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Acta Prataculturae Sinica ›› 2024, Vol. 33 ›› Issue (12): 201-213.DOI: 10.11686/cyxb2024053

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Toxicity of 10 insecticides to alfalfa aphid Therioaphis trifolii and thrip Odontothrips loti and assessment of their field efficacy

Bin PENG1(), Xiao-ning CUI1(), Bo ZHANG1, Bo-xin XI2, Gui-xin HU1, Tuo YAO1, Chang-ning LI1, Kui-ju NIU1, Feng-mei CHANG1, Jian-hai BAI3   

  1. 1.College of Pratacultural Science,Gansu Agricultural University,Key Laboratory for Grassland Ecosystem of Education Ministry,Key Laboratory of Forage Germplasm Innovation and New Variety Breeding of Ministry of Agriculture and Rural Affairs,Lanzhou 730070,China
    2.College of Plant Protection,Gansu Agricultural University,Lanzhou 730070,China
    3.Gansu Xinhai Herbage Feed Technology Co,Ltd,Lanzhou 730070,China
  • Received:2024-02-05 Revised:2024-04-22 Online:2024-12-20 Published:2024-10-09
  • Contact: Xiao-ning CUI

Abstract:

Therioaphis trifolii aphid and Odontothrips loti thrip are the most important pests threatening alfalfa (Medicago sativaproduction in China. This study, conducted in Minqin county, Gansu Province, aimed to identify highly effective and low-toxicity biopesticides against T. trifolii and O. loti for field control. We investigated the field population dynamics of these two insect species through the clapper boarding method. The toxicity of 10 different insecticides against T. trifolii and O. loti was determined using the leaf dipping method in laboratory, and the field control efficacy was also evaluated in spraying tests. The results showed that the population densities of T. trifolii and O. loti were highest during the second and third alfalfa regrowth cycles, and the peaks occurred on July 9 and August 10, in the alfalfa bud stage. Laboratory toxicity results indicated that veratrine and matrine were the most toxic to T. trifolii and O. loti, while imidacloprid, β-cypermethrin, rotenone, spinetoram and avermectin were intermediate, and spirotetramat exhibited the least toxicity. Field control efficacy of matrine and rotenone against T. trifolii aphids ranged from 73.47% to 85.16%, and for O. loti thrips ranged from 70.11% to 88.61% during the period from seven to 14 days after application. The control efficacy of spinetoram and avermectin against T. trifolii ranged from 67.80% to 82.00%, and for O. loti ranged from 83.67% to 92.55% in the same period. Based on our results, the high-efficiency and low-toxicity rotenone, matrine, avermectin and spinetoram are recommended as the preferred chemicals for spray control of T. trifolii and O. loti in the field production of alfalfa.

Key words: Therioaphis trifolii, Odontothrips loti, population dynamics, toxicity, field efficacy