Effects of ultraviolet radiation on metabolic rate and fitness of Aedes albopictus and Culex pipiens mosquitoes.

Oswaldo C Villena,Paul T Leisnham,Bahram Momen,Joseph Sullivan

doi:10.7717/peerj.6133

Abstract

Natural and anthropogenic changes (e.g., land use change, pollution) will alter many environmental factors in the coming years, including the amount of solar radiation reaching the earth’s surface. Alterations in solar radiation exposure is likely to impact the ecologies of many living organisms, including invertebrates that inhabit aquatic habitats. In this study, we assessed the effect of UV-B radiation on the metabolic rates and fitness (survival, development time, body size) of Aedes albopictus and Culex pipiens mosquitoes and the activity of their microbial food resources in experimental aquatic microcosms. We exposed single-species cohorts of newly hatched Ae. albopictus and Cx. pipiens larvae and a control treatment with no larvae to three UV-B conditions that mimicked those in full-sun and shade in the field and to a control condition with no UV-B radiation. Our results indicated that UV-B radiation affected the metabolic rates of both Ae. albopictus and Cx. pipiens larvae, with significantly higher rates found in full-sun compared to shade and no-UV conditions, 8 and 15 days after exposure began. Ae. albopictus and Cx. pipiens survival was also affected by UV-B radiation condition, with significantly lower survival in full-sun compared to shade and no UV-B conditions. Microbial metabolic rates were consistently significantly lower in full-sun compared to shade and no-UV conditions, especially at 8 days of exposure. These results show that UV-B radiation at levels found in open spaces showed strong and important impacts on the metabolic rates and survival of Ae. albopictus and Cx. pipiens larvae. Decreased survival of Ae. albopictus and Cx. pipiens with higher UV-B radiation levels may be caused by both direct exposure to radiation as well as the indirect effects of reduced microbial food, resulting in greater metabolic demands and stress. Negative impacts of UV-B radiation on the survival of Ae. albopictus and Cx. pipiens are likely to have important implications for the distribution and abundance of these mosquitoes, and the transmission of pathogens that these two broadly distributed mosquitoes vector.

Highlights

IntroductionEnvironmental changes (e.g., global warming, climate change) will trigger major changes in environmental factors (e.g., temperature, precipitation) in coming years (Macnaghten & Szerszynski, 2013; Bornman et al, 2015)
Environmental changes will trigger major changes in environmental factors in coming years (Macnaghten & Szerszynski, 2013; Bornman et al, 2015)
There was an effect on mosquito metabolic rates related to interactions between UV-B radiation condition and sample day (Table 1, Fig. 1A)

Summary

Introduction

Environmental changes (e.g., global warming, climate change) will trigger major changes in environmental factors (e.g., temperature, precipitation) in coming years (Macnaghten & Szerszynski, 2013; Bornman et al, 2015). These changes are likely to have profound impacts on insect ecology and physiology, including survival, development time, and underlying metabolic processes (Helbling & Zagarese, 2003; Shuman, 2011; Gray, 2013). Other environmental changes, including increased exposure to ultraviolet radiation (UVR) from climate change (e.g., cloud thickness) and anthropogenic activities (e.g., land use change, pollution), may have subtler yet important effects that have so far been poorly studied. There is considerable variation in exposure to UV-B radiation throughout the landscape because of varying shade conditions, relatively few studies have examined the effects of UV-B radiation on insect behavior, physiology, and ecology (e.g., Johansen et al, 2011; Tuncbilek, Ercan & Canpolat, 2012; Shimoda & Honda, 2013; Sliney, Gilbert II & Lyon, 2016)

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