Invasive pests—insects and diseases

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  • Authors: Duerr, Donald A.; Mistretta, Paul A.
  • Publication Year: 2013
  • Publication Series: Paper (invited, offered, keynote)
  • Source: In: Wear, David N.; Greis, John G., eds. 2013. The Southern Forest Futures Project: technical report. Gen. Tech. Rep. SRS-GTR-178. Asheville, NC: USDA-Forest Service, Southern Research Station. 457-508.


Key Findings

  • Nonnative pest species have increasing impacts in the South regardless of climate change, patterns of land ownership, or changes in the composition of vegetation.
  • “New” nonnative invasive insects and diseases will have serious impacts on southern forests over the next 50 years. Some species such as emerald ash borer, laurel wilt, and thousand cankers disease are expanding rapidly; they threaten the ecological viability of their hosts throughout large areas of the South.
  • Given the trend in introductions of nonnative insect pests and plant pathogens over the last 100 years, we can expect additional introductions of previously undocumented pests (insects, fungal pathogens, plant parasitic nematodes, etc.) from foreign countries that will have serious consequences for some native forest plant species.
  • When host material for a given insect or disease is projected to increase over the next 50 years as a result of climate change or management choice, we can expect more pest activity; for example, more pine acreage enables more southern pine beetle damage. Conversely, if host material decreases, the overall impact of pests utilizing that host material will likely decrease.
  • Very few indisputable projections can be made about the effects of climate change on native or naturalized pests. Although climate-change-induced host abundance is expected to increase the activity of some pests, others (such as gypsy moth) may become less active with warmer temperatures despite relatively similar levels of host availability.
  • The scientific literature and the body of expert opinion are inconclusive in predicting the effects of climate change on many pests’ activity levels, often even lacking historic trend data. However, based on anecdotal reports from professionals, and in the absence of other data, we generally assume that pest activity levels over the next 50 years will be similar to the past 50 years with respect to impact on preferred hosts.
  • A significant source of uncertainty in projecting pest impacts is the adequacy of prevention and suppression methods: how effective are existing methods, compared with those that might be available in the future; how willing and able are land managers or landowners to adopt management/control methods; how much funding is available compared to the amount needed for implementation.
  • Under the influence of climate warming host plants, pests and pest complexes are expected to migrate northward and to higher elevations. Because migration rates differ among the affected species, migrating plants are expected to form new associations, which will then affect the pests, their host populations, and the interactions among them. Unexpected pests very likely will become important, while some that are currently active will be less severe in their new habitats. As host plants “migrate” to the north an increase in the incidence of decline syndrome of plants in their previous range is expected.
  • Although not expected to be a significant problem in the next 50 years, the migration of lower elevation plants to higher elevations could ultimately eliminate or at least severely restrict the host ranges of current high elevation plant associations. Pests that act on a restricted host base, such as the balsam woolly adelgid and butternut canker, could become far more significant ecologically in areas of relict host populations.
  • Climate change will lead to extra uncertainty in decision making, especially in areas where the changes cause increased variability in local (fragmented) climate regimes that exceed historical variability of local weather patterns.

  • Citation: Duerr, Donald A.; Mistretta, Paul A. 2013. Invasive pests—insects and diseases. In: Wear, David N.; Greis, John G., eds. 2013. The Southern Forest Futures Project: technical report. Gen. Tech. Rep. SRS-GTR-178. Asheville, NC: USDA-Forest Service, Southern Research Station. 457-508.
  • Posted Date: September 4, 2013
  • Modified Date: September 4, 2013
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