The yeast Wickerhamomyces anomalus (Pichia anomala) inhabits the midgut and reproductive system of the Asian malaria vector Anopheles stephensi

Yeast endosymbionts of insects have been known for many years, but the discovery of yeasts associated with insects has increased dramatically in the last ten years. Although there are certain clades that are composed primarily of insect-associated yeasts, it is clear that these associations evolved many times and that these yeasts occur throughout the yeasts phylogenetic tree. Many of these yeasts have been reported from frass or insect habitats, but others have been shown to reside in specific parts of the gut or other internal organs. Few yeasts are known from associations with mosquitoes. Recent reports described the isolation of members of the genus Pichia from the gut of the mosquito vector Aedes aegypti. Here we report the isolation of another yeast, Wickerhamomyces anomalus, previously known as Pichia anomala, from specimens of the malaria vector Anopheles stephensi. Within the mosquito body, W. anomalus was detected in the midgut and in both male and female reproductive systems, suggesting the possibility that this yeast is vertically inherited. The localization of W. anomalus in the mosquito gonads is quite peculiar since very few reports described yeasts residing in reproductive system of insects. The potential application of W. anomalus as a tool for the “symbiotic control” of mosquito-borne diseases is discussed