Neoaplectana Carpocapsae: Toxin Production By Axenic Insect Parasitic Nematodes

Abstract

The insect parasitic nematode Neoaplectana carpocapsae produces toxin(s) periodically during its life cycle. Maximal toxic activity is observed in axenic synchronous cultures containing a high percentage of adult nematodes. After hatching of their offspring, the toxicity is sharply reduced or disappears, but the toxin(s) reappears with the development of the third and fourth stage juveniles. Wax moth larvae, Galleria mellonella, injected with the toxic culture extract are rapidly affected. After 10-30 minutes the heart beats became weak and erratic. After about 1 hour the activity and behaviour of the insect larvae are affected. Injection of a higher concentration kills Galleria larvae and larvae of the large pine weevil, Hylobius abietis, within 24 hours. The toxic substance(s) in the nematode growth extract is stable to freezing and treatment with sodium periodate, but is inactivated by 60° for 10 minutes or by trypsin digestion.