Do non‐native plants contribute to insect declines?

Abstract

1. With evidence of significant global insect declines mounting, urgent calls to mitigate such declines are also increasing. Efforts to reverse insect declines will only succeed, however, if we correctly identify and address their major causes.2. One potential cause that has received little mention is the global spread of non-native plants as invasive species, agroforestry products, and ornamental plants.3. Here we (a) review the theory predicting that most insect herbivores are evolutionarily constrained to use a fraction of available plant lineages; (b) document the extent to which nonnative plants have displaced native plant communities around the globe; (c) examine the evidence that non-native plants reduce insect abundance and diversity; and (d) suggest guidelines for measuring the impact of non-native plants on insect populations.4. We conclude that host range expansions to non-natives do occur among many insect herbivores but not at the frequency required to prevent insect declines when non-native plants replace native plant communities. Accordingly, we suggest that curbing the spread and use of non-native plants at local, national, and international scales will be a necessary and effective way to reduce some insect declines.

Sensitivity of Tropical Insectivorous Birds to the Anthropocene: A Review of Multiple Mechanisms and Conservation Implications

“…Insect declines are widely documented and reviewed, probably because of their profound ecological importance (Dirzo et al, 2014;Sánchez-Bayo and Wyckhuys, 2019;Cardoso et al, 2020;Montgomery et al, 2020;Tallamy et al, 2020;van Klink et al, 2020;Wagner, 2020;Wagner et al, 2021). These references identify multiple causes of insect decline (including the ultimate cause, human impacts; Figure 1): habitat loss and fragmentation, pollutants associated with agriculture, invasive insect species (e.g., competitors), climate change, overexploitation of some insects, invasive plants that host few herbivores (Tallamy et al, 2020); and coextinction of specialized insects such as parasites on other insects, mutualists such as insect pollinators, coprophages such as dung beetles, and mycophages (fungal feeders; Cardoso et al, 2020). These multiple threats to insects amount to death by a thousand cuts (Wagner et al, 2021)-an apt phrase for insectivorous tropical bird declines as well.…”

Current conservation policies in the UK and Ireland overlook endangered insects and are taxonomically biased towards Lepidoptera

“…This is already being pioneered by the Buglife project, which aims to create 'super highways' across the UK, connecting insect habitats (Buglife, 2021). In addition, strict control of pesticides (Goulson, 2013;Sánchez-Bayo, 2014;Sluijs et al, 2013), and invasive species (Tallamy et al, 2021) would be of benefit to insect biodiversity. 4.…”

Invasive Plants Differentially Impact Forest Invertebrates, Providing Taxon-Specific Benefits by Enhancing Structural Complexity

“…Collembola, comprised of detritivorous species, may be reduced in abundance with greater A. petiolata ground cover as this plant species has shown to accelerate decomposition of leaf litter (Rodgers et al, 2008) and A. petiolata may reach higher densities in litter-free environments (Bartuszevige et al, 2007). The Lepidoptera include numerous specialist and oligotrophic feeders that are tightly correlated with host plants (Forister et al, 2015;Tallamy et al, 2021) and may therefore avoid areas of dense A. petiolata populations. Although correlated with A. petiolata and invasive herbs, our invertebrate groups were not significantly correlated with the percent cover of remaining, non-invasive herbaceous plants.…”