We reviewed the application of carbaryl (1-naphthyl N-methylcarbamate) against bark beetles (Scolytidae) in forest trees (Pinaceae) of North America. Our objective was to encapsulate carbaryl’s 30-yr history of successes and limitations against these beetles and to present appropriate safety and environmental information that relates to this usage.

Characterizing temperature responses of predatory insects is an important part of understanding their life history, and is often necessary for predicting their potential as bio-control agents of herbivorous insects. To illustrate the power of current methods of calorespirometry in determining the response of energy metabolism to environmental variables, we used isothermal calorimetry to measure metabolic heat and CO₂ production rates of convergent lady beetles (Hippodamia convergens, Guérin-Méneville) as a function of temperature. For comparison, CO₂ production rates were also measured with an infrared gas analyzer. Anabolic rates and energy use efficiencies were calculated as functions of temperature from the calorespirometric data. For this species, both heat and CO₂ rates are small (≈1 μW/mg and 8 pmol/s/mg, respectively) and essentially constant below 10°C, above which both rise approximately linearly up to ≈15 μW/mg and 50 pmol/s/mg at 40°C. The anabolic rate is approximately zero below 0°C, rises to a broad maximum of ≈7 μW/mg around 20°C, decreases above 25°C, and then exhibits an increase due to stress above 35°C. Energy use efficiency is roughly constant at ≈70% from 0 to 15°C, above which it decreases to ≈25% from 30 to 40°C. The beetles are predicted to be most successful in the temperature range from 10 to 35°C, with an optimum from 15 to 25°C. These conclusions agree with results from behavioral studies, but the calorespirometric methods are much faster, less labor intensive, and can be applied to any stage of development.

Mycotoxins, injected or orally ingested, adversely affect the development rate, fertility, and fitness of many insects. It is thought that the inhibition of protein translation in insect cells is among the possible reasons for such deleterious effects. Because Spodoptera littoralis (Boisduval) larvae may encounter mycotoxins in their natural habitat, we investigated the effect of three orally administered mycotoxins, aflatoxin B₁ (AFB₁), aflatoxin B₂ (AFB₂), and aflatoxin G₁ (AFG₁), on protein metabolism of the insect. The incorporation of phenylalanine into protein was investigated in penultimate and final instar larvae and pupae. There was a significant drop of phenylalanine incorporation into proteins during either the fifth larval or the larval-pupal molt. Nervous system and fat body of larvae had the highest rates of incorporation of phenylalanine into protein. Both AFB₁ and AFG₁ (at concentrations of 2.5 and 4 ppm, respectively) had profound inhibitory effects on the incorporation of phenylalanine into protein in both larvae and pupae, whereas AFB₂ (4 ppm) had only a slight effect. The typical breakdown of proteins following molting was less remarkable in AFB₁- and AFG₁-treated animals. The inhibitory effects of AFG₁ on protein metabolism in either nervous system or fat body of the last larval instar were more prominent than in alimentary canal tissues, while AFB₁ inhibited protein metabolism in all investigated tissues except hemolymph. Possible reasons for the differences in the effects of the involved aflatoxins are discussed.

Effects of ozone (O₃) stress of potato, Solanum tuberosum L., on fecundity, larval growth and survival of Colorado potato beetles, Leptinotarsa decemlineata (Say), were measured in greenhouse and field experiments. Chronic O₃ exposure caused moderate to severe foliar injury on an O₃-sensitive cultivar (‘Red Norland’) but caused only minor injury an O₃-resistant cultivar (‘Superior’). Foliar injury caused by O₃ was greater on old than on young leaves but feeding by adult beetles was greater on young leaves in all experiments. Foliar analyses of the five uppermost leaves (nodes 1–5) showed higher carbon (C) and higher nitrogen (N) concentration in Superior than in Norland. There were no significant O₃ effects on C or N and no cultivar × O₃ interactions. Egg production by newly emerged adult beetles feeding on plants exposed to high O₃ levels was not significantly different from egg production on plants exposed to low O₃ levels, regardless of cultivar O₃ sensitivity. Feeding and energy conversion efficiency of neonates and survival of larvae to the adult stage were not significantly affected by the O₃ treatment. Although present levels of tropospheric O₃ are high enough to significantly affect yield of sensitive potato cultivars, our results indicate no significant effect of ambient O₃ concentrations on Colorado potato beetle populations.

