Thermoregulation and Adaptation to Temperature in Dragonflies (Odonata: Anisoptera)

Abstract

Several of Anisoptera maintain their body temperature more constant than ambient temperature. Species that spend most of their active period on perches (perchers) and make only short flights thermoregulate heliothermically, primarily by means of postural adjustments. Some of the species that fly continuously (fliers) are endothermic regulators during flight. They control body temperature by: (1) controlling metabolic heat production by alternately using gliding or powered flight; (2) controlling heat loss by altering circulation between thorax and abdomen. Small fliers are unable to regulate well because they are subject to high rates of convective heat loss. Cooling constants, as defined by Newton's law of cooling, are related to thoracic weight by a negative power function over a wide size range. Cooling constants are higher in live dragonflies than in dead ones, a difference that is accentuated at high ambient temperatures. High cooling constants at high temperatures probably result from increased rates of circulation. Most fliers, and some large perchers, are able to elevate their body temperature by "wing—whirring." In some species the rate of heat production apparently varies in response to ambient temperature. The body temperature at which flight begins after warm—up is positively correlated with body weight, probably because wing loading increases with increasing body size. The maximum voluntarily tolerated temperature and the threshold of heat torpor of several species were determined. Both parameters are correlated with habitat. The minimum temperature at which flight is possible is positively correlated with body weight and is slightly higher in tropical dragonflies than in temperate zone species. Body temperature is probably more variable relative to air temperature in tropical than in temperate zone species. The ability of dragonflies to maintain a relatively constant body temperature is determined primarily by climate, body size, and behavior.

Thermoregulatory constraints on behavior: patterns in a neotropical dragonfly assemblage

“…Body size, that strongly affects these behavioral patterns, also appears to be similar in this congeneric species. May (1976May ( , 1977May ( , 1980May ( , 1991 carefully demonstrated differences in thermoregulatory abilities among perchers related to body size. Because thermoregulation could restrict the activity time and the local where territorial defense could occur, it also determines an evolutionary landscape where other characteristics, as reproductive behaviors, could vary.…”

“…In high air temperatures they open the dorsal vessel and hover, facilitating fast heat loss by convection, mainly from the abdomen (May 1977, Heinrich & Casey 1978. For the perchers, thermoregulation is mainly by body posture adjustments in relation to the sun (May 1976(May , 1977, microhabitat choice (Clausnitzer 1996, De Marco 1998 and activity time shifts (May 1980, De Marco & Resende 2002. These species are more dependent on air temperature to initiate their activities and are especially affected by higher air temperatures in the middle of the day, which could overheat their thoracic muscles (May 1991, De Marco & Resende 2002.…”

“…These species are more dependent on air temperature to initiate their activities and are especially affected by higher air temperatures in the middle of the day, which could overheat their thoracic muscles (May 1991, De Marco & Resende 2002. May (1976) suggests that some postures, like droop-wing perching (that face the thorax to the sun) are related to heating the thoracic muscle, while the so-called "obelisk" posture (the wing-tips are held below the body and the abdomen with an angle near 90º to the substrate) could minimise overheating by reducing exposure to the sun.…”

The role of landmarks in territory maintenance by the black saddlebags dragonfly, Tramea lacerata

“…Their flight season is fairly predictable because they tend to emerge at the same time each year (Kormondy and Gower 1965). They have poor thermoregulatory ability like other members of Tramea (May 1976), so all aspects of their behavior including territoriality may be affected by temperature. They seem to possess some capacity to assess objects and recognize places they should not cross, as they have been shown to cross roadways less frequently than expected (Soluk et al 2011 ).…”

Behavioral ecology of Heteragrion consors Hagen (Odonata, Megapodagrionidae): a shade-seek Atlantic forest damselfly

“…Corbet (1962; but see also a general re-evaluation of the original work by Corbet & May 2008) classified odonate species into two categories in relation to thermoregulatory behaviors: fliers, expected to be endothermic, can regulate the internal production of heat and use gliding as a heat exchange behavior; and perchers, expected to present different degrees of exothermy, and control body temperature only by body posture adjustments and exposition to solar incidence. Small sized odonates are expected to be thermal conformers that are highly dependent on environment temperature and medium sized to larger exotermic species are usually heliothermic more dependent on solar incidence to attained normal activity (May 1976;De Marco & Resende 2002). These thermoregulatory constrains may help understand other aspects of odonate biology, especially the territoriality and other aspects of their reproductive biology (De Marco et al 2005).…”