Stress effects of five pesticides on reproduction and development of Bursaphelenchus xylophilus
To avoid the resistance of Bursaphelenchus xylophilus to pesticides caused by using single agent in the long time,it is urgent to explore alternative agents for the effective prevention and control of B.xylophilus.Fluopyram 10%suspension concentrate(SC)+avermectin 2%microemulsion(ME)and fluopyram 10%SC+emamectin benzoate 1%ME were made by compounding of emamectin benzoate,avermectin and fluopyram,respectively.The toxicity of the two compounding pesticides with that of emamectin benzoate 2%ME,avermectin 1.8%ME and fluopyram 5%SC were compared.The reproduction and development indexes of B.xylophilus were also quantitatively analyzed under sublethal concentration(LC20),including oviposition amount,egg hatching rate,developmental progress,sex ratio and body length.The results showed that emamectin benzoate 2%ME had the strongest toxicity to the second-stage juveniles of B.xylophilus,with the LC50 of 0.017 2 mg/L for treatment 36 h,followed by fluopyram 10%SC+avermectin 2%ME with the LC50 of 0.058 5 mg/L.Compared with the control group,emamectin benzoate 2%ME had the strongest inhibition,with the oviposition amount(3.73±0.43),egg hatching rate(49.56±5.85)%,the proportion of sexual maturity nematode(25.33±2.83)%,the sex ratio of B.xylophilus(2.15±0.04)and body length(925.43±10.68)μm of female B.xylophilus,and all were significantly decreased after treatment with pesticides.The second was fluopyram 10%SC+avermectin 2%ME,with the oviposition amount(6.80±0.47),egg hatching rate(61.08±0.71)%and the proportion of sexual maturity nematode(36.56±1.46)%,which significantly decreased.Emamectin benzoate 2%ME and compounding agent fluopyram 10%SC+avermectin 2%ME could effectively inhibit the reproduction and development of B.xylophilus.Therefore,these two agents can be alternated to control pine wilt disease and delay the resistance of B.xylophilus.
Bursaphelenchus xylophilusnematicidetoxicity determinationreproduction and developmentchemical stress