This research investigated whether organic and inorganic landscape mulches, which buffer soils against temperature extremes and desiccation, create conditions conducive to subterranean foraging by Reticulitermes virginicus (Banks). In the field, termite activity was measured with cardboard monitors placed beneath and within plots of eucalyptus, hardwood, pine bark, and pea gravel mulches, and bare ground (control). Gravel mulch provided higher feeding rates in underground monitors. Groundcover type had no significant effect on the number of monitors discovered by termites or the number of termites within each monitor. All groundcovers significantly reduced the temperature of the soil surface compared with bare soils, but temperature and moisture levels 12 cm below mulch-covered surfaces were not significantly different from those beneath bare soil. In the laboratory, R. virginicus were fed one of the three organic mulches or a control diet of white birch, Betula papyrifera (Marsh), as their only food source. All diet types were consumed at equivalent rates, but the mulch-fed termites suffered significantly lower survivorship.

We tested two formulations of verbenone for efficacy in protecting ponderosa pine trees from attack by the red turpentine beetle, Dendroctonus valens LeConte: (1) polyethylene bubblecaps filled with 800 mg of neat verbenone, and (2) a sprayable water suspension of microencapsulated verbenone. We baited artificial trees (cardboard cylinders coupled with Lindgren pheromone traps) with host kairomones and the verbenone formulations. Efficacy was measured by numbers of beetles captured in baited traps. Both release systems significantly reduced trap catch, and there was no significant difference between them. Both systems have promise for use in forest stands, depending on management objectives and land use. Verbenone was an interruptant for some nontarget insects, especially Coleoptera, and none were consistently attracted to verbenone. We report on verbenone as an interruptant to host attraction in the red turpentine beetle, and also on the efficacy of a microencapsulated scolytid semiochemical.

The relationship between ants and their habitats was examined in oak-dominated mixed forests in the central Appalachian mountains. Ants were sampled using pitfall traps over the summers of 1995, 1996, and 1997. Principal component and correlation analysis indicated that ant diversity (Shannon’s H′), species richness, and abundance were closely correlated with habitat principal components. Fewer ants, lower number of species, and lower ant diversity were found at sites with higher elevation and soil moisture. Diversity (H′) of ants and species richness decreased by 0.1 (R² = 0.75) and 2.2 (R² = 0.57) when the elevation increased 100 m, respectively. As the elevation increased, there were relatively less Formica neogagates Emery and more Aphaenogaster rudis (Emery). More ant species and individuals were found on ridges than in valleys.

Symbiotic ectomycorrhizal fungi enhance plant nutrient uptake and growth, especially in nutrient-poor conditions. The changes in plant metabolism due to mycorrhizal colonization could lead to alterations in plant suitability for herbivory. I investigated the effects of these fungal symbionts on oak, Quercus, growth and insect herbivory, and assessed the extent to which herbivore performance was affected by mycorrhizal colonization due to shifts in plant carbon allocation. Northern red oak, Quercus rubra L., acorns were inoculated with the ectomycorrhizal fungus, Pisolithus tinctorius (Persoon), and planted in either a nutrient-rich peat:perlite mixture or a nutrient-poor mine spoil:sand mixture. Plants were grown under greenhouse conditions for 45 d, after which seedling productivity was measured and herbivore performance trials were conducted. Gypsy moth, Lymantria dispar (L.), caterpillars were allowed to feed for the duration of the third instar, and performance was measured. Nonmycorrhizal, nutrient-poor plants had the lowest height growth, and produced the fewest leaves with the lowest leaf area and leaf mass, when compared with plants in the other treatments. Seedlings colonized by fungal symbionts showed enhanced productivity relative to noncolonized seedlings in several respects, including the number of leaves produced, leaf area, and basal stem diameter. Acorns grown in nutrient-rich substrate had a greater number of leaves, leaf area, leaf mass, and leaf area ratio, when compared with acorns grown in nutrient poor substrate, regardless of colonization status. Caterpillar growth and consumption rates were lowest on nutrient-rich, mycorrhizal plants, suggesting that colonized plants decrease herbivore performance in nutrient-rich conditions, when mycorrhizae are functioning parasitically. The data do not support the hypothesis that herbivore performance would increase on nutrient-poor, mycorrhizal plants, when mycorrhizal colonization provides the greatest benefits to the host plant.

