Lethal and sublethal effects of fenpropathrin on the biological performance of Scolothrips longicornis (Thysanoptera: Thripidae).
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 microg 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.
Department of Plant Protection, Faculty of Agriculture, Islamic Azad University, Takestan Branch, Iran. Pakyari@tiau.ac.ir
Hajar
H
Pakyari
Department of Agroecology, Research Centre Flakkebjerg, Aarhus-University, Science and Technology, DK-4200 Slagelse, Denmark.
Annie
A
Enkegaard
D000818:Animals; D061046:Biological Control Agents; D005260:Female; D007306:Insecticides / Q000633:toxicity*; D015993:Life Tables; D008297:Male; D011722:Pyrethrins / Q000633:toxicity*; D012727:Sex Characteristics; D040102:Tetranychidae / Q000254:growth & development; D061149:Thysanoptera / Q000187:drug effects* / Q000502:physiology
D061046:Biological Control Agents; D007306:Insecticides; D011722:Pyrethrins; C044267:fenpropathrin