Abstract:
Objective Rhagoletis batava obseuriosa (RBO) has caused serious damage to Hippophae rhamnoides fruit in Dengkou County, Inner Mongolia, China. This study aims at Selecting high efficiency, low residue and easy degradable environmental friendly pesticides to prevent and control RBO.
Method The pupae of RBO were collected at sea-buckthorn orchard in Dengkou County in April, 2017. After the emergence of adults in the laboratory, the female and male adults were separately bioassayed with different concentrations of four pesticides to evaluate the contact lethal effects of the four pesticides by dish tests.
Result The results of KT50 (median knockdown time) data analysis showed that the male's contact toxicity of four pesticides was a little higher than that of female. When the concentration of matrine was 0.005 mg·mL-1, the male's KT50 value was 39.21 h, less than the female's KT50 value of 56.13 h, but there was some exceptions, for example, when the concentration of matrine was 0.05 mg·mL-1, the male's KT50 value (15.76 h) was higher than the female's KT50 value of 12.39 h. The results of LC50 (median lethal dose) analysis showed that the contact toxicity of four pesticides to RRO was different. When the adults were treated with 12 hours, LC50 of the four different pesticides were azadirachtin 7.737 mg·mL-1, lambda-cyhalothrin 0.002 mg·mL-1, matrine 0.042 mg·mL-1 and avermectins 0.008 mg·mL-1, respectively. The lethal effect of the four pesticides from high to low were lambda-cyhalothrin, avermectins, matrine and azadirachtin; when the adults were treated with 24 hours, LC50 of four pesticides were azadirachtin 6.963 mg·mL-1, lambda-cyhalothrin 0.001 mg·mL-1, matrine 0.008 mg·mL-1 and avermectins 0 mg·mL-1, respectively. The lethal effects from high to low were avermectins, lambda-cyhalothrin, matrine and azadirachtin; when adults were treated with 48 hours:LC50 of four pesticides were azadirachtin 0.891 mg·mL-1, lambda-cyhalothrin 0 mg·mL-1, matrine 0.002 mg·mL-1 and avermectins 0 mg·mL-1, respectively. The lethal effects of the four pesticides from high to low were avermectins, lambda-cyhalothrin, matrine and azadirachtin.
Conclusion Avermectins and lambda-cyhalothrin have high contact lethal effect to RBO adults, followed by matrine. Azadirachtin shows no effective contact lethal ability to RBO adults. More bioassay need to be carried to check their control effect on RBO in the field.