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The occurrence of a large spider web at Lake Tawakoni State Park has received considerable attention by the media and the public. This study reports the identifications of a sample of the spiders found at that site. Various explanations of this case are discussed.
In field experiments conducted in 2005 and 2006, panicles of rice, Oryza sativa L., were infested for 48 h with one male or female rice stink bug, Oebalus pugnax (F.), at heading, milk, soft and hard dough stages of development. Number of grains, number and weight of filled grains, number and weight of empty grains, and percentage whole kernels per panicle were not significantly affected by infestation at any stage of panicle development, nor were any significant differences found in percentage peck caused by male or female O. pugnax. In 2005, percentage peck was significantly lower in uninfested panicles and panicles infested during hard dough than in panicles infested during heading, milk or soft dough. No differences were found in percentage peck caused by O. pugnax during heading, milk or soft dough. In 2006, no significant differences were found in percentage peck produced by O. pugnax in panicles infested during heading, milk, soft dough or hard dough. Higher percentage peck in hard dough may have been the result of late drainage of the field.
The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), is a severe pest of wheat in the High Plains region of the United States. Remote sensing may be an effective way to detect RWA infestations in fields for pest management decision-making purposes. We evaluated an airborne multi-spectral remote sensing system for its ability to differentiate varying levels of injury caused by RWA infestation in winter wheat fields. Two fields located in southeastern Colorado were studied in spring 2004 and two fields located in far western Oklahoma were studied in spring 2005. The proportion of wheat stems damaged by RWA in each field was measured in 20 to 24 3×3-m plots with varying levels of RWA infestation. Prior to sampling plots, multi-spectral imagery was obtained using an SSTCRIS® multi-spectral imaging system mounted NADIR in a Cessna 172 aircraft. The multi-spectral data were compared with the intensity of RWA damage to wheat plants within the plots. Correlations between vegetation indices calculated from the multi-spectral data with the proportion of RWA damaged wheat tillers per plot were negative for all vegetation indices. Regressions of vegetation indices versus the proportion of RWA damaged wheat tillers per plot were usually significant and had negative slopes. However, slopes and intercepts of regressions differed significantly among fields. Any one or a combination of differences in time of day, atmospheric conditions, edaphic factors (e.g. soil type and soil moisture), wheat variety, and possibly other factors could have caused the differences observed in regressions.
Aerially applied spinosad (Tracer®) at 154 ml/ha was evaluated in a large-scale field study for thrips control in early season cotton and compared to conventionally applied dicrotophos (Bidrin 8®) at 292 ml/ha. Larvae and adult thrips counts were significantly less than the untreated control across all sampling dates except for larvae per plant count at 1 DAT with dicrotophos and adult numbers at 7 DAT. The greatest percentage reductions of adult thrips occurred at 1 DAT when all aerial application treatments were significantly lower than the control. At 7 DAT, the three spinosad applications made with CP nozzles showed the greatest control for adults and reduction of larvae. There were increases in adult numbers in the electrostatic and rotary treatments of 41 % and 10%, respectively, over the control at 7 DAT. Based on spray droplet deposition data collected and thrips control obtained in this study, the optimum aerial application treatments were conventional hydraulic nozzles (CP-03) with a volume median diameter of 175 μm at spray rates of 18.7 and 46.8 l/ha with Tracer® as the active ingredient. The addition of an adjuvant did not have a significant effect on efficacy. Tracer® provided as good as or better control of larval or adult thrips than the conventional application of dicrotophos.
Western flower thrips, Frankliniella occidentalis (Pergande), and onion thrips, Thrips tabaci Lindeman, are economic pest insects of head lettuce, Lactuca sativa L, and dehydrator onions, Allium cepa L, in the Imperial Valley, California. Colored sticky traps were evaluated as potential detection and monitoring devices of the two thrip species over a two-month period in 2006. Results showed that blue sticky card traps consistently captured more adult thrips of both species compared to yellow sticky card traps. Numbers of thrips captured on blue sticky traps were positively correlated to numbers captured on yellow sticky traps. Adult thrips were captured in much higher numbers on sticky card traps than recovered from whole plant samples. Significant negative correlations between F. occidentalis numbers on plant samples and colored sticky traps suggest that adults left lettuce plants and were attracted to nearby traps In addition, the numbers of thrips caught on traps relative to estimated plant populations support the hypothesis that mass trapping was significant in the treated area. Spectroradiometric and RGB (red, green, blue) digital image color analysis of the traps in sunlight showed the blue sticky cards reflected considerably more light in the 400–500 nm range (R = 49, G = 187, B = 255) than the yellow sticky cards that reflected more light in the 550–700 nm range (R = 227, G = 234, B = 67). Because blue sticky card traps captured many times more adult thrips than recovered from whole plant samples, blue traps may be more sensitive in detecting early presence of thrips in lettuce and onion fields.