Patogenicidade de nematóides entomopatogênicos a cochonilha-da-raiz-do-cafeeiro Dysmicoccus texensis (Tinsley) (Hemiptera: Pseudococcidae) em laboratório

Abstract

The coffee root mealybug Dysmicoccus texensis (Tinsley) attacks the roots of this plant and can cause serious damage to crops, and consequent losses in production. The entomopathogenic nematodes (EPNs) are effective agents in controlling pests found in soil, which suggests a likely effectiveness in controlling the coffee root mealybug. Therefore, this study aimed to evaluate the pathogenicity of some strains of EPNs against the coffee root mealybug through selection tests of isolates, determination of the maximum lethal concentration (LC99) and the pathogenicity of crypts collected in the field. The isolated Heterorhabditis sp. CCA, Heterorhabditis bacteriophora, Heterorhabditis sp. JPM3.1 and Heterorhabditis sp. JPM3 presented higher virulence, reaching maximum mortality values of 100, 94, 94 and 82% respectively at the highest concentration that was tested (100 infective juveniles IJ/insect). The LC99 determined for Heterorhabditis sp. CCA was estimated at 530 IJ/plate. A similar value was found for Heterorhabditis sp. JPM3, which had the LC99 equal to 560 IJ/plate. Estimating the concentration by area, the value obtained for Heterorhabditis sp. CCA and Heterorhabditis sp. JPM3 was 28 and 29 IJ/cm2 , respectively. In the test conducted with crypts, both isolated from EPNs were pathogenic to insects.