Control of the larva of the sugarcane rootstalk borer, Diaprepes abbreviatus (L), with the entomogenous nematode Neoaplectana carpocapsae Weiser

Abstract

In a series of greenhouse tests to determine the susceptibility of the larval stage of the curculionid Diaprepes abbreviatus to the entomogenous nematode Neoaplectana carpocapsae, the nematodes controlled the insect larvae. Grubs 1.5 to 3 months old (smaller than one inch long) were less vulnerable to death than older 3- to 4-month-old grubs. The highest grub mortality, 86.66%, was obtained with the nematode density of 40,000 nematodes per pot. When nematode density was increased from 40,000 to 400,000 nematodes per pot grub mortality did not increase. Grubs placed in direct contact with nematodes in petri plates were equally killed, independently of the nematode density used. Direct nematode inoculation through grub's mouth, anus or a combination of mouth and anus or steeped in water containing nematodes did not increase grub mortality beyond that already obtained in the soil. If similar results are obtained in the field, this method of control could be of great value to reduce D. abbreviatus populations.