Threshold temperatures and relative humidities, growth rates, and physiological development times were calculated for egg laying, larval development, progeny production, and sex ratio of the endoparasitoid Pediobius furvus (Gahan) (Hymenoptera: Eulophidae), a key pupal parasitoid of several graminaceos stem borers, among which is Chilo partellus Swinhoe (Lepidoptera: Pyralidae). These studies were conducted within a temperature range of 15–35°C, with a relative humidity of 30–80% at each temperature, and have shown that neither oviposition nor development is possible under extremes of temperature conditions such as 15 and 35°C. Optimum conditions for oviposition and development lie between 25 and 30°C and 60–80% RH. Low temperatures resulted in longer developmental period(s) and a preponderance of male progeny. However, parasitization activity increased with temperatures up to 30 ± 1.5°C under relative humidity levels of 60–80%. Thus, the criteria for optimum parasitoid production may not only be associated with unfavorable temperatures and relative humidity regimens during oviposition, but more importantly, with temperatures at which parasitoid development takes place.

The harvestman Phalangium opilio L. is an abundant predator in an array of habitats, including agricultural systems. In these systems, P. opilio has been noted to feed on pest species (e.g., Colorado potato beetle larvae, various aphid species, and lepidopteran eggs). Although the potential importance of P. opilio has been recognized, little is known about this harvestman’s development or reproductive biology. We investigated the influence of diet on development time, survival, reproduction, and female longevity. We compared the effects of two diets, Helicoverpa zea (Boddie) eggs and Aphis glycines Matsumura, on development of P. opilio because this predator is known to feed on those prey in soybean agroecosystems. Individuals fed A. glycines from emergence to adulthood suffered from higher mortality, longer development time, and smaller body size than those fed H. zea eggs. Four diet treatments were used in a separate study to test their effects on reproduction: standard laboratory diet (cornmeal, bacon, and H. zea eggs), H. zea eggs only, A. glycines only, and mixed diet (A. glycines and H. zea eggs). A diet of A. glycines alone yielded higher mortality, smaller body size, and lower fecundity than the standard laboratory diet. The presence of A. glycines in a monotypic or mixed diet lengthened the preoviposition period compared with diets without this prey and yielded a smaller first clutch and smaller average clutch sizes compared with the standard laboratory diet. A. glycines is detrimental to the growth and reproduction of this predator.

Laboratory studies were conducted on the effect of temperature and host instar on lifetime and age-specific fertility of honey-fed and starved adults of Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae) parasitizing larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). The relationships between the number of progeny produced with adult longevity and body size also were investigated. Highest mean fertility of honey-fed wasps was recorded at 20°C, followed, in decreasing order, by 25, 30, and 15°C, with most offspring emerging during the first 5 d. In contrast, temperature did not have a strong effect on progeny production in the case of starved adults. Provision of adult parasitoids with honey resulted in a significant increase in production of total offspring at all temperatures. Wasps that parasitized second-instar hosts produced significantly fewer descendants than those that oviposited in third- to fifth-instar hosts, which produced similar numbers of offspring. Interactions between temperature and feeding were significant. The total number of offspring produced by honey-fed adults increased with longevity and body size, regardless of temperature or host instar. Conversely, number of progeny produced by starved wasps was correlated only with body size.

The effect of temperature on development time, reproductive capacity, and rate of survival for Aphis punicae was studied at five different (constant) temperatures (17.5, 20, 22.5, 25, and 27.5°C). The development period for immature instar stages ranged from 11.72 d at 17.5°C to 4.30 d at 27.5°C. The lowest developmental threshold was 11.8°C, and the thermal constant (K) was 66.4 DD. The percentage survivorship of immature stages varied from 72.0 to 90.0% over a temperature range of 17.5–27.5°C. The average longevity of adult females was 16.50, 17.17, 18.16, 12.04, and 8.91 d at temperatures of 17.5, 20, 22.5, 25, and 27.5°C, respectively. The average number of offspring produced by a single female was 14.65, 22.68, 31.34, 21.31, and 11.27 at temperatures of 17.5, 20, 22.5, 25, and 27.5°C, respectively. The greatest r_m (0.3292) was observed at 25°C. The optimal temperature for A. punicae growth, development, and reproduction was 22.5–25°C.

Greenbug, Schizaphis graminum (Rodani); bird cherry-oat aphid, Rhopalosiphum padi L.; and Russian wheat aphid, Diuraphis noxia (Mordvilko), developed and reproduced successfully on TAM 107 wheat (Triticum aestivum L.) from 21.0 to 22.6°C when transferred to individual plants as single first instars. Both D. noxia “foundresses” and second-generation nymphs developed slower than those of S. graminum and R. padi. In all three species, nymphs developed faster in small colonies of siblings than did their foundress mother developing in solitude. However, when nymphs developed in solitude, only those of S. graminum developed faster than their mothers on the same plants, suggesting maternal induction of plant suitability. Isolated nymphs of D. noxia did not differ in developmental rate from their mothers on maternal plants, and those of R. padi developed more slowly, suggesting that effects of group feeding were responsible for the faster development of second-generation nymphs observed within growing colonies of these species. D. noxia cumulative foundress fecundity and daily reproductive rate were lower than those of S. graminum and R. padi. The estimated intrinsic rates of increase were S. graminum > R. padi > D. noxia. The preferred feeding location of S. graminum foundresses was the primary leaf, whereas for R. padi, it was the stem, and for D. noxia, it was the upper leaves, primarily the terminal leaf. Foundresses of R. padi were observed to change position on the plant from day to day more often than did those of S. graminum or D. noxia. R. padi colonies initiated from 10 first instars accumulated more biomass over a 10-d period than did those of S. graminum or D. noxia.

