Flight potential, a poorly understood phenomenon in the migratory true armyworm, Pseudaletia unipuncta (Haworth), was investigated in a laboratory population using tethered-flight techniques. True armyworm exhibited strong flight potential relative to other known migratory noctuids whose flight potentials were previously determined by similar techniques. Flight potential was generally low for 1-d-old moths and increased with age to day 5 of adult life. Flight speed and distance flown decreased for female moths from day 5 to day 10 as their reproductive system developed. The greatest average flight speed, total flight duration, and distance flown was exhibited by 5-d-old females and 10-d-old males, suggesting that flight potential may differ by sex. Ten-day-old moths had the longest flight duration. Factor analysis showed that total flight distance, total flight duration, and average flight speed are strongly correlated to the factor variable, but the correlation for longest flight duration was weaker. The significance of these findings to migratory flight and reproductive behavior of P. unipuncta is discussed in the light of published findings.

This research tested the effects of paper birch, Betula papyrifera Marshall, condensed tannin on larval performance of the whitemarked tussock moth, Orgyia leucostigma (J. E. Smith). We conducted laboratory bioassays on fifth stadium larvae. Larvae were reared on one of three diets: control (no condensed tannin), moderate condensed tannin (8.8% dry mass), and high condensed tannin (17.6% dry mass). Although survivorship was not different between the treatments, larvae fed diets amended with condensed tannin exhibited increased stadium duration, decreased relative growth rate, and decreased food conversion efficiencies. Prolonged development times enabled larvae to compensate for low consumption and growth rates such that insects on tannin diets ate more and grew larger than insects on the control diet. Analysis of tannin levels in food, frass, and body tissue indicated that larvae do not metabolize condensed tannin, but concentrate and egest it. Our results show that paper birch condensed tannin has both positive and negative effects on the performance indices of whitemarked tussock moths. However, whether the benefits of increased final size (and possibly fecundity) outweigh the risks of increased development time and prolonged exposure to natural enemies remains unclear.

A lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), larval attractant from peanut (Arachis hypogaea L. variety ‘Florunner’) plants was collected and determined using Tenax collection, cryogenic collection, olfactory bioassay, and infrared gas analyzer. All tests used larvae (third-fifth instar). Samples collected with a Tenax column did not induce significant olfactory responses by the larvae in the doses tested. In a cryogenic collection system using liquid nitrogen, plant volatiles were allowed to simultaneously pass through different treatments (air, water, activated carbon, or KOH) before they were cryogenized. After the airflow carrying volatiles from underground peanut plant parts was passed through water or activated carbon, the attractiveness was not significantly changed compared with the nonadsorption-treated collection. The attractiveness was totally eliminated after the airflow (carrying volatiles) was bubbled through KOH solution, indicating that the active component had been absorbed before being cryogenized. Cryogenically collected air, to a certain extent, was attractive to the larvae, indicating that an active component existed in normal air but the concentration was not high enough to attract the larvae. Among cryogenic collection samples, only those maintaining high carbon dioxide concentration were attractive to lesser cornstalk borer larvae. Lesser cornstalk borer larvae were attracted to commercial carbon dioxide. No significant difference in lesser cornstalk borer attraction was detected between 4 g of peanut root and a combination of urea and urease with similar carbon dioxide-releasing rate. It is concluded that lesser cornstalk borer larvae use carbon dioxide from underground peanut plant parts as a primary guide for locating the host plants.

