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Showing papers in "Environmental Entomology in 2002"


Journal ArticleDOI
TL;DR: Development of the coccinellid Stethorus punctillum Weise and the spider mite Tetranychus mcdanieli is studied, and results indicate potential synchrony between them.
Abstract: 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 developmen...

247 citations


Journal ArticleDOI
TL;DR: Field data collected from the major citrus-producing regions of Florida over the past 5 yr indicate that the introduction of the multicolored Asian lady beetle, Harmonia axyridis (Pallas), has increased in abundance while the formerly dominant Cycloneda sanguinea (L.) has declined.
Abstract: Field data collected from the major citrus-producing regions of Florida over the past 5 yr indicate that the introduction of the multicolored Asian lady beetle, Harmonia axyridis (Pallas), has increased in abundance while the formerly dominant Cycloneda sanguinea (L.) has declined. What is known of the diet breadth, habitat preferences, and thermal thresholds for development of these two species indicates considerable niche overlap. The larger H. axyridis has many intrinsic advantages over C. sanguinea, including higher fecundity and fertility, and a lower rate of larval cannibalism. In laboratory tests, adults and larvae of H. axyridis consumed eggs of C. sanguinea more readily than vice versa. All H. axyridis adults provided with either a conspecific or a heterospecific second-instar larva killed and ate it, whereas only 15% of C. sanguinea adults consumed a second-instar larva of H. axyridis over a 24-h period. Larvae of H. axyridis were more aggressive against larvae of C. sanguinea in laboratory tests than vice versa; even when H. axyridis larvae were paired with a C. sanguinea larva 2 d older and two to three times as large, they won 67% of contests. In choice tests, larvae of both species preferred to feed on dead C. sanguinea larvae than on dead H. axyridis larvae. Larvae of H. axyridis were capable of completing development exclusively as intraguild predators on C. sanguinea larvae, whereas the reverse was not true. The data suggest that H. axyridis is a highly evolved interspecific competitor, whereas C. sanguinea is adapted more to intraspecific competition and has few defenses against H. axyridis. Competitive displacement of C. sanguinea by H. axyridis appears to be in progress in the citrus ecosystem in Florida.

237 citations


Journal ArticleDOI
TL;DR: Investigating the effect of plot-based and unrestricted (plot-less) sampling on an inventory of a megadiverse taxon, spiders, in an Afrotropical forest for the purpose of species richness estimates found collector experience did affect the number of species collected per hour and thereby overall species composition of the sample but was less important than sampling methods used and time of day.
Abstract: Environ. Entomol. 31(2): 319Ð330 (2002) ABSTRACT We investigated the effect of plot-based and unrestricted (plot-less) sampling on an inventory of a megadiverse taxon, spiders, in an Afrotropical forest for the purpose of species richness estimates. We also investigated the efÞciency of human-based sampling methods and the effect of allocation of sampling effort to different sampling methodsto cover asmany microhabitatsaspossible. In the 10-d sampling period in the montane forest of the Uzungwa Scarp Forest Reserve in Tanzania, eight collectors sampled spiders for 350 h and 800 pitfall "trap-days." Two hundred hoursof sampling were restricted to a 1-ha plot and 150 h of sampling took place outside the plot. The sampling team included both experienced and inexperienced collectorsusing Þve different hand collecting methods during day and night sampling periods. Sampling yielded 9,096 adult spiders representing 170 species in total. Number of species and adult spiders per sample and overall species composition depended mainly on the sampling methods used and time of day. Whether the sampling took place within or at random outside the plot did not affect species composition or number of species per sample. Collector experience did affect the number of species collected per hour and thereby overall species composition of the sample but was less important than sampling methods used and time of day.

189 citations


Journal ArticleDOI
TL;DR: The CLIMEX model was used to infer the climatic requirements of the Mediterranean fruit fly, Ceratitis capitata, from the fruit fly’s observed geographical distribution, and a global risk map for medfly was produced, which highlights the areas at risk from this major quarantine pest.
Abstract: The CLIMEX model was used to infer the climatic requirements of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), from the fruit fly’s observed geographical distribution in the Mediterranean region. The model indicated that the potential distribution was limited by cold to the north in Europe and by dryness in northern Africa and in the south of Spain and Portugal. The model was then used to estimate the potential geographical distribution of the species in Argentina and Australia. The results agreed with the observed distribution in Argentina and much of the historical distribution in Australia, but they did not agree with the present distribution in eastern Australia. In the latter region, another species of fruit fly, Bactrocera (Dacus) tryoni (Froggatt) has been credited with displacing C. capitata. Seasonal and year-to-year variation in climatic suitability was explored at three selected locations in Argentina. The results indicated that some detrimental effects of summer temperat...