Increased levels of atmospheric carbon dioxide (CO₂) are likely to affect the trophic relationships that exist between plants, their herbivores, and the herbivores’ natural enemies. We examined interactions across three trophic levels, a transgenic Bacillus thuringiensis Berliner cotton, an aphid herbivore (Aphis gossypii Glover), and a coccinellid predator (Leis axyridis Pallas) as affected by elevated CO₂ concentrations. Experimental CO₂ levels included ambient and 2× and 3× ambient CO₂ levels. Plant height, biomass, leaf area, and carbon:nitrogen (C:N) ratios were significantly higher in plants exposed to elevated CO₂ levels compared with that in plants exposed to ambient CO₂. More dry matter and fat content and less soluble protein were found in A. gossypii in elevated CO₂ treatments. Cotton aphid fecundity significantly increased with increased CO₂ concentrations. The aphid fecundity significantly increased through successive generations reared on plants grown under elevated CO₂, suggesting that the changes in plant quality resulting from elevated CO₂ altered aphid quality as prey for L. axyridis through the food chain. Significantly higher mean relative growth rates were observed in lady beetle larvae under elevated CO₂ treatments. Also, the larval and pupal durations of the lady beetle were significantly shorter and aphid consumption rates increased when fed A. gossypii from elevated CO₂ treatments. Our data showed that increasing CO₂ concentrations could alter the preference of lady beetle to aphid prey and enhance the biological control of aphids by lady beetle. This study provides the first empirical evidence that changes in prey reared on host plants grown at different levels of CO₂ can alter the feeding preference of their natural enemies.

Pupal diapause in the blueberry maggot was studied to characterize the relationship between temperature and development during different phases of diapause and determine the traits responsible for the late adult emergence period in some populations present in blueberry fields in southern New Jersey. Pupae in the refractory phase of diapause were exposed to 1, 4, or 7°C for 45, 90, or 135 d, and in a separate experiment, to 11 or 15°C for similar periods of time, to determine temperature thresholds and rates of diapause development at constant temperature. Results showed that pupae took much longer to reach the activated phase of diapause when exposed to 1°C than 4 or 7°C and were able to reach the activated phase when exposed to up to 15°C. In the range of 4–15°C, diapause development was largely independent from temperature. Pupae in the activated phase of diapause were exposed to 7, 15, 20, 25, 30, 25:35 (12:12 h), and 35°C for 10 d. There was a linear increase in the development rate in the range of 7–30°C, and the development rate was similar at 30, 25:35 (12:12 h), and 35°C. The proportion of pupae reaching the activated phase of diapause from August to February in a normal early population and from October to February in a late population was compared by keeping pupae in the refractory phase outdoors in a screenhouse and bringing samples to 20°C monthly. Data showed that pupae of both early and late populations reached the activated phase from October to January. The duration of the activated phase of diapause in pupae of early and late populations kept at 20°C after exposure to cold was compared by measuring changes in their respiration rates. Results showed that the activated phase lasted 10–20 d in the early population versus 60–70 d in the late population. In the blueberry maggot, and possibly in other Rhagoletis species, adaptation of the adult emergence period to the fruiting period of different host plants seems to be mediated by changes in the duration of the activated phase of diapause.

The feasibility of disrupting sexual communication in oriental beetle, Anomala orientalis (Waterhouse), was evaluated by placing 50–75 ChemTica dispensers/ha (50–75 g active ingredient/ha) that released (Z)-7-tetradecen-2-one, the major sex pheromone component of oriental beetle, or red rubber septa deployed at the same density, but loaded with only 5–7.5 g active ingredient/ha, in 2002 and 2003. In both years, pheromone trap captures in plots treated with dispensers and rubber septa were significantly lower compared with pheromone trap captures in untreated control plots. Significantly fewer grubs were found in 2002 in blueberry plants placed in the two disrupter treatments compared with untreated control plots. In 2003, fewer females recovered from disrupter plots were found mated compared with females placed in untreated control plot. These studies indicate that sexual communication in the oriental beetle can be disrupted by deploying retrievable dispensers releasing high rates of pheromone at lower densities than previously thought.

