Global ecosystem functions, services, and commodities are increasingly threatened by biological invasions. As a result, there is an urgent need to manage invasive species through global collaborative research. We propose an ‘applied empirical framework' (AEF) to aggressively confront the current global biological invasion crisis. The AEF builds on existing models for invasion science that advocate 1) standardized research designs to reveal key aspects of biological invasion, and 2) collaborative research to facilitate the sharing of resources and information. The AEF further emphasizes the need for 3) the production of research ‘tools’ (e.g., data, methodologies, technical instruments) designed for direct uptake by agencies that manage biological invasion, and 4) a taxonomically targeted approach in which task forces conduct rapid, in-depth research on top-priority invasive species across their entire geographic range. We review collaborative science and the distinctive roles played by different collaborator types. We then provide an example of the AEF in action through the BioSAFE initiative (Biosurveillance of Alien Forest Enemies), a highly collaborative project aimed at developing genomic research tools to facilitate biosurveillance and intervention for forest invasive species. We illustrate the BioSAFE approach through our research on two polyphagous insect species: the wood-borer Anoplophora glabripennis, Motschusky (Coleoptera: Cerambycidae; Asian longhorned beetle) and the defoliator Lymantria dispar, Linnaeus spp. (Lepidoptera: Lymantriidae; gypsy moth). These examples illustrate how the AEF can focus and accelerate our response to the global biological invasion crisis by applying the resource capabilities of collaborative research groups to generate management tools for top-priority invasive species.

Insect pests destroy ∼15% of all U.S. crops, resulting in losses of $15 billion annually. Thus, developing cheap, quick, and reliable methods for detecting harmful species is critical to curtail insect damage and lessen economic impact. The apple maggot fly, Rhagoletis pomonella, is a major invasive pest threatening the multibillion-dollar apple industry in the Pacific Northwest United States. The fly is also sympatric with a benign but morphologically similar and genetically closely related species, R. zephyria, which attacks noncommercial snowberry. Unambiguous species identification is essential due to a zero-infestation policy of apple maggot for fruit export. Mistaking R. zephyria for R. pomonella triggers unnecessary and costly quarantines, diverting valuable control resources. Here we develop and apply a relatively simple and cost-effective diagnostic approach using Illumina sequencing of double-digest restriction site-associated DNA markers. We identified five informative single-nucleotide polymorphisms (SNPs) and designed a diagnostic test based on agarose gel electrophoresis of restriction enzyme-digested polymerase chain reaction amplification products (RFLPs) to distinguish fly species. We demonstrated the utility of this approach for immediate, 1-d species identification by scoring apple- and snowberry-infesting flies from known hosts, reared from fruit collected at 11 sites throughout Washington. However, if immediate diagnosis is not required, or hundreds to thousands of specimens must be assessed, then a direct Illumina-based sequencing strategy, similar to that used here for diagnostic SNP identification, can be powerful and cost-effective. The genomic strategy we present is effective for R. pomonella and also transferable to many cryptic pests.

The sugarcane aphid (SCA), Melanaphis Sacchari (Zehntner) (Hemiptera: Aphididae), has been considered an invasive pest of sugarcane in the continental United States since 1977. Then, in 2013, SCA abruptly became a serious pest of U.S. sorghum and is now a sorghum pest in 22 states across the continental United States. Changes in insect-associated microbial community composition are known to influence host-plant range in aphids. In this study, we assessed whether changes in microbiota composition may explain the SCA outbreak in U.S. sorghum. We characterized the SCA bacterial microbiota on sugarcane and grain sorghum in four U.S. states, using a metabarcoding approach. In addition, we used taxon-specific polymerase chain reaction (PCR) primers to screen for bacteria commonly reported in aphid species. As anticipated, all SCA harbored the primary aphid endosymbiont Buchnera aphidicola, an obligate mutualistic bacterial symbiont. Interestingly, none of the secondary symbionts, facultative bacteria typically associated with aphids (e.g., Arsenophonus, Hamiltonella, Regiella) were present in either the metabarcoding data or PCR screens (with the exception of Rickettsiella and Serratia, which were detected by metabarcoding at low abundances <1%). However, our metabarcoding detected bacteria not previously identified in aphids (Arcobacter, Bifidobacterium, Citrobacter). Lastly, we found microbial host-associated differentiation in aphids that seems to correspond to genetically distinct aphid lineages that prefer to feed on grain sorghum (MLL-F) versus sugarcane (MLL-D).

