Effects of acetamiprid on life cycle development of predatory mite Amblyseius cucumeris (Acari: Phytoseiidae) after contact exposure.

Amblyseius cucumeris (Oudemans) is a beneficial non-target arthropod (NTA) and a key predator of pest mites in integrated pest management (IPM) programs across china. The toxic effects of insecticides have been extensively reported on predatory mites, but few studies devoted to the toxicity of compounds to A. cucumeris. In this study, the effects of a single application of acetamiprid against the A. cucumeris were investigated in a 48-h acute and a 30-d chronic test. In both tests the insecticide acetamiprid was applied once. In the acute test, the "open glass plate method" was used, with a 48-h LC50 value of 223.6 (149.8-336.9) mg a. i. L-1 for adult female. The LC50 was 1.49-fold the Maximum field recommended concentration. In the chronic test, exposure concentrations (1.12, 2.24, 4.47, 8.94, and 22.4 mg a. i. L-1) were designed based on a preliminary 48-h LC50 value for adult female. Above treatment levels of 2.24-4.47 mg a. i. L-1 reduce the total development time, survival rates and food consumption of A. cucumeris in different development stages. In addition, at acetamiprid concentrations higher than 2.24 mg a. i. L-1 serious effect on the capacity of oviposition of female adults were observed. However, even the highest treatment level of 22.4 mg a. i. L-1 did not affect egg hatching rates of exposed eggs. Acetamiprid had significant adverse effects on different development life stages of A. cucumeris. The results provide informative data for implementing biological and chemical control strategies in integrated pest management of spider mites.