Synthetic feeding stimulants enhance insecticide activity against western corn rootworm larvae, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae)
2011
Bernklau, E.J. | Bjostad, L.B. | Hibbard, B.E.
In bioassays, the addition of a synthetic feeding stimulant blend improved the efficacy of the insecticide thiamethoxam against neonate western corn rootworm, Diabrotica virgifera virgifera LeConte, larvae. In 4-h bioassays, the concentration of thiamethoxam required for 50% mortality (LC₅₀) was 2800 pg/ml for the insecticide alone, but was reduced to 0.0075 pg/ml when the synthetic feeding stimulant blend was added (more than a 100,000-fold difference). Dilutions of thiamethoxam and tefluthrin (ranging from 0 pg/ml to 10 μg/ml) were tested in behavioural bioassays alone and in conjunction with a feeding stimulant blend containing 30 : 4 : 4 : 1 mg/ml glucose : fructose : sucrose : linoleic acid. Larvae were placed on insecticide-treated filter paper disks in an arena that allowed them to leave the treated area at will. In 30-min bioassays, and in 4-h bioassays, significantly more larvae fed on thiamethoxam-treated disks when the feeding stimulant blend was present for every concentration of insecticide tested. Larvae fed readily on disks treated with tefluthrin when the feeding stimulants were added, but the feeding stimulant blend did not affect the activity of tefluthrin insecticide at any concentration tested.
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