# Alandmanson/Insect decline
## Biological Invasions and Global Insect Decline

"Biological Invasions and Global Insect Decline"
Chapter One - Biological invasions: a global threat to insect diversity https://doi.org/10.1016/B978-0-323-99918-2.00001-X Abstract Globalization is accelerating the intentional and unintentional introductions of species beyond their natural biogeographic boundaries. Of all introduced species, only a small proportion become invasive, causing a wide variety of negative impacts. Some of them have detrimental consequences for native insects. In this chapter, which serves as an introduction to this book, we discuss the role of biological invasions as a driver of the current global decline in insect diversity, as well as the importance of considering biological invasions when planning insect conservation actions.
Chapter Two - Biodiversity and the importance of insect diversity https://doi.org/10.1016/B978-0-323-99918-2.00002-1 Abstract Insect diversity is the evolutionary basis that enables species adaptation and survival, but also the essential pillar of ecosystem services and homeostasis. In this chapter, we discuss four types of diversity (genetic, behavioral, species, and ecosystem) and justify their relevance to insect conservation. We focus on behavioral variability because of its cryptic relevance, which is often neglected. We discuss the weight that insect diversity has in our lives and how this determines their conservation status.
Chapter Three - The insect decline syndrome https://doi.org/10.1016/B978-0-323-99918-2.00003-3 Abstract Over the last decades, a significant decline of insect biomass and individual numbers has been repeatedly observed. This decline, here denominated as “Insect Decline Syndrome” (IDS), has been intensively discussed in the scientific literature, and in the media. Although some data may have been overinterpreted, some conclusions have been overgeneralized, and regional differences exist, there is no doubt that insect decline is real, far-ranging, and deeply worrying. While enough evidence has accumulated and some causes are undisputable, it is less clear how much each single factor has, does, and will contribute to this negative trend in the past and foreseeable future. We briefly consider the most relevant factors and discuss IDS from a metapopulation perspective, concluding that the current decline might be the consequence of long-term environmental deterioration processes associated with the Anthropocene. We suggest that IDS is a complex, nonlinear and multifactorial, context-dependent phenomenon. While the search for the primarily responsible factors is interesting and required and while more research and rigorous data analysis are certainly needed, this should not distract stakeholders and authorities from urgently taking action now. It is time for dedicated action plans, addressing the major drivers of insect endangerment, to protect and support insects in all habitats and regions, since nothing less than human well-being is at risk when insects are being lost at current rates.
Chapter Four - Global trade in alien species: a challenge for insect conservation https://doi.org/10.1016/B978-0-323-99918-2.00004-5 Abstract Globalization and increased trade have created opportunities for accidental and deliberate introductions of invasive species. Human activities, such as air and sea transport or tourism, have contributed substantially to the movement of alien species, constituting the main pathway for the emergence of invaders, particularly those intended for ornamentation. In this chapter, we emphasize the impact of global trade on the invasion of alien species. The number of traded plant and animal species in the coming decades is expected to increase and raise concern over potential biosecurity risks. To mitigate this trend, action needs to be taken toward proposing alternatives and solutions to this challenge. Implementing measures to prevent the introduction of invasive species and detecting their presence is crucial to managing current and future invasions and promoting insect conservation. Regulating the movement of species, banning trade in invasive species, and improving biosecurity measures are therefore imperative.
Chapter Five - Alien plants and insect diversity https://doi.org/10.1016/B978-0-323-99918-2.00005-7 Abstract Alien plants have invaded nearly all of the world, and humans also have planted them to landscape their surroundings. More often than not, these plants negatively influence arthropod populations. However, arthropod responses to alien plants are not uniform and vary based on the functional or feeding group considered and their degree of association with native plants. In this chapter, we explore how alien plants, including some ornamental species, influence different groups of arthropods, including herbivores, pollinators, predators, detritivores, and ants. Herbivorous and pollinating arthropods typically are negatively affected when alien plants displace native host plants, but the influences of alien plants on other functional groups can manifest in complex ways. Changes in the abundance of prey and hosts influence predatory arthropods and parasitoids, whereas shifts in litter chemistry and other characteristics can affect detritivores. Arthropods fill diverse functional roles, and the novel changes created by alien plants can have widespread and compounding effects at the population, community, and ecosystem levels.
