EFFECT OF ENVIRONMENTAL-TEMPERATURE ON THE SUSCEPTIBILITY OF CULEX-PIPIENS (DIPTERA, CULICIDAE) TO RIFT-VALLEY FEVER VIRUS

Studies were conducted to determine the effect of environmental temper ature on the susceptibility of Culex pipiens (L.) to Rift Valley fever (RVF) virus. Larval rearing temperature (13, 17, 19, or 26 degrees C) did not affect the susceptibility of adult female Cr. pipiens to infe ction with RVF virus. In contrast, the adult holding temperature after a viremic blood meal affected infection rates in females. Significant ly fewer mosquitoes contained detectable virus when they were held at cooler temperatures, 13 degrees C (10%), 17 degrees C (20%), and 19 de grees C (41%) than at a warmer temperature, 28 degrees C (91%). For mo squitoes held at 13 degrees C and then switched to 26 degrees C, infec tion rates increased steadily with increased time at 26 degrees C. The re was no effect on the ability to detect RVF virus in adult females t hat were subjected to cooler holding temperature (17 degrees C) after they were first held at warmer temperature (26 degrees C). The role of environmental temperature needs to be considered in studies on the ep idemiology of arthropod-borne viruses.