Droplet bubbling evaporatively cools a blowfly

Autor(es)

Gomes, Guilherme ^[1] ; Koberle, Roland ^[1] ; Von Zuben, Claudio J. ^[2] ; Andrade, Denis V. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sao Carlos Inst Phys IFSC, Dept Phys & Interdisciplinary Sci, BR-13566590 Sao Carlos, SP - Brazil

^[2] Sao Paulo State Univ, UNESP, Dept Zool, IB, BR-13506900 Rio Claro, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: SCIENTIFIC REPORTS; v. 8, APR 19 2018.
• Citações Web of Science: 4

Resumo

Terrestrial animals often use evaporative cooling to lower body temperature. Evaporation can occur from humid body surfaces or from fluids interfaced to the environment through a number of different mechanisms, such as sweating or panting. In Diptera, some flies move tidally a droplet of fluid out and then back in the buccopharyngeal cavity for a repeated number of cycles before eventually ingesting it. This is referred to as the bubbling behaviour. The droplet fluid consists of a mix of liquids from the ingested food, enzymes from the salivary glands, and antimicrobials, associated to the crop organ system, with evidence pointing to a role in liquid meal dehydration. Herein, we demonstrate that the bubbling behaviour also serves as an effective thermoregulatory mechanism to lower body temperature by means of evaporative cooling. In the blowfly, Chrysomya megacephala, infrared imaging revealed that as the droplet is extruded, evaporation lowers the fluid's temperature, which, upon its reingestion, lowers the blowfly's body temperature. This effect is most prominent at the cephalic region, less in the thorax, and then in the abdomen. Bubbling frequency increases with ambient temperature, while its cooling efficiency decreases at high air humidities. Heat transfer calculations show that droplet cooling depends on a special heat-exchange dynamic, which result in the exponential activation of the cooling effect. Terrestrial animals often use evaporative cooling to lower body temperature. Evaporation can occur from humid body surfaces or from fluids interfaced to the environment through a number of different mechanisms, such as sweating or panting. In Diptera, some flies move tidally a droplet of fluid out and then back in the buccopharyngeal cavity for a repeated number of cycles before eventually ingesting it. This is referred to as the bubbling behaviour. The droplet fluid consists of a mix of liquids from the ingested food, enzymes from the salivary glands, and antimicrobials, associated to the crop organ system, with evidence pointing to a role in liquid meal dehydration. Herein, we demonstrate that the bubbling behaviour also serves as an effective thermoregulatory mechanism to lower body temperature by means of evaporative cooling. In the blowfly, Chrysomya megacephala, infrared imaging revealed that as the droplet is extruded, evaporation lowers the fluid's temperature, which, upon its reingestion, lowers the blowfly's body temperature. This effect is most prominent at the cephalic region, less in the thorax, and then in the abdomen. Bubbling frequency increases with ambient temperature, while its cooling efficiency decreases at high air humidities. Heat transfer calculations show that droplet cooling depends on a special heat-exchange dynamic, which result in the exponential activation of the cooling effect. (AU)

• Processo FAPESP: 13/20627-8 - Percepção sensorial e termorregulação de Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) uma abordagem fisiológica e biomimética.
• Beneficiário: Guilherme Gomes
• Linha de fomento: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 17/17722-0 - SICB Annual Meeting 2018
• Beneficiário: Denis Otavio Vieira de Andrade
• Linha de fomento: Auxílio à Pesquisa - Reunião - Exterior
• Processo FAPESP: 13/04190-9 - Fisiologia termal e balanço de água em anfíbios anuros ao longo de um gradiente altitudinal da Floresta Atlântica
• Beneficiário: Denis Otavio Vieira de Andrade
• Linha de fomento: Auxílio à Pesquisa - Regular
• Processo FAPESP: 07/05080-1 - Ecologia termal da jararaca-ilhoa, Bothrops insularis (Serpentes, Viperidae): um estudo em condições naturais
• Beneficiário: Denis Otavio Vieira de Andrade
• Linha de fomento: Auxílio à Pesquisa - Regular