We sought to gain insights into the mechanism of resistance of glandular-haired alfalfa to the potato leafhopper, by testing the trichomes of proprietary genotypes for chemical versus morphological differences. Two-choice, noncontact tests were conducted using four glandular-haired and one glabrous genotype of alfalfa, representing a spectrum of resistance, to determine whether adult female leafhoppers could detect and be repelled by putative volatiles released from the trichomes. Settling patterns roughly agreed with the degree of resistance reported by industry scientists who provided the plants. Repellency was strong for the most resistant genotypes, and absent with the most susceptible genotype. The remaining, intermediate-to-low-resistance genotypes exhibited variable repellency. A no-choice, plant-contact preference test showed no significant differences in settling among stems left intact or denuded, neither within nor among all genotypes. In all cases, adult leafhoppers settled on glandular-haired alfalfa if given no alternative. Environmental scanning electron microscopy of erect, glandular trichomes of eight proprietary genotypes (including the four used above) showed no obvious morphological differences among genotypes, or between stems and leaves within each genotype, although morphological comparisons were not quantified due to the fragility of the specimens. Taken together, our results suggest that volatile compounds contribute to variable levels of repellency to potato leafhoppers by glandular-haired alfalfa, but that such compounds cannot strongly prevent feeding at all costs.

Soil samples were collected from within and outside six fields where insect-resistant transgenic cotton (Bollgard) encoding the Bacillus thuringiensis Berliner (Bt) subsp. kurstaki cry1Ac gene had been grown and subsequently incorporated into soil by postharvest tillage for 3–6 consecutive years. The level of Cry1Ac protein in these samples (collected 3 mo after the last season’s tillage) was evaluated using both enzyme-linked immunosorbent assays (ELISA) and bioassays with a susceptible insect species, Heliothis virescens (F.), the tobacco budworm. Both methods revealed that no detectable Cry1Ac protein was present in any of the soil samples collected from within or outside the Bollgard fields. Based on the results from reference standards, the limit of detection for the ELISA was 3.68 ng of extractable protein per gram of soil, and that of the bioassay (measured by EC50) was 8 ng of biologically active protein per gram of soil. Together, these findings demonstrate that the amount of Cry1Ac protein accumulated as a result of continuous use of transgenic Bt cotton, and subsequent incorporation of plant residues into the soil by postharvest tillage, is extremely low and does not result in detectable biological activity.

Pitfall traps were used in 1995 and 1996 to sample epedaphic (i.e., dwelling at the soil surface) springtails (Collembola) from four cropping systems in southern Wisconsin. Cropping systems ranged from low- to high-management intensity based on tillage and chemical inputs. The abundance of individuals per species and species diversity were analyzed and the results were used to compare the impact of each cropping system on springtails. We hypothesized that the low-input cropping system (i.e., pasture) would enhance springtail abundance and diversity, whereas high-input cropping systems (e.g., continuous corn) would negatively impact springtails. Although some data supported our initial hypothesis, other cases showed that the low-input pasture system did not favor springtail abundance and diversity, nor did agronomic disturbance necessarily affect these parameters negatively. This suggests that factors other than cropping system can influence springtail populations. Abiotic factors including soil moisture and temperature and biotic factors such as springtail community structure need to be assessed before definitive conclusions can be drawn regarding the influence of agricultural inputs on springtail populations.

Dietary habits of the red imported fire ant, Solenopsis invicta Buren, were investigated in four southern Oklahoma habitats: lakeshore, mixed grassland, wooded roadside, and unimproved pasture. Vegetation characteristics of each site were recorded for spring and late summer, in conjunction with estimates of forager success (the percentage of foragers returning to colonies with solid particles or liquid loads). Foragers collected a wide variety of solid particles, with different arthropod prey dominating samples within different sites. At the lakeshore site (no vegetation), dipteran adults, larvae, and pupae comprised >58% of foraged particles. Isoptera comprised >21% of foraged particles at the wooded roadsite site. At grassland and pasture sites, seeds (17.2 and 15.7%, respectively) were important foraged items. Forager success rates were highest for solids at the lakeshore site (≈30% and 16% in spring and late summer, respectively), and highest for liquids at the pasture site (≈30% and 22% for spring and late summer, respectively). Possible influence of vegetation on success rates, and implications for estimates of foraging energetics, are discussed.

