Resting metabolism and critical thermal maxima of vespine wasps ( Vespula sp.)

Abstract

Graphical abstract

Highlights

► Vespine wasps have a very high mass-specific resting metabolic rate. ► They exhibit a steep increase of resting metabolism with ambient temperature. ► Wasp thermolimit was considerably below that of honeybees (44.9 vs. 48.9 °C). ► Infrared thermography allowed accurate estimation of the respiratory thermolimit.

Abstract

Vespine wasps are known for their high endothermic capacity. Endothermic activity is directly linked to respiration. However, knowledge on wasp respiration is sparse and almost nothing is known about their resting metabolism.

We investigated the yellowjackets’ CO ₂ production in a flow-through respirometer chamber overnight. Endothermic and behavioral activity was observed by real-time infrared thermography. Most resting wasps were ectothermic or only slightly endothermic (thoracic temperature excess against abdomen < 0.6 °C). In the investigated temperature range ( T _a = 2.9–42.4 °C) mean CO ₂ production rate of resting wasps increased steeply according to an exponential function, from 5.658 μl g ⁻¹ min ⁻¹ at 8.3 °C to 8.504 μl g ⁻¹ min ⁻¹ at 20.2 °C, 58.686 μl g ⁻¹ min ⁻¹ at 35.3 °C and 102.84 μl g ⁻¹ min ⁻¹ at 40 °C. The wasps’ respiratory critical thermal maximum (CT _max), marking the upper edge of their viable temperature range, was 45.3 °C. The respiratory CT _max did not differ significantly from the activity CT _max of 44.9 °C. CT _max values were considerably below that of honeybees (48.9 and 49.0 °C for respiration and activity, respectively). This allows honeybees to kill wasps by heat-balling.

Comparison with other arthropods showed that vespine wasps are among the insects with the highest mass-specific resting metabolic rate and the steepest increase of metabolism with ambient temperature.