Acute and sublethal toxicity of novaluron, a novel chitin synthesis inhibitor, to Leptinotarsa decemlineata (Coleoptera: Chrysomelidae).
The acute and sublethal toxicities of novaluron, a novel chitin synthesis inhibitor, to a laboratory-reared insecticide-susceptible strain of Colorado potato beetle, Leptinotarsa decemlineata (Say), were determined. Novaluron exhibited excellent residual (120 h LC(50) = 0.42 mg litre(-1)) and good direct contact (120 h LC(50) = 27 mg litre(-1)) activity against second-instar larvae (L2). Hatch of eggs exposed by direct contact to novaluron solutions > or =100 mg litre(-1) was significantly reduced, as was the ability of emerged first-instar larvae to moult. L2 from eggs exposed to > or =100 mg litre(-1) novaluron weighed significantly less (P < 0.0001) than those from untreated eggs. However, L2 from eggs treated with 1 mg litre(-1) novaluron weighed significantly more (P < or = 0.05) than those from untreated eggs, suggesting novaluron can have a hormetic effect on L decemlineata larval development. Leptinotarsa decemlineata mating pairs fed foliage treated with novaluron at 25 or 75 g AI ha(-1) produced approximately 25% fewer egg masses and eggs per mass. Hatch of eggs on treated foliage was almost completely suppressed, and longevity of male beetles was reduced by approximately 50% when fed foliage treated with novaluron at 75 g AI ha(-1).
Cutler
G Christopher
GC
Department of Environmental Biology, Ontario Agricultural College, University of Guelph, Canada. cutler@uoguelph.ca
Scott-Dupree
Cynthia D
CD
Tolman
Jeffrey H
JH
Harris
C Ronald
CR
D000818:Animals; D002686:Chitin / Q000096:biosynthesis*; D001517:Coleoptera / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007306:Insecticides; D007814:Larva / Q000187:drug effects; D008297:Male; D010058:Oviposition / Q000187:drug effects; D010063:Ovum / Q000187:drug effects; D010671:Phenylurea Compounds / Q000494:pharmacology / Q000633:toxicity*
D007306:Insecticides; D010671:Phenylurea Compounds; D002686:Chitin; C471805:novaluron