Invasive Species: State of the Science & Gaps Faith T. Campbell, Ph.D. Center for Invasive Species Prevention
Situation – bad & getting worse • 3,540 NIS insects established in continental US & Canada – ~500 phytophagous insects & pathogens that attack trees/shrubs … how many attack herbaceous plants? – HI alone – 2,651; 50% of insect fauna; 13% deliberate • Rod Randall > 9,700 naturalized plants • Vertebrates Pimentel - ~400 • Diseases – West Nile virus, white nose syndrome, chytrid fungus of amphibians, whirling disease, fungal disease of snakes, highly pathogenic avian influenza … – in Hawai`i, avian malaria & avian pox
rates of introduction • OTA 1993 - no clear 40 700 35 evidence of rising #s 600 Cumulative value of imports (Trillions of 2010 $) Value of Cumulative Number of Pests Imports 30 500 over past 50 years 25 400 • Aukema 2010 (forest 20 300 15 pests only) – steady rate All Insect 200 Pests 10 of 2.5 / year since 100 5 Wood Borers 1860s 0 0 1750 1800 1850 1900 1950 2000 2050 Leung et al . 2014 Inexorable accumulation of more invaders …
From Liebhold et al. 2012 • multiple species in some regions … at least 3 in all counties • “Bad” pests now contained could spread to new, vulnerable areas (e.g., ALB, PSHB & Kushiro SHB)
Tree-killing insects & pathogens: Since 2003, >30 new tree-killing pests 20 woodborers, including: Palm pests: • • Red palm mite Redbay ambrosia beetle / laurel • wilt disease Red palm weevil • • Sirex woodwasp South American palm weevil • Goldspotted oak borer; • On Pacific islands: Walnut twig beetle and thousand cankers disease • `Ohi`a rust • Soapberry borer • Ceratocystis on `ohi`a • Polyphagous shot hole borer • Rhinoceros beetle • Kushiro shot hole borer • Cycad scale • Cycad blue butterfly Other: spotted lanternfly • Erythrina gall wasp • Pisonia scale
Invasive plants – high numbers US: > 9,700 Rod Randall Western Australia
Invasive plants • Invasive and alien plants are more widely distributed than natives across the continental United States • Average invasive plant now inhabits only ~ 50% of its expected range • Biological factors less important than human actions in facilitating spread (Bradley, B.A., R. Early & C. J. B. Sorte. 2015. Space to invade? Comparative range infilling and potential range of invasive and native plants. Global Ecology and Biogeography)
3 – 8 million in 2011 Courtesy Jack Mayer, U.S. Dept. of Energy Savannah River National Laboratory
Whitenose syndrome locations November 10, 2015 www.whitenosesyndrome.org
New Zealand mudsnail locations
Expect additional introductions • Diseases -- bSal or other new strains of chytrid fungi that kill amphibians (> 4 M amphibians imported /year) • New invasive plants [>500 species invasive in some region are being sold on-line; Humair et al. (2015)] • Wood-borers -- Leung et al . 100 more by 2050
Role of research when • Threat is complex • Don’t expect increased resources for either research or management prioritize • Decision-makers & stakeholders have many demands on attention & want simple answers • Stakeholders have conflicting goals What most important to learn? What can be extrapolated from what have learned? How coordinate efforts to be most efficient – while not sacrificing variety of approaches & ideas?
Balancing approaches What is “right” balance between sustained, focused research on specific questions, e.g. , 1) how important a pathway is movement of wood by woodworkers? 2) How do invasive shrubs & vines – as distinct from grassland herbs – respond to higher atmospheric levels of CO 2 & changing temperatures & precipitation?
