title: Insecticidal activity of destruxin, a mycotoxin from Metarhizium anisopliae (Hypocreales), against Spodoptera litura (Lepidoptera: Noctuidae) larval stages.
abstract: BACKGROUND
  The cyclodepsipeptide destruxin produced by the entomopathogen Metarhizium anisopliae (Metch.) was administered by different methods, topical application, ingestion and a combination of the two, in an attempt to minimize the mycotoxin dose for efficient management of the insect pest Spodoptera litura (Fab.).
  
  
  RESULTS
  The insecticidal activity of destruxin on the larval stages of S. litura showed an ascending trend in LD(50) values with increasing age. The value for 12-day-old larvae in the combined application assay was as low as 0.045 microg g(-1) body weight of crude destruxin from M-19 strain when compared with the corresponding values of 0.17 microg g(-1) body weight in the ingestion assay and 0.237 microg g(-1) body weight in the topical application assay. On the other hand, values were higher in the treatments with crude destruxin from the low-virulence M-10 strain of M. anisopliae showing the least quantities of A and E components of destruxin.
  
  
  CONCLUSIONS
  Laboratory bioevaluation showed the combination assay of ingestion and topical application of crude destruxin to be efficient in enhancing its insecticidal properties. The adopted combination assay apparently simulates application of the insecticide at field level. Quantitative differences between destruxins from low- and high-virulence strains of M. anisopliae are in accordance with its presumed role in virulence.
authors.affiliation: Department of Botany, Andhra University, Visakhapatnam, India.
authors.forename: K
authors.initials: K
authors.lastname: Sowjanya Sree
authors.forename: Vadlamani
authors.initials: V
authors.lastname: Padmaja
authors.forename: Yellajyohula L N
authors.initials: YL
authors.lastname: Murthy
mesh_terms: D000375:Aging; D000818:Animals; D047630:Depsipeptides / Q000737:chemistry / Q000494:pharmacology*; D005656:Fungal Proteins / Q000737:chemistry / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007306:Insecticides / Q000737:chemistry / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D007928:Lethal Dose 50; D052981:Metarhizium / Q000737:chemistry*; D018411:Spodoptera / Q000187:drug effects* / Q000254:growth & development
chemical_list: D047630:Depsipeptides; D005656:Fungal Proteins; D007306:Insecticides; C040423:destruxin A; C040425:destruxin E