168 citations


Journal ArticleDOI
TL;DR: For the purposes of ecological monitoring, using more small pitfall traps would be the most efficient sampling technique to characterize the dominant epigaeic arthropod fauna; small traps collect few nontarget vertebrates, and sorting the samples involves generally less processing time.
Abstract: Cost-effective and ecologically sensitive monitoring techniques are required to assess effects of anthropogenic disturbances on biodiversity. Pitfall trapping is widely used in biodiversity monitoring programs to measure the diversity of organisms active within leaf-litter. We compared catch rates and species richness of ground beetles (Coleoptera: Carabidae), rove beetles (Coleoptera: Staphylinidae), and spiders (Araneae) across five different diameters of pitfall traps (4.5, 6.5, 11, 15, and 20 cm) and three sizes of rain covers (64, 79.2, and 225 cm2) to determine optimal trap size for studying litter-dwelling arthropod biodiversity. In general, larger pitfall traps collected more individuals, and more species, of all three taxa. Further tests on data standardized to trap circumference showed that catch rates are not directly proportional to trap size, and even the smallest traps collected a disproportionately high number of certain taxa. When catch rate data were standardized by trap circumference smaller traps collected more small-bodied carabid and staphylinid species and large traps collected more wolf spiders (Lycosidae) than smaller traps. Roof size had no effect on species richness or catch rate of beetles or spiders. For the purposes of ecological monitoring, using more small pitfall traps would be the most efficient sampling technique to characterize the dominant epigaeic arthropod fauna; small traps collect few nontarget vertebrates, and sorting the samples involves generally less processing time. From a conservation perspective, however, including several large pitfall traps in the sampling regime would help detect rare species.

148 citations


Journal ArticleDOI
TL;DR: The entrenched paradigm that fertilization enhances the insect resistance of woody plants in ornamental landscapes needs to be reassessed.
Abstract: Woody plants are commonly fertilized in ornamental landscapes, based in part on the rationale that fertilization enhances pest resistance. However, a critical evaluation of evidence finds little to support this claim. Rather, many studies have found that fertilization decreased woody plant resistance to spider mites, sap sucking insects, mandibulate folivores, subcortical feeding insects, and browsing mammals by enhancing the nutritional quality of the plant and/or decreasing secondary metabolite concentrations. The growth/differentiation balance hypothesis (GDBH) postulates a physiological trade-off between growth and secondary metabolism, and predicts a parabolic response of secondary metabolism to variation in nutrient availability. Specifically, fertilization of moderately nutrient-deficient plants is predicted to decrease secondary metabolism if growth is increased but photosynthesis is not affected. However, fertilization of extremely nutrient-limited plants is predicted to increase secondary metabolism if photosynthesis is also increased. A number of studies have found fertilization to increase growth and decrease secondary metabolism. A few studies on extremely nutrient-deficient sites found fertilization to increase foliar secondary metabolism, but insect performance was not affected, possibly because increased foliar nitrogen counteracted effects of secondary metabolites on host quality. These studies, while consistent with the GDBH, do not represent adequate tests because none measured effects of fertilization on photosynthesis as well as growth. Only a few studies have addressed effects of fertilization on the ability of woody plants to tolerate herbivory, and all found fertilization to have no effect. The entrenched paradigm that fertilization enhances the insect resistance of woody plants in ornamental landscapes needs to be reassessed.

147 citations


Journal ArticleDOI
Graham P. Head1, James B. Surber1, Jon A. Watson1, John W. Martin1, Jian J. Duan1 
TL;DR: 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.
Abstract: 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.