The effects of food availability and the presence of the entomopathogenic digenean parasite Plagiorchis elegans (Rudolphi) on the probability of Aedes aegypti (L.) preimagos to transform from one developmental stage to the next over consecutive 24- or 48-h periods were quantified. Under conditions of low food availability, 24- and 48-h transition probabilities for all larval instars to the next were reduced. Increases in food availability reversed this process, causing significant decreases in same-stage transition probabilities. However, as transition to successive stages increased among first, second, third, and fourth instars, there was a concomitant, significant increase in first- and fourth-instar mortality. Exposure to P. elegans cercariae caused significant decreases in the 24- and 48-h same-state probabilities for all preimago stages. Successive stage transitions for first, second, and third instars were significantly increased, whereas those of fourth instars and pupae were significantly decreased with exposure to parasites. Mortality among all preimago stages increased significantly with exposure, but was highest among fourth instars and pupae. There were strong food-by-parasite interaction effects among first, second, and third instars. Differences in transition probabilities increased with increasing food levels between control and parasite-exposed sets. Whereas there was no significant interaction effect between food and the presence of the parasite in pupae, significantly more fourth instars died in response to parasite exposure and the food-by-parasite interaction effect on the probability of fourth instars transforming to pupae over 48 h approached significance. Adult emergence reflected the above effects. These findings are discussed in the context of the Ae. aegypti/P. elegans host/parasite association and the role of entomopathogenic digeneans as natural enemies and their potential as agents in the biological control of mosquitoes.

Movement of potato tuberworm, Phthorimaea operculella (Zeller), and diamondback moth, Plutella xylostella (L.), was examined indirectly by estimating their distribution, and directly by using mark-recapture techniques. Trapping techniques including trap tubers and trap plants were used to assess the distance that potato tuberworm moved from infested crops. These experiments suggested that a low proportion of moths foraged beyond 100–250 m to infest tubers or plants. Light traps indicated that the number of moths moving out from crops diminished over a 40-m distance. Dispersing moths penetrated 30 m into new crops to infest the foliage. Direct movement of potato tuberworm and diamondback moth between crops was estimated using mark-recapture experiments. Fluorescent dusts were more effective than felt pen for marking, and moths were recaptured with sweep-nets followed 1 d later by pheromone trapping. From sweep-net collections of potato tuberworm, a mean of ≈17% of moths was shown to move between crops. Only 1.2% of diamondback moth was recaptured by sweep netting outside the release area and very few moths were caught in pheromone traps. These results, together with the literature, suggest that sufficient potato tuberworm would forage between adjacent treated and untreated crops to minimize the development of insecticide resistance. The use of refuges to conserve susceptible pest populations is recommended for managing resistance that may arise from any future use of Bt-transgenic potatoes or Brassica spp. in New Zealand. Refuges that are intended to dilute potential resistance of potato tuberworm to transgenic crops should be placed close to transgenic potato crops.

The spread of Anoplophora glabripennis Motschulsky (Asian long horned bettle), in the United States is dependent on its rates of reproduction and dispersal among host-tree species. Therefore, investigations of the reproductive characteristics of A. glabripennis, including preovipositional period, age specific fecundity and survival, on Norway maple (Acer platanoides L.), red maple (Acer rubrum L.), and black willow (Salix nigra Marshall) were undertaken to quantify its reproductive capacity among these host-tree species under laboratory conditions. Differences were found in preovipositional period, fecundity, egg viability and survival among the host-tree species. Oviposition rate was positively correlated with beetle body size, but negatively correlated with beetle age, bolt area, diameter, and bark thickness. Collectively, results show that in terms of adult female A. glabripennis survival and reproductive capacity, Norway and red maple were more suitable than black willow, with Norway maple somewhat more suitable than red maple. We hypothesize bark thickness and woody-tissue characteristics (i.e., nutritional substances, secondary substances, structural features) caused, at least in part, the observed differences in A. glabripennis survival and reproduction. Comparison of the various measures of A. glabripennis reproductive capacity was made with other cerambycids, specifically species of the subfamily Lamiinae, and implications for development of management strategies in U.S. ecosystems are discussed.

