An analysis of insecticide-resistant aphids in the vegetable ecosystem: a case study

Aphids are cosmopolitan sucking pests that cause considerable harm to vegetable ecosystems by devitalizing plant sap and transferring many plant viruses. To control this nefarious pest, farmers spray many old generic insecticides which often fail to give satisfactory control. To address these issues, the in-vitro toxicity of several newer synthetic pesticide compounds and an organophosphate insecticide was assessed against three aphids found in vegetable ecosystems: Myzus persicae, Aphis craccivora, and Lipaphis erysimi. It has also been used to ascertain whether resistance to these insecticides has developed over the past decade or not. The median lethal concentration (LC₅₀) of Acetamiprid 20% SP, one of the recent neonicotinoid compounds, against the three vegetable aphid species were 0.098, 0.88, and 1.98 ppm for A. craccivora, M. persicae, and L. erysimi, respectively. All the test aphids reacted differently to these test insecticides. A. craccivora was the most susceptible one followed by M. persicae and L. erysimi. M. persicae exhibited 21.93, 3.38 and 4.02 fold resistance to Imidacloprid 17.8% SL, Thiamethoxam 25% WG and Dimethoate 30% EC respectively, according to a comparison of LC₅₀ values for the regularly used and recommended pesticides over a period of twelve years (2010 to 2022). Rotation of insecticides viz., Neonicotinoids (Acetamiprid 20% SP) followed by Phenyl pyrazole (Fipronil 5% SC) and /or Flonicamid (Flonicamid 50% WG) could be viable option for management of these cosmopolitan sucking pests.