Survival and vertical distribution of larvae of Culicoides variipennis (Diptera: Ceratopogonidae) in drying mud habitats.
The ability of third and fourth instars of Culicoides variipennis (Coquillett) to survive in drying sandy loam soil was tested under simulated field conditions. Two hundred larvae were added to each of a number of soil-filled, plastic tubes, which were buried in the field and retrieved after 2, 5, and 7 d. Of 306 pupae or pupal exuviae recovered, 98.1% were in the top 2 cm of mud. Estimated larval mortality on day two ranged from 25.6 to 87.1% among three trials, and 92.3% of live larvae were in the top 2 cm. Estimated larval mortality on day 5 ranged from 81.4 to 97.2%, and 75.5% of live larvae were in the top 2 cm. On day 7 mortality was 95.2-100%, and 63% of surviving larvae were in the top 2 cm. Some larvae dispersed as deep as 7-10 cm (the maximum depth in the tests). Larval tolerance of unfavorable drying conditions may allow relic populations to persist in some situations, but probably this is of little concern in control of this species through water management in most settings.
Mullens
B A
BA
Department of Entomology, University of California, Riverside 92521.
Rodriguez
J L
JL
D000818:Animals; D002140:California; D002519:Ceratopogonidae; D003710:Demography; D004463:Ecology; D007814:Larva