140 citations


Journal ArticleDOI
TL;DR: Survival and development time from egg to adult emergence of the diamondback moth, Plutella xylostella, were determined at 19 constant and 14 alternating temperature regimes from 4 to 40°C.
Abstract: Survival and development time from egg to adult emergence of the diamondback moth, Plutella xylostella (L.), were determined at 19 constant and 14 alternating temperature regimes from 4 to 40°C. Plutella xylostella developed successfully from egg to adult emergence at constant temperatures from 8 to 32°C. At temperatures from 4 to 6°C or from 34 to 40°C, partial or complete development of individual stages or instars was possible, with third and fourth instars having the widest temperature limits. The insect developed successfully from egg to adult emergence under alternating regimes including temperatures as low as 4°C or as high as 38°C. The degree-day model, the logistic equation, and the Wang model were used to describe the relationships between temperature and development rate at both constant and alternating temperatures. The degree-day model described the relationships well from 10 to 30°C. The logistic equation and the Wang model fit the data well at temperatures 32°C. Under alternating regimes, all three models gave good simulations of development in the mid-temperature range, but only the logistic equation gave close simulations in the low temperature range, and none gave close or consistent simulations in the high temperature range. The distribution of development time was described satisfactorily by a Weibull function. These rate and time distribution functions provide tools for simulating population development of P. xylostella over a wide range of temperature conditions.

138 citations


Journal ArticleDOI
TL;DR: Red imported fire ants enhance cotton aphid survival and density in the field through predator interference, and with the addition of fire ants to aphid-predator treatments, Aphid survival approximately doubled.
Abstract: Red imported Þre ants, Solenopsis invicta (Buren) (Hymenoptera: Formicidae), are an invasive species found in high densities throughout southeastern agricultural systems. We tested the hypothesis that Þre ants tend cotton aphids, Aphis gossypii Glover (Homoptera: Aphididae), and thus release them from predation by lady beetle larvae, Coccinella septempunctata L. and Hippodamia convergens Guerin-Meneville (Coleoptera: Coccinellidae), and green lacewing larvae, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae). Fire ants preferentially foraged on aphid-infested cot- ton, Gossypium hirsutum L., plants (x 103 47 ants per plant) compared with plants without aphids (x 5 3 ants per plant). In caged greenhouse experiments, Þre ants reduced survival of lady beetle larvae by 92.9% and green lacewing larvae by 83.3%. Furthermore, strong mortality imposed on aphid predators by Þre ants affected aphid survival. With the addition of Þre ants to aphid-predator treatments, aphid survival approximately doubled. In a Þeld experiment, predator larvae were more abundant in cotton plots with experimentally suppressed densities of Þre ants (0.62 0.11 lady beetle larvae per sample; 0.06 0.02 lacewing larvae per sample) than in plots with high Þre ant densities (0.23 0.06 lady beetle larvae per sample; 0.01 0.01 lacewing larvae per sample). Conversely, cotton aphids were more abundant in high Þre ant density Þeld plots (x 6.83 0.03 aphids per leaf) than in low Þre ant density plots (x 4.04 0.03 aphids per leaf). These data suggest that red imported Þre ants enhance cotton aphid survival and density in the Þeld through predator interference.

124 citations


Journal ArticleDOI
TL;DR: It is shown that dense trichome and pollen levels are favorable to the development of K. aberrans populations and perspective is added on the influence of domatia on this important predaceous mite.
Abstract: We sampled phytoseiid mites (densities, diversity, and age structure) on several plants located in four uncultivated areas surrounding vineyards over 3 yr to determine how leaf structure affects populations. The plant composition of these areas greatly influenced the numbers and species of phytoseiids present. The relationships between leaf structure (trichome, pollen densities, number, and structure of domatia, leaf surface) and Kampimodromus aberrans (Oudemans) densities also were studied. The frequency of occurrence and the abundance of K. aberrans per cm2 were correlated to high trichome densities. A complex phylloplane (many hairs and shelters or domatia) could confer a competitive advantage to K. aberrans over other phytoseiid mite species. The number and the rating of domatia were important to K aberrans development; high proportions of immatures were observed only on plants with these structures. Pollen densities were significantly correlated to trichome densities; domatia structure had only a somewhat lesser effect. Our study shows that dense trichome and pollen levels are favorable to the development of K. aberrans populations and add perspective on the influence of domatia on this important predaceous mite.