Helicoverpa armigera (Hübner) infests many economically important crops in India, including cotton, pigeonpea, chickpea, sunflower, corn, chili, tomato, and okra. These crops are cultivated in proximity to each other in central and southern India. The current study examined the relative abundance of H. armigera on different host crops within a crop mosaic. Field studies conducted over two growing seasons (2000–2001 and 2001–2002) indicated differences in egg and larval densities among the host plant species. All of the host crops supported eggs and larvae of H. armigera, but the populations on pigeonpea and chickpea were significantly greater than on cotton and other host crops. Egg numbers also were significantly higher on sunflower, okra, and tomato than on cotton, but larval numbers were not significantly different from cotton at comparable times. Both egg and larval numbers on corn and chili were not significantly different from those on cotton. This study demonstrates that a number of host crops of H. armigera support large populations at the same time that cotton is infested. Thus, these crops may act as important sources of refuge for Bacillus thuringiensis cotton plantings in central and southern India.

Populations of mimosa webworm, Homadaula anisocentra Meyrick, and its parasitoids Elasmus albizziae (Burks) and Parania geniculata (Holmgren) were observed on thornless honeylocust, Gleditsia triacanthos variety inermis L., at the West Lafayette, IN, campus of Purdue University between 1998 and 2001. Mimosa webworm populations were quantified by visually estimating percentage of browning of each tree canopy. Average browning per tree varied from 10.1 to 13.7% in the first generation and from 19.7 to 32.5% in the second generation. Average parasitism per tree ranged from 9.3 to 15.2% in the first generation and from 28.1 to 30.2% during the second generation. During the course of the study 71.5% of all parasitized mimosa webworm pupae were attacked by E. albizziae. The remaining 28.5% were attacked by P. geniculata. Total numbers of E. albizziae collected per tree in a season were positively correlated with the percentage of canopy turned brown by the second generation of webworms. Annual estimates of E. albizziae abundance were positively correlated with year-to-year declines in second generation webworm injury when average estimates per tree declined by 8.1 and 10%, but absent when average injury declined by 4.7% or increased by 5.7%. The apparent numeric response of these parasitoids and their delayed negative density dependence suggest that these parasites can occasionally contribute to decline of mimosa webworms in an urban forest.

Soil physical and chemical properties can affect plant growth and nutrition, which in turn can affect a plant’s attractiveness and susceptibility to insect herbivores. A further source of variation in these relationships is the spatial scale at which patterns are measured. Both the size of the area being sampled, or scale, and the distance between measurements, or grain, are parameters that affect interpretation of insect abundance patterns. Our objectives in this study were to determine both the relationship of various landscape, plant, and soil characteristics to densities of sap-feeding insect herbivores in cotton and to determine the effects of sampling scale and sampling grain on these relationships. We included three sap-feeding herbivores in our study: Aphis gossypii Glover, Frankliniella occidentalis (Pergande), and Bemisia tabaci Gennadius. We found that abundance of each insect species was related to several single factors within the cotton field and that these relationships were always dependent on the scale and grain of the measurements. No one variable or set of variables was related to a particular insect density for each scale and grain examined. However, some variables were significantly correlated with insect densities at the larger scale (622 by 31 m), although none were significantly correlated for all plots at the smaller scale (154 by 31 m). In comparing the separate effects of each variable using partial correlations, elevation was negatively correlated with A. gossypii density at both grains (samples taken 25 m apart and samples taken 50 m apart), whereas in multiple regression analyses including all variables, plant moisture and soil nitrates were positively correlated and plant height and clay negatively correlated with A. gossypii density. In examining the separate effect of each variable on F. occidentalis density, plant moisture was negatively associated with F. occidentalis density at each grain. In multiple regression analyses, no variable was associated with F. occidentalis density at each grain. For B. tabaci, soil salinity was positively associated when variables were examined separately or in multiple regression. We discuss the possible reasons for why particular variables are related to the densities of each species.

In the northwestern United States, insect pests of potatoes (Solanum tuberosum L.) have typically been controlled using broad-spectrum insecticides. However, the loss or impending loss of many broad-spectrum chemicals is increasing the use of selective insecticides, and organic potato production is growing in the region. In the 2001 and 2002 growing seasons, we intensively sampled the arthropods in 31 (14 in 2001 and 17 in 2002) production potato fields under three pest management regimens: conventional fields treated with broad-spectrum insecticides (Hard), conventional fields treated with selective insecticides (Soft), and organic fields treated with insecticides certified for organic production (Organic). All fields were within the Columbia Basin of Washington, grown under center-pivot irrigation. We sampled arthropods using three techniques: D-vac suction sampling, pitfall trapping, and visual searching. Geocoris spp. and Nabis spp. bugs (Hemiptera) and spiders (Araneae) were the most abundant predators in plant foliage, together making up >90% of the foliar predator community in both years. Total predator densities and densities of Geocoris, Nabis, and spiders not in the family Linyphiidae were highest in Organic and Soft, and lowest in Hard fields. Linyphiid spider densities were marginally elevated in Soft compared with Hard fields. On the ground, carabid (Coleoptera: Carabidae) and staphylinid (Coleoptera: Staphylinidae) beetles and a diverse group of spiders dominated the community, together making up >90% of the ground-active predator community in both years. Total predator densities and densities of carabid beetles, staphylinid beetles, and linyphiid spiders were highest in Organic and Soft and lowest in Hard fields, whereas densities of these arthropods did not differ between Organic and Soft. Densities of nonlinyphiid spiders were highest in Organic, intermediate in Soft, and lowest in Hard fields. While predator densities were generally high in organic fields, these fields also had the highest densities of the two most injurious insect pests, the green peach aphid (Myzus persicae Sulzer) and the Colorado potato beetle (Leptinotarsa decemlineata Say). Selective insecticides allowed conventional growers to achieve predator densities similar to those seen in organic fields while retaining low pest densities typical of fields treated with broad-spectrum insecticides.

