Insecticide degradation potential of aphid associated bacteria

Abstract

Microorganisms that are naturally present in the insect gut play a crucial role in regulating physiological and metabolic functions, ultimately enhancing the host's fitness and adaptability to challenging environments. This includes detoxification processes that break down harmful substances and xenobiotics, such as insecticides. This study investigated the capacity of bacteria associated with aphids to degrade imidacloprid residues in agricultural soils, a crucial factor in mitigating environmental pollution. Two bacterial strains, Exiguobacterium indicum MPB-2 and Pseudomonas hibiscicola CCF 2-2, were isolated from the midgut of aphids and assessed for their ability to degrade imidacloprid in both sterile and non-sterile organic soils. E. indicum MPB-2 exhibited superior imidacloprid degradation efficiency, realizing 45.65 % imidacloprid breakdown in sterile soil and 33.45 % in non-sterile soil. A field experiment within a cabbage cropping system further validated the efficacy of E. indicum MPB-2 and P. hibiscicola CCF 2-2, which reduced imidacloprid residues by 31.4 % and 31.0 %, respectively. In multi-location trials, consistent degradation performance was observed across all test locations, with E. indicum MPB-2 outperforming P. hibiscicola CCF 2-2. These findings suggest that these bacterial strains facilitated imidacloprid degradation and possess the metabolic flexibility to utilize insecticides as their primary carbon and nitrogen sources. Accordingly, their presence in the aphid gut could enhance host resilience while contributing to bioremediation efforts in agricultural ecosystems. This study highlighted the potential application of aphid-associated bacteria in reducing the toxicity of imidacloprid pesticide and promoting sustainable agriculture.