title: The utility of camptothecin as a synergist of Bacillus thuringiensis var. kurstaki and nucleopolyhedroviruses against Trichoplusia ni and Spodoptera exigua.
abstract: We studied the effect of combining microbial pesticides with camptothecin (CPT) on the mortality of two lepidopteran insects: Trichoplusia ni (Hübner) and Spodoptera exigua (Hübner). CPT is an alkaloid that is often used as an anticancer agent. Here, CPT was evaluated as a microbial pesticide synergist of Bacillus thuringiensis (Bt) and insect baculovirus. The toxicity of CPT and its synergistic effects on two microbial pesticides were studied using the diet overlay method. Bioassay results showed that CPT significantly enhances the toxicity of Bt variety kurstaki to S. exigua and T ni. In addition, CPT strongly enhanced the infectivity of Autographa californica (Speyer) multinucleocapsid nucleopolyhedrovirus (AcMNPV) and S. exigua nucleopolyhedrovirus (SeMNPV). Using light microscopy, we found that CPT disrupts the peritrophic membrane of T. ni larvae and severely affects the structure of the midgut, resulting in an abnormal gut lumen morphology. We speculate that CPT increases toxicity by affecting the permeability of the peritrophic membrane.
authors.affiliation: State Key Laboratory of Biocontrol, College of Life Sciences, Sun Yat-sen University, No. 135 XingangXi Road, Guangzhou, Guangdong 510275, People's Republic of China.
authors.forename: Shifeng
authors.initials: S
authors.lastname: Sun
authors.forename: Zhongshan
authors.initials: Z
authors.lastname: Cheng
authors.forename: Jing
authors.initials: J
authors.lastname: Fan
authors.forename: Xinghu
authors.initials: X
authors.lastname: Cheng
authors.forename: Yi
authors.initials: Y
authors.lastname: Pang
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis; D061046:Biological Control Agents; D002166:Camptothecin / Q000494:pharmacology; D041981:Gastrointestinal Tract / Q000187:drug effects; D054884:Host-Pathogen Interactions / Q000187:drug effects; D007300:Insect Control; D007814:Larva; D017924:Nucleopolyhedroviruses; D010574:Pesticide Synergists / Q000494:pharmacology; D018411:Spodoptera / Q000187:drug effects
chemical_list: D061046:Biological Control Agents; D010574:Pesticide Synergists; D002166:Camptothecin