We examined the role of cattle grazing, plants, and soil attributes on species richness, abundance, and composition of ground-dwelling ants in northern California serpentine and nonserpentine grasslands. In addition, we analyzed the relationship between three numerically dominant ant species and overall ant species richness and abundance. We used pitfall traps to collect worker ants at 80 sites over a 2-wk period in May 2002. Twenty species of ants were identified from a total of 5,149 worker ants; 80% of all individuals belonged to three dominant species: Messor andrei (Mayr), Pheidole californica Mayr, and Solenopsis xyloni McCook. Ant species richness was negatively affected by grazing on nonserpentine soils only. In general, soil chemistry and texture formed the most consistent associations with the ant community. Plants were less important than soil attributes in explaining variation in overall ant species richness and abundance, but the abundance of the three dominant ant species was significantly correlated with plant biomass or plant richness. Based on logistic regression analysis, the presence or absence of each dominant ant species was negatively correlated with the abundance of the other two dominants. However, the three numerically dominant ant species did not correlate with overall ant species richness or abundance.

Field studies were conducted from 2000 through 2002 to determine whether the abundance of predaceous arthropods was negatively affected by Bollgard and Bollgard II transgenic cotton, Gossypium hirsutum (L.), that expresses one or two insecticidal proteins of Bacillus thuringiensis Berliner (Bt) for control of lepidopteran pests. During 2000, populations of predators and lepidopteran pests were monitored in small plots of DP50 (non-Bt), DP50B (Bollgard, expresses Cry1Ac), and DP50BII (Bollgard II, expresses Cry1Ac and Cry2Ab) under untreated conditions. In subsequent studies, plot sizes were increased and insect populations were monitored under conditions in which predators were either allowed to develop normally (untreated) or were disrupted with insecticides in early season. Populations of predators (Geocoris spp., Orius insidiosus [Say], Nabis spp., Solenopsis invicta Buren, spiders, coccinellids, and lacewings [Chrysopidae and Hemerobiidae]) were consistently as high or higher in Bollgard and Bollgard II compared with non-Bt. Under untreated and disrupted conditions, season-long populations of Helicoverpa zea (Boddie) were consistently but not significantly lower in DP50BII compared with DP50B. In this study and in previous studies, DP50BII provided excellent control of H. zea despite predator disruption. However, under high population pressure in 2002, H. zea numbers exceeded economic thresholds when predators were disrupted (five larvae >2/3 cm in length per 100 plants on 26 July) and would have required insecticidal intervention. Compared with DP50B, DP50BII provided significantly better control of Pseudoplusia includens (Walker) and Spodoptera frugiperda (J.E. Smith) under both disrupted and untreated conditions. Until experience is gained in wide scale commercial plantings, Bollgard II varieties should be monitored closely for lepidopteran pests that might survive the toxins, particularly where populations of predaceous arthropods have been disrupted.

The effectiveness of predators and parasitoids of the Russian wheat aphid was experimentally evaluated using mechanical exclusion in production winter wheat, Triticum aestivum L., fields at four locations in southeastern Colorado. Three types of enclosure were used: complete exclusion enclosures, partial exclusion enclosures that permitted entry by parasitic Hymenoptera, and environmental exclusion enclosures that reduced the effects of wind and rain on Russian wheat aphids and trapped emigrating alate Russian wheat aphids so that they could not return to plants within the enclosure. Russian wheat aphids in nonenclosed plots were also studied. Russian wheat aphid density varied among treatments in the following order: complete exclusion ≥ partial exclusion > environmental exclusion > nonenclosed plots. The trapping of alatae within enclosures and reduced adverse stresses such as rain and wind within enclosures were partially responsible for the greater Russian wheat aphid density in complete and partial exclusion enclosures compared with environmental exclusion enclosures and nonenclosed plots. The aphidophagous coccinellid, Hippodamia convergens Guèrin-Mèneville, and the generalist Nabis spp. were the most abundant predators during the increasing phase of Russian wheat aphid population development, but they did not substantially reduce Russian wheat aphid numbers. H. convergens, Coccinella septempuntata L., and H. sinuata Mulsant were the most abundant predators during the declining phase of Russian wheat aphid population growth. The dominant parasitoid was Lysiphlebus testaceipes (Cresson), but parasitism rates were very low. Canonical correspondence analysis showed close associations between the abundance of predators and Russian wheat aphid density, Russian wheat aphid density and wind during the increasing phase of Russian wheat aphid population development, and Russian wheat aphid density and rainfall late in the growing season.

