Safety evaluation of Parthenium beetle, Zegogramma bicolorata Pallister (Chrysomelidae: Coleoptera) against entomopathogenic nematode, Steinernema glaseri (Steiner)

Bioefficacy of entomopathogenic nematode (EPN), Steinernema glaseri was evaluated on the grubs and adults of Zygogramma bicolorata in the laboratory. Mortality induced by the nematode occurred faster in adult (67 hrs) than a grub stage (72 hrs), but with higher parasitization efficacy of EPN on the grubs (42.8%) as compared to the adults (31.5%). The proportion of infected hosts permitting EPN proliferation was significantly reduced as compared to the total parasitized insects, in both the stages tested, with more evident effect in adults than in grubs. Harvesting period of infective juveniles (IJs) in grub and adult ranged between 5.8 to 6.5 days with no significant difference in these two stages. Observations indicated that Z. bicolorata was not a promising host for EPN.