid, Aphis gossypii Glover, adults. Feeding behavior of individual G. punctipes females was observed in the laboratory using caged cotton terminals with prey on the leaves. A. gossypii adults were less acceptable to G. punctipes females as prey than H. zea eggs and first instars. Female G. punctipes fed much less on cotton plants than prey when more acceptable prey, H. zea eggs and first instars, were available but exhibited no feeding preference for the cotton plant versus prey when less acceptable prey, A. gossypii adults, were available. Nevertheless, because G. punctipes females fed on cotton plants regardless of acceptability of prey even in the presence of abundant prey, we conclude that plant feeding is an integral part of the feeding behavior of G. punctipes in cotton. Conservation of G. punctipes by reducing applications of insecticides that are toxic to these predators when they feed on insecticide-treated foliage or by providing nutritionally good plant resources could increase their effectiveness as natural enemies of H. zea and other pests in cotton.