123 citations


Journal ArticleDOI
TL;DR: The complex of predators feeding on lepidopteran eggs [Helicoverpa zea (Boddie)] and the key predators discovered in this study were different in each crop and the period of peak egg predation did also.
Abstract: Predation on lepidopteran eggs in soybean and corn and the temporal partitioning of predation among the predator species were examined in soybean Glycine max (L.) and sweet corn Zea mays (L.). The complex of predators feeding on lepidopteran eggs [Helicoverpa zea (Boddie)] and the key predators discovered in this study were different in each crop. The dominant predator in each crop was consistent from year to year but the secondary predators varied in importance. Nabids were the dominant predator group in soybean contributing 51 and 50% of the observed predation events in 1993 and 1994, respectively. The coccinellid, Coleomegilla maculata (DeGeer), was the dominant predator in corn contributing 43.9 and 46.3% of the observed predation events in 1993 and 1994, respectively. Other predators causing ≥10% of the observed predation events included Geocoris punctipes Say and the Phalangiidae in soybean, and the nabids, Orius insidiosus Say and Lygus lineolaris (Palisot de Beauvois) in sweet corn. All p...

Journal ArticleDOI
TL;DR: The data demonstrate that induction responses negatively affected both Pieris and Phyllotreta and suggest that trichomes may be relatively important in the increased resistance.
Abstract: This study addressed whether prior damage to black mustard, Brassica nigra (L.) Koch, would reduce growth, herbivory, or mortality of two specialist herbivores on new leaves. Plants received either no initial damage or 12 h of feeding by two third instars of Pieris rapae (L.) or 50 adult Phyllotreta cruciferae (Goeze) when plants had four leaves. Later, the seventh leaf of plants was either harvested for measurement of trichome density and glucosinolate concentration or enclosed in a mesh cage containing two neonate P. rapae or 10 adult P. cruciferae. Caged herbivores were measured for mass gain, leaf consumption, and mortality after 1 wk. Damage by P. rapae caused substantial increases in trichome density and sinigrin concentration, whereas damage by P. cruciferae had no effect. Larvae of P. rapae grew 30% more slowly on plants initially damaged by conspecifics than on control plants. Percent herbivory by P. rapae was 33% lower on plants initially damaged by either P. rapae or P. cruciferae than on control plants. Growth rate and percent herbivory by P. cruciferae were not generally affected by prior plant damage. However, mortality of P. cruciferae was 84% higher on plants previously damaged by conspecifics than on control plants. Together, the data demonstrate that induction responses negatively affected both Pieris and Phyllotreta and suggest that trichomes may be relatively important in the increased resistance. Test herbivores generally performed similarly on plants damaged by either herbivore, suggesting a low specificity of effect for the induction response.

Journal ArticleDOI
TL;DR: It is concluded that the impact of Cry3Bb-expressing transgenic corn pollen (event MON863) did not detect any effects on the fitness of C. maculata that ingested pollen, and these results do not necessarily apply to other transgenic crops expressing toxins specific to Coleoptera.
Abstract: Coleomegilla maculata DeGeer is a polyphagous predator that is important for suppressing pest populations in corn. We evaluated the impact of Cry3Bb-expressing transgenic corn pollen (event MON863) on C. maculata fitness parameters in the laboratory. C. maculata larvae were fed mixtures of pollen containing 0, 25, 50, 75, or 100% transgenic pollen, aphids, or were not fed; and the duration of each instar and pupal weight were compared among treatments. In a second trial, other C. maculata larvae were reared on one of the pollen mixtures or artificial diet; and the duration of larval and pupal stages, pupal weight, adult mobility, adult survivorship, and female fecundity were compared among treatments. There were no differences in any of the fitness parameters among C. maculata in the treatments fed different mixtures of pollen. Beetles in the pollen mixture treatments had faster larval development times, greater larval survivorship, and greater pupal weight than the beetles fed only aphids or an artificial diet. We conclude that we did not detect any effects on the fitness of C. maculata that ingested pollen from event MON863. However, these results do not necessarily apply to other transgenic crops expressing toxins specific to Coleoptera.

