A significant field discovery analyzing how natural temperature fluctuations affect the growth rate of the dengue mosquito could lead to crucial control-and-prevention strategies, according to newly published research from Thomas Scott’s Mosquito Research Laboratory and the Center for Vectorborne Diseases (CVEC), University of California, Davis.

The research, published March 8 in the PLOS ONE  journal, shows that that “temperature effects on larval development time, larval survival and adult reproduction depend on the combination of mean temperature and magnitude of fluctuations,” said lead author Lauren Carrington, a former postdoctoral fellow in the Scott lab and CVEC. (see http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0058824)

The scientists investigated how realistic fluctuations in temperature during the day influence the life-history traits and population dynamics of the dengue mosquito, Aedes aegypti.

“The effect of temperature on insect biology is well understood under constant temperature conditions, but less so under more natural, fluctuation conditions,” said Carrington, who completed her three-year postdoctoral fellowship last December at UC Davis but continues research projects with the Scott lab. She is now based at the Nossal Institute for Global Health, University of Melbourne, Australia.

The research, “Effects of Fluctuating Daily Temperatures at Critical Thermal Extremes on Aedes aegypti Life-History Traits,” is expected to lead to greater accuracy of applications for mosquito surveillance and disease prevention.

 

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“An improved understanding of mosquito responses to natural temperature variation,” Carrington said, “will enhance the effectiveness of vector control strategies, thereby reducing transmission of mosquito-borne diseases, such as dengue fever.” By using constant temperatures, scientists can under- or -over estimate values, she said.

“In the field, mosquitoes, and other insects, are exposed to a constantly changing environment, with fluctuations in temperature throughout the day, every day. In the lab, however, experimental protocols generally try to minimize as much variability as possible, and temperature is often the first element to be standardized.”

“After assessing a number of life-history traits at constant temperatures ranging from 12ºC-40ºC to identify the thermal limits of this population of mosquitoes from Thailand, we then reexamined the same traits under cyclic temperatures around a low (16ºC), intermediate (26ºC) and high (35ºC) mean temperature and compared these to appropriate constant temperature controls,” Carrington said.

“Our results demonstrate that testing mosquitoes under either large (~20ºC) or small (8ºC) fluctuations produced often largely variable results when compared to a constant temperature profile with the same mean. The direction of changes in development time, egg laying and immature survival were dependent upon whether the fluctuations were large or small, and around low or high mean temperatures.”