Chapter Six - Invasive alien insects and insect decline https://doi.org/10.1016/B978-0-323-99918-2.00006-9 Abstract The number of insect species introduced beyond their native range by human activities and established within an alien range is unknown, but recent data indicate it is several thousand globally, with many more predicted to arrive in the next decades. They travel through a variety of pathways, with unintentional introductions nowadays prevailing over intentional ones. We briefly discuss environmental impact mechanisms and provide some case studies of alien insects within the context of insect declines. While the majority of alien insects prevail in anthropogenic, modified, and disturbed habitats where their impacts on the environment are minimal, invasive alien insects can have significant negative impacts on native insects, including decrease in abundance, diversity, and ultimately extinction of other species. Impacts are often modulated by other environmental factors, including species interactions, land-use, and climate change. In conclusion, invasive alien insects are contributing to insect decline but do not seem to be a major driver of the global phenomenon of insect decline.
Chapter Seven - Invasive alien non-insect invertebrates and insect diversity https://doi.org/10.1016/B978-0-323-99918-2.00007-0 Abstract This chapter deals with the impacts caused by invasive alien noninsect invertebrates on native insect diversity through direct (e.g., predation) and indirect (e.g., modification of the environment or food webs) impact mechanisms. Reported and potential impacts are analyzed for (1) freshwater ecosystems, where, for example, invasive alien crayfish can prey on aquatic insect adults and larvae, leading to their extinctions in some cases but also facilitating some other insects, and for (2) terrestrial ecosystems where new records of alien flatworms, earthworms, and arachnids are rapidly increasing without an in-depth assessment of their impacts. Finally, this chapter discusses knowledge gaps and future directions for research.
Chapter Eight - The impact of invasive alien vertebrates on native insects https://doi.org/10.1016/B978-0-323-99918-2.00008-2 Abstract Thousands of vertebrate species have been intentionally and unintentionally introduced to new locations beyond their native range. Many of these species have established alien populations, and some have become invasive and caused adverse impacts on native biodiversity. Research has improved our understanding of how these impacts affect native vertebrates, but comparatively little is known about how they affect native invertebrates, including insects. Yet, alien vertebrates may directly or indirectly interact with native insects wherever they are introduced (e.g., directly, by feeding on insects, and indirectly, by profoundly altering ecosystems). In this chapter, through a literature review, we identify direct and indirect impacts caused by a range of alien vertebrate species, and from many regions worldwide. We find that most research has focused on impacts affecting individuals of a native insect species, often by analyzing the stomach or fecal contents of an alien vertebrate species, and that reports of positive impacts are scarce and often inferred rather than measured. We conclude that the impacts of alien vertebrate species on insects remain largely unexplored. Future studies should aim to identify and quantify population-level impacts. Their robustness may be improved by adopting exclusion and before/after experiments, and collaborating with entomologists and insect ecologists.
Chapter Nine - Microorganisms and disease-mediated invasions affecting native insect conservation https://doi.org/10.1016/B978-0-323-99918-2.00009-4 Abstract Many authors have warned about a global insect decline, but few have underlined the role of invasive microorganisms as one of the factors driving insect loss. The introduction of plants and insects into new biogeographic regions due to human activities could bring about the cointroduction of potential pathogens that may threaten native insect diversity in invaded regions. Global trade and transport, combined with gaps in international policies of rearing insect species, lead to new invasions including the cointroduction of microorganisms. Insect pathogens include several groups of microorganisms that are difficult to detect. This chapter attempts to summarize the most relevant aspects that determine the role of coinvasive microorganisms in the decline of native insects. We highlight cointroductions of insect microorganisms, the risk of introducing them as biocontrol agents, spillover effects, and the side effects of using insects as a source of revenue.
