Glass vial technique for monitoring insecticide resistance in Helicoverpa armigera (Hubner) in the Philippines
1999
Ocampo, V.R. | Facundo, J.B.dL. (Philippines Univ. Los Banos, College, Laguna (Philippines). Dept. of Entomology)
A diagnostic monitoring technique that uses glass vials treated with a single dose of insecticide with a known response from a susceptible population was developed in Texas (McCutchen, B.F., F.W. Plapp Jr., S.J. Nemec and C. Campanhola, 1989, J, Econ, Entomol., 82(6):1502-1507) to monitor pyrethroid resistance in larval stages of the tobacco budworm, Heliothis virescens (F.) and the bollworm, H. Zea (Boddie). This technique was evaluated for adaption under Philippine conditions in anticipation of a future insecticide resistance management (IRM) program on field populations of corn earworm, Helicoverpa armigera (Hubner). Discriminating concentrations were developed for 16 insecticide formulations using the glass vial technique and the dry run was conducted on a laboratory colony of H. armigera. The response of the F9 and F13 fourth instar corn earworm larvae to the selected insecticides were summarized. Most of the insecticides produced mortalities higher than 90%, as expected. The discriminating concentrations were tested using larvae that were several generations removed from the initial batch of larvae used to develop the discriminating concentrations. Insects become more and more susceptible through generations of laboratory rearing because of the absence of insecticide selection pressure. For field testing, glass vials were treated in the laboratory long before they were to be used in the field and the residual toxicity was maintained for more than a month
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