Warm Blood Meal Increases Digestion Rate and Milk Protein Production to Maximize Reproductive Output for the Tsetse Fly, Glossina morsitans

SIMPLE SUMMARY: Consumption of a bloodmeal represents a stressful period for arthropod vectors. A general consensus is that thermal stress from a bloodmeal is detrimental. Here, we examined if the warm bloodmeal is critical to digestion and reproduction in tsetse flies. These results show that warm blood consumption is critical to reach maximum digestion efficiency. This increased digestion rate allows the flies to maximize the production of milk proteins. Importantly, modeling indicates that this consumption of warm blood contributes to increased population growth rates when compared to ingesting a cool bloodmeal. These studies are important as thermal impact of a warm bloodmeal can vary between beneficial or detrimental depending on the species arthropod vector. ABSTRACT: The ingestion of blood represents a significant burden that immediately increases water, oxidative, and thermal stress, but provides a significant nutrient source to generate resources necessary for the development of progeny. Thermal stress has been assumed to solely be a negative byproduct that has to be alleviated to prevent stress. Here, we examined if the short thermal bouts incurred during a warm blood meal are beneficial to reproduction. To do so, we examined the duration of pregnancy and milk gland protein expression in the tsetse fly, Glossina morsitans, that consumed a warm or cool blood meal. We noted that an optimal temperature for blood ingestion yielded a reduction in the duration of pregnancy. This decline in the duration of pregnancy is due to increased rate of blood digestion when consuming warm blood. This increased digestion likely provided more energy that leads to increased expression of transcript for milk-associated proteins. The shorter duration of pregnancy is predicted to yield an increase in population growth compared to those that consume cool or above host temperatures. These studies provide evidence that consumption of a warm blood meal is likely beneficial for specific aspects of vector biology.