Avaliação da toxicidade de inseticidas utilizados em algodoeiro para cycloneda sanguinea (Linnaeus, 1763) (Coleoptera: Coccinellidae)

Abstract

To assess the effects of three insecticides used in cotton crop on third-ínstar larvae and adults of the ladybeetle Cycloneda sanguinea (Linnaeus), four trials were conducted under greenhouse conditions. For the accomplishment of the tests, the cultivar BRS IPÊ, with twenty five days, were used and the insecticides were sprayed with a manual sprayer. After this, each plant, totalizing 10 for treatment, was infested with three third-ínstar larvae or one couple of adults and after that confined using a plastic container. As food source, two yellow paper stripes contending eggs of Anagasta kuehniella (Zeller) were fixed in the plants with double face adhesive tape. The products and concentrations evaluated, lower and higher respectively, in g a.i.L-1 of water were: imidacloprid/ß-cyfluthrin (Connect 100/12.5 SC - 0.25/0.03 e 0.33/0.04), clothianidin (Focus 500 WP - 0.33 e 0.66) e chlorfenapyr (Pirate 240 SC - 0.80 e 1.20), totalizing 300L for hectare. Distilled water was used as control. The evaluations had been made 1, 12, 24 and 48 hours after the release of the insects in the contaminated plants, counting the number of dead specimens. As result of the research all the tested insecticides had been toxic to third-ínstar larvae and adults of the predator C. sanguinea, in both concentrations, for causing more than 75% of mortality, according IOBC. Imidaclopride/ß-cyfluthrin and chlorfenapyr affected in 100% the survival of larvae and adults of the predator, in both concentrations tested. Clothianidin held a little different and in the control group, mortality it was not observed. Experiments in field are necessary to affirm that these products aren´t compatible with integrated management of cotton pests.