Survival and development of larvae of Aedes aegypti (L.) and Aedes albopictus (Skuse) were examined under field conditions on the campus of Nagasaki University School of Medicine, Nagasaki, Japan, to explore the possibility of the establishment of Ae. aegypti in Kyusyu, southern Japan. Exposure experiments with hatched larvae were conducted 11 times at about 1-mo intervals from January 1998 to January 1999. In both species, larvae could develop to adults under field conditions from April to November, but not in January, February, and December 1998. In March 1998, only Ae. albopictus could develop to adults. The results suggest that there are differences in the resistance of hatched larvae to low temperatures between Ae. aegypti and Ae. albopictus and a threshold air temperature of larval development below 10°C for both species. To estimate the threshold temperatures of larval development, the relationships between the average air temperature and the developmental rate observed in March–November 1998 were analyzed by linear regression analysis. The estimated threshold air temperatures for Ae. aegypti were 8.52 and 9.45°C for females and males, respectively, and were higher than those of Ae. albopictus. A clear seasonal change was also observed in the body size of pupae. In both species, body size was largest at the beginning of the breeding season and continuously became gradually smaller until July. The results were compared with those from previous field studies in Nagasaki and the possibility of the establishment of Ae. aegypti in Nagasaki, Japan, is discussed from the viewpoint of adaptive life history to seasonally changing environments.

Monkey beetles (Scarabaeidae: Rutelinae: Hopliini) visit mostly unscented flowers with conspicuous dark center patterns that have been suggested to mimic resting beetles. Field observations in South Africa showed that monkey beetles are the primary pollen vectors of the dark-centered flowers of Ixia dubia Vent. (Iridaceae) and Spiloxene capensis (L.) Garside (Hypoxidaceae), and the dark-centered flowerheads of Gazania pectinata (Thunb.) Spreng. (Asteraceae). Monkey beetles used the flowers of these species as mating rendezvous sites and consequently showed a significant clumped distribution in flowers. We used model flowers approximating the study species to determine which traits are important for eliciting alighting behavior in monkey beetles. Contrary to expectations, beetles did not significantly prefer dark-centered to plain models in 7 of 8 independent experiments, nor did beetles discriminate significantly between plain models and models with male or female beetles glued to their surface. However, beetles did show a strong preference for orange over red, yellow, and blue models. The results of this study indicate that alighting behavior of monkey beetles is influenced primarily by flower color rather than flower patterning or presence of other beetles.

The spatial-temporal population dynamics of an imported parasitoid of stemborers, Cotesia flavipes Cameron, were analyzed. A two-step spatial interpolation method, spatial splines with Kriging of the residuals, was developed for interpolating the distribution of C. flavipes in Kenya. The results indicate that C. flavipes has become established throughout the whole southern part of Kenya and northern part of Tanzania, and that the population density of C. flavipes in maize fields is still increasing. The maximum C. flavipes density was about one parasitized borer per plant in the first growing season of 1999. The mean C. flavipes densities varied from region to region in 1999, with the highest density (five parasitized borers per 20 plants) in the southeast and the lowest parasitism in central Kenya (one parasitized borer per 20 plants). The percentage of sites occupied by C. flavipes was 90% in the southeastern area during the first growing season of 1999. In coastal Kenya, C. flavipes occupied >70% of the sampling sites, compared with ≈50% in both central and western Kenya. Over the whole sampling area, C. flavipes increased its distribution from 60% of sites occupied in 1994–80% in 1999. Temporally, C. flavipes population density remained low, with an average of less than one parasitized borer per 20 plants, until the second growing season of 1997–1998, when there was a sharp increase. The suppression of stemborer populations by C. flavipes appeared in southeastern and coastal Kenya from 1998. Analyses indicated that C. flavipes was a minor parasitoid before 1995, but had become the predominant parasitoid after 1998. The results of the spatial interpolation showed that the C. flavipes population did not spread much from the release sites before the first growing season of 1996, but expanded tremendously after the first growing season of 1997. The spatial interpolation model was validated with field data from 1999. The model predicted the C. flavipes density well at the zonal level but underestimated C. flavipes density country-wide. The possible displacement of an ecologically similar native congener, C. sesamiae, is discussed.