Populations of endemic soil entomopathogens (nematodes and fungi) were monitored in vegetable production systems incorporating varying degrees of sustainable practices in Fletcher, NC. Two tillage types (conventional plow and disk versus conservation tillage), two input approaches (chemically versus biologically based), and two cropping schedules (continuous tomato versus 3-yr rotation of corn, cucumber, cabbage, and tomato) were employed in large plots from 1995 to 1998. A Galleria mellonella (L.) trap bioassay was used to identify and monitor activity of Steinernema carpocapsae, Heterorhabditis bacteriophora, Beauveria bassiana, and Metarhizium anisopliae populations during the vegetable growing season (April–September). Seasonal detection of entomopathogens was significantly higher in conservation compared with conventional tillage systems. The strip-till operation did not affect levels of detection of S. carpocapsae. Pesticide use significantly reduced detection of entomopathogenic fungi. Type of ground cover significantly affected temperature in the upper 12 cm of soil; highest soil temperatures were observed under black plastic mulch and bare ground, whereas lowest temperatures were observed under rye mulch and clover intercrop. The high soil temperatures associated with certain ground covers may have reduced entomopathogen detection or survival. Although type of tillage appeared to be the primary factor affecting survival of endemic soil entomopathogens in our system, other factors, such as pesticide use and type of ground cover, can negate the positive effects of strip-tillage.

A 2-yr pitfall-trap study was conducted to examine the species composition of the Opiliones and the seasonal age-structure of Phalangium opilio (L.) in central Kentucky soybean, grassland, and alfalfa habitats. Phalangium opilio was the most commonly caught opilionid in all habitats, accounting for >90% of the adult specimens captured in soybean and alfalfa. Pitfall-trap results also suggest that Kentucky P. opilio populations have three generations per year and overwinter in the egg stage. Absolute sampling indicated that P. opilio was present at densities of <0.5 per m² in soybean.

The effects of food quantity on the morphology and development of the paper wasp Polistes metricus Say are studied, and experimental results are compared with predictions of the parental manipulation hypothesis. Food deprivation led to smaller female offspring. By hand feeding larvae we used a technique that counteracts the queen’s hypothesized ability to restrict food provisioning. Hand feeding larvae did not result in larger offspring, but their abdomen was wider and heavier and the hand-fed wasps survived longer in a cold test. We infer that hand-fed colonies produced more gynes and fewer workers than did control colonies. Results of a restricted nourishment treatment do not support the differential feeding hypothesis, because in fasting colonies the emergence of all larvae was delayed by a month, and we did not detect discriminatory feeding of particular larvae for faster emergence. Although fasting colonies produced fewer offspring, the sex ratio did not show significant differences from the other groups. These data suggest that Polistes metricus colonies are partly able to respond to different nutritional conditions by allocating excess food to increase the number of gynes at the expense of workers.

The polyphagous lady beetle Coleomegilla maculata (DeGeer) was previously shown to oviposit more frequently on the weed, Acalypha ostryaefolia Riddell, than on sweet corn, Zea mays L. In that earlier study, the presence of A. ostryaefolia led to higher densities of C. maculata larvae on nearby corn. To determine if C. maculata’s apparent oviposition preference for A. ostryaefolia was limited to that weed species, we conducted a 2-yr field study using A. ostryaefolia along with eight other common broadleaf annual weeds. A separate field experiment compared oviposition on just A. ostryaefolia and the weed Abutilon theophrasti Medicus. The possible influence of whitefly Trialeurodes abutiloneus (Haldeman) presence on C. maculata oviposition site selection also was examined. When nine weed species were available, significant oviposition preference was found for A. theophrasti. Similarly, far more egg clusters were found on A. theophrasti than on A. ostryaefolia when only those two species were available. When given a choice between A. theophrasti plants heavily infested with whiteflies and A. theophrasti virtually lacking whiteflies, C. maculata showed no significant oviposition preference between the two types of plants.

