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Editorial overview: Global change biology: everything connects to everything else
COIS-388; NO. OF PAGES 3
Available online at www.sciencedirect.com
ScienceDirect Editorial overview: Global change biology: Global change and insects: everything connects to everything else Brandon T Barton and Jason P Harmon Current Opinion in Insect Science 2017, 23:xx–yy
http://dx.doi.org/10.1016/j.cois.2017.09.009 2214-5745/ã 2017 Published by Elsevier Inc.
Brandon T Barton
Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, United States e-mail: [email protected] Brandon T Barton is an assistant professor in the Department of Biological Sciences at Mississippi State University. His research group examines the abiotic and biotic factors that affect ecological communities. He is particularly interested in the top-down effects of predators on herbivores and plants, and how these interactions are influenced by global change.
Jason P Harmon
Department of Entomology, North Dakota State University, Fargo, ND 58108, United States Jason P Harmon is an associate professor in the Entomology Department at North Dakota State University. His laboratory explores the context-dependent ecology of insects in www.sciencedirect.com
Leonardo DaVinci famously wrote, ‘everything connects to everything else.’ While unlikely that he was referencing the diverse direct and indirect effects of global change on Earth and its inhabitants, the quote is strikingly appropriate. Our planet is undergoing myriad changes, each of which can affect species differently. Since species do not live in isolation, even if global change affected only one species, interspecific interactions may be altered and consequently affect other species. Such indirect effects can cascade throughout a community without concern for geographical or political boundaries. Even in our modernized world, humans are dependent on countless ecosystem services of biodiversity. Consequently, it does not take much effort to imagine how global change that affects one species produce tangible effects on humans. Justifying the importance of understanding the effects of global change on insects is not difficult. Insects are essential for biological processes like pollination, decomposition, and nutrient transportation, while also being key elements in food chains as both predator and prey. Additionally, they are a foundational component of experimental ecology, serving as model systems to ask questions relevant to other taxonomic groups that are more difficult to study [1]. Thus, studying and understanding the effects of global change on these species has both applied and conceptual benefits. In this special issue, leading entomologists review the diverse consequences of global change on insects and their ecosystems. These reviews span a wide range of global change drivers and effects, including direct effects from altered physiology [2,3], indirect effects that arise and affect other species [10,11], and finally how changes in insect pests evoke human responses in order to maintain agricultural efficiency and control insect pests [15,16]. Among the most conspicuous signs of global change is the mean increase in global temperatures experienced during the 20th century. While much attention has been given to mean increases in temperature, actual warming is more complex. Two reviews highlight the importance of recognizing and studying the subtleties of how warming occurs. Stoks et al. [3] draw attention to the consequences of extreme temperatures, an important factor that is expected to increase in frequency due to global climate change. Extreme heat events and subsequent changes in daily temperature variation (DTV) can affect insects by altering individual performance, which has subsequent consequences for interactions and communities. Although heat shocks and extreme events are becoming more common, the warming trend occurring in many places is not due to daytime high temperatures getting hotter, but instead low temperatures that are not cooling off during the night [4]. Speights et al. [2] review existing evidence on the effects of nighttime Current Opinion in Insect Science 2017, 23:1–3
Please cite this article in press as: Barton BT, Harmon JP: Editorial overview: Global change biology: Global change and insects: everything connects to everything else, Curr Opin Insect Sci (2017), http://dx.doi.org/10.1016/j.cois.2017.09.009
COIS-388; NO. OF PAGES 3
2 Global change biology
agroecosystems and other working landscapes. Explorations include interactions among changing abiotic (e.g. temperature and salinity) and biotic conditions (e.g. predation and community composition).
