EFEITOS DA TERRA DIATOMÁCEA SOBRE Diabrotica speciosa (GERMAR, 1824) (COLEOPTERA: CHR YSOMELIDAE) EM BA TATA INGLESA Effects of diatomaceous earth on Diabrotica speciosa (Germar, 1824) (Coleoptera: Chrysomelidae) in potato

RESUMOA especie Diabrotica speciosa e um crisomelideo responsavel por causar danos consideraveis a batateira, o que tornaindispensavel seu controle com inseticidas para minimizar os prejuizos causados a cultura. Assim, objetivou-se, com este trabalho,avaliar os efeitos da terra diatomacea sobre o comportamento alimentar e a mortalidade de D. speciosa em batata inglesa em condicoesde laboratorio. Adotou-se o DIC com tres tratamentos e oito repeticoes, sendo: 1 - testemunha; 2 - TD polvilhada (0,5 g/vaso) e 3 -TD pulverizada a 1%. As batateiras, cv. Emeraude, foram polvilhadas ou pulverizadas com TD, 30 dias apos o plantio e, 24 horasapos a aplicacao, as plantas foram fornecidas aos insetos, sem e com chance de escolha. Houve diferenca significativa entre ostratamentos, sendo a menor porcentagem de foliolos com injurias observada em plantas que receberam a aplicacao de TD pulverizada(teste sem chance de escolha) e TD polvilhada ou pulverizada (teste com chance de escolha). Tambem houve reducao do numero deinjurias foliares as 24 e as 48 horas (TD polvilhada ou pulverizada) e, as 72 horas, a reducao foi observada somente com a aplicacaoda TD polvilhada. Com relacao a acao inseticida da TD, foi verificado seu efeito apos 48 horas, tanto via polvilhamento, quanto viapulverizacao. Assim, a aplicacao de TD pode auxiliar no manejo de D. speciosa, contribuindo para conferir protecao as plantas debatata inglesa e aumentar a mortalidade desse inseto-praga.Termos para indexacao: Insecta, dioxido de silica, MIP.ABSTRACTThe species D. speciosa is a chrysomelid responsible for causing considerable damage on potato plant, making its controlwith insecticides essential to minimize the damage caused to this culture. The objective of this study was to evaluate the effects ofdiatomaceous earth (DE) on feeding behavior and mortality of D. speciosa in potato under laboratory conditions. A completelyrandomized design was used with three treatments and eight replicates being: 1 - control; 2 - sprinkled DE (0.5 g/vase) and 3 - 1%sprayed DE. The potato plants, cv. Emeraude, were sprinkled or sprayed with DE 30 days after the planting and 24 hours after theapplication, the plants were supplied to insects, with and without a chance of choice. There was significant difference amongtreatments with a lower leaflet with injury percentage observed in plants that received the application of powdered DE (tests withoutchance of choice) and sprinkled or powdered DE (tests without chance of choice). There was also reduction of the number of leafinjuries at 24 and 48 hours (sprinkled or powdered DE) and, at 72 hours, the reduction was only observed with the application ofsprinkled DE. Regarding the insecticidal activity of TD, its effect was verified after 48 hours, through sprinkling or spraying. As aresult, the application of DE may help in the management of D. speciosa, contributing to provide protection to potato plants and toincrease the mortality of this insect pest.Index terms: Insecta, silicon dioxide, IPM.