Coleomegilla maculata (DeGeer), a polyphagous lady beetle, is one of the most common predators in corn fields in the eastern United States. Previous work on C. maculata showed an oviposition preference for the weed Acalypha ostryaefolia Riddell (hophornbeam copperleaf), compared with three other weed species and corn. In a separate field study, we found far more C. maculata eggs on Abutilon theophrasti Medic (velvetleaf) than on eight other plant species. Here we report on studies designed to assess the potential roles that prey densities and weed attractiveness may play in the selection of oviposition sites by C. maculata. We also examined diurnal and nocturnal predation of C. maculata eggs on Zea mays L., A. ostryaefolia, A. theophrasti, and Amaranthus hybridus L. (pigweed). We found that C. maculata’s choice of plants on which to oviposit was not significantly influenced by the availability of potential prey on those plants. There was no difference in the number of C. maculata adults captured on sticky traps placed over preferred weeds, nonpreferred weeds, or bare soil, suggesting that oviposition choices are made after the beetles land on plants. Coleomegilla maculata egg clusters on A. theophrasti and A. ostryaefolia were preyed upon less frequently than clusters on A. hybridus and corn, indicating that A. theophrasti and A. ostryaefolia provide refuge from predation (including cannibalism) of C. maculata eggs. Unlike the other plant species tested, both A. theophrasti and A. ostryaefolia possess numerous glandular trichomes, which may reduce foraging activity of potential predators of C. maculata eggs on those plants.

To understand the effects of plant growth stage on the performance of grape phylloxera, Daktulosphaira vitifoliae (Fitch), demographic analyses were done using attached roots in a Vitis vinifera L. ‘Chardonnay’ vineyard during the vegetative, mid-ripening, and postharvest periods of grapevines. Survival of first instars was <30%. First instars coincide with the time of gall formation, and their survival was higher during postharvest than during the vegetative and mid-ripening periods. Survival after the second instar did not decrease with development but was stable, generally above 90% for the postharvest period and below 75% for the other experimental periods. Sucrose levels in root phloem parenchyma tissues were highest during postharvest compared with vegetative and mid-ripening periods and reflect a more rapid development during this period but only by a few days. The limiting step of grape phylloxera population growth appears to occur simultaneously with gall formation and is associated with survival. Survival and developmental rate of a virulent grape phylloxera strain were limiting with greenhouse vines of the resistant rootstocks 5C and SO4. Survival and developmental rates were more limiting for attached than detached roots.

Survival at low temperatures is an important parameter determining distribution of imported fire ants in the United States. Supercooling points and survival at low temperatures, and the effects of species, individual size, and Thelohania solenopsae Knell, Allen & Hazard (Microsporida: Thelohaniidae) infection on these parameters, were examined. We tested Solenopsis richteri Forel, S. richteri X invicta hybrid, and Solenopsis invicta Buren. Great variation was observed in the supercooling points, which are not an appropriate measure of cold hardiness for imported fire ants. When exposed to near-freezing temperatures above their supercooling points, fire ants died at different rates depending on the species and T. solenopsae-infection status. Extended exposure to 4°C resulted in both the hybrid and S. invicta infected with T. solenopsae having significantly lower mortality rates than either the S. richteri or the uninfected S. invicta. At 0.5°C, the hybrids had significantly lower mortality than the uninfected S. invicta, but mortalities for S. richteri and T. solenopsae-infected S. invicta were not significantly different from each other or the hybrid. Ant mortality was 100% for all ant types after 7 d at −4°C. The uninfected S. invicta was consistently less cold-tolerant than the other ant types. The hybrid fire ants and the T. solenopsae-infected S. invicta had the lowest mortalities. These results support the hypothesis that extended cold injury causes winter kill of fire ants, and may partially explain the distribution of fire ant species in the United States.

The effects of breeding habitat characteristics on the larval density of Anopheles minimus Theobald were studied in a perennial stream in the foothills of Chiang Mai province, northern Thailand. Data on 41 different variables related to plant cover and stream physical attributes in 200 sections, each 10 m long, were collected along with larval data during the dry and wet seasons of 1998 and 1999. Larval density was significantly higher in the dry season than in the wet season. In the dry season, An. minimus density was negatively correlated with water current velocity, height of aquatic large-leaved plants, and height of riparian small-leaved plants; and positively correlated with the cover of riparian ferns. The dry season prediction model, which explained 51% of the variation of An. minimus, was as follows: y_min = 0.1980–0.1733*water velocity – 0.0317*height of aquatic large-leaved plants – 0.0249*height of riparian small-leaved plants 0.0192*cover of riparian ferns – 0.0170*height of stream banks. The influence of vegetation characteristics on larval density may not be as large as previously assumed. We conclude that factors other than those measured here may account for a large part of the variation in larval density.