Chapter Ten - Reconciling invasive alien species management and insect conservation in terrestrial ecosystems https://doi.org/10.1016/B978-0-323-99918-2.00010-0 Abstract The management of invasive alien species can affect the physical environment and the biota of ecosystems, with potential positive and deleterious impacts on insect diversity. These impacts may vary depending on the context, such as the invasive species targeted for management, the management method used, and how this is applied. In this chapter, we discuss how traditional methods of management of terrestrial invasive alien species (i.e., plants, insects, vertebrates) affect insect diversity. We review the following management methods: prescribed burning, physical removal (e.g., uprooting, trapping), grazing, mowing, chemical compound application (including selective trapping or luring), and biological control.
Chapter Eleven - The role of citizen science in biodiversity monitoring: when invasive species and insects meet https://doi.org/10.1016/B978-0-323-99918-2.00011-2 Abstract The important contribution of citizen science to the monitoring of biodiversity, including invasive alien species (IAS), is increasingly recognized, with implications for the science per se and for IAS management. In this chapter, after a contextualization of citizen science and biodiversity monitoring, with a particular focus on IAS, examples of projects related to IAS and insects are presented. These include the use of citizen science to monitor IAS in general, invasive alien insects, invasive alien plants (IAPs), and alien insects used as biocontrol agents of IAP. Although citizen science is more prevalent in North America and Europe and somewhat biased toward some taxa, the number of initiatives to monitor biodiversity and, in particular, IAS has increased substantially in the last 2 decades around the world. Citizen science data is increasingly used by scientists, although still a rather small proportion, being also important for IAS management and implementation of regulations.
Chapter Twelve - From trade regulations to socio-ecological solutions: Present and future actions to promote insect conservation https://doi.org/10.1016/B978-0-323-99918-2.00012-4 Abstract In recent years, insect populations around the globe have experienced significant declines in species numbers and diversity, which can have far-reaching consequences for the stability of ecosystems. This decline has been attributed to various factors, including habitat loss, climate change, pesticide use, and the invasion of alien species. In particular, invasive alien species can have devastating negative impacts on native insects, making them a significant contributor to the global insect decline. If, despite scientists' warnings, governments, economies, and the public continue to neglect the impacts of biological invasions on native insects, many more extinctions will occur in the coming decades. To reverse this trend, it is crucial to rapidly identify and implement feasible invasive species management actions. In this final chapter, we emphasize the need for managing biological invasions to promote native insect conservation.
Noa Núñez-González, Ana Novoa, Petr Pyšek, Jonatan Rodríguez, Chapter One - Biological invasions: a global threat to insect diversity, Editor(s): Jonatan Rodríguez, Petr Pyšek, Ana Novoa, Biological Invasions and Global Insect Decline, Academic Press, 2024, Pages 1-15, ISBN 9780323999182, https://doi.org/10.1016/B978-0-323-99918-2.00001-X. (https://www.sciencedirect.com/science/article/pii/B978032399918200001X)
Rabitsch, W., & Zulka, K. P. (2024). The insect decline syndrome. In Biological Invasions and Global Insect Decline (pp. 47-89). Academic Press. https://doi.org/10.1016/B978-0-323-99918-2.00003-3
Litt, A. R., Mitchell, A. B., & Tallamy, D. W. (2024). Alien plants and insect diversity. In Biological Invasions and Global Insect Decline (pp. 119-142). Academic Press.
Rodríguez, J., Novoa, A., & Pyšek, P. (2024). Microorganisms and disease-mediated invasions affecting native insect conservation. In Biological Invasions and Global Insect Decline (pp. 225-255). Academic Press. https://doi.org/10.1016/B978-0-323-99918-2.00009-4