Ability of amitraz to maintain the predator Exochomus quadripustulatus L. (Col., Coccinellidae) in an integrated management of Eupulvinaria hydrangeae (Steinw.) (Hom., Coccidae)
1993
Tondeur, R. (U.E.R., Gembloux (Belgium). Chimie Analytique et Phytopharmacie) | Merlin, J. | Schiffers, B. | Verstraeten, C. | Squerens, N.
To investigate the possibility of using amitraz in an integrated control programme of Eupulvinaria hydrangeae, the selectivity of the insecticide to Exochomus quadripustulatus was studied in the laboratory and the effects of amitraz spraying on the predator populations were evaluated under natural conditions. Laboratory experiments included three complementary methods. The first involved topical application of the active ingredient (amitraz). The second method investigated the effects of the commercial formulation MITAC(R), emulsifiable concentrate (EC) at 190 g/l amitraz, on ladybeetles dipped in the insecticide mixture. The third method tested the effects of the same commercial product when ladybeetles were fed with scale insecticide treated under field conditions. Amitraz or its MITAC(R) formulation applied in concentrations of up to 0.1% equivalent active ingredient did not affect mortality or fecundity of E. quadripustulatus. However, when treatment was particularly severe as when adults were dipped in a MITAC(R) solution, a reversible tetanization was observed. Assuming that toxicity will also be low under field conditions, a preliminary field experiment was designed to investigate how E. quadripustulatus reacts to a partial MITAC(R) treatment of the vegetation. It was found that spraying induced a decrease in the number of E. quadripustulatus although there was no way of distinguishing between mortality and dispersal. Anyway the decrease of the predator is at worst in the same order of magnitude as for its prey: E. hydrangeae. The results of these laboratory and field experiments indicate that MITAC(R) could be a useful component in an integrated pest management scheme of E. hydrangeae
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