Beet armyworm, Spodoptera exigua (Hübner), oviposition preferences were determined on five host plants: cabbage (Brassica oleracea capitata L.), cotton (Gossypium hirsutum L.), bell pepper (Capsicum annuum L.), pigweed (Amaranthus retroflexus L.), and sunflower (Helianthus annuus L.) in no-choice, two-choice, and five-choice tests. Tests were conducted in the laboratory, greenhouse, and field cages. Oviposition preferences were compared on the basis of two measurements, the proportion of eggs laid on the plants to total that were deposited, and the oviposition preference index defined as [(number of eggs laid on the plant) - (number of eggs laid on the cage)] × 100/total number of eggs laid. The proportion of eggs laid on the plants to total that were deposited was highest for pigweed and lowest for cabbage in all tests. Beet armyworm females were significantly deterred from laying eggs on cabbage and sunflower, while pigweed and cotton elicited a positive oviposition preference. Pepper tended to be neutral or slightly unattractive. Apparent interactions among plant species in choice tests produced measurable shifts in oviposition preference. Most notably, female response to pepper was enhanced in the presence of cotton or pigweed. Egg masses laid on the plants contained significantly higher numbers of eggs than those laid on the surface of the cage, except in the case of cabbage leaves. Knowledge of hierarchies of host plant oviposition preference by beet armyworm females will be useful in understanding the population dynamics of this important agricultural pest, and for developing effective monitoring and management strategies.

Concern over insecticide resistance has led to the suggestion of spatially variable within-field management of Colorado potato beetle, Leptinotarsa decemlineata (Say). Here we compare L. decemlineata spatial and temporal dynamics, and potato yield, in fields treated with a narrow perimeter (5.5 m) of systemic imidacloprid supplemented with spatially targeted sprays to untreated fields and to fields where all rows received the systemic. The systemic targeted immigrating individuals which, having acquired the field through either flight or walking, first established themselves in the outer 5.5 m of the field. The perimeter treatment (≈25% of field area) reduced mean densities with no effect on timing of peak densities. Immigrating adults established similar spatial trends in both perimeter and untreated fields. Although trends in F₁ larval densities have been shown to follow the patterns established by immigrating adults, trends in the F₁ larval densities of the perimeter treatments diverged from adult patterns and developed highest densities in field centers. Immigrating adults had little to no spatial dependence in the covariance structure in any treatments. Spatial dependence in the covariance structure of F₁ larval and F₁ adult populations developed as density increased in both perimeter and untreated fields, with a tendency for increasing spatial dependence in perimeter fields, though this was not statistically significant. Comparing the perimeter to untreated fields, yields increased at a proportion that was higher than the proportion of land area treated, but remained significantly lower than the whole-field treatment. These results suggest that the perimeter tactic has promise as a site-specific resistance management program, but that refinement of border width is needed to optimize trade-offs among yield, quality, and long-term maintenance of susceptibility.

The small-scale spatial distribution of European corn borer, Ostrinia nubilalis (Hübner), larvae and damage in whorl stage corn, Zea mays L., was characterized using geostatistics. Spatial distribution of O. nubilalis larval feeding damage was studied at Clay Center, North Platte, and Concord, NE, during June–July 1992–1994, and spatial distribution of O. nubilalis larvae and damage was studied at Clay Center in June 1997. Semivariograms were calculated to model the change in spatial correlation with increasing distance between samples. Spatial distribution of larval damage during 1992–1994 was best described using a spherical model. Damage was spatially correlated among plants at distances up to 2.84 m apart. The spatial distribution of larvae in 1997 was best described using an exponential model for three of seven data sets, a spherical model for one of seven data sets and no model fit three of seven data sets. Larvae were spatially correlated among plants at distances up to 3.05 m apart. These data have implications for developing sampling plans for management of O. nubilialis, and for site-specific agriculture.

