Prediction and prevention remain the most lauded approach to address alien invasive species. The intent seems simple enough: forecast which species or pathways pose unacceptable risks and keep them from arriving in an area of concern. This strategy requires a clear benchmark of success. As the number of introduced arthropod species continues to increase at a steady rate, each new incursion might be viewed as evidence of a biosecurity failure (11). However, global trade has increased more rapidly than species arrivals, a pattern that suggests biosecurity efforts have been somewhat effective (17) but is far from a clear measure of achievement (18).

We see promise in future systems integration to forecast threats and prevent introductions. We remain optimistic that advances in horizon scanning and real-time global pest surveillance can provide more dynamic representations of encroaching threats (19, 20). We see opportunities in systems approaches to keep invasive alien insects out of supply chains for goods destined for foreign markets. Advances in commodity disinfestation technologies remain needed, with alternatives to methyl bromide still a priority (21). In addition, more sophisticated tools, perhaps based on environmental DNA or volatile chemical profiles, are needed to detect insects en route (22, 23).

Spatially-explicit pest risk assessment will remain a cornerstone of biosecurity efforts both to inform the permissibility of a good for import, to structure surveillance programs, and to conduct post incursion responses should a species arrive within an endangered area (24). These assessments generally describe where a species is most likely to invade and/or cause harm, often focusing on conditions needed for pest establishment. However, approaches for developing these assessments are needed that are reliable, scalable, and affordable. The conceptual challenge of developing models that are reliably transferable to new space and time is becoming increasingly recognized, particularly for machine learning and other statistical models (25). Process-based models have appeal, but extensive data requirements make the approach prohibitive for application to the hundreds, if not thousands, of species of concern (26). Advances in the democratization of data collection through apps and open access databases improve capacity to capture changes in distribution, abundance, and phenology of insect populations. Developments in phylogeography will provide a more detailed accounting of invasions, identify invasive phenotypes, and more explicitly account for genotype x environment interactions to improve the rigor of forecasts (27–29).

Should prediction and prevention efforts fail, the next best alternative is to locate nascent populations of high-risk species early and eradicate or contain them quickly. Despite the global development of methods for early detection of invasive insects, initial observations of alien species in both agricultural and forest systems are still too often fortuitous (17). Research to improve this strategy is needed to address where/when/how to look for new invasive species and how to confirm their identity if encountered.

Pest risk maps highlight areas where species might invade or cause harm, and as such, provide useful direction about areas to consider for early-detection surveys. The endangered area may be too large to survey effectively with available resources. We believe more research is needed to quantify the probability of detecting low densities of invasive arthropods with a particular sampling scheme (30). A “risk-based surveillance” approach has been developed for plant pathogens that targets sampling effort where most preferred and valuable host plants occur (31). The cost of invasive species detection can therefore be reduced, yet more research is needed to examine this approach for invasive insects. Yemshanov et al. (32, 33) have taken spatial optimization of sampling effort to a new level, but the methods can be computationally intensive to apply.

Within endangered areas, the next major challenge becomes how to sample for the early detection of targeted species. Sentinel plots of appropriate plant species can be used effectively to detect species or suites of invasive arthropods that share a common host, for example, maize (34) or maples (35). The deployment of traps, particularly when appropriate semio-chemical lures are available, remains a preferred monitoring option because traps are more convenient and cost-effective than visual inspections. Nevertheless, visual inspections may be unavoidable if lures are unavailable or traps become impractical. Citizen science to assist with trap monitoring or visual inspection has been embraced for the early detection of spotted-wing drosophila, Drosophila suzukii, in the United States (36) and the multicolored Asian lady beetle, Harmonia axyridis, in Europe (37), for example.

Recent advances in genomics, bolstered by traditional taxonomic expertise, offer a path to rapid confirmation of species identity. An additional advantage of genomic approaches is that various strains, biotypes or haplotypes can be distinguished within a species. Specific haplotype data can thereby reflect more precisely the geographic origins of an invasive population, as demonstrated for walnut twig beetle, Pityophthorus juglandis (38), H. halys (39), and S. frugiperda (40). With accurate knowledge of pest origins, specific countries can be targeted early in the search for natural enemies, usually species-specific parasitoids, for subsequent safety and efficacy evaluation and release for biological control within the invaded countries (41).

Following early establishment and spread of invasive arthropods, immediate investment in research and development to support integrated pest management (IPM) solutions continues to be a valid paradigm. IPM is “an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. Pesticides are used only after monitoring indicates they are needed according to established guidelines, and treatments are made with the goal of removing only the target organism. Pest control materials are selected and applied in a manner that minimizes risks to human health, beneficial and non-target organisms, and the environment” (42). Area-wide pest management extends these decision-making principles beyond individual farms or landholdings.

Ironically, for many cropping systems, IPM is often in place for endemic pests when invasive pests arrive. Some arrivals disrupt existing IPM programs where biological control and/or reduced-risk insecticides are being used; H. halys in U.S. apple production is a prime example, where >$37 million was lost due to damage and increased insecticide application costs (43). As with endemic pests, the IPM response to invasive species typically requires both near-term and long-term strategies. To protect grower investments, the initial focus is often insecticidal control, with simultaneous commitments to fund research on biological control, pest-resistant varieties, cultural controls (44), physical exclusions (45), and “attract and kill” trap-based systems based on insect behavior (46). Breeding for resistance to invasive pests is increasingly important for trees and perennial crops. Transgenic insecticidal plants (47) or genetic biocontrol agents (48, 49), as through gene-drives, are novel technologies that could supplement or supplant IPM programs, pending requisite regulatory approvals.