Evaluation of the larvicidal efficacy of pyriproxyfen and the effect on life history traits of anopheles arabiensis

Juvenile hormone analogs have been used as larvicides to control malaria vectors. They are specific, with minimum effects to non-target organisms which co-habit with vectors in breeding sites. They suppress immature stages of malaria vectors. Pyriproxyfen is among of JHA which has high potency for vector control. This study aimed to determine the threshold concentration which can control emergence of An. arabiensis, the impact of sublethal dose on the emerged adults and persistence of PPF in the resting sites (contamination sites) and in breeding habitats after dissemination. The pyriproxyfen powder was dissolved in acetone. Serial dilution was done to obtain 10 different concentrations. Fifteen An. arabiensis larvae were treated with each concentration in triplicates against control. For sublethal experiments, An. arabiensis larvae were treated with 0.01 ppb, emerged adults were tested for blood feeding, fertility, fecundity and longevity against control. Persistence of PPF was investigated by allowing mosquitoes to blood fed a calf and rest in PPF dusted pots, thereafter oviposits in artificial breeding sites, transferring PPF into water. Threshold concentration was found ranging from 1.10 to 1.60 ppb. Sublethal results showed that longevity of all female mosquitoes was significantly affected (p<0.05). Males from control lived longer than sublethal ones (p<0.0279). Sublethal adults produced a few offsprings (p=0.0025) than control ones when compared with number of eggs oviposited. Pyriproxyfen powder was found biologically active for two months in pots. It was found to control emergence at 90% for 48 days post water contamination. Pyriproxyfen is a potent larvicide for the control of malaria vectors to complement the existing interventions.