Two hemlock woolly adelgid, Adelges tsugae Annand, generations complete their development on hemlocks (Tsuga spp.) that are native to eastern North America. Progrediens are present in the spring and sistens are present from early summer until the following spring. Following the settling of sistens crawlers at the base of hemlock needles, first-instar sistens go into aestival diapause for ≈4 mo. We conducted studies to determine if we could prevent the induction of diapause and determine the environmental conditions required to do so. Diapause was determined to be maternally regulated. We were able to prevent the induction of diapause by preconditioning parents at 12 and 14.5°C, but not at 17°C, indicating that temperature is a critical preconditioning cue. Preventing the induction of diapause was also most successful under a photoperiod of 12:12 (L:D) h and was therefore chosen as a standard for rearing hemlock woolly adelgid. Egg stage through second-instar progrediens were found to be the maternal lifestages sensitive to diapause-inducing cues.

Populations of western blackheaded budworm, Acleris gloverana (Walsingham), have fluctuated widely over the length of Vancouver Island with five outbreaks having occurred since 1941. The core of the severe defoliation occurred in the southern and northern portions of a central mountain chain running the length of the Island. Four monitoring sites were established in the central core area and five in peripheral sites during the 1970–1973 outbreak. At each site, samples were taken during five different life stages per generation, beginning at the peak of defoliation and ending when larval densities declined below detectable levels. The largest losses during the population collapse occurred during the larval period when large numbers abandoned the damaged trees by spinning off on silk threads. In addition, when age-specific survival ratios for each developmental stage were compared with the generation survival ratio, the closest relationship occurred between generation survival and the adult dispersal and oviposition period. Large emigration away from the central core area of defoliation to peripheral stands was detected, particularly during the first year of collapse. We suggest that, in response to damaged foliage, larvae and adults disperse from the stands and the outbreak collapses before the trees are killed. The dispersal response of defoliating populations appears to dampen the upward population trend. The trees survive, refoliate, and thus preserve the habitat for potential population increases during the next outbreak period. Host interrelationships during population gradations of the blackheaded budworm are compared with other conifer defoliators of British Columbia, particularly the western spruce budworm and the Douglas-fir tussock moth.

Abundance of Scirtothrips perseae Nakahara (Thysanoptera: Thripidae), Oligonychus perseae Tuttle, Baker & Abbatiello (Acari: Tetranychidae), predators, and associations among their population trends on avocado leaves and fruit were determined in three untreated avocado orchards in Ventura and Santa Barbara Counties, CA, from 1998 to 2000. Objectives were to understand pest-predator dynamics and to assess which predators have potential as biological control agents. Numbers of S. perseae and predators from leaf litter/soil were also determined in one orchard from 1998 to 2000. On leaves, O. perseae was the most abundant pest, followed by S. perseae, and Oligonychus puniciae (Hirst) (Acari: Tetranychidae). Phytoseiid mites and spiders were the most abundant predators. The predatory thrips Franklinothrips orizabensis Johansen and Aeolothrips kuwanaii Moulton (Thysanoptera: Aeolothripidae) were also relatively abundant compared with at least 13 other species of predators on leaves. On immature avocado fruit, S. perseae was the most abundant pest and phytoseiid mites, F. orizabensis, and A. kuwanaii were the three most abundant predators. No consistent positive associations between pests and predators were seen on leaves, but F. orizabensis, A. kuwanaii, and phytoseiid numbers on fruit and S. perseae numbers on fruit were positively and significantly associated in all three orchards. In addition, there were significant positive associations between S. perseae and predatory thrips populations from leaf litter in two of the 3 yr. These pest-predator interactions may play a role in developing new control strategies and the importance of these relationships needs to be experimentally investigated.

A 4-yr blacklight trapping project involving 18 trapping sites was conducted in Kansas. From 1996 through 1999, six species of Cyclocephala were recorded: Cyclocephala borealis Arrow, Cyclocephala hirta LeConte, Cyclocephala longula LeConte, Cyclocephala lurida Bland, Cyclocephala melanocephala (F.), and Cyclocephala pasadenae (Casey). Cyclocephala pasadenae and C. lurida were the most plentiful species (132,915 and 93,799 specimens, respectively) with the former being most dominant in western Kansas, and the latter dominating eastern Kansas. Cyclocephala borealis was most concentrated at the southeastern trapping site. The highest concentrations of C. longula and C. hirta were in a pocket of counties in southcentral Kansas. Whereas C. hirta and C. melanocephala were captured only in 1999, all other species were active during each year of the study.

