Estudo do comportamento reprodutivo e olfativo de Zabrotes subfasciatus (COLEOPTERA: BRUCHIDAE) e identificação dos constituintes químicos presentes nos extratos de machos e fêmeas dessa espécie

Abstract

The Zabrotes subfasciatus (Boh 1833) (Coleoptera: Bruchidae) is known popularly as weevil of beans being one of the more important pests of stored grains. The pest control is performed basically using efficient chemical insecticides, however, they cause harm to men, fauna and flora, in the surroundings, being non-specific. In the search for alternative and less aggressive control, we study the action of infochemicals in the control of the Zabrotes subfasciatus. The study of reproductive aspects and of the intra- and interespecific communication had been carried out as well as the identification of the chemical constituents of the extracts of males and females of Zabrotes subfasciatus. The sequence of courtship and mating of the Z. subfasciatus had been first observed, which resulted in an etogram. After that the selective behavior of the female in relation to the partner and the differences of the sexual reasons that had influenced in the reduction of the number of mating were analyzed. For studies of the intra and interspecific communication, the study had been conducted through olfatometric and electroanthenographic tests. Using olfatometry, it was confirmed that the females are responsible for the release of the sexual pheromone, which exerted attractiveness only toward the males. The plant hostess did not influence in the production of the pheromone. Extracts prepared with dichloromethane had been more efficient in the attractiveness than hexanic extracts, but were less attractive than the alive females. In the electroantenography tests only the males had answered in a positive way to the treatments that consisted of alive females and extracts of females, females plus beans, using dichloromethane as solvent, in order to strengthen the idea of the female being the releaser of the sexual pheromone. The extracts of males and females had been analyzed through GC-MS, to know their chemical contents. Extracts of females had presented greater amount and variety of chemical compounds than the extracts of the males. In the extracts of females, a homologous series of hydrocarbons, alcohols, carboxylic acids, esters and ethers had been found. Morphology differences between the bristles of males and females of Z. subfasciatus were observed. The females present ramified and voluminous bristles, while the males possess filiform bristles