Efeitos letais e subletais de inseticidas botânicos sobre Aphis gossypii Glover (Hemiptera : Aphididae) e Cycloneda sanguinea (Linnaeus) (Coleoptera : Coccinellidae) em cultivares de algodão de fibra branca e colorida

Abstract

Aphis gossypii Glover is one of the major pest of cotton in Brazil, causing direct and indirect damage through viruses transmission. In alternative production systems, the control of this pest is carried out by natural biological control and by application of botanical insecticides. However, the performance of A. gossypii, its natural enemies and insecticides may be affected by different features of cotton cultivars, as the tricomas density. The objectives of this study were examine the interactions between white (BRS 8H and BRS 201) and colored fiber cotton cultivars (BRS Verde, BRS Safira and BRS Rubi), botanical insecticide (Azamax®, castor bean oil emulsion, aqueous extract of neem seeds, Eucalyptus citrioda Hook and E. staigeriana essential oils), A. gossypii and its natural enemy Cycloneda sanguinea (L.).Tested cultivars did not influence the development and feeding preference of A. gossypii, the locomotion and search ability of C. sanguinea and the effectiveness of tested botanical insecticides. The essential oils of E. staigeriana e E. citriodora showed no decrease in pest population and caused severe phytotoxicity in all cotton cultivars. Azamax® showed A. gossypii mortality ranging between 64 and 100%, and negative instantaneous growth rate (ri), from the concentration of 1.25%. For aqueous extract of neem seeds aphid mortality ranged between 12 and 92% and the ri was negative from concentration above 2.5%. Castor bean oil emulsion had low toxicity, with mortality rates ranging between 8 and 68% and negative ri, from concentration of 3.0%. Azamax® 0.25 and 1.25%, aqueous extract of neem seeds 2.25% and castor bean oil emulsion 3.0% showed high mortality to larvae of the 1st and 4th instars of C. sanguinea preventing the emergence of adults.