Efeitos letais e subletais de inseticidas químicos e biológicos sobre Euscepes postfasciatus (Fairmaire, 1849) (Coleoptera: Curculionidae) em batata-doce

Abstract

The sweet potato (Ipomoea potatoes L.), due to its food and energy importance, has been gaining prominence on the world stage. However, the occurrence of population outbreaks of pest insects such as Euscepes postfasciatus (Fairmaire, 1849) (Coleoptera: Curculionidae) has limited the production of this vegetable. Thus, this work aimed to evaluate chemical and biological control tactics for the management of E. postfasciatus. To this end, chemical insecticides (spinetoram, spiromesifen, lambda-cyhalothrin, thiamethoxam, thiamethoxam + lambda-cyhalothrin and azadirachtin) and biological insecticides (based on Beauveria bassiana and Metarhizium anisopliae) were tested under laboratory conditions. For all products, lethal effects were evaluated, based on adult mortality, in addition to sublethal effects, through repellency and population growth estimates. Statistical analyzes were performed in the programs SAS and Assistat. With the data obtained, lethal concentrations (LCs), mean lethal time (LT50), percentage of repellency (PR) and instantaneous population growth rate (ri) were determined. The results showed that the insecticides lambda-cyhalothrin, thiamethoxam, spinetoram and thiamethoxam + lambda-cyhalothrin were effective in terms of adult mortality of E. postfasciatus and provided significant reductions in the population growth rate, however, they did not present a repellent effect. The fungi B. bassiana and M. anisopliae were pathogenic to the pest, but the co-application proved to be antagonistic. Thus, the results obtained added relevant information for the control of E. postfasciatus that could serve as a basis for the development of Integrated Pest Management (IPM) programs in sweet potato.

Keywords: Ipomoea batatas. West Indian sweetpotato weevils. Chemical control. Biological control.