Seletividade de compostos reguladores de crescimento de insetos à Chrysoperla externa (Hagen, 1861) (Neuroptera, Chrysopidae)

Abstract

The effects of the insect growth regulator insecticides buprofezin, chlorfluazuron, diflubenzuron, flufenoxuron, teflubenzuron, triflumuron, pyriproxyfen and cyromazine on eggs, larvae and adults of Chrysoperla externa were evaluated in the laboratory under controlled conditions of temperature (25 ± 2°C), relative humidity (55 ± 10%) and photophase (12 hours). The compounds were diluted in distilled water at doses recommended for pest control. The sprayings were done with an adapted model of the Potter tower with an average application volume equivalent to 400 1 /ha. The compounds chlorfluazuron, diflubenzuron, flufenoxuron, teflubenzuron and triflumuron proved themselves to be highly deleterious when sprayed on second instar larvae of C. externa, while the buprofezin, pyriproxyfen and cyromazine were innocuous. The latter were selected for later experiments aiming to verify if these products, under different conditions, would continue to be selective to this insect. C. externa eggs showed high tolerance to buprofezin, pyriproxyfen and cyromazine. Larvae showed high tolerance to buprofezin and cyromazine. On the other hand, third instar larvae in contact with surfaces treated with pyriproxyfen were maintained in the larval phase, and died eventually, showing that this product acts as a mimic of the juvenile hormone also in C. externa larvae. The compounds buprofezin pyriproxyfen and cyromazine did not affect oviposition and survival of treated females and the viability of the eggs laid by them. According to the observed effects of the compounds on every developmental phase of C. externa, only buprofezin and cyromazine were considered selective to this species.