Journal ArticleDOI
TL;DR: It is suggested that red imported fire ants are major intraguild predators of important beneficial arthropods in cotton.
Abstract: The red imported fire ant, Solenopsis invicta (Buren), is an invasive species in the southern United States and is expanding its range westward to California and eastward up the Atlantic Coast. This voracious predator can reach extremely high densities and have widespread effects once it invades an ecosystem. We conducted a 2-yr sampling study and a series of greenhouse and field experiments to document the impact of red imported fire ants on beneficial insects in cotton. We found that the densities of 12 of 13 natural enemies sampled on cotton plants in 1999, and 8 out of 8 sampled in 2000, were negatively correlated with the densities of foraging fire ant workers. Red imported fire ants reduced the survival of lady beetles (Coccinella septempunctata L., and Hippodamia convergens Guerin-Meneville) (Coleoptera: Coccinellidae) by 50% and green lacewing larvae (Chrysoperla carnea Stephens) (Neuroptera: Chrysopidae) by 38% in greenhouse experiments. Fire ants did not, however, reduce the survival of spiders (Oxyopidae, Thomisidae, and Clubionidae). We used a commercially available fire ant bait to suppress fire ant populations in cotton fields during the 2000 growing season and compared the densities of beneficial arthropods in treated versus control fields. Densities of lady beetles, spiders, and big-eyed bugs (Heteroptera: Geocoridae) were significantly higher in fields with suppressed fire ant populations than in fields with relatively large fire ant populations. The effect of fire ants on minute pirate bugs (Heteroptera: Anthocoridae) was inconsistent, and populations of damsel bugs (Heteroptera: Nabidae) and hooded beetles (Coleoptera: Anthicidae) were not affected by fire ant suppression. The results of this study suggest that red imported fire ants are major intraguild predators of important beneficial arthropods in cotton.

Journal ArticleDOI
TL;DR: It is concluded that the structure of the landscape matrix plays an important role in determining the abundance of aphid predators in alfalfa fields, as does the plant community in a field.
Abstract: We used multiple regression modeling to investigate the numerical response by the predatory insects Hippodamia convergens Guerin-Meneville, H. parenthesis (Say), and C. septempunctata L. (Coleoptera: Coccinellidae), Chrysoperla plorabunda (Fitch) (Neuroptera: Chrysopidae), and Nabis americoferus Carayon (Hemiptera: Nabidae) to aphids during 5 yr in three geographically separated alfalfa fields in eastern South Dakota. Regression models for abundance of adults of all species were significant. Regression models for immature H. convergens, H. parenthesis, and C. septempunctata were significant, but regression models for immature C. plorabunda and N. americoferus were not significant. Regression parameters differed among the three fields for most predator species, indicating that the numerical response was dependent on geographical location. To obtain insight into why the numerical response by predators differed among fields we determined how the abundance of predators in alfalfa fields was influenced by the landscape surrounding a field and the vegetation in it. Variables describing the complexity of the landscape surrounding alfalfa fields and the plant community in the fields entered into regression models for predator abundance and explained a greater proportion of the variance in predator abundance than aphid abundance did. We conclude that the structure of the landscape matrix plays an important role in determining the abundance of aphid predators in alfalfa fields, as does the plant community in a field. These effects can sometimes overshadow the direct numerical response by predators to aphids.

Journal ArticleDOI
TL;DR: Neem extract may be compatible with integrated pest management programs in citrus and should be evaluated for field efficacy because parasite emergences were similar between treated and untreated parasitized aphids.
Abstract: 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...

Journal ArticleDOI
TL;DR: Type of tillage appeared to be the primary factor affecting survival of endemic soil entomopathogens in the authors' system, but other factors, such as pesticide use and type of ground cover, can negate the positive effects of strip-tillage.
Abstract: 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. Typ...

Journal ArticleDOI
TL;DR: Catches of species requiring relatively fresh host tissue were reduced by verbenone, whereas catches of species accepting aged tissue were unaffected, consistent with differences in host-age preference.
Abstract: The response by five species of bark beetles to a range of verbenone doses were tested in bioassays using Lindgren funnel traps baited with attractant semiochemicals. The objective was to determine how these bark beetles respond to verbenone, a purported anti-aggregation pheromone of several economically significant bark beetle species. Catches of Dendroctonus ponderosae Hopkins, a species attacking live trees, were unaffected relative to a control trap (no verbenone) at release rates of 0.2 mg/24 h or less, but were significantly reduced at rates of 1.8 mg/24 h or more. Catches of Ips pini (Say) and I. latidens (LeConte), two opportunistic species normally attacking fresh, dead host material, were gradually reduced with increasing verbenone dose. Verbenone did not affect catches of Hylurgops porosus (LeConte) and Hylastes longicollis Swaine, two species normally associated with bark in contact with the ground, where saprophytic microorganisms quickly invade phloem tissue. The effect by verbenone on catches of the five species was consistent with differences in host-age preference. Catches of species requiring relatively fresh host tissue were reduced by verbenone, whereas catches of species accepting aged tissue were unaffected.

