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A plant extract from kudzu, Pueraria lobata (Willd.) Ohwi (Fabaceae), was tested as a UV protectant for the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), nucleopolyhedrovirus (SeMNPV), with and without the addition of an oil/emulsifier (cottonseed oil/lecithin) formulation. Aqueous and oil emulsion formulations of SeMNPV were applied to collards and the residual virus activity was determined for 7 d. Sunlight exposure of SeMNPV resulted in an activity loss of 42%, 85%, and 95% at days 2, 4, and 7, respectively. The addition of the oil/emulsifier to SeMNPV did not provide UV protection. At days 2, 4, and 7, activity losses were 67%, 84%, and 92%, respectively. Whereas the addition of kudzu (5%) to SeMNPV provided significant UV protection during the sunlight exposure period, activity losses of 17%, 62%, and 76% occurred at days 2, 4, and 7, respectively. The greatest UV protection for SeMNPV was achieved when cottonseed oil/lecithin were used in conjunction with kudzu. In this formulation, activity losses were 2%, 40%, and 55% at days 2, 4, and 7, respectively. Although the mode of action is currently unknown, the addition of cottonseed oil to kudzu resulted in an increase of both UVB (280 - 320 nm) and UVA (320 - 400 nm) absorbance.
The impact of adult weight, age, and density on reproduction of Tenebrio molitor L. (Coleoptera: Tenebrionidae) was studied. The impact of adult weight on reproduction was determined by: (1) counting the daily progeny of individual adult pairs of known weight and analyzing the data with linear regression and (2) creating 5 weight classes of 10-mg intervals starting at 60 mg (60 - 69.9mg) and ending at 100 mg (100 - 109.9 mg), then the progeny of 10 groups of 5 males and 5 females of each weight class were compared using ANOVA. To determine the impact of adult density on reproduction, adults were grouped at 8 different densities by increasing numbers per box (at 1:1 sex ratio). Weekly progeny production of 8 groups per density treatment was compared using ANOVA. There was no significant relationship between female weight and progeny production in the individual pair analysis. Fecundity was significantly different among weight classes, but the relationship was not linear. Adult density had a significant impact on progeny per female and progeny per unit area. Reproductive output per female decreased as adult density increased. Progeny per unit area increased to a maximum at a density of 14 adults/dm2 and then declined sharply. Adult age had a significant impact on reproduction. The highest reproductive output occurred at 2 and 3 wk of age and was significantly higher than at any other age. Adult density and age may be manipulated to maximize production of T. molitor larvae.
Amblyomma maculatum Koch is the primary vector in the United States for Rickettsia parkeri, an emerging human pathogen, as well as Hepatozoon americanum, a protozoan causing disease in canines. We evaluated the host preference and feeding success of immature A. maculatum for 3 potential host species, the Carolina anole (Anolis carolinensis Voigt), the bobwhite quail (Colinus virginianus Linnaeus), and the hispid cotton rat (Sigmodon hispidus Say and Ord). To determine host preference, ticks were given an option of two different hosts at a time. No ticks fed on anoles in the host preference study and no significant difference in preference could be determined for rats compared with quail. In a separate experiment to study feeding success, we placed ticks directly onto 10 individual animals of these same species. No ticks fed on anoles. Larvae did not statistically differ in number of days to engorge when feeding on rats (5.7 d) compared with quail (5.6 d). Nymphs, however, took significantly longer to engorge on rats (8.2 d) than on quail (7 d). Engorged larvae from rats and quail were not statistically different in weight, whereas nymphs that engorged on rats were significantly heavier (15.8 mg) than those from quail (13.2 mg). Engorged larvae and nymphs did not significantly differ in their molting success between hosts. Results of this study suggest that anoles were not good hosts for immature stages of A. maculatum. No clear host preference was identified for quail or cotton rats, although differences in time-to-engorgement and engorged specimen weights were noted.
