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Acute and sublethal toxicity of novaluron, a novel chitin synthesis inhibitor, to Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

Authors

  • G Christopher Cutler,

    Corresponding author
    1. Department of Environmental Biology, Ontario Agricultural College, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
    • Department of Environmental Biology, Ontario Agricultural College, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
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  • Cynthia D Scott-Dupree,

    1. Department of Environmental Biology, Ontario Agricultural College, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
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  • Jeffrey H Tolman,

    1. Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, Ontario, Canada, N5V 4T3
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  • C Ronald Harris

    1. Department of Environmental Biology, Ontario Agricultural College, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
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Abstract

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 LC50 = 0.42 mg litre−1) and good direct contact (120 h LC50 = 27 mg litre−1) activity against second-instar larvae (L2). Hatch of eggs exposed by direct contact to novaluron solutions ≥100 mg litre−1 was significantly reduced, as was the ability of emerged first-instar larvae to moult. L2 from eggs exposed to ≥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 ≤ 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. Copyright © 2005 Society of Chemical Industry

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