A study was conducted on populations of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), infected with the microsporidia Vairimorpha invictae Jouvenaz and Ellis (Microsporidia: Burenellidae) and Thelohania solenopsae Knell, Allen, and Hazard (Microsporidia: Thelohaniidae). Fire ant populations and microsporidia prevalence were monitored three to five times per year for 3–4 yr in eight field plots in northern Argentina. The mean population index per plot showed an overall reduction of 69%. The percentage of infection with V. invictae and T. solenopsae showed fluctuations that ranged from 29.2 to 1.4% and 13.6 to 2.6%, respectively. The highest infection rates were observed at the beginning of the study. A total of 394 colonies were sampled during the study: 325 (82.5%) were healthy and 69 (17.5%) were infected with microsporidia. The proportion of infected colonies with brood was 81% (56/69), similar to the proportion of healthy colonies with brood (78%; 255/325). The proportion of infected and healthy colonies in the population index categories was significantly different. Of the infected colonies with brood, 49.3% were medium and 1.4% were large in size. In contrast, healthy colonies were generally larger, with 29.7 and 10.4% being medium and large, respectively. The general environmental conditions in the area of the plots were appropriate for fire ant population growth; consequently, they do not explain the overall reduction in the populations. These results, combined with additional evidence reported previously, suggest that infection with V. invictae and T. solenopsae has a deleterious effect on native populations of S. invicta.

Pupal parasitoids are released as biocontrol agents against house flies and stable flies in livestock production systems, and entomopathogenic fungi may be compatible with the parasitoids. However, little is known on the dynamic interactions between pupal parasitoids and entomopathogenic fungi when based on releases of both biological control agents. Therefore, the compatibility of the pupal parasitoid Spalangia cameroni Perkins and the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin was examined in laboratory experiments. As a first step in this study, the susceptibility of S. cameroni to fungus infection was examined in a dose-response experiment, which was followed by a study on the effect of M. anisopliae on female survival and reproduction. The female parasitoids were moderately susceptible to M. anisopliae, with an LC₅₀ value 6 d after treatment of 2.97 × 10⁷ conidia/ml. When previously infected S. cameroni were provided with surplus fly puparia, no overall effect of fungal treatment on reproduction was found, although treatments with 1 × 10⁸ conidia/ml resulted in 50% infected individuals. The fungus infection significantly reduced the survival of the females, while the total fecundity (86.26 ± 8.63 progeny per female) was not statistically different from that of uninfected parasitoids (95.23 ± 6.88 progeny per female). As a result, the susceptibility of the parasitoids to fungal infection had no discernible effect on the intrinsic rate of natural increase (r_m). This strongly suggests that the isolate of M. anisopliae and S. cameroni could be compatible under field conditions. The results are discussed in relation to integrated fly control by combined use of S. cameroni and hyphomycetous fungi.

Greenhouse studies of mole cricket tunneling architecture were conducted with adult southern, Scapteriscus borellii Giglio-Tos and tawny, Scapteriscus vicinus Scudder, mole crickets exposed to Beauveria bassiana (Balsamo) Vuillemin. Three different strains of B. bassiana as well as the commercially available insecticide Talstar (bifenthrin) were evaluated for avoidance behaviors by examining tunneling characteristics. Each treated container was inspected 24 h after treatment for specific tunneling behaviors in association with the presence of a control agent and the cricket’s response to the conidia or chemical. One of the B. bassiana strains tested, DB-2, caused changes in mole cricket behavior, including significantly less new surface tunneling, fewer vertical tunnels descending into the soil, less tunneling along the perimeter of the containers, and significantly more occurrences of the crickets remaining in an area that reduced exposure to the conidia. Two of the other treatments, strain 10-22 and Talstar, produced some of these same altered behaviors in mole crickets. Mole crickets exposed to a third strain of B. bassiana, BotaniGard, as well as two carrier formulations did not exhibit these same levels of avoidance. These observations indicate that the presence of environmentally “friendly” control agents, such as entomogenous fungi, may affect pest behavior, and strain selection may be critical to eliminate detection and avoidance by the target insect.

