Trial of a quantified mass rearing method for Toxorhynchites splendens.

In recent years there has been considerable interest in laboratory rearing of Toxorhynchites mosquitoes for use as biological control agents (Vongtangswad and Trpis 1980) and foi the assay of dengue viruses (Eshita et al. 1982). Although larvae of these mosquitoes are cannibalistic (Steffan and Evenhuis 1981), mass rearing methods have been described for some species which have yielded pupation rates from ?B to 94V0, provided adequate prey density is maintained (Focks et al. 197?, Focks and Boston 1979, Horio and Tsukamoto 198b). In our laboratory, Tx. splendens (Wied.) are reared for dengue virus isolation. In order to increase production efficiency and reduce inputs of time and manpower, we attempted to employ mass rearing methods similar to those described by Focks and Boston (1979). Five hundred 0 to 24-hour-old ?r. spl,endens eggs were counted and placed in a 54 x 45 x 6.75 cm plastic developing tray containing b liters of water. Approximately 10,000 newly hatched Aedes aegypti larvae and 100 ml of slurry (Focks and Boston 19?9) were added to the tray. A second tray was set up containing 4 Iiters of water, ca. 6,500 Aedes aegypti (Linn.) eggs, and 70 ml of slurry. The larvae from this tray were added to the first tray 3 days later. A fresh tray was set at each feeding and was added to the predator tray when Ae. aegypti larvae were 4 days old. Thus, additional prey were added on days 4, 7, 10 and 13. Prey larvae were deliberately underfed to retard pupation. In preliminary trials of this method when prey larvae were provided with greater amounts of food [i.e., a second feeding as described by Focks and Boston (19?9)1, pupation and emergence of adult Ae. aegypti ftom predator pans became a problem as all prey larvae were not consumed between feedings.