warming versus daytime warming. Just as increasing extreme heat events can have direct and indirect effects on communities, so can decreasing DTV that arises by nighttime warming. Additionally, warming during the night versus during the day may generate species-specific effects on organisms that have temperature-dependent behaviors or physiologies that correlate with specific times of days. Warming receives a disproportionate amount of attention in the literature [5], but insects are affected by a wide array of global change drivers. Reviewing all of these effects is beyond the scope of even a special issue. However, we highlight a few important factors beyond temperature. McCluney [6] reviews the effects of drought and water stress on insects and their interactions within communities. Despite evidence of the importance of animal water balance, there is a great need for explicitly investigating how changes in water affects food webs, particularly when involving organisms that are less adapted to conserve water. In addition to temperature and precipitation, Jamison and colleagues [7] explore the effects of carbon dioxide, ozone, and nitrogen on plants and their interactions with insects. They approach the issue of global change from a perspective of chemical ecology, providing a mechanistic view of how insects are affected by altered plant chemistry. They conclude, as others have [8,9], that the effects of change are context dependent and therefore multiple factor studies are essential to understanding the real effects of global change. A recurring theme in this issue is how aspects of global change can modify species interactions. The reviews by Lenhart [10] and Laws [11] explicitly reinforce this discussion by reviewing important conceptual advancements related to changing consumptive interactions. Lenhart [10] reviews how herbivorous insects alter their feeding to balance plant macronutrients, and then connects climate-induced shifts in these plant nutrients to shifts in the nutrient landscape for herbivores. While global change does not necessarily produce simple changes in plant nutrients, the filter of nutrient landscapes can help provide an extremely useful tool for understanding how global change can alter different insect herbivores. Laws [11] looks at the contextdependent nature of interspecific interactions, including how we can better understand climate change effects by looking at chemical signaling, stoichiometry and nutritional ecology. She calls for a better understanding of how such changes to interactions will scale to larger shifts in communities. Insects provide many ecosystem services that humans benefit from. This special issue highlights two of these services: pollination and decomposition. Rafferty [12] reviews the effects that climate change, invasive species, and altered habitats are having on insect pollinators, with special emphasis on native bees. Besides restructuring communities in situ, global change drivers are inducing phenological, latitudinal, and elevational shifts that create novel communities with novel interactions. In many examples, these novel communities do not provide the same pollination services as their predecessors. While Rafferty [12] and other studies have focused on the consequences of global change on ecosystem services, Tomberlin and colleagues [13] investigate the importance of necrophageous insects in mitigating one consequence of global change, mass mortality events. These large die-offs of animals are becoming more frequent due to multiple aspects of global change [14]. Breaking down and recycling carrion from these events is an important ecosystem service of biodiversity [17], and Tomberlin et al. that the relative importance of microbes, insects, vertebrates, and abiotic factors in decomposition changes along a gradient of carrion biomass. Because naturally-occurring mass mortality events are difficult to study, they
Current Opinion in Insect Science 2017, 23:1–3
www.sciencedirect.com
Please cite this article in press as: Barton BT, Harmon JP: Editorial overview: Global change biology: Global change and insects: everything connects to everything else, Curr Opin Insect Sci (2017), http://dx.doi.org/10.1016/j.cois.2017.09.009
COIS-388; NO. OF PAGES 3
Editorial overview: Global change biology: Global change and insects: everything connects to everything else Barton and Harmon 3
advocate an experimental approached to simulate these events and test hypotheses while providing a framework for doing so. While many insects provide ecosystem services that benefit humans, others are pests that destroy billions of dollars in crops each year. As climate and other aspects of the environment change, farmers most cope with how to produce crops under novel environmental conditions, while also dealing with extant and emerging insect pests. Murrell [15] reviews common climate-mitigating agricultural practices and their potential for also mitigating the effects of insect pests. The good news is that many practices enhance pest suppression and biological control, although more explicit testing of pest and predator responses under predicted climate scenarios are needed before large-scale recommendations can be made. Global change can increase agricultural pest problems through multiple mechanisms, including range shifts, loss of biological control, and increased volitinism. Thurman et al. [16] review these mechanisms and provide appropriate mitigation strategies for each. Their suggestions include traditional ecological ideas, such as maintaining predator diversity and increasing realism in mathematical models, but also maintaining dialog with land managers who have a working knowledge of the insects attacking plants that only comes through years of hands-on experience. It is good to be reminded that knowledge to help mitigate the effects of global change can be obtained through mechanisms other than controlled experiments and complex modeling endeavors. Despite the diversity of the papers that comprise this issue, several common themes stand out. First is that insects and their communities are being affected my multiple simultaneous changes. Although some papers focus on a single factor (e.g. temperature, drought), it is clear that the net effect of any component of global change is potentially influenced by several other factors. For example, it is likely that high temperatures exacerbate the effects of drought, just as dry, drought conditions can exacerbate the effects of high temperatures. Thus, it is paramount that studies simultaneously consider of multiple factors if we are to develop a predictive understanding of global change. Second, because species do not live in isolation, we must consider both direct and indirect effects in order to understand the net effect of global change on a species. This is not always an easy task, especially since extant communities may not reflect future communities, which may lose species through extinction or range contraction, or gain species through range expansion or exotic invasion. However, this difficult task is worth taking on for very practical reasons, including our dependence on the ecosystem services provided
www.sciencedirect.com
by insects. Biological control of pests in agriculture, pollination of plants, decomposition and nutrient recycling are invaluable services, but these services are affected by global change and can have tangible consequences for humans. Indeed, we are not insulated from the direct and indirect effects of global change; everything connects to everything else, including us.