Graphical abstract

Emerging technologies have the potential to offer new applications for managing invasive insects. While scientific and technological advancements are vital to realizing this potential, the successful development and use of these applications will also largely depend on community and stakeholder engagement. To contribute to a relevant and rigorous envisioning of engagement for emerging technologies for invasive insects (ETII), we begin by reviewing key insights on engagement from three scholarly fields: invasive species management, responsible research and innovation, and ecological risk assessment. Across these fields we glean best practices for engagement for ETII: 1) pursue engagement across decision phases and sectors; 2) select context-appropriate participants and methods; and 3) recognize and navigate engagement-related tensions. We illustrate these best practices by describing an ongoing project that uses engagement to inform risk assessment and broader decision making on biotechnologies being developed to address the Spotted-wing Drosophila (Drosophila suzukii) invasive fruit fly. We describe completed and planned engagement activities designed to identify and prioritize potential adverse effects, benefits, management actions, and research actions of the proposed genetically engineered sterile male, gene drive, and RNAi biotechnologies. In the face of broadening calls for engagement on emerging technologies, this article provides theoretical and empirical insights that can guide future engagement for ETII.

In North America Amylostereum areolatum (Chaillet ex Fr.) Boidin is a fungal symbiont associated with both the non-native Sirex noctilio Fabricius (Hymenoptera: Siricidae) and less commonly the native Sirex nigricornis Fabricius (Hymenoptera: Siricidae) woodwasps. The relationship between S. noctilio and A. areolatum constitutes a serious threat to pine plantation in the southern hemisphere. Studies have shown evidence of exchange of symbionts between non-native and native Sirex species. Our objectives were 1) to identify and assemble a panel of rDNA intergenic spacer–single nucleotide polymorphisms (IGS-SNPs) for genotyping strains of A. areolatum symbionts associated with Sirex species in North America, and 2) to develop genetic markers for monitoring the spread of specific A. areolatum haplotypes associated with S. noctilio across regions. The IGS-SNPs panel analyzed included haplotypes B1, B2, D1, D2 (from known IGS type B and D), E, and F. Genetic markers and haplotype-specific primers were designed to detect the IGS haplotypes D and E of A. areolatum. We found that haplotype D was absent in A. areolatum from S. nigricornis in Louisiana, while haplotype E was detected in all A. areolatum from S. nigricornis in Canada and Louisiana. Both haplotype D and E were co-detected in approximately 5% of samples from Canada. The IGS-SNP markers detected specific haplotypes accurately. Observing haplotype D in any A. areolatum from the native S. nigricornis likely indicates the presence of the potentially harmful S. noctilo-A. areolatum complex. The work highlights how IGS-SNPs can help in early detection without direct occurrence/observations of the non-native species of concern.

Exotic fruit flies in the family Tephritidae pose a threat to U.S. agriculture and natural resources. As part of ongoing fruit fly detection and exclusion programs, invasive fruit fly adults are periodically trapped in and introduced populations are eradicated from two major fruit producing states: California and Florida. Although the pathways used by flies to enter these states are not clear, one possible introduction pathway is hand-carrying fruits and vegetables infested with eggs or larvae through ports of entry during border crossings or international air travel. These collections represent an important resource for determining what species are most commonly associated with particular ports of entry, their host plants, and source country, making the identification of the intercepted larvae fundamental. Here, we examine cytochrome c oxidase subunit I sequences obtained with Sanger DNA sequencing and Single Molecule Real-time sequencing (SMRT) technologies on a collection of hundreds of intercepted larvae and pupae that are suspected to be fruit pests found in the subfamily Dacinae, in addition to a collection of field-caught flies. Utilizing Pacific Biosciences (PacBio) Circular Consensus Sequencing, we sequenced thousands of independent amplicons in a single SMRT cell. We present our implementation of PacBio's method by describing wet-lab procedures as well as analytical protocols to automate the process. Finally, for the intercepted material, we compared the generated SMRT data to sequences produced with Sanger and evaluate their quality as a means to identify flies. Using intercepted material, we obtained a sequencing success of over 88% with PacBio's SMRT sequencing. As the spread of invasive insects grow, so will the size of collections of intercepted material; we found technologies such as SMRT sequencing to be excellent resources to simplify the generation of large amounts of molecular data and to reduce or eliminate all together the manipulation of the sequences.

