Selectivity of seven insecticides against pupae and adults of Chrysoperla externa (Neuroptera: Chrysopidae)

Abstract

The aim of this study was to evaluate the toxicity of seven insecticides (g a.i./L): chlorpyrifos (2.25), cartap hydrochloride (1.66), pyriproxyfen (0.33), profenofos/lufenuron (1.33/0.13), fenpropathrin (0.40), deltamethrin/ triazophos (0.02/0.70), and zeta-cypermethrin (0.05). These insecticides are commonly used on coffee crop in Brazil and they were sprayed, by using a Potter tower, on pupae and adults of the insect predator Chrysoperla externa. The time of development of the treated pupae were not affected during the testing period and ranged from 9.2 to 9.5 days, although their survival was lower when chlorpyrifos and deltamethrin/triazophos were used, at approximately 62.5 and 75%, respectively. The other compounds did not aid in reducing this specific biological trait, with averages ranging from 90% to 95%. Chlorpyrifos and fenpropathrin were highly toxic to adults of C. externa, causing 100% mortality. Adult insects treated with deltamethrin/triazophos and zeta-cypermethrin showed survival rates of 15% and 22.5%, respectively. The other products did not affect the mortality of directly treated adult insects. Deltamethrin/ triazophos and chlorpyrifos were classified as slightly harmful (class 2), whereas the other were considered harmless to C. externa pupae. The insecticides cartap hydrochloride and pyriproxyfen were considered harmless to adults; profenofos/lufenuron was slightly harmful; and chlorpyrifos, fenpropathrin, deltamethrin/triazophos, and zetacypermethrin were considered harmful.