A laboratory bioassay was developed for determining the toxicity of spinosad, chlorfenapyr, and thiamethoxam against the eggplant flea beetle, Epitrix fuscula Crotch, on eggplant foliage. Four days after initial exposure, LC50 values were 1.99, 2.50, and 0.88 ppm for spinosad, chlorfenapyr, and thiamethoxam, respectively. By dividing the recommended field rate in ppm by the LC50 value, a field toxicity ratio was determined and ranged from 13.5 for spinosad to 73.9 for thiamethoxam. The high ratios suggest that field rates for all three insecticides could likely be reduced. This was supported by field studies in 2000 in which reduced rates of spinosad and thiamethoxam significantly reduced flea beetle numbers on eggplant. Mortality produced by thiamethoxam occurred more quickly than that for the other tested materials as shown with LT50 values of 1.8, 3.0, and 3.6 and days for thiamethoxam, chlorfenapyr, and spinosad, respectively. Persistence studies indicated that while all three of the tested compounds initially produced high levels of mortality, chlorfenapyr and thiamethoxam produced 50% or greater mortality after 6 d. Our data suggest that future management strategies for E. fuscula on eggplant can be successfully altered to meet the changing needs of the producer. Spinosad was recently registered, is effective against the E. fuscula, and offers a viable alternative to carbamate and pyrethroid insecticides. Thiamethoxam and chlorfenapyr offer high levels of toxicity to E. fuscula and upon registration will offer additional effective tools for management.

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Thrips were sampled in a commercial tomato field in southeast Arkansas with yellow sticky traps. The effect of the type of mulch used (black plastic, aluminum-painted plastic or no mulch) on aerial thrips population abundance was investigated. Thrips species identified included Frankliniella fusca (Hinds), F. tritici (Fitch), Sericothrips variabilis (Beech), Leptothrips mali (Fitch) and Haplothrips graminis Hood; F. fusca and F. tritici were most numerous. Aluminum-painted mulch was most effective in reducing the numbers of thrips captured, while black plastic was more effective than no mulch. Numbers of F. fusca peaked at five weeks after transplanting; however, numbers of thirps were low in all plots for the first three weeks after transplanting. Peak numbers of F. fusca trapped in the aluminum-painted plots were one-third the numbers in non-mulched plots, while numbers in the black plastic plots were intermediate. Effectiveness of the mulch in decreasing the numbers of thrips generally disappeared later in the season, as lower leaves shaded the mulch, and traps were raised to accommodate increasing plant height.