Clothianidin exposure enhances fecundity in Bactrocera dorsalis via metabolic activation and endocrine modulation: implications for pest resurgence

Abstract

Chemical insecticides have been fundamental in managing agricultural pests, yet prolonged use can cause sublethal effects that promote pest resurgence. This study investigated the effects of the neonicotinoid insecticide clothianidin on the reproduction, physiological metabolism, and population dynamics of Bactrocera dorsalis. Exposure to sublethal and lethal concentrations (LC₂₀ and LC₅₀) of clothianidin led to an increase in the reproductive capacity of F₀ females. Furthermore, this reproductive enhancement was transferred to the F₁ generation, especially in the LC₅₀ treatment group. Further analysis revealed that clothianidin exposure led to significant alterations in lipid and carbohydrate metabolism, with increases in glycogen and glucose levels contributing to enhanced reproductive success in the F₀ generation. This enhancement correlates with elevated levels of juvenile hormone (JH) and 20-hydroxyecdysone (20E), both of which are crucial for reproductive regulation, along with increased expression of vitellogenin (Vg) and its receptor (VgR). Consequently, the life parameters of the F₁ population, including fecundity (f_x), survival rate (v_xj), intrinsic growth rate (r), finite growth rate (λ), and net reproductive rate (R₀), exhibited significant increases. Concurrently, the average generation time (T) decreased, leading to an overall acceleration in population growth. These findings provide important insights into the physiological adaptations of B. dorsalis to clothianidin, suggesting that its use, while effective against pest populations, may lead to unintended consequences on pest resurgence, thus contributing to our understanding of the complexities involved in pest management strategies and highlights the need for careful application of insecticides to mitigate risks associated with pest resurgence.