Susceptibility of the cockroach Periplaneta americana to Steinernema carpocapsae: Histopathological changes in the cockroach midgut

Laboratory assessment of the virulence of Steinernema carpocapsae to cockroach. Periplaneta americana, using filter paper exposure method at 25°C, revealed that at dosage levels of 5000 infective juveniles per insect caused 70 and 50 percent mortality in males and females respectively. LD 50 values were 3467.78 and 4986.05 for male and female cockroaches respectivelv. Histopathological changes due to movement and penetration of nematode larvae in host midgut showed increase vacuolization and disintegration of columar cells. Destruction of cytoplasm followed by degeneration of nuclei was also noticed.