Pathogenicity and infectivity of the Thai-strain densovirus (AThDNV) in Anopheles minimus S.L.

We report the first experimental infection of an anopheline, An. minimus s.l., with the Thai-strain densovirus, AThDNV. Two hundred first-instar larvae were raised in 2 virus concentrations; mortality in the low virus concentration was no different than that in controls (9.5% vs 7.5%, respectively). Mortality in the high virus concentration was 17.5%. Among surviving adults, infection rates were 33.3% (low concentration) and 15.5% (high concentration), as judged by PCR-screening. Infection rates did not differ between males and females. All orally-infected females transmitted densovirus to at least some of their offspring. Vertical transmission rates ranged from 25.0-53.8%. Densovirus infection did not appear to affect fecundity, either in the number of eggs laid or the number of eggs hatched.

Biting behavior and seasonal variation in the abundance of Anopheles minimus species A and C in Thailand.

We measured the seasonal abundance and bloodfeeding behavior of species A and C of the mosquito Anopheles minimus Theobald 1901 in an endemic malarious area of western Thailand. An. minimus s.l. is a major vector of human malarial and filarial parasites in Southeast Asia. Mosquitos were collected once a month for one year using four collection methods: human-baiting indoors, human-baiting outdoors, human-baiting in the forest, and cow-baiting. We found that both species A and C tend to feed from cows rather than humans; we did not find any preference for indoor, outdoor or forest-biting in either species. Both species had a peak biting density in October/November, at the end of the rainy season, and species C showed a second, smaller peak at the end of the cool season. These findings are discussed in relation to previous reports of the behavior of An. minimus s.l., particularly in light of suggestions that An. minimus s.l. has changed its feeding behavior in response to DDT spraying.