Journal ArticleDOI
TL;DR: It is suggested that changes in foraging substrate, prey availability or microclimatic conditions since fire may have interacted with life history characteristics to influence the abundance of these organisms.
Abstract: The objective of this study was to determine if prescribed fire affects spider (Araneae) and carabid beetle (Carabidae) abundance, and whether the magnitude of this effect varies with time since fire. Within mixed conifer stands, nine understory fuels-reduction burns, ranging from 120 species, and 14,793 carabid beetles from 17 species, were identified from the samples. Seven spider families and five species of carabid beetles were abundant enough to be analyzed statistically. Four spider families were more abundant in unburned sites (Antrodiaetidae, Cybaeidae, Thomisidae and Linyphiidae) while three families were more numerous in burned sites (Lycosidae, Gnaphosidae and Dictynidae). Four of five carabid beetle species were more abundant in unburned sites [Pterostichus herculaneus Mannerheim, P. setosus Hatch, Scaphinotus rugiceps rugiceps (Horn) and Zacotus matthewsii LeConte]. There was no difference found for Omus cazieri van den Berghe. No differences in species richness or diversity (Simpson, Shannon-Wiener and Berger-Parker indices) were found for spiders or carabid beetles. Overall, the relationship between abundance and time since burning was weak, with marginal significance found only for Dictynidae and Gnaphosidae. We suggest that changes in foraging substrate, prey availability or microclimatic conditions since fire may have interacted with life history characteristics to influence the abundance of these organisms. Differences in fire intensities among years may have masked patterns in arthropod abundance associated with time since burning.

Journal ArticleDOI
TL;DR: Longevity significantly decreased for Orius tristicolor White and Geocoris punctipes Say and no effect was found for Nabis sp.
Abstract: The management of agroecosystems affects intricately linked assemblages of organisms, and nontarget species are not necessarily unimpacted. We examined the effect of Bt-cotton and of lepidopteran prey (Spodoptera exigua Hubner) that had ingested it on the adult survivorship of four important heteropteran predators of cotton pests. Longevity significantly decreased for Orius tristicolor White and Geocoris punctipes Say (by 28 and 27% of the control value, respectively), whereas no effect was found for Nabis sp. and Zelus renardii Kolenati. This finding contrasts with the results of previous studies in which Orius spp. and G. punctipes were either fed only plant material or nonlepidopteran prey. S. exigua is a lepidopteran with low susceptibility to the Bt toxin expressed in cotton and therefore exemplifies the possible effect on predators of lepidopteran pests that would become resistant to Bt. The importance of Bt toxin type, the difference between plants and prey and between different prey species as routes of ingestion of Bt toxins, and the need for studies assessing the population and ecosystem-level effects of Bt cotton are discussed.

Journal ArticleDOI
TL;DR: Females laid more eggs and survived longer in the laboratory on sugar maple, Acer saccharum Marshall, than has generally been reported for this tree species, and Larval food source and quality had significant effects on female fecundity and longevity.
Abstract: Reproductive traits and longevity of Anoplophora glabripennis (Motschulsky) from the Ravenswood, Chicago, IL, and Bayside, Queens, NY, populations were compared for first-generation adults that emerged from cut infested wood and for second-generation adults that were reared on artificial diet. Illinois females were significantly more fecund than those from New York when they emerged from infested wood and tended to be more fecund when reared on artificial diet. Weights of adult females that emerged from infested wood varied with the hosts they emerged from; but when reared on artificial diet, Illinois females were significantly heavier than New York females. There were no significant differences between the two populations in egg viability or adult longevity. In general, females laid more eggs and survived longer in the laboratory on sugar maple, Acer saccharum Marshall, than has generally been reported for this tree species. Larval food source and quality had significant effects on female fecundity and longevity. The above differences between the two populations and the effects of host quality and host species should be taken into account when management decisions are made in the current eradication program for A. glabripennis in the United States.