Polydrusus sericeus (Schaller) and Phyllobius oblongus (L.) are nonindigenous root-feeding weevils in northern hardwood forests of Wisconsin and Michigan. Detailed studies of adult host range, tree species preferences, and effects of food source on fecundity and longevity have not been conducted in North America. P. sericeus and P. oblongus adults fed on leaves of all 11 deciduous tree species offered in no-choice assays, but amount of consumption varied among species. P. sericeus consumed more yellow birch (Betula alleghaniensis Britton), basswood (Tilia americana L.), and ironwood [Ostrya virginiana (Miller) K. Koch] than maple (Acer spp.). Conversely, P. oblongus consumed more ironwood than poplar (Populus spp.) and yellow birch, with maple being intermediate. Females ate 2.5 times as much as males. Mean frass production by P. sericeus was strongly correlated with foliage consumption among host tree species. In feeding choice assays, P. sericeus preferred yellow birch over ironwood, basswood, and aspen (Populus tremuloides Michaux). P. sericeus produced 29.93 ± 1.43 eggs/d when feeding on yellow birch compared with 2.04 ± 0.36 eggs/d on sugar maple (Acer saccharum Marshall). P. oblongus produced 4.32 ± 1.45 eggs/d when feeding on sugar maple compared with just 0.2 ± 0.1 eggs/d on yellow birch. Overall, total egg production for P. sericeus and P. oblongus averaged 830.1 ± 154.8 and 23.8 ± 11.8 eggs, respectively, when feeding on their optimal host plants. P. sericeus survived approximately five times longer in assays than P. oblongus, and it oviposited a total of 25.8 ± 4.0 d, whereas P. oblongus oviposited 1.9 ± 0.9 d. Egg size among P. sericeus and P. oblongus was 0.53 ± 0.008 by 0.32 ± 0.003 and 0.56 ± 0.005 by 0.29 ± 0.004 mm, respectively. In laboratory rearing of P. sericeus on yellow birch seedlings, 18% of the initial 500 larvae completed development to adults.

Using bucket traps baited with 2-tetradecanone, the sex pheromone of Hoplia equina LeConte, an important pest of cranberries in Massachusetts, we investigated the effect of trap height, color, pheromone load, and lure aging on male capture, as well as captures of nontarget arthropods including pollinators. Male capture was inversely related to height of traps over the four heights tested (0, 20, 60, and 100 cm). Captures increased with increasing pheromone load over the doses of 0, 100, 300, and 600 μg, but captures at the highest load, 1,000 μg, were not significantly different from 300 or 600 μg. H. equina captures were strongly diurnal, with a flight period spanning ≈6 wk starting in mid-June. Vane color of traps (white, yellow, green, blue, red, black) did not affect H. equina capture but significantly influenced capture of nontargets, including pollinators. A bucket trap with the funnel opening at 20 cm, and green (or red) vanes, baited with 600 μg of 2-tetradecanone, was the optimal design for high male capture and low nontarget capture. The low-cost capture of over 50,000 H. equina on a 2.4-ha commercial bog in Massachusetts with this lure-trap combination indicates the feasibility of mass trapping for managing established infestations of H. equina.

Tribolium castaneum (Herbst) is a cosmopolitan pest of stored products, grain processing, and food warehouses. This study was initiated to more fully characterize the role of structure, sanitation, and trap location on capture of T. castaneum in pheromone-baited pitfall traps commonly used in insect monitoring programs. Food patches, spatial structure, and trap position were manipulated in pilot scale warehouses with a known density of insects. Significantly greater quantities of insects were captured in traps placed in warehouses without food patches than those with food patches. Insects tended to be captured with greater frequency in the corners and underneath shelves than in the middle of warehouses. Correlation between actual density and trap captures was stronger in warehouses without food patches, suggesting that sanitation is an important part of pest monitoring. Finally, placement of concrete blocks in the middle of the warehouse did not increase the number of beetles captured in that area compared with warehouses without concrete blocks. Results from this study should be considered when developing guidelines for trap interpretation.

The aphid Aphis glycines Matsumura, which was first observed in North America in 2000, is a pest of soybean, Glycine max L., in the United States and southern Canada. This study focused on the distribution and sampling of this aphid at two spatial scales: field and township. We sampled 14 soybean fields in each of two townships in Kendall and Champaign counties in Illinois on four sampling dates during the summers of 2001–2003. Generally, there was little synchrony of population dynamics (increases or decreases) across the fields in either township during the middle of the summers. There was significant field-to-field variability in mean number of aphids per plant. Thus, multiple fields must be sampled to accurately understand the infestation levels in a township. For Kendall Township in all years, drilled soybean fields always had the highest mean density at the second and third sampling dates, but fields with wide rows (0.61–0.76-m widths) had the highest mean density at the fourth date. However, row spacing had no significant influence on the mean density in most of the other analyses of variance. The probability of finding an infested field by mid-July when mean density in the township is less than two aphids per plant is 50% for Kendall County and 11% for Champaign County. Thus, at least two and 14 fields in Kendall and Champaign counties, respectively, must be sampled (50 plants per field) to have at least a 75% chance of finding a new invader in at least one infested field in a township during that period. Variance was related to mean number of aphids per plant, M, in a field by S² = 6.39911 × M^1.71779. This specific form of Taylor’s power law allowed us to calculate the appropriate sample sizes (plants/field) needed to obtain different levels of precision. Regression analysis showed no relationship between aphid density and distance from the field edge over the 50-m transects used in sampling. The relationship between the proportion of infested plants in a field, P, and mean aphid density, M, is represented by P = 1 − exp(−0.195764M). The proportion exceeds 0.99 for mean densities exceeding 24 aphids per plant in a field. Thus, our results suggest that aphids should be counted on 50 plants per field to obtain a reliable estimate of the population.