References 1.
Meadows AJ, Crowder DW, Snyder WE: Are wolves just wasps with teeth? What invertebrates can teach us about mammal top predators. Food Webs 2016.
2.
Speights CJ, Harmon JP, Barton BT: Contrasting the potential effects of daytime versus nighttime warming on insects. Curr Opin Insect Sci 2017, 23:1-6.
3.
Stoks R, Verheyen J, Van Dievel M, Tu¨zu¨n N: Daily temperature variation and extreme high temperatures drive performance and biotic interactions in a warming world. Curr Opin Insect Sci 2017, 23:35-42.
4.
Davy R, Esau I, Chernokulsky A, Outten S, Zilitinkevich S: Diurnal asymmetry to the observed global warming. Int J Climatol 2016.
5.
Barton BT: Beyond global warming: putting the “climate” back into “climate change ecology”. Food Webs 2017.
6.
McCluney KE: Implications of animal water balance for terrestrial food webs. Curr Opin Insect Sci 2017, 23:13-21.
7.
Jamieson MA, Burkle LA, Manson J, Runyon JB, Trowbridge AM, Zientek J: Global change effects on plant–insect interactions: the role of phytochemistry. Curr Opin Insect Sci 2017, 23:70-80.
8.
Laws AN, Joern A: Predator–prey interactions are context dependent in a grassland plant–grasshopper–wolf spider food chain. Environ Entomol 2015, 44:519-528.
9.
Rosenblatt AE, Smith-Ramesh LM, Schmitz OJ: Interactive effects of multiple climate change variables on food web dynamics: modeling the effects of changing temperature, CO2, and water availability on a tri-trophic food web. Food Webs 2016.
10. Lenhart PA: Using plant nutrient landscapes to assess anthropocene effects on insect herbivores. Curr Opin Insect Sci 2017, 23:51-58. 11. Laws AN: Climate change effects on predator–prey interactions. Curr Opin Insect Sci 2017, 23:28-34. 12. Rafferty NE: Effects of global change on insect pollinators: multiple drivers lead to novel communities. Curr Opin Insect Sci 2017, 23:22-27. 13. Tomberlin JK, Barton BT, Lashley MA, Jordan HR: Mass mortality events and the role of necrophagous invertebrates. Curr Opin Insect Sci 2017, 23:7-12. 14. Fey SB, Siepielski AM, Nussle´ S, Cervantes-Yoshida K, Hwan JL, Huber ER, Fey MJ, Catenazzi A, Carlson SM: Recent shifts in the occurrence, cause, and magnitude of animal mass mortality events. Proc Natl Acad Sci USA 2015, 112:1083-1088. 15. Murrell EG: Can agricultural practices that mitigate or improve crop resilience to climate change also manage crop pests? Curr Opin Insect Sci 2017, 23:81-88. 16. Thurman JH, Crowder DW, Northfield TD: Biological control agents in the anthropocene: current risks and future options. Curr Opin Insect Sci 2017, 23:59-64. 17. Lashley MA, Jordan HR, Tomberlin JK, Barton BT: Indirect effects of larvae dispersal following mass mortality events. Ecology 2017 http://dx.doi.org/10.1002/ecy.2027.
