Indian honey bees ( Apis cerana indica ) detoxify imidacloprid and clothianidin: in silico and in vivo analyses of key detoxifying enzymes

Indian honey bee (Apis cerana indica F.) is a commercially exploited bee species in Southern India. The prime cause of recent bee colony declines is related to neonicotinoid toxicity. The molecular responses of this species to neonicotinoids remain unexplored. The major detoxifying enzyme families (CYP and GST) were selected for in silico analysis (docking studies) and in vivo analysis (qRT-PCR) to reveal the mechanism of insecticide resistance in bees. The real-time monitoring was performed at different intervals, viz., 15 min after exposure (MAE), 2 h after exposure (HAE), 6 HAE, and 24 HAE, at sub-lethal doses (LC20) of imidacloprid and clothianidin. The most suitable detoxifying enzymes for imidacloprid were CYP9Q3 and GSTD, registering the lowest docking energies (−6.37 and −6.76 Kcal mol−1) and increased gene activities (3.79 and 3.10-fold), respectively. Whereas for clothianidin, the detoxifying enzymes CYP9Q2 and GSTZ resulted in maximum interaction with −6.86 and −6.98 Kcal mol−1, followed by 4.04 and 3.81-fold upregulation, respectively. Since the upregulation of detoxification genes is considered one of the primary mechanisms by which insecticides are metabolized, it plays a crucial role in the development of resistance to insecticides in bees. This work is the first to report a detoxifying enzyme-mediated defense mechanism in Indian honey bees to overcome neonicotinoid toxicity, which is presumed to be present in all bee species.