Efeito de fungos entomopatogênicos sobre formas imaturas de Diatraea flavipennella (Box) (Lepidoptera : Crambidae)

Abstract

Diatraea flavipennella (Box), is a pest of great economic importance to the cultivation of sugar cane in Northeast Brazil. The use of the larval parasitoid Cotesia flavipes (Cam) has not succeeded in controlling the D. flavipennella. The use of entomopathogenic fungi is a viable alternative within the context of integrated management of this pest. Thus, this study aimed to evaluate the effect of isolated URPE-3, URPE-4, URPE-18, URPE-22, and ESALQ 447 of Beauveria bassiana (Bals.) Vuilleman and PL43, E9, ESALQ 1189, URPE-11, and URPE-19 Metarhizium anisopliae (Metsch.) Sorokin on eggs of 24, 48, and 72 hours old and the 2nd-instar larvae of D. flavipennella in laboratory conditions. The eggs and larvae were sprayed with 1 mL of suspensions (1x107 conidia / mL) (treatment) and sterile distilled water over wetting agent Tween® 80 at 0.01% (control). Tests conducted on eggs of D. flavipennella consisted of four replications, each consisting of approximately 30 eggs. The experiments with caterpillars consisted of six replications, each consisting of seven larvae, totaling 42 larvae per treatment. Eggs and larvae were kept inside of growth chamber at 27 ± 1 ºC, 70 ± 10% RH and 12h photophase. The fungus M. anisopliae was more virulent to eggs, particularly the isolated URPE- 11, which provided 100% of infection in eggs of 24, 48, and 72 hours old, and the LC50 at 2.0x105 conidia. The isolates ESALQ 447 and ESALQ 1189 were more virulent to borer larvae, with mean survival values of 5.76 and 3.23 days, respectively. The LC50 for these isolates was estimated at 1.2 x107 conidia. The results suggest that the fungi M. anisopliae and B. bassiana are important for further evaluation in the applied integrated management of D. flavipennella contributing to the sustainability of sugarcane production in northeastern Brazil.