Resistance to fenpropathrin, chlorpyriphos and abamectin in different populations of Amblyseius longispinosus (Acari: Phytoseiidae) from vegetable crops in South China

• Resistance of these mites was demonstrated under laboratory bioassay conditions.
• Mites collected from different regions had parallel resistance to the same insecticide.
• The safety of insecticides to Amblyseius longispinosus was assessed.
• The results were the first report of resistance of A. longispinosus in China.

The predacious phytoseiid mite Amblyseius longispinosus is an important agent for the biological control of spider mites on the vegetable crops in South China. Monitoring the resistance to pesticides would be helpful to protect the A. longispinosus on the commercial vegetable crops. Resistance of three A. longispinosus strains to fenpropathrin, chlorpyriphos and abamectin was demonstrated under laboratory bioassay conditions. Resistance ratios (RR50 and RR90) were calculated by dividing the LC50 (or LC90) value of the three strains of predatory mites collected from different regions by the LC50 (or LC90) value of a very highly susceptible strain. RR50 of fenpropathrin, chlorpyriphos and abamectin for the three resistant strains were 591.53–864.84, 282.46–379.88 and 25.79–31.60, respectively, and RR90 were 291.33–321.53, 38.67–54.07 and 8.33–11.57, respectively. Compared to the field recommended concentration and the tested concentration, the safety of pesticides to A. longispinosus was assessed based on dose-mortality probit lines of various A. longispinosus strains. This study provided useful information for pesticide use to protect and utilize the predatory mites, completely, combined the biological and chemical control methods.

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