Field experiments were carried out in 2000 and 2001 in northern Italy, with the aim of developing a composite sampling strategy for estimating populations of Liriomyza huidobrensis (Blanchard) larvae and mines on lettuce. Larval parasitoid populations also were sampled to estimate the contribution of these beneficials to pest control. Covariance analysis and parallelism test indicated that there were not significant differences in the coefficient of Taylor’s power law between treatments (untreated versus treated) and between seasons (2000 versus 2001) for both pest and parasitoid stages. The slope of each regression was significantly >1 for L. huidobrensis mines and larvae, and endoparasitoid and ectoparasitoid larvae, indicating a clumped distribution of both pest and parasitoids. Constant precision level stoplines for mines and larvae of L. huidobrensis and for endoparasitoid and ectoparasitoid larvae were calculated, by using the common a and b derived from Taylor’s power law. Wilson and Room binomial sampling was used to estimate the mean number of L. huidobrensis mines or live larvae from the ratio of leaves with mines. In this way, it is possible to estimate the mean density of L. huidobrensis by counting the leaves with mines, an index parameter easy to obtain in field sampling. Validation of the presence-absence sampling plan by using field data collected in 2002 and 2003 seasons, showed that the Wilson and Room model fits very well empirical data. Statistical analysis does not show any significant difference between observed and predicted data.

Populations of red oak borer, Enaphalodes rufulus (Haldeman), a native wood-boring beetle, seem to be at unprecedented levels that are coinciding with extensive oak mortality occurring in the Ozark Mountains of Arkansas, Oklahoma, and Missouri. To quantify population levels, we developed intensive and extensive sampling methods with respect to the seasonal phenology of active and quiescent stages of the borer’s synchronous 2-yr life cycle. Intensive whole-tree sampling yields data for the entire infested tree bole and provides baseline data for development of less time-consuming sampling methods. Extensive partial-tree sampling uses a nine-sample proportional sampling scheme to estimate densities, which are extrapolated to the whole tree. Data comparison reveals extensive estimates and intensive data are not significantly different, thus verifying extensive sampling as a relatively accurate and acceptable sampling method. Preliminary data from 58 trees confirm epidemic population levels in three areas of the Ozark National Forest in northern Arkansas. Mean number of phloem galleries initiated by current generation larvae on 38 trees was 599 ± 50 (SE) per tree, average number of live red oak borer found in 57 trees was 77 ± 15 per tree, and mean number of previous generation heartwood galleries present in 38 trees was 185 ± 30. Data generated through this research will permit detailed studies of red oak borer biology and mortality, facilitate development of less time-consuming field sampling techniques, and set the stage for further study of factors contributing to the current outbreak and associated tree mortality.

The goal of this research was to describe within-plant distribution for Acyrthosiphon kondoi Shinji and Kondo on alfalfa (Medicago sativa L.). Alfalfa entries used in this study were from breeding lines selected for moderate and high levels of resistance to A. kondoi and from the susceptible cultivar ‘OK08’. From each of the three entries, three stems on each of 12 established alfalfa plants grown in pots were infested with aphids when stems had four to five nodes. At 2-d intervals through 10 d after infestation, stem heights, numbers of nodes per stem, and numbers of trifoliolates per node (as axillary branching occurred) were recorded. Also recorded for each node were numbers of A. kondoi on leaf blades, petioles, and the internodal stem section below the node. Aphid counts were analyzed to determine significant differences among alfalfa entries and among plant parts (leaf blades, petioles, and stem sections) within entries. Plant profiles were prepared to show within-plant distributions. Regression of mean aphid numbers versus days after infestation gave a highly significant (P < 0.01) slope for the susceptible alfalfa entry. Slopes for regressions calculated for moderately resistant and highly resistant entries were not significant (P = 0.07 and P = 0.89, respectively), indicating that aphid numbers did not increase significantly on these entries. Leaf blades were used most frequently as feeding sites on the resistant entries over the 10-d infestation period. However, the highest proportions of aphids were found on stems of susceptible plants. Plant profiles show that A. kondoi preferred stems or leaves along the mid-portions of the foliar canopy and trifoliolates near the plant terminals on all three alfalfa entries. Relatively few aphids occurred on nodes near the soil surface or on nodes near the tops of stems aside from the plant terminal.

