Abstract
The sterile insect technique (SIT) is a promising pest control method in terms of efficacy and environmental compatibility. In this study, we determined the efficacy of thiotepa-sterilised males in reducing the target Aedes aegypti populations. Treated male pupae were released weekly into large laboratory cages at a constant ratio of either 5:1 or 2:1 sterile-to-fertile males. A two-to-one release ratio reduced the hatch rate of eggs laid in the cage by approximately a third and reduced the adult catch rate by approximately a quarter, but a 5:1 release drove the population to elimination after 15 weeks of release. These results indicate that thiotepa exposure is an effective means of sterilising Ae. aegypti and males thus treated are able to reduce the reproductive capacity of a stable population under laboratory conditions. Further testing of the method in semi-field enclosures is required to evaluate the mating competitiveness of sterile males when exposed to natural environmental conditions. If proven effective, SIT using thiotepa-sterilised males may be incorporated into an integrated programme of vector control to combat dengue in Cuba.
Highlights
Since 1981, when the first haemorrhagic dengue epidemic in the Americas was reported in Cuba, the country has remained dengue free, with the exception of sporadic, isolated clusters of cases (Guzman 2012)
After an initial drop in the hatch rate between weeks 4 and 7, the hatch rate stabilised at approximately 65-70% and remained stable with only minor fluctuations until the suppression phase was initiated at week 20 (Fig. 2)
One of these stable populations was randomly assigned as a control cage and the others were used as treatment cages with two or five sterile male pupae added weekly for each fertile male pupa
Summary
Since 1981, when the first haemorrhagic dengue epidemic in the Americas was reported in Cuba, the country has remained dengue free, with the exception of sporadic, isolated clusters of cases (Guzman 2012). Several alkylating agents and aziridinyl compounds have been tested as mosquito sterilants (Dame et al 2009). The risk of environmental contamination with the sterilising agent from the release of mosquitoes exposed in the pupal stage is very low because the amount of the thiotepa residue detected in adults is negligible (La Brecque et al 1972, Seawright et al 1973, 1976). The success of SIT in controlling the malaria vector Anopheles albimanus in El Salvador demonstrated the effectiveness of thiotepa as a sterilant (Lofgren et al 1974), so its potential as a sterilising agent for SIT programmes should not be overlooked. The performance of sterile mosquitoes following release is essential for the success of SIT (Dame et al 2009). Somatic damage as a consequence of the sterilisation process has been well documented (Proverbs 1969) and is known to affect the longevity (Oliva et al 2013), sexual vigour and competitiveness of sterilised male mosquitoes (Helinski & Knols 2009), with severity depending on the species (Helinski et al 2009)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call