Effects of attachment substrate, larval diet, and temperature on development and survival of immature Coquillettidia linealis (Skuse) and Coquillettidia xanthogaster (Edwards).

A sustainable colony allowed investigations into attachment substrates, diet and temperature in the development of the immature stages of Cq. linealis and its local congener Cq. xanthogaster. As immatures, these mosquitoes attach to submerged plants for respiration, and various field-collected and laboratory-raised plants were compared with non-living substrates. Hydroponically-grown wheat plant seedlings provided the most suitable attachment substrate. Development and survival of immatures to eclosion were investigated with three types and three quantities of a standardized diet. Development and survival at rearing temperatures between 10 degrees and 30 degrees C were also investigated. Diet type appeared to have little influence on development. However, at the lowest diet quantity, development to pupation was significantly reduced while the highest diet quantity impacted on the eclosion of pupae. Mean duration of immature development for Cq. linealis increased as temperature decreased. Time from 1(st) instar to median eclosion did not differ significantly between 23 degrees C (6.0 weeks) and 25 degrees C (5.3 weeks), although it was 10 weeks at 20 degrees C, and 30 degrees C was lethal. For Cq. xanthogaster, similarly, mean duration of immature development increased as temperature decreased, with development time from 1(st) instar to median eclosion significantly longer at 20 degrees C (7.5 weeks) compared to 23 degrees C (5.0 weeks) and 30 degrees C (4.0 weeks).