Effects of 7 concentrations of chlorpyrifos (Dursban 50W), halofenozide (Mach 2) and spinosad (Conserve SC) were tested on bigeyed bugs (Geocoris spp.: Heteroptera: Geocoridae) in bioassays with or without turfgrass as a potential moderating influence. Survival of bigeyed bugs was recorded at 1, 3, 7 and 10 d posttreatment. In a bioassay without turfgrass, the lowest chlorpyrifos dose of 62.5 ppm resulted in 100% adult bigeyed bug mortality; however, significantly more fifth-instar nymphs survived than first to fourth instars, whereas none of the adults survived. Spinosad at the recommended rate significantly reduced bigeyed bug density compared with the untreated check. Similarly, halofenozide influenced bigeyed bug survival only at the full-recommended rate in Petri dish assays. Effects of the same 6 concentrations of insecticides described above were studied on geocorids when 3 turfgrass genotypes, ‘Cavalier’ zoysiagrass (Zoysia japonica von Steudel and Z. matrella L. Merrill), ‘Sea Isle 1’ seashore paspalum (Paspalum vaginatum Swartz), and ‘TifSport’ bermudagrass (Cynodon dactylon L. × C. transvaalensis Burtt-Davy), were present. Chlorpyrifos affected survival of geocorids even at 62.5 ppm in all turfgrass genotypes evaluated at 1 or 3 d posttreatment. More bigeyed bugs survived on ‘Cavalier’ zoysiagrass than other turfgrass genotypes treated with chlorpyrifos. None of the turf-mediated residual concentrations of spinosad caused predator mortality. Insecticide-induced nontarget mortality is influenced by turfgrass genotype and may depend on mode of action of insecticide, type of host plant resistance and plant morphology and architecture.
The effectiveness of a pour-on formulation of novaluron (Novatack Pour-on 5% Al, Clarion Biociencias LTDA, Goiania, Brazil), a benzoylphenyl urea acaricide, was evaluated by applying a low and high concentrations (1 mg/20 kg body weight and 1 mg/10 kg body weight) to cattle infested with all parasitic developmental stages (adults, nymphs, and larvae) of Rhipicephalus (Boophilus) microplus (Canestrini). The therapeutic percentage reduction in the number of females that reached repletion following treatment was 24.8 and 24.6% for the low and high rates, respectively. No difference in the weight of engorged females recovered from treated calves or in the index of fecundity (IF) was observed for either rate in comparison with the untreated control, and no significant difference in the overall therapeutic level of control was observed between the low and the high rates. Results obtained from the analysis of persistent (residual) efficacy of both rates showed no significant differences between the treatments at weekly intervals; however, the percent control of the IF observed against larvae infested 1 and 2 wks after treatment of both rates was moderate indicating that novaluron appears to be more effective against larvae that come into contact with cattle after treatment than against adults or nymphs already infesting the animal at the time of treatment.
The azalea lace bug, Stephanitis pyrioides (Scott) (Tingidae: Hempitera), is a major pest of azaleas (Rhododendron L. spp.). Since its introduction from Asia in the 1940s, the pest has spread considerably within and outside the US. It causes severe economic damage to azaleas and also attacks other ericaceous hosts. The widespread acceptance and cultivation of its preferred host plants, azaleas, in landscapes and home gardens prompted extensive research on S. pyrioides with respect to biology, damage and management. This review summarizes the work done on this pest and provides directions for future research.
CO2 release rates were measured from groups of 10 Reticulitermes virginicus Banks workers, soldiers, and nymphs. For workers, Vijco2, (μl·mg−1·h−1) increased linearly with temperature between 16.2 - 30.4°C. Vijco2 recorded at ≈20°C was 0.177 ± 0.005 μl·mg−1·h−1 for soldiers and 0.219 ± 0.027 (μl·mg−1·h−1 tor nymphs. Assuming a similar slope of temperature increase in Vijco2 for all castes, predicted mass-corrected CO2 release values for grouped R. virginicus workers, soldiers and nymphs at 23.6°C were 27, 52 and 27% lower than literature values for the same castes of R. flavipes measured individually at that temperature. CO2 release rate (μl·mg−1·h−1) for R. virginicus nearly doubled over the 20°C to 30°C temperature range (Q10 = 1.91), similar to literature values for Zootermopsis nevadensis (Hagen) over the same range. For all temperatures except 25.2°C, CO2 release rate (in μl·h−1) increased significantly with mass, with coefficients ranging from 0.123 (16.2°C) to 0.599 (30.4°C).
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