Current Opinion in Insect Science 2017, 23:1–3
Please cite this article in press as: Barton BT, Harmon JP: Editorial overview: Global change biology: Global change and insects: everything connects to everything else, Curr Opin Insect Sci (2017), http://dx.doi.org/10.1016/j.cois.2017.09.009
Available online at www.sciencedirect.com
ScienceDirect Editorial overview: Global change biology: Global change and insects: everything connects to everything else Brandon T Barton and Jason P Harmon Current Opinion in Insect Science 2017, 23:xx–yy
http://dx.doi.org/10.1016/j.cois.2017.09.009 2214-5745/ã 2017 Published by Elsevier Inc.
Brandon T Barton
Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, United States e-mail: [email protected] Brandon T Barton is an assistant professor in the Department of Biological Sciences at Mississippi State University. His research group examines the abiotic and biotic factors that affect ecological communities. He is particularly interested in the top-down effects of predators on herbivores and plants, and how these interactions are influenced by global change.
Jason P Harmon
Department of Entomology, North Dakota State University, Fargo, ND 58108, United States Jason P Harmon is an associate professor in the Entomology Department at North Dakota State University. His laboratory explores the context-dependent ecology of insects in www.sciencedirect.com
Leonardo DaVinci famously wrote, ‘everything connects to everything else.’ While unlikely that he was referencing the diverse direct and indirect effects of global change on Earth and its inhabitants, the quote is strikingly appropriate. Our planet is undergoing myriad changes, each of which can affect species differently. Since species do not live in isolation, even if global change affected only one species, interspecific interactions may be altered and consequently affect other species. Such indirect effects can cascade throughout a community without concern for geographical or political boundaries. Even in our modernized world, humans are dependent on countless ecosystem services of biodiversity. Consequently, it does not take much effort to imagine how global change that affects one species produce tangible effects on humans. Justifying the importance of understanding the effects of global change on insects is not difficult. Insects are essential for biological processes like pollination, decomposition, and nutrient transportation, while also being key elements in food chains as both predator and prey. Additionally, they are a foundational component of experimental ecology, serving as model systems to ask questions relevant to other taxonomic groups that are more difficult to study [1]. Thus, studying and understanding the effects of global change on these species has both applied and conceptual benefits. In this special issue, leading entomologists review the diverse consequences of global change on insects and their ecosystems. These reviews span a wide range of global change drivers and effects, including direct effects from altered physiology [2,3], indirect effects that arise and affect other species [10,11], and finally how changes in insect pests evoke human responses in order to maintain agricultural efficiency and control insect pests [15,16]. Among the most conspicuous signs of global change is the mean increase in global temperatures experienced during the 20th century. While much attention has been given to mean increases in temperature, actual warming is more complex. Two reviews highlight the importance of recognizing and studying the subtleties of how warming occurs. Stoks et al. [3] draw attention to the consequences of extreme temperatures, an important factor that is expected to increase in frequency due to global climate change. Extreme heat events and subsequent changes in daily temperature variation (DTV) can affect insects by altering individual performance, which has subsequent consequences for interactions and communities. Although heat shocks and extreme events are becoming more common, the warming trend occurring in many places is not due to daytime high temperatures getting hotter, but instead low temperatures that are not cooling off during the night [4]. Speights et al. [2] review existing evidence on the effects of nighttime Current Opinion in Insect Science 2017, 23:1–3
Please cite this article in press as: Barton BT, Harmon JP: Editorial overview: Global change biology: Global change and insects: everything connects to everything else, Curr Opin Insect Sci (2017), http://dx.doi.org/10.1016/j.cois.2017.09.009
COIS-388; NO. OF PAGES 3
2 Global change biology
agroecosystems and other working landscapes. Explorations include interactions among changing abiotic (e.g. temperature and salinity) and biotic conditions (e.g. predation and community composition).
