A Predictive Analysis of Insecticide Resistance Trend on Culex quinquefasciatus (Diptera: Culicidae) Mosquito Larvae Over Generations Upon Sublethal Treatment With DDT, Malathion and Deltamethrin

Background and objectives: Prior studies showed that, repeated exposure of insecticides during the larval stage led to increase in vector resistance. However, a gap of knowledge persisted in analysing the trend of insecticide resistance and cross resistance in mosquitoes upon sublethal treatment during its larval stage over generations with different insecticides. Therefore, the goal of the current study was to comprehend the pattern of insecticide resistance and cross resistance in Cx. quinquefasciatus larvae following four generations of sublethal deltamethrin, DDT and malathion treatment. The current study's research questions were [I] would there be an increasing trend of larval resistance observed upon repeated sublethal treatment on Cx. quinquefasciatus larvae with several insecticides in each generation, and [II] will the trend of resistance be different for each insecticide? Methods: The larvae of Cx. quinquefasciatus in their early 3 ^rd instar were therefore subjected to sublethal doses of deltamethrin (0.01 mg/ml), DDT (1 mg/ml), and malathion (1 mg/ml). The resilience of the larvae was noted after 24hours of exposure Statistical analyses were performed using Generalised Mixed Modelling (glmm) and Log likelihood ratio tests (LRT). Results: The results revealed a trend displaying increase in the larval resistance across the generations. Moreover, it was found that the larvae were showing more resistance against DDT followed by deltamethrin and malathion. The cross-resistance analysis demonstrated that larvae resistant to one class of insecticide exhibited an increased level of resistance to other insecticides across successive generations. Interpretation and conclusion: Thus, the study successfully evaluated a trend of increase larval resistance in Cx. quinquefasciatus upon continuous exposure with DDT followed by malathion and deltamethrin over multigeneration. The study can act as a reference for future studies especially in vector control management to develop novel vector strategies and stimulating resistance trend for different mosquito species.