Rearing Dictya floridensis (Diptera: Sciomyzidae) in a continuously producing colony and evaluation of larval food sources.

Abstract

Methods for large-scale continuous propagation of Dictya floridensis Steyskal were developed. A colony originating from 22 specimens of several Dictya species collected in Alachua County, Fla., became a single species colony after several generations because of failure of all but D. floridensis to survive colonization. The colony was maintained as separate generations until the F5, after which new D. floridensis adults were pooled into mass colony cages. During the F7 generation, colony production was in excess of 1,000 neonate larvae per day, the number of adults was continually increasing, and the females had extended longevity and fecundity. At that time, the colony was considered to be continuously producing, and size of the colony was limited only by the availability of food and rearing facilities. Larvae were reared on living, freshly crushed, frozen snails, Physella hendersoni hendersoni (Clench) and Pseudosuccinea columella Say. Larval development and their survival rate to pupariation was the same whether reared on freshly crushed snails or on live food. Larvae reared on frozen snail tissue compared with live snails had the same sex ratio but were lighter in weight and had extended development time to pupariation and lowered survival rates. Larvae fed and developed successfully upon living embryonated snail egg masses but were unable to use egg masses that had been frozen.