Determination of negative nontarget effects of pesticides on beneficial organisms by measuring only lethal effects is likely to underestimate effects of sublethal doses. In this study, the sublethal effects of fenpropathrin on the predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on Tetranychus urticae Koch (Acari: Tetranychidae) were evaluated under laboratory conditions. The estimated values of LC50 for female and male predators were 6.53 and 5.47 μg a.i./ml, respectively. Exposure to low-lethal concentrations (LC10, LC20, and LC30) of fenpropathrin significantly affected the biological characteristics of treated females of S. longicornis, the most noticeable effects being a shortening of female life span by >70% accompanied by large reductions in oviposition period and fecundity. The offspring of females treated with low-lethal concentrations of fenpropathrin likewise had significantly reduced longevity, oviposition period, and fecundity, although not to the same extent as experienced by their mothers. Their juvenile development time was, however, not affected. These effects on the offspring were reflected in reduced rates of population increase and increased doubling times.
Journal of Economic Entomology, 2013, Vol 106, Issue 6, p. 2371-2377
biological control; fecundity; life table; nontarget effect; twospotted spider mite