SUSCEPTIBILITY OF Elasmopalpus lignosellus PUPAE TO ENTOMOPATHOGENIC NEMATODES IN MAIZE

Abstract

Virulence and concentration of entomopathogenic nematodes (NEPs)
in Elasmopalpus lignosellus pupae were evaluated. In the laboratory, the virulence of the isolates Heterorhabditis amazonensis MC01, H. amazonensis JPM3, H. amazonensis GL, Steinernema carpocapsae All and Heterorhabditis sp. Nepet 11 was evaluated and, subsequently, H. amazonensis GL was applied at concentrations of 8; 16; 24 and 32 IJ cm-2. The EPNs were applied to Petri dishes containing ten pupae with five replications. Mortality was assessed every 24 hours for three days. In a greenhouse, H. amazonensis GL was tested at concentrations 24, 25, 26 and 27 IJ cm-2. The IJs were applied in pots containing a 20-cm high ‘BM 3061’ maize plant, besides six pupae with four replications. Knowing that the efficiency of EPNss is directly related to the ability to search and penetrate the host, it was found that H. amazonensis GL is highly virulent to E. lignosellus, presenting an LC50 of 6.49 IJ cm-2 after 48 hours, 5.61 IJ cm-2 in 72 hours and LC90 of 39.70 IJ cm-2 in 48 and 27.73 IJ cm-2 in 72 hours under laboratory conditions. In the soil, pupal mortality was lower and a concentration of 25 IJ cm-2 was responsible for the death of 50% of the population, since environmental variability influences the dynamics of IJ infection and insect defense.