Malaise trapping efforts for Therevidae (Diptera: Asiloidea) have uncovered a relationship between brachyceran Diptera and mites of the family Microtrombidiidae (Acarina: Trombidioidea). Malaise trap samples from a Juniperus forest in McKinley County, New Mexico produced 39 brachyceran families, 14 of which were parasitized by microtrombidiid mites in the genera Platytrombidium Thor and Microtrombidium Haller. The frequency of parasitization was significantly higher in Tachinidae and Therevidae than the other 12 brachyceran families with parasitized individuals. Mite loads, i.e., the number of mites per individual, were also statistically different among families; some individuals were parasitized by as many as 21 mites. Mites preferred to attach at sites with soft, weakly sclerotized cuticle; the ventral cervical area and the membrane behind the hind coxae were most densely infested. Female Therevidae were attacked by mites at a significantly higher frequency than their male counterparts, but mite loads were similar. Insights into the host-parasite relationships between the flies are discussed, but the paucity of both mite and dipteran information limits their interpretation.

Ambrosia beetles can be important pests of nursery production. The beetles are difficult to control with insecticides, requiring that pesticides be closely timed before tree attack, applied repeatedly, or have long residual activity. The goal of this project was to improve management decisions for ambrosia beetle control in nurseries. This study used ethanol-baited traps, field observations of tree attacks, and emergence cages over beetle galleries to determine the following: (1) composition of ambrosia beetle fauna in middle Tennessee, (2) species responsible for attacks on chestnut (Castanea mollissima Blume), a susceptible tree species, (3) timing of tree attacks and progeny emergence, and (4) the relationship between tree attacks, progeny emergence, and beetle collections in ethanol-baited traps. Ambrosia beetles were surveyed using ethanol-baited Lindgren traps at the Tennessee State University Nursery Crop Research Station in McMinnville, TN, and at two commercial nurseries near Dibrell and Tarlton, TN, during 1998 and 1999. At the Nursery Station, species composition of ambrosia beetles attacking chestnut trees was determined in 1999. Xyleborinus saxeseni Ratzeburg, Xylosandrus crassiusculus Motschulsky, and Monarthrum fasciatum Say were the dominant ambrosia beetle species collected in traps. Xyleborinus saxeseni was the dominant species at all three locations when both 1998 and 1999 collections were totaled. Other commonly trapped species included Monarthrum mali Fitch, Xyleborus atratus Eichhoff, and Xyleborus pelliculosus Eichhoff. Tree attacks began on 2 April before trees broke dormancy. The majority of chestnut attacks occurred in April and May. Progeny emerged from 48% of the caged galleries, including 35.9, 10.3, 3.3, and 1.1% X. germanus, X. crassiusculus, Hypothenemus spp., and X. saxeseni, respectively. Beetles exhibited several unusual behaviors during this study, including emergence of female X. germanus from trees the following spring, emergence of live male X. germanus and X. crassiusculus, a staggered chronology of progeny emergence, and presence of multiple beetle species emerging from the same gallery. Xylosandrus crassiusculus and X. germanus were the dominant species attacking chestnut, but total trap collections of X. germanus were small (≤1.7%). Several findings from this study have significance to the nursery industry. The timing of peak trap collections during April (particularly collections of X. crassiusculus and X. saxeseni) coincided with peak tree attacks. The factors responsible for chestnut susceptibility to attack were not measured in this study, but since the majority of trees were attacked before dormancy break, tree phenological state probably is an important determinant of tree vulnerability. The collection of some species like X. germanus in trap collections may be a more important indicator of tree attack than abundance in the trap. Progeny emergence from chestnut trees during June and July did not coincide with increased trap collections or renewed attacks on chestnut. Therefore, traps may not always indicate ambrosia beetle abundance. Several new state records were collected during this study, including X. crassiusculus, a species capable of serious economic damage to nursery stock.

