Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 28, 1999
Publication Date: N/A
Interpretive Summary: Dengue is the most important human viral disease transmitted by arthropod vectors with an estimated 50 -100 million cases of dengue and 250,000 B 500,000 cases of dengue haemorrhagic fever annually. The mosquito, Aedes aegypti, is the major vector of dengue in urban tropical and subtropical regions of the world. There is no vaccine for dengue and the only effective method to prevent transmission is vector control. Control of Ae. aegypti has relied on source reduction and broad spectrum chemical larvicides and adulticides. Both methods can be effective but it is difficult to sustain long term source reduction efforts and the development of resistance to insecticides by mosquitoes, as well as the need for environmental conservation, indicates a necessity for alternative control strategies. The effectiveness of a naturally occurring protozoan parasites to control Aedes aegypti was evaluated in the field over a 2 yea period. In the first year, inoculative release of this parasite resulted in dispersal by infected Ae. aegypti females to all containers within the study site (a large screen cage) over a 20 week period. In the second year of the study, inundative release produced high larval and adult infections and successfully eliminated the population of Ae. aegypti within 11 weeks of the introduction. Based on the results of this study, this pathogen should be considered a serious candidate for introduction as a classical biological control against Ae. aegypti.
Technical Abstract: The effectiveness of the microsporidium, Edhazardia aedis, to control a seminatural population of Aedes aegypti was evaluated over a 2 year period. The tests were conducted in a large screened enclosure against an established population of Aedes aegypti provided caged rabbits as an ad-lib blood supply. In year one, inoculative release of E. aedis resulted in dispersal of the microsporidium by infected Ae. aegypti females to all containers within the enclosed study site over a 20 week period. In the second year of the study, inundative release of E. aedis produced high larval and adult infections and successfully eliminated the population of Ae. aegypti within 11 weeks of the introduction. In both years, a deviation from the typical life cycle that produced horizontally infectious spores was critical for persistence of E. aedis within containers. This study has demonstrated that E. aedis is superbly adapted to Ae. aegypti having evolved a number of strategies that ensure long term survival and make it a serious candidate for introduction as a classical biological control agent.