Physiological Metabolic Responses of Ophraella communa to High Temperature Stress.

Hongsong Chen,Chenchen Zhao,Jianying Guo,Fanghao Wan,Zhongshi Zhou,Ghulam Sarwar Solangi,Lang Yang

doi:10.3389/fphys.2019.01053

Abstract

Considering the predicted rising temperatures under current climate change and heat wave scenarios, organisms are expected to suffer more intense and frequent thermal stress. Induced heat is accumulated by organisms and can cause a variety of physiological stress responses. Ophraella communa is an effective biological control agent of common ragweed, Ambrosia artemisiifolia, but the responses of this biocontrol agent to heat stress have not been fully elucidated and, therefore, its potential responses to climate change are uncertain. We investigated the physiological metabolism of subsequent O. communa adults after: (1) different developmental stages (egg, larval, pupal, and adult) were exposed to thermal stress for 3 h each day for 3, 5, 5, and 5 days, respectively (by stage); and (2) individuals were exposed to thermal stress throughout the egg-to-adult period for 3 h each day. The high temperatures of 40, 42, and 44°C were used to induce thermal stress. A control group was reared at 28 ± 2°C. The results showed that short- or long-term exposure to daily phasic high temperatures significantly decreased water and lipid contents and significantly increased glycogen and glycerol contents in all adults (i.e., after exposure of different stages or throughout the egg-to-adult period). However, the total sugar content significantly increased in adults after the eggs and larvae were exposed to brief short-term thermal stress. Compared to the control, the total sugar content was also significantly higher in the adults and pupae exposed to 44°C. Total sugar content in females increased significantly in response to long-term phasic thermal stress at 40°C. However, sugar content of males exposed to 44°C decreased significantly. After long-term phasic thermal stress, water and glycogen contents in males were significantly higher than in females; however, females had higher total sugar and lipid contents. Therefore, our study provides a basic understanding of the metabolic responses of O. communa to thermal stress and offers insights into its potential as a natural biocontrol agent against A. artemisiifolia during the summer season and under predicted climate change scenarios.

Highlights

Is the common ragweed, Ambrosia artemisiifolia L. (Asterales: Asteraceae, hereafter referred to as ragweed) a highly invasive alien species that causes substantial crop-yield losses in many parts of the world, but its prolific production of highly allergenic pollen creates considerable public health problems (Essl et al, 2015; Zhou et al, 2017)
After the eggs and larvae were exposed to brief thermal stress treatments, the total sugar content in both subsequent O. communa female and male adults increased significantly compared to the control
We previously studied the effects of brief exposure to high temperatures on the life history parameters (Zhou et al, 2011; Chen et al, 2018c) and body size (Chen et al, 2014) of O. communa, and the antioxidant responses of this beetle to thermal stress (Chen et al, 2018b)

Summary

Introduction

Is the common ragweed, Ambrosia artemisiifolia L. (Asterales: Asteraceae, hereafter referred to as ragweed) a highly invasive alien species that causes substantial crop-yield losses in many parts of the world, but its prolific production of highly allergenic pollen creates considerable public health problems (Essl et al, 2015; Zhou et al, 2017). The ragweed leaf beetle, Ophraella communa LeSage (Coleoptera: Chrysomelidae) is indigenous to North America, and has been shown to be an effective biological control agent of ragweed (Zhou et al, 2017). Ophraella communa was first recorded in China in 2001 (Meng and Li, 2005), where it was shown to be an effective biocontrol agent against ragweed (Zhou et al, 2014, 2017; Chen et al, 2018a). In the presence of O. communa, the spread of ragweed in China has been greatly suppressed by reduced flowering, seed set, and dispersal (Zhou et al, 2017). A decrease in airborne pollen, allergenic potential, and medical costs of ragweed was observed in the areas of Italy and France where O. communa was released (Bonini et al, 2018; Cardarelli et al, 2018; Mouttet et al, 2018)

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Results

Conclusion