Chemical control of the two spotted spider mite Tetranychus urticae Koch on Hedera helix Anneborgh
2001
Heungens, A. | Tirry, L. (Universiteit Gent, Gent (Belgium). Fac. van de Landbouwkundige en Toegepast Biologische Wetenschappen. Lab. voor Agrozoologie)
A comparative control experiment with 11 acaricides or insecticides with known or expected acaricidal activity was carried out using Hedera helix infested by Tetranychus urticae. The plants were treated thoroughly once, using a knapsack sprayer. Mortality was assessed one week after treatment. Imidacloprid showed a rather limited acaricidal ativity. Methornyl, endosulfan and chlorfenapyr proved to have acaricidal properties, but the control results at the used dose rates were significantly lower than those of the better products. The six typical acaricides (tebufenpyrad, bifenthrin, dicofol, fenbutatinoxide, amitraz and abamectine) all gave a proper control result, varying from 85.7 to 98.5 percent mortality, depending the compound and the treated life stage. Methamidophos treatment resulted in mortality percentages similar to those of the acaricides. Treatment with abamectine at 0.5 ml formulated compound per liter water resulted in a mortality of 96 to 98 percent for the mobile stages; amitraz at 2 ml commercial per liter water gave similar results for the larvae and nymphs, but not for the adults (90.9 percent). From these results it appears that abamectine and amitraz are the more appropiate acaricides for the control of Tetranychus urticae. Fenbutatinoxide, dicofol, bifenthrin, tebufenpyrad and methamidophos approximate both acaricides; they could most probably give an similar result, providing an adjustment of the dose or a second treatment.
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