Patterns of starch accumulation in alfalfa, Medicago sativa L., were studied in response to injury caused by potato leafhopper, Empoasca fabae (Harris). Using image analysis of iodine-stained leaf tissues, we compared lightness scores of leaves from leafhopper-injured and healthy plants sampled at early morning and mid-afternoon. In addition, we related lightness scores to standard chemical analyses for starch and sugar. The lightness scores were significantly related to starch concentrations but not to sugar concentrations. In the morning samples, all fully developed and developing leaves above the site of feeding indicated higher starch concentrations than comparable leaves on healthy plants. In contrast, all leaves from mid-afternoon samples and leaves below the site of feeding from morning samples did not significantly differ between injured and healthy plants. The observation that the lack of starch degradation during the night occurs in all tissues distal to the feeding site, and especially in developing leaves, suggests that the mechanism of starch accumulation is not just feedback from phloem blockage caused by leafhopper feeding but also a change in starch degradation in all chloroplasts without regard to source-sink status.

Four cultivars of broccoli (Brassica oleracea L. variety ‘italica’), two cultivars of early cauliflower (Brassica oleracea L. variety ‘botrytis’), four cultivars of late cauliflower, and one cultivar of red cabbage (Brassica oleracea L. variety ‘capitata’) were screened to determine some reproductive parameters of Aleyrodes proletella L. in a no-choice assay. The highest and lowest oviposition rates and production of pupae and adults were obtained with late cauliflower (cultivar Picasso) and red cabbage (cultivar Cabeza negra), respectively. The highest percentages of adult emergence (indicating survival from egg to adult) were obtained on broccoli (cultivar Chevalier) and late cauliflower (cultivars Mayfair and Picasso), whereas the lowest was obtained on late cauliflower (cultivar Arbon). In a choice experiment, A. proletella preferred late cauliflower (cultivar Picasso) and broccoli (cultivar Agripa) to red cabbage (cultivar Cabeza negra). Significantly more adults per day, and more pupae and empty pupal cases per plant, were found on broccoli and cauliflower cultivars than on red cabbage. In another no-choice assay at 22 ± 1.5°C, A. proletella required significantly more days for development on red cabbage than on broccoli and cauliflower cultivars. A. proletella developed significantly faster on broccoli cultivars Agripa and Chevalier and late cauliflower cultivars Mayfair and Picasso. These results suggest that it is important to minimize the use of broccoli (cultivars Agripa and Chevalier) and late cauliflower (cultivars Mayfair and Picasso) to avoid the risk of further expansion of whitefly populations where these Brassica crops and A. proletella are present.

Host-plant preferences were assessed by field measurement of grasshopper abundance in relation to measurements of floral community and by laboratory host-plant preferences. Correlations between grasshoppers and plants (biomass and percentage cover) were based on data gathered at 29 study sites in five distinct Florida habitats (including disturbed, freshwater marsh, high pine, oak hammock, and swamp). Relationships among plants in these habitats and 10 abundant grasshopper species were examined to clarify differences in grasshopper assemblages among habitats. The grasshoppers studied were Aptenopedes sphenarioides Scudder, Chortophaga australior (Rehn and Hebard), Eritettix obscurus (Scudder), Melanoplus bispinosus Scudder, Melanoplus querneus Rehn and Hebard, Paroxya clavuliger (Serville), Schistocerca americana (Drury), Schistocerca ceratiola Hubbell and Walker, and Spharagemon crepitans (Saussure). In addition to correlations among individual plants and the abundance of grasshoppers, multiple regression analysis was used to assess how groups of plants were related to grasshopper abundance. These analyses identified grasshopper-plant associations, but some plants were found to be host plants, whereas others were indicators of preferred habitats (indicator plants). Host-plant preferences were determined in the laboratory using five plant-choice tests to help distinguish between host and indicator plants. The 10 grasshopper species examined for laboratory host-plant preferences were the same species scrutinized in the field study. In almost every case, grasshoppers showed specific plant preferences, and the preference studies successfully distinguished between host plants and indicator species. Similar results were obtained whether biomass or percent cover measurements were used to assess the floral community, although percent cover is much easier and faster to determine.

The responses and impacts of five insect species that feed on Centaurea diffusa Lamarck, diffuse knapweed, to soil nitrogen and phosphorus additions were studied in grasslands east of the Colorado Front Range. We predicted that fertilization was unlikely to have a direct effect on herbivory but that if the insects preferentially select vigorous plants, increased tissue nitrogen, plant density, or plant mass resulting from fertilization would increase plant susceptibility to biological control insects. Fertilization caused a modest increase in the biomass of C. diffusa adults and the nutritive content of aboveground plant biomass. Larinus minutus Gyllenhal, a seed head weevil, was less abundant and exhibited reduced impacts on fertilized C. diffusa plants. Abundance of gall fly larvae, Urophora spp., was negatively influenced by the presence of L. minutus and had no detectable effect on seed abundance. No positive or negative impacts of root feeders on knapweed were observed, but the root-feeding Cyphocleonus achates (Fahraeus) selected plants in fertilized plots, whereas the root phytophage Sphenoptera jugoslavica Obenberger was more common on knapweed in unfertilized plots. Our results indicate that these specialist biological control insects exhibit little preference based on plant biomass, density, or nutritive quality. However, variables that affect the timing of knapweed seed production, such as fertilization, mowing, and grazing, reduce insect impacts and may explain some of the regional variation in effectiveness of these insects as biological controls on knapweed.