Susceptibility of Chrysoperla externa eggs (Neuroptera: Chrisopidae) to conventional and biorational insecticides

RIMOLDI, FEDERICO; SCHNEIDER, MARCELA INÉS; RONCO ALICIA

ENVIRONMENTAL ENTOMOLOGY

ESA

Año: 2008 vol. 37 p. 1252 - 1257

0046-225X

Chrysoperla externa (Hagen) is a relevant generalist predator of several lepidopteran pests. The present study assessed the effect of cypermethrin, endosulfan, methoxyfenozide and spinosad on immature development time, survivorship, sex ratio, fecundity and fertility in laboratory toxicity tests. Effects on second generation organisms were also studied. Exposures were realized by dipping ¡Ü24 h-old eggs in pesticide solution at maximum field recommended concentrations. Although no significant ovicidal effect was detected with any of the compounds tested, treatments with endosulfan and cypermethrin produced 96 and 100% mortality, respectively, on larvae 48 h after hatching. Spinosad caused significantly higher mortality than controls but this effect was less immediate, lasted longer and was less intense than effects with conventional insecticides. Methoxifenozide did not produce significant mortality in any stages. Spinosad and cypermethrin reduced egg development time, but no similar effects were observed with other pesticides. Methoxyfenozide inhibited the fecundity during the first 24 h; however, fertility was not affected. Spinosad had no effect on fecundity or fertility of the adults. No long-term detrimental effects on the progeny were detected for spinosad and methoxyfenozide. Conventional insecticides (endosulfan and cypermethrin) were more toxic than biorationals ones when applied to eggs of C. externa. The ecotoxicological studies showed the neonate-L1 larvae as a susceptible developmental stage. The current data indicate that conventional insecticides should be used with caution as they did not result compatible with the predator under laboratory conditions. Key words: Chrysoperla externa, cypermethrin, endosulfan, methoxyfenozide, spinosad, side-effects