The invasive cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae), occurs in the United States only along the Texas border as incursions from Mexico. Intensive acaricide treatment of cattle herds in Mexico to reduce tick populations has resulted in the development of resistance to an array of acaricides. Resistance to permethrin has increased both in incidence and level inTexas over the last decade, even though permethrin is not used to control fever ticks on the U.S. side of the border. From 3 to 4% of submittals in 2008 to over 50% in 2016 and 2017 showed resistance based on standardized pesticide bioassays. Moreover, by 2017, the highly resistant ticks had spread to include all five of the southmostTexas counties and were found on both cattle and sylvatic hosts. Improved diagnostic tools developed by our group include a panel of DNA-based real-time PCR assays to detect mutations within the voltage-sensitive sodium channel (Vssc) that are involved in permethrin resistance. Further, a positive correlation between the presence of multiple Vssc mutations and phenotypic resistance was validated. These assays can be completed within days of receiving field collected ticks providing timely, valuable information to program managers. Microsatellite marker analysis of these pyrethroid resistant tick populations provided evidence that separate incursions of resistant ticks had enteredTexas independently.

Coconut rhinoceros beetle, Oryctes rhinoceros (L., 1758), is a large scarab beetle native to Southeast Asia and a major pest of coconut (Cocos nucifera) and oil (Elaeis guineensis) palms in its invaded range. Few tools are available for coconut rhinoceros beetle management, particularly for an emerging haplotype with resistance to known strains of Oryctes rhinoceros nudivirus, the traditional biological control agent used in coconut rhinoceros beetle management programs. RNA interference (RNAi) represents an emerging tool for insect pest control that exploits an existing pathway for gene regulation in the target organism. In this study, we evaluated RNAi as a potential tool for coconut rhinoceros beetle management. Using transcriptome data generated from gut tissue of early instar larvae, we identified 24 RNAi target sequences that were either highly expressed or had demonstrated efficacy in other insect systems. Double-stranded (ds)RNAs ranging from 249 to 297 bp in length were generated for 23 of these target sequences and 150 ng were microinjected into coconut rhinoceros beetle 1^st, 2^nd, and 3^rd instar larvae and adults. Five of these dsRNAs that targeted genes putatively encoding V-type ATPase, polyadenylate binding protein, and three forms of actin induced 30.8–100% mortality within 14 days post injection (dpi). Microinjection of 2nd instars with 10 and 100 ng of these same five dsRNAs induced 20–100% and 80–100% mortality at 7 and 14 dpi, respectively. These results indicate RNAi should be explored as a possible management option for coconut rhinoceros beetle. Coconut rhinoceros beetle may also represent a model species for using RNAi in the management of large invasive insect species.

Invasive species have devastating economic and ecological impacts worldwide, but proactive monitoring programs are rare on the global stage. By definition, tramp ants are associated with disturbance and human-mediated dispersal, making them especially concerning invasive threats. A proactive—rather than reactive—approach to monitoring for, preventing, and managing invasive species depends on taxonomic preparedness, which enables rapid and accurate identification. Emerging tools and technologies, including genomic barcoding and interactive online keys, can aid in species delimitation and diagnosis. However, resolving tramp species' identities remains the fundamental first step in invasive species management because diagnostic tools cannot be developed and disseminated until species names are stable. Diagnosis of morphologically difficult species requires basic knowledge of species boundaries, biogeography, and phylogenetic relationships. This review comprehensively synthesizes information available for 15 known and five potential tramp ant species in Nylanderia (Emery) (Hymenoptera: Formicidae): a globally distributed genus of over 130 described species, many of which are only diagnosable by subtle morphological characters. Nylanderia records were drawn from published literature, specimen databases, and museum collections to compile known distributions, biology, natural history, and taxonomy for each species. We review existing resources for visualizing known geographic ranges and high-resolution images of ants globally and encourage the use of these types of tools in support of invasive species diagnosis and distribution tracking. Finally, we discuss how taxonomic and life history information can be used synergistically with genomic and digital technology to develop tools for identification of these, and other emerging invasive insect species.