Avaliação da atividade inseticida do regulador de crescimento de insetos diflubenzuron contra anopheles darlingi root, 1926 (diptera, culicidae), em condições de laboratório.

Abstract

Anopheles darlingi is the main malaria vector in Brazil and, therefore it is the species targets in the control of that endemy. Therefore, the researches are necessary with new insecticide substances that allow the control of vector in a safe and efficient way. This study aims to assess the larvicide and pupicide activity of Diflubenzuron, a insect growth regulator, on Anopheles darlingi under laboratory conditions. Diflubenzuron showed to be effective against 3rd and 4th instar larvae. It provoked 100% mortality on 3rd instar larvae when used in high concentrations with a significant drop on the survival rate as time went by. CL50 and CL90 were determined for 4th instar larvae at 0.006 and 0.013 ppm, respectively. Pupicide activity was evident showing that the insecticide also works by, with young pupae being more susceptible than one day old ones. Regarding the period of exposure, larvae which were exposed for 24 h presented significant mortality not differing from those which had been exposed for 48 h. The 3rd instar larvae showed a gradual decrease on the swimming, mouth part, and head turning, movements. In addition to these, the lengthening of the cervix region, and higher mortality at the time of the ecdise with the overflowing of tissues were also observed. For the 4th instar larvae the decrease of the movements mentioned above, as well as, at the time of the ecdise production of deformations in the subsequent stages in which, larvae attached to exuvia, pre-pupae and pupae with overflowing of tissue, pupae with exposed appendages, and adults in different degrees of emergence, were also detected. With these findings it was possible to conclude that Diflubenzuron is highly effective against A. darlingi immature for forms bringing about their mortality and/or morphological alterations that lead to the reduction on the emergence of adults.