Introduction : Asian Tiger Mosquito (Aedes albopictus) Control Project


Project introduction and objectives:

The mosquito Aedes albopictus has long been a nuisance in Hawaii , and the recent outbreak of Dengue fever has focused the publicís attention on controlling this pest. Between mid-2001, when this outbreak began, and January 2002, there have been 106 confirmed cases of dengue fever statewide. Dengue is one of the most important virus diseases worldwide. Tens of millions of cases of dengue fever occur every year, and hundreds of thousands of the much more serious dengue hemorrhagic fever and dengue shock syndrome occur every year. Any of the four related dengue virus serotypes can cause dengue fever, and dengue hemorrhagic fever and dengue shock syndrome are usually associated with sequential infections involving different virus serotypes. Clearly, it is extremely important to prevent the establishment of the dengue viruses in Hawaii . There is no vaccine or cure for the dengue virus-caused diseases, so control methods are appropriately aimed at controlling the vector of the virus, the Aedes mosquitoes.

As a first step, we will establish an ovitrap monitoring system for mosquito populations. An ovitrap is a small water-containing vessel (such as a 12 ounce cup) with a surface (such as a tongue depressor) for mosquitoes to lay their eggs on. The surface containing the eggs are collected weekly and counted to determine the density of the reproductive mosquito population. These ovitraps will provide initial and ongoing data on mosquito populations. 

We will then evaluate different methods of mosquito control, such as cleaning up standing water around dwellings, application of insecticides including malathion and preparations of Bti-toxin. The wet environment in East Hawaii provides a particular challenge, as the dense vegetation provides a sheltered and humid environment in which mosquitoes can thrive. In 1999, the efficacy of using ultra-low volume aerosols of malathion for A. albopictus control was evaluated in a study at the U.S. Naval Communication Area Master Station near Waianae on Oahu . This facility is surrounded by the Ewa Forest Preserve, and the study showed that malathion application within the facility were ineffective in reducing the mosquito population, as virtually all of the mosquitoes were coming from the forest. The weekly applications of malathion for mosquito control at this facility were therefore terminated.

Since it would be impractical to clean up standing water or to apply enough malathion for mosquito control in heavily forested areas, we would also like to explore the possibility of using numerous ovitraps to reduce the mosquito population. These devices would include a biodegradable container attractive to gravid female mosquitoes, with an agent such as Bti-toxin or the insect growth regulator methoprene.

In summary, we intend to identify areas in East Hawaii where forested, mosquito-dense areas border a managed, populated space. The UHH CAFNRM Panaewa experimental farm is such an area, and we will identify others as well. We will set up ovitrap monitoring stations and evaluate the mosquito populations in these areas. We will then implement control measures such as insecticide application, environmental mitigation and toxic ovitraps and evaluate their efficacies over and 8 month period.

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