Predicting how altering propagule pressure changes establishment rates of biological invaders across species pools

Abstract

Abstract. Biological invasions resulting from international trade can cause major environmental and economic impacts. Propagule pressure is perhaps the most important factor influencing establishment, although actual arrival rates of species are rarely recorded. Furthermore, the pool of potential invaders includes many species that vary in their arrival rate and establishment potential. Therefore, we stress that it is essential to consider the size and composition of species pools arriving from source regions when estimating probabilities of establishment and effects of pathway infestation rates. To address this, we developed a novel framework and modeling approach to enable prediction of future establishments in relation to changes in arrival rate across entire species pools. We utilized 13 828 border interception records from the United States and New Zealand for 444 true bark beetle (Scolytinae) and longhorned beetle (Cerambycidae) species detected between 1949 and 2008 as proxies for arrival rates to model the relationship between arrival and establishment rates. Nonlinearity in this relationship implies that measures intended to reduce the unintended transport of potential invaders (such as phytosanitary treatments) must be highly effective in order to substantially reduce the rate of future invasions, particularly if trade volumes continue to increase.

Effectiveness of the International Phytosanitary Standard ISPM No. 15 on Reducing Wood Borer Infestation Rates in Wood Packaging Material Entering the United States

“…Based on those two figures, and assuming the cargo in each container represents a single consignment, an infestation rate of 0.1% of 13 million containers ( = 52% of 25 million) would represent 13,000 containers per year entering the United States with live wood pests. Such a large number of infested consignments could lead to new pest establishments given that the probability of establishment increases with pathway volume [15], [62].…”

Planted forest health: The need for a global strategy

“…Phytosanitary measures are the major line of defense available to limit the global movement of pests, and various international policies seek to promote them [such as the International Standards For Phytosanitary Measures No. 15 (ISPM 15) (12, 13) that regulates the treatment of wood pallets to avoid bark beetle and wood borer invasions (14)]. …”

“…There is evidence that strictly applied phytosanitary measures can reduce the rate of pest introductions into new environments (12,14), and this is the most cost-effective way to deal with the challenge. Some wealthy and biogeographically isolated countries in particular, such as New Zealand and Australia, have tackled this quite successfully (15).…”

International variation in phytosanitary legislation and regulations governing importation of plants for planting

“…For example, European imports of P4P from China have increased fivefold over the past ten years and are now on a par with the volume imported from North America, which remained static (Eschen et al, 2014). Concomitant with increasing trade will be a similar increase in invertebrate plant pests and infective propagules of plant pathogens (Liebhold et al, 2012;Brockerhoff et al, 2014). There is, therefore, an urgent need to understand the efficacy of existing measures and what measures are needed to reduce and mitigate the risk of introducing pests through intercontinental trade in P4P.…”