Journal ArticleDOI
TL;DR: Investigation of the reproductive characteristics of Anoplophora glabripennis on Norway maple, red maple, and black willow found differences were found in preovipositional period, fecundity, egg viability and survival among the host-tree species, and hypothesize bark thickness and woody-tissue characteristics caused the observed differences in survival and reproduction.
Abstract: 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.

Journal ArticleDOI
TL;DR: Most beneficial taxa, even Geocoris uliginosus, which was more common in turfgrass, were represented in flowers, suggesting that these floral plantings may be useful in providing refugia for beneficials when insecticide applications are required to suppress turfgrass pests.
Abstract: Conservation and augmentation of indigenous natural enemies are promising strategies for biologically based pest management in outdoor urban environments. This research sought to determine whether the addition of wildflower plantings would enhance the occurrence, abundance and impact of beneficial arthropods in the landscape, and to determine the potential compatibility of pest-resistant turfgrass and natural control of Japanese beetle, Popillia japonica Newman, and fall armyworm, Spodoptera frugiperda (J.E. Smith). A bermudagrass cultivar (susceptible to fall armyworm), a zoysiagrass cultivar (resistant to fall armyworm), and two different commercially available wildflower mixes all harbored a diverse array of beneficial arthropods in both large and small plot evaluations. A wildflower mix containing 15 species of flowers provided significant, season-long increases in foliar-dwelling spiders and bigeyed bugs during 1-yr of a 2-yr study in large (1,512 m2) plots. Ground-dwelling spiders were more...

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TL;DR: The 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.
Abstract: 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 queenOs hypothesized ability to restrict food provi- sioning. 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 signiÞcant 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.

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TL;DR: Overall, female parasitoids parasitized, on average, <1 egg/h, except when they foraged 4 h in the presence of 16 eggs, and plant structure affects host-encountering success, which operates by increasing costs associated with host finding.
Abstract: While searching for hosts on plants, female parasitoids meet different plant structures and host densities that will influence their host finding success. In this study, we determined whether plant structure, host density, and foraging duration influenced the percentage of Ephestia kuehniella Zeller eggs parasitized by Trichogramma evanescens Westwood. One female was introduced to forage either 4 or 24 h on artificial plants of three different structures (simple, intermediate, and complex) on which 4 or 16 host eggs were glued. Plant structure influenced rate of parasitism in both foraging durations, whereas host density was found to be significant only when female had 4 h to forage. Mean rate of parasitism generally decreased with an increase in complexity of plant structure and host density in both foraging durations. Almost twice as many eggs were parasitized on simple plants compared with complex plants for all host densities and foraging durations. Overall, female parasitoids parasitized, on average, <1 egg/h, except when they foraged 4 h in the presence of 16 eggs. Plant structure therefore affects host-encountering success. Physical structure of a plant mediates ecological interactions and is involved in parasitoid-host population dynamics. It operates by increasing costs associated with host finding.

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TL;DR: Whereas coleopterans appeared most influenced by plant community composition, orthopterans showed sensitivity to mechanical disturbance associated with haying on native prairie, demonstrating that arthropod groups can reflect differences in a landscape that may not be apparent from examining plant communities alone.
Abstract: Macroinvertebrate communities in a central Kansas grassland were examined to assess their responses to differences in land management and explore their viability for biological assessment of grasslands. Canopy (drop-trap) and ground-dwelling (pitfall traps) communities were quantitatively sampled from June-September 1998 and 1999. The responses of the whole arthropod community and two focal groups, Coleopteran families and Orthopteran species, to three land use types (brome fields, old fields, and native prairies) were examined. Vegetation analyses reflected clear differences among land use types. Bromus inermis Leyss, an exotic grass, and Andropogon gerardii Vitman, a native grass, dominated brome fields and native prairie sites, respectively. Old fields were composed of a mixture of native and exotic plant species. Coleopteran family richness and diversity were significantly greater in native prairies than brome fields (P < 0.05), whereas orthopteran species richness and diversity peaked in brome fields. Diversity and richness of all arthropod groups examined were significantly, positively correlated with plant species diversity and richness in drop-trap samples (P < 0.05). Coleopteran family diversity and richness in pitfall samples were positively correlated with abundance of native plants, but orthopteran species diversity and richness were negatively correlated with native plant abundance. Coleopteran and orthopteran responses to land use appeared linked to differences in management practices. Whereas coleopterans appeared most influenced by plant community composition, orthopterans showed sensitivity to mechanical disturbance associated with haying on native prairie. Plant and arthropod group diversities were not consistently correlated, demonstrating that arthropod groups can reflect differences in a landscape that may not be apparent from examining plant communities alone.

