Mosquitoes Cool Down during Blood Feeding to Avoid Overheating

Abstract

Temperature is one of the most important factors affecting the life of insects [1]. For instance, high temperatures can have deleterious effects on insects' physiology. Therefore, many of them have developed various strategies to avoid the risk of thermal stress [2]. They can seek a fresher environment or adjust their water loss, but hematophagous insects, such as mosquitoes, must confront the issue of thermal stress at each feeding event on a warm-blooded host [3]. To better understand to what extent mosquitoes are exposed to thermal stress while feeding, we conducted a real-time infrared thermographic analysis of mosquitoes' body temperature during feeding on both warm blood and sugar solution. First, our results highlighted differences in temperature between the body parts of the mosquito (i.e., heterothermy) during blood intake, but not during sugar meals. We also found that anopheline mosquitoes can decrease their body temperature during blood feeding thanks to evaporative cooling of fluid droplets, which are excreted and maintained at the end of the abdomen. This mechanism protects the insect itself, probably as well as the sheltered microorganisms, both symbionts and parasites, from thermal stress. These findings constitute the first evidence of thermoregulation among hematophagous insects and explain the paradox of fresh blood excretion during feeding.

Survival and arm abscission are linked to regional heterothermy in an intertidal sea star

“…Harrison, 1999)], mosquitoes [~4°C (Lahondère and Lazzari, 2012)] and triatomine bugs [~8°C (C. Lahondère, personal communication)] when feeding on hot blood, and even plant leaf surfaces [~4°C (Jones, 1999)]. Taken globally, these comparisons suggest that body surface thermal heterogeneity occurs over a wide range of body sizes and morphologies.…”

“…For example, infrared cameras can be used to measure directly, non-invasively and simultaneously the surface temperature of all body regions for a single or multiple individuals (e.g. Pincebourde et al, 2009;Lahondère and Lazzari, 2012), and biomimetic sensors (e.g. Lima and Wethey, 2009) could potentially be designed to record temperatures of different body regions over prolonged periods in the field, although this has yet to be attempted.…”

“…Flying insects such as bees or bumblebees keep their thorax hot and their abdomen relatively cool via continuous circulation of hemolymph between the two body regions through a counter-current heat exchanger, with heat being exchanged between outgoing and ingoing fluids (Heinrich, 1996). Liquid drop exudation to lower a body region temperature is another strategy used by mosquitoes (Lahondère and Lazzari, 2012) and some hymenopterans (Coelho and Ross, 1996;Heinrich, 1996). More generally, strategies involving heat exchangers (including exudation drops) to cope with sublethal temperatures might be widespread and are associated with withinbody thermal heterogeneity.…”

It's Not a Bug, It's a Feature: Functional Materials in Insects

“…The liquid of the drop evaporates and dissipates the excess heat gained from ingesting a relatively large volume of warm blood. [411] Similarly, sawfly larvae produce a fluid anal secretion that they spread over their bodies to cool down by as much as 7 °C when the temperature is above the lethal 42 °C. [412] Structural and pigment-based cuticle coloration (Section 6) can also influence insect body temperature.…”

“…Biphasic secretion True bugs, [469,470] tenebrionid beetles, [638] fire ants [639] Built structures Green lacewings [640] Froths and foams Pyrgomorphid grasshoppers, [641] lubber grasshoppers, [642] froghopper nymphs [474] Hemolymph defense Sawflies, [643,644] katydids, [450,645] stoneflies, [645] stonefly nymphs [646] Projectile dispersal Stick insects, [451,459] termites [647] Material motif General functionality System of interest Insect and reference Thermoregulation Cooling Honeybees, [410] mosquitos, [411] sawflies [412] Water active properties Surface excretion Leafhoppers [166,167,648] Layering Collective materials Built structures Social wasps [649,650] Raft building to survive flooding Fire ants [580] Bivouac assemblies Army ants [512] Color vision and color manipulation Impedance matching Dragonflies, [337] cicadas, [339] butterflies, [338,341,342] moths, [342,343] beetles [342] Water active properties Desiccation resistance Antarctic midges, [651] African lake flies [652] Regular repeated patterns…”