warming versus daytime warming. Just as increasing extreme heat events can have direct and indirect effects on communities, so can decreasing DTV that arises by nighttime warming. Additionally, warming during the night versus during the day may generate species-specific effects on organisms that have temperature-dependent behaviors or physiologies that correlate with specific times of days. Warming receives a disproportionate amount of attention in the literature [5], but insects are affected by a wide array of global change drivers. Reviewing all of these effects is beyond the scope of even a special issue. However, we highlight a few important factors beyond temperature. McCluney [6] reviews the effects of drought and water stress on insects and their interactions within communities. Despite evidence of the importance of animal water balance, there is a great need for explicitly investigating how changes in water affects food webs, particularly when involving organisms that are less adapted to conserve water. In addition to temperature and precipitation, Jamison and colleagues [7] explore the effects of carbon dioxide, ozone, and nitrogen on plants and their interactions with insects. They approach the issue of global change from a perspective of chemical ecology, providing a mechanistic view of how insects are affected by altered plant chemistry. They conclude, as others have [8,9], that the effects of change are context dependent and therefore multiple factor studies are essential to understanding the real effects of global change. A recurring theme in this issue is how aspects of global change can modify species interactions. The reviews by Lenhart [10] and Laws [11] explicitly reinforce this discussion by reviewing important conceptual advancements related to changing consumptive interactions. Lenhart [10] reviews how herbivorous insects alter their feeding to balance plant macronutrients, and then connects climate-induced shifts in these plant nutrients to shifts in the nutrient landscape for herbivores. While global change does not necessarily produce simple changes in plant nutrients, the filter of nutrient landscapes can help provide an extremely useful tool for understanding how global change can alter different insect herbivores. Laws [11] looks at the contextdependent nature of interspecific interactions, including how we can better understand climate change effects by looking at chemical signaling, stoichiometry and nutritional ecology. She calls for a better understanding of how such changes to interactions will scale to larger shifts in communities. Insects provide many ecosystem services that humans benefit from. This special issue highlights two of these services: pollination and decomposition. Rafferty [12] reviews the effects that climate change, invasive species, and altered habitats are having on insect pollinators, with special emphasis on native bees. Besides restructuring communities in situ, global change drivers are inducing phenological, latitudinal, and elevational shifts that create novel communities with novel interactions. In many examples, these novel communities do not provide the same pollination services as their predecessors. While Rafferty [12] and other studies have focused on the consequences of global change on ecosystem services, Tomberlin and colleagues [13] investigate the importance of necrophageous insects in mitigating one consequence of global change, mass mortality events. These large die-offs of animals are becoming more frequent due to multiple aspects of global change [14]. Breaking down and recycling carrion from these events is an important ecosystem service of biodiversity [17], and Tomberlin et al. that the relative importance of microbes, insects, vertebrates, and abiotic factors in decomposition changes along a gradient of carrion biomass. Because naturally-occurring mass mortality events are difficult to study, they
Current Opinion in Insect Science 2017, 23:1–3
www.sciencedirect.com
Please cite this article in press as: Barton BT, Harmon JP: Editorial overview: Global change biology: Global change and insects: everything connects to everything else, Curr Opin Insect Sci (2017), http://dx.doi.org/10.1016/j.cois.2017.09.009
COIS-388; NO. OF PAGES 3
Editorial overview: Global change biology: Global change and insects: everything connects to everything else Barton and Harmon 3
advocate an experimental approached to simulate these events and test hypotheses while providing a framework for doing so. While many insects provide ecosystem services that benefit humans, others are pests that destroy billions of dollars in crops each year. As climate and other aspects of the environment change, farmers most cope with how to produce crops under novel environmental conditions, while also dealing with extant and emerging insect pests. Murrell [15] reviews common climate-mitigating agricultural practices and their potential for also mitigating the effects of insect pests. The good news is that many practices enhance pest suppression and biological control, although more explicit testing of pest and predator responses under predicted climate scenarios are needed before large-scale recommendations can be made. Global change can increase agricultural pest problems through multiple mechanisms, including range shifts, loss of biological control, and increased volitinism. Thurman et al. [16] review these mechanisms and provide appropriate mitigation strategies for each. Their suggestions include traditional ecological ideas, such as maintaining predator diversity and increasing realism in mathematical models, but also maintaining dialog with land managers who have a working knowledge of the insects attacking plants that only comes through years of hands-on experience. It is good to be reminded that knowledge to help mitigate the effects of global change can be obtained through mechanisms other than controlled experiments and complex modeling endeavors. Despite the diversity of the papers that comprise this issue, several common themes stand out. First is that insects and their communities are being affected my multiple simultaneous changes. Although some papers focus on a single factor (e.g. temperature, drought), it is clear that the net effect of any component of global change is potentially influenced by several other factors. For example, it is likely that high temperatures exacerbate the effects of drought, just as dry, drought conditions can exacerbate the effects of high temperatures. Thus, it is paramount that studies simultaneously consider of multiple factors if we are to develop a predictive understanding of global change. Second, because species do not live in isolation, we must consider both direct and indirect effects in order to understand the net effect of global change on a species. This is not always an easy task, especially since extant communities may not reflect future communities, which may lose species through extinction or range contraction, or gain species through range expansion or exotic invasion. However, this difficult task is worth taking on for very practical reasons, including our dependence on the ecosystem services provided
www.sciencedirect.com
by insects. Biological control of pests in agriculture, pollination of plants, decomposition and nutrient recycling are invaluable services, but these services are affected by global change and can have tangible consequences for humans. Indeed, we are not insulated from the direct and indirect effects of global change; everything connects to everything else, including us.
