The effects of thermal acclimation on lethal temperatures and critical thermal limits in the green vegetable bug, Nezara viridula (L.) (Hemiptera: Pentatomidae)

Pol Chanthy,Robin V Gunning,Robert J Martin,Nigel R Andrew

doi:10.3389/fphys.2012.00465

Pol Chanthy, Robin V Gunning + Show 2 more

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https://doi.org/10.3389/fphys.2012.00465

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Abstract

According to geographical distribution, Nezara viridula (Heteroptera: Pentatomidae) can be found across tropical, subtropical, and temperate regions and this pattern is assumed to reflect differences in thermal adaptation, particularly in cold tolerance. Here the lethal temperature (LT) and critical thermal limits (CTL) (thermal tolerance) are examined for N. viridula. The upper LT for N. viridula at two contrasting climate locations (Breeza and Grafton, New South Wales, Australia) was 40.3°C with 20% survival under the stress of high temperature. The lower LT did not differ between these two populations and was −8.0°C with 20% survival under low temperature stress. Survival of N. viridula increased after acclimation at high temperature for 7 days. In contrast, when acclimated at lower temperatures (10 and 15°C), survival of Breeza and Grafton N. viridula was lower than 20% at −8.0°C. Control-reared N. viridula adults (25°C) had a mean CTMinOnset (cold stupor) of 1.3 ± 2.1°C and a mean CTMax (heat coma) of 45.9 ± 0.9°C. After 7 days of acclimation at 10, 20, 30, or 35°C, N. viridula adults exhibited a 1°C change in CTMax and a ~1.5°C change in CTMinOnset. CTMax and CTMinOnset of Breeza and Grafton N. viridula populations did not differ across acclimation temperatures. These results suggest that short-term temperature acclimation is more important than provenance for determining LTs and CTL in N. viridula.

Highlights

The relationships between potentially lethal environmental temperatures and survival of animals have long fascinated physiologists
critical thermal maxima (CTMax) and CTMinOnset of Breeza and Grafton N. viridula populations did not differ across acclimation temperatures. These results suggest that short-term temperature acclimation is more important than provenance for determining lethal temperatures (LT) and critical thermal limits (CTL) in N. viridula
The aim of this paper is to determine for N. viridula: (1) whether the LT of populations differs between the two different climatic locations; (2) whether acclimation increases or decreases survival LT; and (3) the effect of acclimation on the critical thermal limits (CTL)

Summary

Introduction

The relationships between potentially lethal environmental temperatures and survival of animals have long fascinated physiologists. Relevant measures of tolerance to potentially lethal temperatures (LT) have been recently reviewed by Terblanche et al (2011). Ways in which these relationships are modified through time and space has attracted study (Chen et al, 1990; Watson and Hoffmann, 1996; Terblanche et al, 2005a,b). An extremely rapid cold-hardening response was observed in non-overwintering stages of insects and conferred protection against injury due to cold shock at temperatures above the supercooling point (SCP) (Lee et al, 1987). In studies of insect cold-hardiness, the SCP is defined as the temperature at which spontaneous nucleation of body fluids occurs (Salt, 1961; Zachariassen, 1985; Czajka and Lee, 1990; Carrillo et al, 2005)

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