Efficacy of Ginkgo biloba L. and Derris trifoliata binary extract combinations against aphids (Hemiptera: Aphididae)

Abstract

Combinations of Ginkgo biloba (G. biloba) extract (active ingredient ginkgolic acid (GA)) and Derris trifoliata (D. trifoliata) extract (active ingredient rotenone (R)) were evaluated through bioassays and field trials to develop botanical insecticides as alternatives to chemical pesticides for aphid control. The bioassay results showed that the G. biloba extract exhibited high insecticidal activity against Acyrthosiphon pisum, Myzus persicae, and Aphis spiraecola adults, with LC50 values of 333.89 μg/mL, 282.52 μg/mL, and 250.41 μg/mL, respectively. D. trifoliata extract exhibited better insecticidal activity against A. pisum, M. persicae, and A. spiraecola adults, with LC50 values of 19.22 μg/mL, 12.70 μg/mL, and 3.99 μg/mL, respectively. Moreover, the extract combination of G. biloba and D. trifoliata at a ratio of 84:16 exhibited significant synergy against A. pisum, with a cotoxicity coefficient of 219.01. Additionally, two insecticidal formulations of 23% GA soluble liquid (SL) and 11.5% GA-R SL were developed using G. biloba extract (GA) and G. biloba with D. trifoliata extract (GA-R) combinations as the active substances. Field trials in 2020 and 2021 indicated that 11.5% GA-R SL had efficacies of 84.38% and 85.19%, respectively, against A. spiraecola seven days after a 721.28 a.i. g/hm2 application; 23% GA SL had 65.33% and 66.09% efficacies, respectively, against A. spiraecola seven days after a 1442.56 a.i. g/hm2 application. Based on these results, 11.5% GA-R SL has potential as a botanical pesticide for aphid control.