Temperature Tolerance and Thermal Environment of European Seed Bugs.

Helmut Käfer,Arne K D Schmidt,Anton Stabentheiner,Andrea Battisti,Nikolay Simov,Helmut Kovac,Bettina Erregger

doi:10.3390/insects11030197

Abstract

Heteroptera, or true bugs populate many climate zones, coping with different environmental conditions. The aim of this study was the evaluation of their thermal limits and derived traits, as well as climatological parameters which might influence their distribution. We assessed the thermal limits (critical thermal maxima, CTmax, and minima, CTmin) of eight seed bug species (Lygaeidae, Pyrrhocoridae) distributed over four Köppen–Geiger climate classification types (KCC), approximately 6° of latitude, and four European countries (Austria, Italy, Croatia, Bulgaria). In test tubes, a temperature ramp was driven down to −5 °C for CTmin and up to 50 °C for CTmax (0.25 °C/min) until the bugs’ voluntary, coordinated movement stopped. In contrast to CTmin, CTmax depended significantly on KCC, species, and body mass. CTmax showed high correlation with bioclimatic parameters such as annual mean temperature and mean maximum temperature of warmest month (BIO5), as well as three parameters representing temperature variability. CTmin correlated with mean annual temperature, mean minimum temperature of coldest month (BIO6), and two parameters representing variability. Although the derived trait cold tolerance (TC = BIO6 − CTmin) depended on several bioclimatic variables, heat tolerance (TH = CTmax − BIO5) showed no correlation. Seed bugs seem to have potential for further range shifts in the face of global warming.

Highlights

Heteroptera, or true bugs, are a widely distributed, highly diverse insect taxon with approximately45,300 [1] species worldwide
Some species thrive over wide latitudinal ranges, other closely related species are more restricted in their distribution range
Mean Critical Thermal Maximum (CTmax) ranged from 40.8 ± 0.6 ◦ C in Scolopostethus pictus (Bad Radkersburg, AT, Cfb climate type) to 48.9 ± 0.5 ◦ C

Summary

Introduction

Heteroptera, or true bugs, are a widely distributed, highly diverse insect taxon with approximately. 45,300 [1] species worldwide They populate every climate zone from arctic to desert [2,3,4], showing great ability to cope with a variety of environmental factors. This leads to a substantial potential for invasiveness, and many bug species are known to be highly invasive. Species such as Oxycarenus lavaterae are known to have spread from their Mediterranean

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