Submitted to: Journal of Thermal Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2021
Publication Date: 4/22/2021
Citation: Melicher, D.M., Bowsher, J.H., Rinehart, J.P. 2021. Fluctuating temperatures extend longevity in pupae and adult stages of the sepsid Themira biloba. Journal of Thermal Biology. 99: 102959. https://doi.org/10.1016/j.jtherbio.2021.102959.
Interpretive Summary: Caring for insects in the laboratory can be time consuming and expensive and this can be a barrier to working with species critical for research. Some species, especially agricultural pests and pollinators such as bees are seasonal and can only be collected during brief windows. Other species require lots of labor and specialized consumable supplies to maintain in the laboratory which can be expensive and limits the number of insect species we can work with. Researchers from the Insect Genetics and Biochemistry unit of the USDA-ARS facilities in Fargo, ND in collaboration with scientists from North Dakota State University have developed a protocol that uses changes in temperature to extend the life of adult and pupating flies from 20 days to over 100 days while keeping them healthy. This reduces labor from daily or weekly maintenance to monthly. It reduces the consumption of supplies by about 80 - 90%. It also allows us to save extra insects for long periods of time as insurance against loss, gives us the ability to extend the season in which insects are available for research, and the reduced investment of time and money per insect colony allows us to work with more species and perform larger experiments.
Technical Abstract: Fluctuating Thermal Regimes (FTR) where organisms are held at a low temperature with a brief, daily warm pulse, have been shown to increase longevity in adult insects and improve pupa survival while reducing sublethal effects. We used FTR to extend the longevity and thus generation time of the fly species Themira biloba (Diptera: Sepsidae). T. biloba can be maintained in continuous culture and requires an insecticide-free dung substrate for larval growth and development. Our objective was to decrease labor and consumable materials required to maintain insect species in critical scientific collections using FTR. We extended pupation time from 4 days up to 8 weeks with no increase in mortality, and mean adult longevity was increased from 12 days to 50 days. FTR is a valuable tool for reducing the investment required to maintain rare and exotic insects.