Chill coma recovery of Ceratitis capitata adults across the Northern Hemisphere

Abstract

The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), is an invasive pest, that is currently expanding its geographic distribution from the Mediterranean coasts to more temperate areas of Europe. Given that low temperature is a primary determinant of insect species’ range boundaries especially in the Northern Hemisphere with pronounced seasonality, we used chill coma recovery time for assessing latitudinal clines in basal chill tolerance of C. capitata adults. We selected six populations obtained from areas with broad climatic variability based on the main bioclimatic variables of temperature and precipitation, spanning a latitudinal range of about 19oN from Middle East to Central Europe. Adults were exposed to 0oC for 4h, and time to regain the typical standing position of a fly at 25oC were recorded. The post-stress survival after a period of 8 days was also recorded. Results revealed that adults from Israel and Austria were less chill tolerant than those from Greece, resulting in curvilinear trends with latitude. Analysis of macroclimatic conditions revealed combined effects of latitude (as a proxy of photoperiod) and macroclimatic conditions on chill coma recovery time. Nonetheless, there was not a deleterious effect on post-recovery survival, except for flies obtained from the northern most point (Vienna, Austria). Overall, it seems that evolutionary patterns of basal chill coma recovery time of C. capitata adults are driven mainly by local climatic variability.

Rapid Evolution of a Cold Stress Cline in Mediterranean Fruit Fly During Northward Range Expansion

“…Summers in Yotvata are hot and dry, while winters are mild with rainfall characteristic of arid regions, varying among the years. Hence, the Southern Arava population in this study, represents a climatic edge population in the temperate zone of the Northern Hemisphere, and Vienna a range -edge population in the highest latitude of C. capitata highest distribution (Papadopoulos et al, 2022). The climatic data of the sites used to collect different populations are represented in Supplementary Tables (S1).…”