Effects of temperature on development, mortality, mating and blood feedingbehavior of Culiseta incidens (Diptera : Culicidae)

Culiseta incidens Thomson is distributed over most of the western USA and C anada northward to Alaska. Because this mosquito is difficult to colonize, its biology has not been well investigated. We colonized this species in 19 98 and studied the effects of temperature on various aspects of its life cy cle. The time required for egg melanization and the duration of the egg sta ge were negatively correlated with temperature. The proportion of fertile e gg rafts was temperature-independent. An inverse relationship existed betwe en temperature and egg hatch. Molting and stadium duration after hatching w ere temperature-dependent, with higher temperature accelerating development and molting. Larvae and pupae experienced lower mortality and higher molti ng success at lower temperatures. Survivorship of adult mosquitoes fed on s ugar solution was inversely proportional to temperature, lethal times for 5 0% mortality (LT50) were greater at the lower temperature than at the highe r temperature. Females survived longer than did males at all test temperatu res. Because this species is eurygamous, mating only occurred in large cage s. Mating success was also affected by temperature. At the test temperature s, 20 degreesC, 25 degreesC and 30 degreesC, mating started from 3-5 days a fter emergence and reached a peak on days 13-15 after emergence. Maximum ma ting rates at 20 degreesC and 25 degreesC were higher than at 30 degreesC. Blood feeding, as indicated by cumulative feeding rates, was affected by ca ge size, mosquito age and temperature. Mosquitoes in large cages exhibited a much higher feeding rate than in small cages. With age, the cumulative bl ood feeding rate increased, with the highest rate at 25 degreesC, followed by 20 degreesC and 30 degreesC. At all temperatures tested, most of the blo od fed females were mated.