Drought and heat waves associated with climate change affect performance of the potato aphid Macrosiphum euphorbiae

Lezel Beetge,Kerstin Krüger

doi:10.1038/s41598-018-37493-8

Abstract

The combined effect of drought and heat waves on insect-plant interactions is complex and not fully understood. Insects may indirectly benefit from water-deficit stress through increased plant nitrogen levels. Heat stress may have a direct negative effect, yet insect performance may be improved when day-time heat is followed by cooler night temperatures. We show that moderate water-deficit stress (25–30% pot capacity) and high day-night temperatures (30/20 °C) affected Macrosiphum euphorbiae on potato (Solanum tuberosum) differently than their interactions. Water stress lowered stomatal conductance, and both water and heat stress reduced leaf area. The effect of water stress on nymphal and adult survival depended on temperature. Water stress added to reduced nymphal survival at high but not current (25/15 °C) day-night temperatures. Adult survival at high temperatures was reduced only when combined with water stress. Water stress and high temperatures independently but not interactively reduced the number of daily offspring. Moderate water stress when combined with high temperatures had a negative bottom-up effect on aphid survival even though lower night temperatures aided in the recovery from direct heat stress. Our study illustrates the importance of combining multiple stressors to better understand their impact on insect-plant interactions in the context of climate change.

Highlights

Understanding the impact of changing climatic conditions on the ecology and evolution of animals and plants has been central to recent research efforts
The influence of moderately water-deficit stressed plants on the survival of M. euphorbiae depended on temperature
Continuous moderate water-deficit stress at high day-night temperatures (30/20 °C) reduced nymphal survival and added to the negative impact of heat stress, whereas water stress had no effect on their survival at current day-night temperatures (25/15 °C)

Summary

Introduction

Understanding the impact of changing climatic conditions on the ecology and evolution of animals and plants has been central to recent research efforts. Whereas numerous studies have been published on the single stressors or combined with other stressors[4,5], studies on water-deficit stress and high temperature simultaneously are scarce The interaction between these two stressors and their influence on insect herbivores is complex. In support of the hypothesis that abiotic stresses improve performance of herbivores[7], Dale and Frank[8] observed that urban warming and drought stress combined increased the fitness of a scale insect species on trees[8]. Environmental factors, such as heat stress, drought and nutrients, influence plant morphology, physiology and chemistry, resulting in bottom-up effects on insect herbivore survival and performance[9,10,11,12,13]. Cultivar and age, duration and severity of water-deficit stress and aphid species, aphid abundance may be affected positively[16,17,18,19], negatively[16,17,20,21,22] or remain unaffected[17,18,19]

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