DEVELOPMENT AND SURVIVAL OF CULEX-SITIENS WIEDEMANN (DIPTERA, CULICIDAE) IN RELATION TO TEMPERATURE AND SALINITY

The effect of water temperature and salinity on the develop-ent and su rvival of immature Culex sitiens were studied in the laboratory and at Pimpama Weir, 60 km S Brisbane. The optimum temperature for Cx sitien s survival and development was 30-degrees-C, the threshold for develop ment was 11.94 +/- 1.5-degrees-C, and the thermal constant of 188.68 /- 13.33 degree-days. Survival of the immatures was highest at a salin ity of 6-8 ppK and lowest at 20 ppK. Although the newly hatched Cx sit iens were killed at 25 ppK the older stages could tolerate higher conc entrations if the increase was gradual. In the field, a high daily inc rease of salinity combined with fluctuating water temperatures. contri buted to very low survival of the immatures. As a result, it is sugges ted that chemical control of breeding sites is unnecessary if the sali nity is 20 ppK or over.