Effect of Temperature Regimes on the Development, Survival and Emergence of Culicoides brevitarsis Kieffer (Diptera: Ceratopogonidae) in Bovine Dung

Abstract

Culicoides brevitursis is a biting midge and a vector of several viruses affecting livestock in Australia. An emergence chamber for collecting Culicoides spp. from dung was evaluated to determine its suitability for the study of C. brevitursis developing in dung at different temperatures in the laboratory. It enabled experiments to be carried out in the natural breeding medium, relative humidity to be maintained at high levels and temperature through the dung to be stabilised at treatment temperatures relatively quickly. C. brevitursis emerged within a temperature range of 17°C to 36°C with the greatest numbers between 25°C and 36°C. Males were dominant at low temperatures and females were dominant at high temperatures. Development times (to 50% emergence from deposition of the dung) and response times (to 50% emergence after starting to emerge) were least at the highest temperatures. Development times at the same temperature differed between experiments and this was associated with the temperature in the field before the dung was placed at a temperature treatment. Some survival occurred outside the 17°C to 36°C range, but emergence was dependent on the temperature eventually being changed to a more suitable level. The approximate lower threshold for emergence was about 17°C. At this temperature, numbers emerging were low, development was delayed significantly and none survived for more than 50 d. High numbers of adults started to emerge within 24 h from dung held at 17 "C for up to 42 d from the deposition of the dung when the temperature was raised to 25 "C or 28 "C. The results support field temperature data and were used in predicting the areas that may be free of the vector.

Flight behavior of adult Culicoides oxystoma and Culicoides maculatus under different temperatures in the laboratory

“…The activity period of adult C. maculatus during the year was observed longer than that of C. oxystoma at same collection sites and extended to late autumn or early winter (Ueno et al 1956;Yanase, personal communication). It is known that temperature also has an impact on the developing stage of Culicoides species (Kitaoka 1982;Bishop et al 1996) and, thus, the presence of adult insects. Further studies would be necessary to elucidate the particular influence of temperature for the different distribution of these two species.…”

Mosquitoes and Culicoides biting midges: vector range and the influence of climate change

“…temperature, precipitation) that can influence distribution, abundance and vectorial capacity in Culicoides. In the main, it would seem clear that, in the future, increased temperatures will lengthen the Culicoides biting season, quicken the larval developmental cycle (thereby increasing the number of generations completed) (58,59) and, importantly, accelerate vector-biting and extrinsic virus replication rates. At the more local farm level, the interplay between climatic and environmental variables (including temperature, relative humidity, light intensity, wind speed and the like) is complex, with changes in optimality from one species to the next.…”

Olfaction in vector-host interactions

“…Climate change, and more specifically alterations in temperature, may affect larval stages of some Culicoides species. Allingham (1991) and Bishop et al (1996) demonstrated that Culicoides brevitarsis Kieffer emerge between 17-36 °C, with most emergence occurring in the 25-36 °C range. They also showed that average temperature in the field prior to their experiment starting, i.e.…”