The Thermoregulatory Behavior of Nectar Foraging Polistine Wasps (Polistes dominula and Polistes gallicus) in Different Climate Conditions.

Helmut Kovac,Anton Stabentheiner,Helmut Käfer

doi:10.3390/insects10070187

Abstract

Polistine wasps collect nectar for their energetic demand and for the provision of the brood. They are mainly ectothermic during different behavioral tasks. We investigated the body temperature of two species living in differing habitats and climate regions, in order to reveal the environmental influence on their thermoregulatory behavior. The species were Polistes dominula in the temperate climate of Central Europe, and Polistes gallicus in the warm Mediterranean climate of Southern Europe. The wasp’s body temperature was measured during foraging on lovage (Levisticum officinale) and fennel (Foeniculum vulgare) by infrared thermography in the entire ambient temperature range they are usually exposed to (Ta ~ 20–40 °C). The temperature of all body parts increased nearly linearly with ambient temperature, with the thorax as the warmest part. To achieve optimal foraging temperatures, they preferably use solar radiation. An “operative temperature model” enabled the evaluation of the endothermic effort. Polistes dominula foraging on lovage exhibited no endothermic activity. However, while foraging on fennel they had a weak and almost constant endothermic performance of about 1 °C. Polistes gallicus, by contrast, exhibited mostly no or only minor endothermy during foraging. Both wasps avoid a high energetic effort and this way reduce their foraging costs.

Highlights

Polistine wasps exhibit a “low-level energetic” lifestyle
In contrast to Vespine wasps, which achieve a high agility by means of endothermic heat production [1,2], the body temperature of Polistine wasps depends much more on the ambient temperature
While it is clear that an insect of the size of a Polistes wasp is endothermic during flight, e.g., [6,7,8,9], because of the high flight energy expenditure [7], it is unknown whether they improve their agility during foraging for nectar by an elevated thoracic temperature

Summary

Introduction

Polistine wasps exhibit a “low-level energetic” lifestyle They spend a lot of time nearly immobile at their nests, and they are mainly ectothermic during different behavioral tasks at the nest. They prey on other insects and collect nectar for their own energetic demand and for provision of the brood. During foraging, they are exposed to a broad range of ambient temperatures and solar radiation conditions. In contrast to Vespine wasps, which achieve a high agility by means of endothermic heat production [1,2], the body temperature of Polistine wasps depends much more on the ambient temperature. In insects with little or no endothermic activity, the use of solar radiation is highly important for thermoregulation [6]

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