Thermal Biology and Seasonal Population Abundance of Hendel (Diptera: Tephritidae): Implications on Pest Management.

Since the first detection of in Botswana in 2010, the establishment, spread, and response to prevailing Botswana microclimates under rapidly changing environments remain unknown. This study investigated the presence, seasonal population abundance, and thermal biology of in Botswana. We measured thermal tolerance critical thermal limits (CTLs) and lethal temperature assays (LTAs) to understand how temperature largely impacts on fitness and hence invasive potential. Seasonal monitoring results indicated establishment in the Chobe district (its first area of detection). Trap catches showed continuous adult flies' presence all year round and high average monthly trap catches as compared with other districts. Furthermore, was detected south of Botswana, including Kgatleng, Kweneng, South-east, and Southern districts. Critical thermal maxima (CT) to activity for adults and larvae were 46.16°C and 45.23°C, whereas critical thermal minima (CT) to activity for adults and larvae were 9.1°C and 7.3°C, respectively. Moreover, we found an improved CT for larvae at a slower ramping rate, indicating potential rapid cold hardening. The lower lethal temperature (LLT) and upper lethal temperature (ULT) assays revealed a reduction in survival at all the developmental stages as severity and duration of both temperature extremes increased. Microclimatic temperatures recorded in Botswana showed that environmental temperatures fall within the thermal breath of activity measured here, indicating a potential conducive climate niche for the insect pest across the country, albeit other factors, e.g., host availability, play a significant role. These results therefore suggest that Botswana microclimatic temperatures aided activity and invasion pathway are thus significant in mapping invasions and pest risk analysis, and may also aid in designing pest management strategies.