Asian Tiger Mosquito, Aedes albopictus

The Situation: The Asian tiger mosquito entered the United States in shipments of used tires from northern Asia in the mid-1980s. It can survive in a broad range of climates and has spread rapidly from the point of first detection in the south-central United States. Prior to its successful invasion of the southeastern U.S., isolated introductions of this mosquito were detected and eradicated in California in 1971 and 1987. In 2001, the Asian tiger mosquito was found in two northern and four southern counties of California. This mosquito did not spread to California from the ongoing invasion in eastern and central U.S., but was introduced into the State in shipments of ornamental bamboo ("Lucky Bamboo") from South China. Rapid detection of introduction and control efforts prohibited the spread of this species throughout California. The tiger mosquito is a very efficient vector of a variety of mosquito-borne pathogens that cause debilitating diseases in humans and domestic animals, especially horses and dogs.

Description: Adults of this mosquito have black bodies with conspicuous white stripes. A distinctive single white stripe runs the length of the back. Body length is approximately 0.5 centimeter. Distinct silver-white bands are evident on the palpus and tarsi. Eggs are approximately 0.1 centimeter in length and dark brown to black. Eggs are laid in moist areas just above the water surface and are capable of overwintering. Eggs hatch upon inundation and immature stages (larvae and pupae) of the life cycle occur in water. Larvae are filter feeders and occur in standing water found in discarded tires, small containers and tree holes. Pupae are comma-shaped and dark brown in color.

Health Risks: The Asian tiger mosquito is an aggressive biter that feeds primarily during the day and has a broad host range including man, domestic and wild animals, and birds. It is a potential vector of encephalitis, dengue (all four serotypes), yellow fever and dog heartworm. West Nile virus has been detected in this species in the eastern U.S. This mosquito is a competent vector of LaCrosse encephalitis and eastern equine encephalitis viruses. The Asian tiger mosquito also is a competent vector of two encephalitis viruses routinely monitored throughout California, St. Louis encephalitis (SLE) and western equine encephalomyelitis viruses. However, recent studies suggest that SLE levels in naturally infected avian hosts are generally insufficient to infect this mosquito. Therefore, it might not pose as great a threat for SLE transmission in California as do Culex mosquitoes. SLE is a viral disease which is often very serious in young children and the elderly, attacking the central nervous system and occasionally causing death. Yellow fever is an extremely serious disease that is not established in the U.S. or in regions adjacent to the contiguous United States. Although the Asian tiger mosquito is a competent laboratory vector of several viral pathogens, there is no evidence to date that this mosquito has caused human disease in the U.S.

Distribution: The Asian tiger mosquito is native to Southeast Asia and has been spread along major transportation routes by human activities, particularly commercial movement of scrap tires, to more than 900 counties in 26 states in the continental USA as well as Hawaii. Aedes albopictus was found again in California in 2001 and sporadically thereafter through 2004. Although introductions to ports and nurseries have been controlled, this species continues to pose a threat to public health in California. Introduction of this species in standing water, enclosed containers where pools of water are present, or by desiccation-resistant eggs associated with previous pools of standing water are likely mechanisms of invasion by this species.

Research: There is no ongoing research on this species in California. Research programs carried out by the CDC and in several southeastern states are focusing on documenting the distribution of the Asian tiger mosquito, studying the competitive interactions between Aedes albopictus and closely related species in the same genus, examining the disease incidence in specimens collected in nature, and carrying out laboratory vector competence studies. Cooperation between federal agencies and universities has greatly aided understanding of the distribution and ecology of this mosquito.