SPECIFIC AND ALLOSPECIFIC LARVAE EXTRACTS MAY BE USED AS A MOSQUITO CONTROL STRATEGY

Abstract

One of the strategies for integrated mosquito management is to attract gravid females to stimulate egg laying in traps containing biolarvicide that eliminate offspring for population control. Usually, the great challenge of this approach is the development of an attraction that stimulates oviposition combined with toxin without deterrent effect. Biolarvicide Bacillus thuringiensis var. israelensis (Bti) meets the last criterion, but the development of baits is required to optimize trap performance. In this study, we evaluated extracts of immature forms of mosquitoes as oviposition stimulants. Eggs, 4th stage larvae and pupae of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus were used for extract production. The bioassays were performed using cages in which 2 oviposition containers (test versus control) were placed as sources of choice. We used the equivalence of 0.33 larva or pupa/ml and 1 egg/ml for production of immature extracts. Groups of 30 gravid females were used at each repetition (N = 12) for 7 days. We observed that A. aegypti, A. albopictus and C. quinquefasciatus laid significantly more eggs in containers with 4th stage larvae extract of the same or different species. Lyophilized larval extracts were stimulatory even after one month of freeze drying. Testing concentrations of 0.1 to 1 larva-equivalent per milliliter, oviposition activity gradually increased as the dose was more concentrated. The results show efficiency in the use of larval extracts and to enhance egg collection. Studies related to the isolation and identification of oviposition stimulating compounds that are present in the larval body can generate products that optimize the performance of entomological surveillance and control traps.