References 1.
Meadows AJ, Crowder DW, Snyder WE: Are wolves just wasps with teeth? What invertebrates can teach us about mammal top predators. Food Webs 2016.
2.
Speights CJ, Harmon JP, Barton BT: Contrasting the potential effects of daytime versus nighttime warming on insects. Curr Opin Insect Sci 2017, 23:1-6.
3.
Stoks R, Verheyen J, Van Dievel M, Tu¨zu¨n N: Daily temperature variation and extreme high temperatures drive performance and biotic interactions in a warming world. Curr Opin Insect Sci 2017, 23:35-42.
4.
Davy R, Esau I, Chernokulsky A, Outten S, Zilitinkevich S: Diurnal asymmetry to the observed global warming. Int J Climatol 2016.
5.
Barton BT: Beyond global warming: putting the “climate” back into “climate change ecology”. Food Webs 2017.
6.
McCluney KE: Implications of animal water balance for terrestrial food webs. Curr Opin Insect Sci 2017, 23:13-21.
7.
Jamieson MA, Burkle LA, Manson J, Runyon JB, Trowbridge AM, Zientek J: Global change effects on plant–insect interactions: the role of phytochemistry. Curr Opin Insect Sci 2017, 23:70-80.
8.
Laws AN, Joern A: Predator–prey interactions are context dependent in a grassland plant–grasshopper–wolf spider food chain. Environ Entomol 2015, 44:519-528.
9.
Rosenblatt AE, Smith-Ramesh LM, Schmitz OJ: Interactive effects of multiple climate change variables on food web dynamics: modeling the effects of changing temperature, CO2, and water availability on a tri-trophic food web. Food Webs 2016.
10. Lenhart PA: Using plant nutrient landscapes to assess anthropocene effects on insect herbivores. Curr Opin Insect Sci 2017, 23:51-58. 11. Laws AN: Climate change effects on predator–prey interactions. Curr Opin Insect Sci 2017, 23:28-34. 12. Rafferty NE: Effects of global change on insect pollinators: multiple drivers lead to novel communities. Curr Opin Insect Sci 2017, 23:22-27. 13. Tomberlin JK, Barton BT, Lashley MA, Jordan HR: Mass mortality events and the role of necrophagous invertebrates. Curr Opin Insect Sci 2017, 23:7-12. 14. Fey SB, Siepielski AM, Nussle´ S, Cervantes-Yoshida K, Hwan JL, Huber ER, Fey MJ, Catenazzi A, Carlson SM: Recent shifts in the occurrence, cause, and magnitude of animal mass mortality events. Proc Natl Acad Sci USA 2015, 112:1083-1088. 15. Murrell EG: Can agricultural practices that mitigate or improve crop resilience to climate change also manage crop pests? Curr Opin Insect Sci 2017, 23:81-88. 16. Thurman JH, Crowder DW, Northfield TD: Biological control agents in the anthropocene: current risks and future options. Curr Opin Insect Sci 2017, 23:59-64. 17. Lashley MA, Jordan HR, Tomberlin JK, Barton BT: Indirect effects of larvae dispersal following mass mortality events. Ecology 2017 http://dx.doi.org/10.1002/ecy.2027.
Current Opinion in Insect Science 2017, 23:1–3
Please cite this article in press as: Barton BT, Harmon JP: Editorial overview: Global change biology: Global change and insects: everything connects to everything else, Curr Opin Insect Sci (2017), http://dx.doi.org/10.1016/j.cois.2017.09.009