Infectivity of Entomopathogenic Nematode, Steinernema carpocapsae, on the Mango Shoot Borer, Rhytidodera simulans

Abstract

Infectivity of Steinernema carpocapsae strain All on larvae of the mango shoot borer Rhytidodera simulans, a serious pest of mango trees in Malaysia, was investigated under laboratory conditions. When the insect larvae were placed individually in a 6-cm-d petri dish containing 5g of moistened mango sawdust with 0, 10, 100, 1, 000 or 10, 000 infective juveniles (J3), the nematode caused insect death 2 days or later after inoculation at the inoculum levels higher than 1, 000 J3 and then grew and reproduced in the insect cadavers. Most of the insects which escaped nematode infection or those died later made gallery-like tunnel along the petri dish wall. About 1/2 to 1/6 individuals of insects introduced in the galleries artificially made in mango cut-branches were infected when the branches were either injected through small side holes reaching the galleries or sprayed over the holes with 1 m/l of nematode suspension containing 10, 000 or 100, 000 J3. The nematode infection on R. simulans larvae in galleries was found to be greatly affected by the insect feeding behavior.