Reproduction in bark beetles (Coleoptera: Scolytidae) is known to be affected by abiotic factors, especially temperature, and by the quality of individual beetles. Both of these factors are affected by forest structure, yet the effects of forest structure on reproduction in bark beetles have not been widely shown in field studies. Here we investigate how changes in forest structure due to thinning of mature lodgepole pine, Pinus contorta variety latifolia Engelmann, stands affect reproduction in pine engravers, Ips pini (Say), breeding in felled trees. To do this, we excavated pine engraver gallery systems in thinned and unthinned stands at the end of the breeding season. Males in thinned stands attracted more females than in unthinned stands. Also, females in thinned stands extended their egg galleries farther, laid more eggs, and had higher egg densities than in unthinned stands. These results are consistent with increased temperatures in thinned stands, but may also be attributable to differences in individual quality resulting from easier dispersal in thinned stands. Regardless, the observed increases in reproduction likely reflect higher reproductive success in thinned stands than in unthinned stands, and the effects of thinning on population dynamics of bark beetles should be further investigated.

Predictive models were developed to forecast the emergence of female blueberry maggot flies in highbush blueberries. Time to emergence at 20°C for pupal samples transferred from outdoors late February through mid-March, in 1997 and 1998, was very similar, suggesting both diapause completion and minimal postdiapause development at this time. Linear and nonlinear models were fitted to postdiapause development rates at several constant temperatures (7, 11, 15, 20, 25, and 30°C). The low temperature development threshold for the linear model was estimated at 4.7°C, and the heat accumulation required for median emergence was 934.3 degree-days. Rate summation was initiated on 1 March, over 3 yr, and model predictions were validated with field emergence data. The linear model predicted emergence with an average error of <4 d of observed field emergence, for percentiles at and below the median, over a 3-yr period, compared with 4.0–5.4 d for the nonlinear biophysical model. The results of this study indicate that a simple linear model, driven by soil temperatures, can assist the monitoring of blueberry maggot fly in integrated pest management programs.

Scirtothrips perseae Nakahara causes significant scarring of avocado fruit and is the most serious pest of avocado in southern California. Because it was described only in 1997, no information that can be used for its control exists, including the relationships between its densities on leaves and fruit and scarring damage on fruit. To determine these relationships, percentages of scarring damage on avocado fruit were regressed against thrips numbers/leaf and numbers/fruit using data collected from three orchards in Ventura and Santa Barbara Counties, CA, from 1997 through 1999. Thrips population increases were positively related to leaf growth flushes. Numbers of first and second instars, total larvae, and adults/leaf were all predictive of scarring on fruit. Peaks of three to five larvae/leaf before and during fruit set predicted 6–15% economic scarring damage on fruit from October through December, whereas means of 0.5–1.5 larvae/small fruit predicted 22–51% scarring. Fruit were most susceptible to damage within a 2-wk period during and shortly after fruit set when they measured 0.53–1.42 cm long. Results suggest S. perseae numbers on leaves during fruit set can be used to predict scarring damage on fruit, and that damage thresholds may be ≤5 larvae/leaf during this time. Because low numbers of larvae on fruit within a 2-wk period can result in high scarring damage, early treatments when thrips are on leaves, just before they move onto fruit, may help prevent damage to fruit.

Taylor’s power law (s² = a x̄ ^b) was fitted to the means and variances of numbers of adult Diaprepes abbreviatus L. and Pachnaeus litus (Germar) caught monthly in modified Tedders traps (citrus Tedders traps). Data for D. abbreviatus were obtained in six Florida citrus groves, two located on the central ridge and the others in the central and southern flatwoods. Parameters for P. litus (a = 2.15, b = 1.17) using data pooled from two sites were consistent with parameters derived from the individual sites. Parameters derived from pooled data for D. abbreviatus were a = 2.69, b = 1.33; however, there was significant variability of the parameter b among sites. For specified levels of precision (confidence interval half-length:mean ratio), from 0–30% fewer traps were needed to estimate numbers of P. litus compared with D. abbreviatus at densities encountered in these groves. Plot size from 0.06 to >12 ha affected the numbers of traps needed to obtain monthly mean estimates of adult weevils per trap with a given level of precision. In general, sample precision was equal in large and small plots when population density in large plots was double that in small plots. At a given population density, ≈70% more traps were required in large compared with small plots to achieve a similar level of precision. Changes in trapped weevil abundance larger than 2.5-fold were detected as significantly different with the sampling plans used in these studies. Seasonality in the numbers of each species was evident at all sites (P = 0.05) because monthly means varied by 30- to 60-fold. In a separate study, the numbers of weevils recovered monthly from citrus Tedders traps were approximately congruent (r = 0.78, n = 33, P = 0.01) with numbers recovered from cone-shaped ground traps that only recover adult weevils as they emerge from soil. Annual maxima for both types of traps occurred at the same times during 33 mo, but each year weevil emergence from soil (as measured by cone traps) remained high for 1–2 mo after weevil recovery from citrus Tedders traps declined. Polynomial regression on monthly recovery from citrus Tedders traps explained 66% of the variation in monthly emergence of weevils from soil. Results of this study support the use of citrus Tedders traps in integrated pest management programs to detect the onset of emergence from soil by weevil cohorts, and to measure relative differences in weevil population density due to experimental treatments.