The effect of host diet on the immature developmental time, fecundity, sex ratio, adult longevity, and size of Apanteles galleriae Wilkinson, a koinobiont, solitary, and early instar larval endoparasitoid of the lesser wax moth, Achroia grisella (F.), was investigated. All experiments related to the effect of diet were conducted at 25 ± 1°C, 60 ± 5% RH, and a photoperiod of 12:12 (L:D) h. The experiments were conducted by supplying hosts with three types of natural food (blackened, dark yellowish, and pure comb). The change in the type of host diet from blackened, to yellowish, and to pure comb prolonged immature developmental time, shortened the life span, increased sex ratio in favor of males, and reduced fertility and adult size of parasitoid species. The first adult eclosion occurred at 25, 30, and 52 d for males and 27, 33, and 54 d for females, with blackened, dark yellowish, and pure comb, respectively. The mean production of progeny per female parasitoid for each diet was 105.09, 45.49, and 0.46 (n = 30). Males lived an average of 43.46, 14.52, and 5.75 d and females lived an average of 40.86, 16.8, and 10 d in relation to host diet changes. Parasitoid length varied considerably with 2.84, 2.5, 2.2 mm, and 2.51, 2.27, 1.94 mm for females and males, respectively. Of the three kinds of natural food, the first was determined to be the most optimal diet for the parasitoid species.

The biological effects of a commercially available neem seed extract (Neemix^. 4.5, 4.5% azadirachtin, AZ) were assessed on the brown citrus aphid, Toxoptera citricida (Kirklady), a recently introduced insect pest of citrus in the United States and its parasitoid, Lysiphlebus testaceipes. When small citrus seedlings were dipped with the neem extract at 11–180 ppm AZ, 0–8% of nymphs and 0–17.5% of adults survived 7 d after the treatment while 95% of nymphs and 42.5% of adults in the control survived for the same period. The extract drastically reduced longevity of both adults and nymphs, adult fecundity, and molting of nymphs at all tested concentrations. Spraying neem extract (11–180 ppm AZ) onto potted citrus plants in the greenhouse also significantly reduced aphids by 20–100%, while control aphid populations increased by 950% 7 d after treatment. Application of the extract had little impact on the survival of adult parasitoids and developing parasitoids within aphids because parasite emergences were similar between treated and untreated parasitized aphids. These results indicate that neem extract may be compatible with integrated pest management programs in citrus and should be evaluated for field efficacy.

Temperature affects insect and mite development, allowing species-specific traits including optimal temperature and low and high temperature thresholds to be observed. Development rate models and biological parameters estimated from them can help determining if synchrony exists between pests and natural enemies. We studied development of the coccinellid Stethorus punctillum Weise and the spider mite Tetranychus mcdanieli McGregor at 12 constant temperatures ranging 10–38°C (±0.5°C), and modeled their development rates as a function of temperature. This predator-prey complex is typical of red raspberry, Rubus idaeus L., in Quebec, which is characterized by a short season. Eleven published models were compared for accuracy in predicting development rate of all stages of both species, and estimating their temperature thresholds and optima. The spider mite developed to the adult stage in the 14–36°C range, compared with 14–34°C for the coccinellid. Males and females did not differ, and the development rates steadily increased from 14 to 30°C, leveling off in the range 34–36°C for the spider mite, or 30–32°C for its predator. Most models were rejected for failure to satisfy criteria of goodness-of-fit and estimable temperature threshold parameters. The Lactin-2 model for T. mcdanieli and the Brière-1 model for S. punctillum, were superior at estimating low temperature threshold, which is critical where temperatures are frequently low in the spring, and were separately fitted to all development stages of both organisms. Based on the predictable early spring development of S. punctillum and T. mcdanieli, the results indicate potential synchrony between them.