Atividade biológica de extratos de timbó (Derris scandens Aubl. e Deguelia floribundus Benth)sobre Cerotoma tingomarianus Bechyné (Coleoptera: Chrysomelidae) E Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae).

Abstract

The abundance, potential insecticide and evidence of synergism among the major constituents of timbo extracts (Derris and Deguelia) and the need to control of Cerotoma tingomarianus Bechyné (Coleoptera: Chrysomelidae) and Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) stimulated the realization of this study, which aimed to evaluate the biological effects of timbo extracts and its purified fractions compared to rotenone, as well as combined in different concentrations, on adults of C. tingomarianus and S. frugiperda larvae. Samples timbo roots were collected of plants in the Acre and Amazonas states, and obtained extracts by hot extraction of dry material method. The timbo extracts were grouped into six distinct groups and the bioassays were carried out by means of topical contact, contact by contaminated surface (filter-paper) and intake of contaminated diet in a completely randomized design. The mortality values of two insect species were submitted to Probit analysis to determine the LC50, LD50 and LT50. The other variables were subjected to variance analysis, when possible, using the Scott-Knott test (P> 0.05) for grouping treatment means. The intoxication by intake of contaminated diet/leaves is the most effective mean of contact for adults of C. tingomarianus and S. frugiperda larvae. The toxicity of timbo species extracts is variable and is related to the chemical composition of the extracts, as well as at form of exposure and the target insect species. Rotenone alone was not toxic to adult C. tingomarianus and showed low toxicity to S. frugiperda larvae, enhancing their biological effects on the insects/larvae when associated with the fractions containing timbo extracts, constituent A, constituent B and deguelin. The toxicity of timbo extracts for C. tingomarianus adult may be related to the combined action of several constituents. Extracts containing high levels of rotenone and deguelin are indicators of toxicity to S. frugiperda larvae. The association the constituent A with constituent B probably causes mortalities in the pre-pupal and pupal weight of S. frugiperda. The extract of timbo G1 and G3 showed the highest toxicity to insects and can be considered as the most promising for the development of biotechnology products for the control of C. tingomarianus adults and S. frugiperda larvae.