Secondary plant substances, also called allelochemicals, play a major role in pest infestations. Glucosinolates (GLS) and their degradation products are powerful phagostimulants for herbivores feeding on Brassicaceae and deter the noncrucifer feeders but are tolerated by some generalist phytophagous insects such as the peach-potato aphid, Myzus persicae Sultzer. Do the allelochemical substances only effect the herbivores or do they also influence the predators of the pest? Broad bean, Vicia faba L. (GLS free), oilseed rape, Brassica napus L. (low GLS level), and white mustard, Sinapis alba L. (high GLS level), were used in this work as host plant for the prey. Although the two latter Brassicaceae species had positive effects on aphid reproductive rates, host plants displayed mixed influences on the performance of the predaceous twospotted lady beetle, Adalia bipunctata L. Both rape and mustard shortened development duration and increased adult weight of the twospotted lady beetle. No significant difference of lady beetle mortality was observed, depending on the prey host plant. Whereas, rape-fed M. persicae enhanced larger egg production and larvae emergence, mustard-fed M. persicae induced lower fecundity and egg viability of the beetles. Fitness of M. persicae on high GLS plant-fed A. bipunctata was lower than the other plants. Biological parameters of aphid predators are closely linked to chemical composition of Brassicaceae species. This work on allelochemical impact gave opportunities to better understand interactions of the plant-aphid-lady beetle tritrophic model and demonstrated that successful biological control of pests must integrate the environmental aspects of each trophic level.

In mid-1996, we detected an unintentionally introduced seed-head fly, Chaetorellia succinea (Costa), destroying seeds of yellow starthistle, Centaurea solstitialis L., one of the worst weeds in the western United States. In overseas studies, Chaetorellia succinea had been considered as a potential biological control agent for yellow starthistle, but had been rejected because of fears that it might become a pest of safflower, Carthamus tinctorius L., in the United States. From mid-1996 through early 2000, we conducted both laboratory and field evaluations to determine whether this fly could cause significant damage to safflower, a widely planted crop in California. In laboratory no-choice host range evaluations, adult females would oviposit, and the larvae completed development, on all five varieties of safflower that we tested. However, in choice tests, only one head each of two varieties of safflower was attacked. No safflower was attacked at three sites in California and Oregon, with large populations of Chaetorellia succinea, where we grew five varieties of safflower as ‘trap plants.’ Our monitoring of possible Chaetorellia succinea attack on safflower growing in 47 fields in California detected a small, but persistent population of this fly infesting an uncommon safflower variety at one field. We feel that our results indicate a minimal risk to commercial safflower growers, and this fly continues to show promise in assisting toward the eventual biological control of yellow starthistle.

Coleomegilla maculata (DeGeer) and Hippodamia convergens Guérin-Méneville larvae were supplied daily with ≈1.2, 2.2, 4.3, 8.2, or 16.4 mg of Acyrthosiphon pisum Harris reared on either alfalfa Medicago sativa L. (‘OK08’) or faba beans Vicia faba L. (‘Windsor’). Myristic acid and total fatty acid content (μg/mg aphid fresh weight) were 6.3 and 2.7 times greater, respectively, in pea aphids reared on alfalfa as compared with faba beans, resulting in a 1.17-fold increase in caloric content. Higher survival ratios were observed for both C. maculata and H. convergens supplied with low daily prey levels of pea aphids reared on alfalfa versus faba beans, but no differences were observed at higher prey levels. When pea aphids reared on alfalfa were supplied to C. maculata and H. convergens larvae at low prey levels, preimaginal developmental times were significantly reduced compared with those supplied with pea aphids reared on faba beans at the same prey levels. At higher daily pea aphid levels, C. maculata and H. convergens developmental times were not significantly different between host plants. At lower daily prey levels, C. maculata and H. convergens elliptical body area was larger when supplied with pea aphids reared on alfalfa, but body areas were similar at higher daily prey levels. Convergence of survival ratios, developmental times, and elliptical body areas for C. maculata and H. convergens at high (less limiting) prey levels supports the hypothesis that differences in prey nutritional value between pea aphids reared on alfalfa versus faba beans are quantitative and appear to be primarily influenced by differences in pea aphid myristic acid content.

