Mosquito life cycle
Malaria parasites are transmitted through the bites of female Anopheline mosquitoes, there are ~460 species of Anopheles mosquitoes in the world of which ~100 are known to transmit malaria. The primary vector of malaria on the African continent is Anopheles gambiae and the main vector in South East Asia is Anopheles stephensi. The Pakpour lab maintains a colony of A. stephensi mosquitoes for their research.
All mosquitoes undergo complete metamorphosis as they progress through the following four stages: egg, larvae, pupae, and adult. Depending on climatic and ecological conditions this process can take 5-14 days, in the laboratory our mosquito colony cycles every 8-9 days. The first three stages of the mosquito lifecycle (egg to pupae) are aquatic. Female mosquitoes will deposit 50-200 individual eggs on the surface of the water. After 2-3 days, first instar larvae will hatch and begin filter feeding on algae, bacteria and other microorganisms in the water. Anopheles larva can be found in an incredibly diverse array of habitats from marshes, rice fields, and streams to the small temporary pools of water that form in the niches of trees to the water containers of humans. Mosquito larvae will molt through 4 instars and will then form a non-feeding (but still motile) pupae stage from which adults will emerge. Male mosquitoes tend to emerge first and live for ~1 week and feed primarily on plant-based sugar sources such as nectar. Female mosquitoes will also use sugar sources for energy but require a blood meal for the development of eggs. Thus, only female mosquitoes ever ‘bite’. For an amazing video of the six needle mouthparts of a female mosquito go here. Following a blood meal, female mosquitoes will rest in order to digest and subsequently produce eggs, which generally takes 2-3 days. After laying her batch of eggs, a female will begin her host-seeking behavior, a process that relies on heat, CO2, and odor cues.
SOURCE: Purdue University (Scott Charlesworth)
Although California has three species of Anopheline mosquitoes capable of transmitting malaria (Anopheles freeborni, Anopheles hermsi, and Anopheles punctipennis) we have not had active transmission of the disease since the 1940s. This is partially due to improved socioeconomic conditions such as screens on windows, television and air conditioning which act to keep people indoors. As well as better water management and vector control efforts through our mosquito abatement districts. However, malaria remains a threat in California because of the large Anopheles populations that persist and the infected humans (international travelers and immigrants) who live or visit the state. The California Mosquito Abatement Districts were formed in 1915 to control mosquito and other vector of disease and are celebrating their 100 year anniversary this year. The first anti-malaria program in California was started in the Sacramento Valley in 1910. Currently, all 38 million Californians reside within a mosquito abatement district, CSUEB resides within the Alameda mosquito abatement district.