Versus Broad approaches that elucidate big management issues or cross-cutting issues • Can scientists identify high-risk sites for introductions? How handle surprises? ( e.g. , ALB in Clermont Co, OH; few forest pests introduced to Portland / Seattle / Vancouver) • Can managers protect high-value sites? Or must containment/slow-the-spread efforts focus on sites of initial introduction? • Compare efforts to persuade visitors to avoid moving firewood, aquatic organisms on boats & gear, weed seeds on trucks, etc. to find synergies
breakthroughs • eDNA detection of aquatic organisms • Baited leaves in streams to detect Phytophtora s • Increasingly sophisticated climate matching models • PRE system (UCDavis & UW) to predict invasiveness of “new” plant species • CRISPR-Cas9 gene-splicing technology
Topics for scientific study • Evaluating programs’ efficacy • Determining propagule pressure • Invasive species’ impacts • Management & prevention strategies • Tools and technologies • Economic consequences • Change the culture to make IAS everyone’s business
Complexity (biological) Structure & chemistry of soil & associated leaf litter – they can be altered by • Rooting by feral hogs • Activity of alien earthworms & other soil organisms • Rain of insect excreta • Changes in above-ground plant composition as result of either or both – Invasion by alien plants – High mortality of some plant taxa caused by alien insects or pathogens
… Complexity (biological) insect / host plant interactions in period of heightened atmospheric CO 2 - leaf chemistry (in addition to changing temperatures, precipitation patterns, phenological mismatches associated with climate change ) • Evan DeLucia (U. of IL) forest studies with elevated CO 2 saw decreased herbivore populations, increased predator populations
… Complexity (socio -economic) Role of research in determining pathways, detection & control methods … evaluating program options & relative efficacy • 3 pest pathways studied – but information dated (2009) – SWPM Haack & Leung approach rate reduced but still “leaks”; likely triple #s of woodborers by 2050; rules changed – need to update analysis – Plants Liebhold high pest approach rates on a subset of imports; how representative was that set? How relevant to US natural systems? Changes since? – Firewood Koch et al . distance travelled by campers
… Complexity (socio -economic) Role of research in determining & documenting invasive species’ impacts • E.g. , insects & pathogens attacking trees in urban areas, affecting – removal costs for homeowners & municipalities – ecosystem services (& their economic values) – human health – setbacks to efforts to counter climate change (=urban “greening”)
Can research reduce the # of “unknown unknowns”? • 1998, Mycological Society of America: … estimated that 95 percent of fungal species in the world remain undescribed, let alone understood in terms of ecological function.” Current status? Progress in predicting impacts? Rapid ohia death; Ceratocystis fimbriata
Broaden efficacy evaluations of programs? • USDA plans to rely on HACCP programs to reduce pest risk associated with nursery stock … should we study reasons for failures of HACCP programs in other areas, e.g. , food safety, in order to anticipate & forestall weaknesses in plant nursery HACCP programs?
How address social constraints? • Possible loss of biologically effective controls … e.g., neonicotenoids … or biocontrol agents • Managing popular animals – Cats – Feral hogs – 2 nd most popular big-game trophy in North America -- Non-native game fish
Other topics … • Pursue understudied pathways • Strengthen global invasive plant datasets & models for predicting future ranges of invasive plants within US • Quantifying/monetizing invasive plant impacts Nancy Loewenstein, Auburn University bugwood
Ecological restoration of forest trees decimated by alien pests a multiple-step procedure requiring long-term commitment, strong infrastructure, & funds Each activity … – Preparation : • Achieve control of the invasive pest • Collect, store & evaluate germplasm – breeding and selection – traditional & molecular techniques – production of propagules – in large numbers/mass propagation – site preparation of former habitat – planting ; and – post-planting maintenance requires own skill sets, protocols, equipment, facilities, & infrastructure
Gaps • For most taxonomic groups, lack nation-wide picture – numbers, species, where established … much less potential range Need national-level mapping of invasive species – helps set priorities, coordinate landscape-level efforts, demonstrate success • Digests that synthesize numerous studies • Collaborate with Canadian & Mexican colleagues since species, pathways, forest systems cross borders
… Communication • Determine decision- makers’ & stakeholders’ perspectives & package scientific findings to address them Relevance to management (including prevention) should guide selection of research topics/agenda; decision- makers’ & stakeholders’ perspectives guide much of presentation -- but NEITHER guides research approach or – esp. – findings/conclusions
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