Effect of a formulation of Anticarsia gemmatalis (Lepidoptera: Noctuidae) nuclear polyhedrosis virus on the predator Podisus nigrispinus (Heteroptera: Pentatomidae: Asopinae), using the fertility life table parameters

Abstract

Two experiments were carried out in the laboratory to evaluate the effect of a formulation of the nuclear polyhedrosis virus (NPV) of the velvetbean caterpillar, Anticarsia gemmatalis Hübner (AgNPV), on the predator Podisus nigrispinus Dallas. In the first experiment, predators were exclusively fed A. gemmatalis reared on artificial diet, treated with one formulation of the AgNPV (infected prey) or with water (healthy prey) as the control. In the second experiment, an additional treatment was incorporated in which the artificial diet was treated with an inactive (autoclaved) AgNPV formulation. The predators were fed on these exclusive prey during their entire lifespans for three or four consecutive generations, during the first and second experiment, respectively. Daily observation of oviposition and mortality were performed to provide data for the construction of fertility life tables and to determine daily oviposition patterns and survival distribution curves. For both experiments, no adverse effects were observed in the first generation. However, significant effects in the predator population were observed throughout the subsequent generations, when the predators were fed with prey that fed on infective or inactivated AgNPV diet compared with the healthy prey. The adverse effects observed might be due to some inert components present in the commercial formulation, because the AgNPV has been demonstrated to be highly specific to Lepidoptera and neither does it replicate nor has any adverse effect on P. nigrispinus. The fertility life tables proved to be a good tool to measure the potential impact of biopesticides on nontarget population under laboratory conditions.