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TL;DR: The results showed that the four fungi tested are susceptible to various glyphosate formulations when exposed to field concentrations, and RoundUp Ready-To-Use was consistently the glyphosate formulation with one of the strongest fungicidal properties.
Abstract: Fungicidal effects of glyphosate and glyphosate formulations on the entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin, Metarhizium anisopliae (Metchnikoff) Sorokin, Nomuraea rileyi (Farlow) Samson, and Neozygites floridana Weiser & Muma were evaluated under laboratory conditions. Media previously inoculated with entomopathogenic fungi were exposed to distilled water, glyphosate (active ingredient), seven glyphosate formulations, and five blank formulations (carrier only). The fungicidal activity was determined by measuring inhibition in mycelial growth in solid media (B. bassiana, M. anisopliae, and N. rileyi), and spore concentration in liquid medium (N. floridana). Glyphosate did not have fungicidal activity against any of the fungi tested. Fungicidal properties of glyphosate formulations varied among fungal species. Neozygites floridana and M. anisopliae were susceptible to all glyphosate formulations. RoundUp Ready-To-Use was consistently the glyphosate formulation with one of the...

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TL;DR: It is concluded that the Colorado potato beetle has considerable variation in both the incidence and duration of prolonged dormancy, and that this variation has strong environmental and genetic determinants.
Abstract: This 10-yr field study examined prolonged dormancy (dormancy of more than 1 yr) in Colorado potato beetles, Leptinotarsa decemlineata (Say), from Upstate New York. The research focused on whether the life cycle of the Colorado potato beetle could reduce the effectiveness of crop rotation as a pest management tactic. One set of experiments quantified variation in the occurrence and duration of prolonged dormancy in a natural population. A second set of experiments tested the effect of artificial selection for increased incidence of prolonged dormancy. Of the ≈12,600 unselected beetles in the field cages overall survival (= % emergence) averaged 56.5 ± 18.4% (mean ± SD, range = 23.5–84.3%, n = 19 cages). Most (97.7%) of the emerging beetles surfaced after one winter; the remainder (2.3%) emerged after more than one winter in dormancy. The range of variation in the incidence of prolonged dormancy among the experimental cages during the 10-yr period was 0–7.2%. The incidence of emergence from prolong...

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TL;DR: Study in a perennial stream in the foothills of Chiang Mai province, northern Thailand concludes that factors other than those measured here may account for a large part of the variation in larval density.
Abstract: 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: ymin = 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 ...

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TL;DR: Egg and larval survivorship of Carposina sasakii Matsumura in fruits was investigated, and its effects on adult population dynamics was examined by comparing the seasonal adult population trends in apple and peach orchards.
Abstract: Egg and larval survivorship of Carposina sasakii Matsumura in fruits was investigated, and its effects on adult population dynamics was examined by comparing the seasonal adult population trends in apple and peach orchards. Egg survivorship was relatively high and did not differ among fruits, cultivars, and seasons. However, larval survivorship in fruits was very low according to fruits, cultivars, and seasons. In late apple (‘Fuji’), no larvae survived inside fruits during mid- to late June, and larval survivorship in mid-July was very low (2.0%). In early apple (‘Tsugaru’) and early peach (‘Kurakatawase’), larval survival was 18.1 and 43.7% during mid- to late June, respectively. However, in late peach (‘Hakuto’), it was much lower (4.5%). The mean numbers of degree-days between the first and the last adult flight peaks were significantly different among different orchard systems. Significantly more degree-days occurred in apple (1029.8 DD) and apple-peach adjacent orchards (939.2 DD) than in peach orchards (681.0 DD). This could have been caused by high larval mortality in apples during the early season, and a mixture of both multivoltine and univoltine components contributing to C. sasakii overall population dynamics. Implications for management of C. sasakii in diverse fruit systems are discussed.