Application of Beauveria bassiana using different baits for the control of grasshopper pest Dichroplus maculipennis under field cage conditions

Abstract

Dichroplus maculipennis is a widely distributed species, occurring in several countries of southern South America. Poisoned baits are effective for the control of insect pests. Adding attractants and phagostimulants could result in improved bait formulations, making bait treatment even more efficacious, for the control of grasshopper pests. The goal of the study was to determine, under laboratory bioassay and field cage conditions, the most effective treatment option using different baits with the entomopathogenic fungi Beauveria bassiana, for the control of the grasshopper pest D. maculipennis. In laboratory bioassays we observed significant differences (df = 11; f = 2.23; p < 0.01) in percentages of mortality against third-instar nymphs of D. maculipennis caused by different strains of B. bassiana, as well as between the different treatments studied. Under field cage conditions, the highest mortality was 100% in treatment 3 (canola oil, wheat bran, and conidia) and the lowest was 73.3 in treatment 1 (conidia only). The lowest value of median survival time (MST) was obtained with the combination LPSc 1227 conidia plus wheat bran and canola oil (6.43 d). In the laboratory bioassays and under field cage conditions the combination of conidia of B. bassiana with wheat bran and canola oil improved the performance of conidia, enhancing mortality of D. maculipennis.