virulência de nematóides entomopatogênicos (Nematoda: Rhabditida) a Sphenophorus levis (Coleoptera: Curculionidae)

Abstract

The sugarcane billbug, Sphenophorus levis (Coleoptera: Curculionidae) is an important underground pest of the sugarcane crop in São Paulo state, causing losses up to 30 tons of cane/ha/year. This study aimed to evaluate the virulence of 17 strains of entomopathogenic nematodes on the genus Steinernema and Heterorhabditis against adults of S. levis, and the effect of the four most virulent ones in three dosage each one. The research was done in laboratory conditions, performing four tests related to the virulence study and one related to the dosage study. S. brazilense IBCB n6, Heterorhabditis sp. IBCB n10, Heterorhabditis sp. IBCB n24 and Heterorhabditis sp. IBCB n44 were the most virulent ones, differing significantly from the respective control with 45%, 40%, 20% and 31% mortality of insects using the concentration of 240 infective juveniles (IJ)/insect. For the dosage test, the strains IBCB n10, IBCB n24 and IBCB n44 of Heterorhabditis noteworthy concerning the virulence for adults of the sugarcane billbug, differing significantly from the control at the higher dosage (1200 IJ/insect) with insect mortality levels of 60%, 65,7% e 74,3%, respectively.