Cholesterol oxidase: an oöstatic and larvicidal agent active against the cotton boll weevil, <i>Anthonomus grandis</i>

Abstract

Abstract The enzyme cholesterol oxidase (E.C. 1.1.3.6), purified from Streptomyces culture filtrate was previously found to have oral insecticidal activity on neonate larvae of the boll weevil ( Anthonomus grandis grandis Boheman) from a laboratory population. In the present study, second instar larvae were also controlled by the enzyme at diet concentrations similar to those which control neonates (12 day LC 50 = 2.4 μg.ml −1 in diet). Larvae from field‐collected adults were similarly susceptible to cholesterol oxidase in the diet. When ingested by adult females during the mating/pre‐oviposition period, cholesterol oxidase greatly reduced subsequent oviposition (83% reduction in eggs laid as compared to controls) and larval survival (97% reduction from controls). Dissection of treated adult females revealed poorly developed ovaries and few developing oöcytes. These studies were conducted to further evaluate the utility of cholesterol oxidase in a program to establish boll weevil‐resistant transgenic cotton.