The recombinant nucleopolyhedrovirus of Autographa californica Speyer (AcMNPV-AaIT) expressing the paralyzing toxin of scorpions (Androtoctonus australis Hector) kills caterpillars 30% faster than wild-type (wt) AcMNPV, and shows a great deal of promise as a bioinsecticide. Although it is generally believed that genetically modified organisms are less fit than their derived wild type and will not persist in the environment, a thorough assessment of the ecological risks associated with the release of AcMNPV-AaIT must be conducted before its commercialization. In this study, we focus on one aspect and compare the fitness of AcMNPV-AaIT and wt-AcMNPV during intra-host competition. Cabbage loopers (Trichoplusia ni Hübner) were synchronously or asynchronously infected with wt-AcMNPV and AcMNPV-AaIT, and the polymerase chain reaction was used to monitor the outcome of intra-host competition. There was no indication that AcMNPV-AaIT was less fit than wt-AcMNPV when T. ni were synchronously fed equal doses of each NPV. Serially passing the occlusion bodies had little effect on the persistence of AcMNPV-AaIT. After seven passages, the recombinant virus was found alone or with wt-AcMNPV in 71% (12/17) of replicates whereas wt-AcMNPV occurred alone or mixed in 88% (15/17) of replicates. Dose and synchrony of infection both affected the outcome of intra-host competition. The virus with the highest dose and the first one given to T. ni had a significant competitive advantage. Finally, the AaIT insert appeared to be stable because there was no evidence that it got deleted from the recombinant genome even after AcMNPV-AaIT was serially passed seven times in T. ni. As a complementary study, we also examined intra-host competition between two wild type NPVs, wt-AcMNPV and the single nucleocapsid (S) nucleopolyhedrovirus of T. ni (TnSNPV). Our results suggest that the two viruses are equally fit during intra-host competition. Serially passing the occlusion bodies did not influence the outcome but NPV dose and synchrony of infection were again strong determinants of intra-host competition.

The effect of temperature on life history parameters of Muscidifurax raptorellus Kogan & Legner was determined and compared with species currently attacking fly pupae in feedlots and dairies in Alberta. Immature developmental times declined from 72 d at 15°C to 13 d at 30°C for females. Male developmental time averaged 96% of female developmental time. Immature survival ranged from 0.23 at 15°C to 0.93 at 25°C, then declined to 0.42 at 33°C. Emerging wasps averaged 0.60 female, with an average of 8.6 and 6.2 progeny produced per parasitized pupa in Musca domestica L. and Stomoxys calcitrans (L.). Female longevity declined from 11 to 5 d as temperatures increased from 15–33°C. Time to 50% progeny production followed a similar pattern. Lifetime progeny production increased from 28–37 progeny per female at 15°C to 85–120 at 20–25°C, then declined to 48–50 progeny per female at 33°C. The net reproductive rate increased from 1.8–2.3 females at 15°C to 39–48 females/female at 25°C, then declined to 13–15 females per female at 33°C. Mean generation time declined with temperature. The intrinsic rate of increase increased from 0.007–0.010 females/female/d at 15°C to 0.203–0.206 females/female/d at 30°C, then declined to 0.173–0.186 females/female/d at 33°C. M. raptorellus had lower lifetime progeny production, net reproductive rate, and intrinsic rate of increase at all temperatures compared with Muscidifurax raptor Girault & Sanders. Life history parameters of M. raptorellus compared favorably to those of Muscidifurax zaraptor Kogan and Legner at all but the highest temperatures, and also with those of Trichomalopsis sarcophagae Gahan at all temperatures. It does not appear that there is any climatic barrier to the use of M. raptorellus for inundative releases for fly control in Alberta.