Potential invasion of exotic ambrosia beetles Xyleborus glabratus and Euwallacea sp. in Mexico: A major threat for native and cultivated forest ecosystems

Andrés Lira-Noriega,Julián Equihua,Jorge Soberón

doi:10.1038/s41598-018-28517-4

Abstract

We analyze the invasive potential of two Asian ambrosia beetles, Xyleborus glabratus and Euwallacea sp., into Mexico and the southern United States. The fungal symbionts of these beetles have been responsible for damage to trees of the family Lauraceae, including Persea americana and other non-cultivated tree species on both coasts of the United States. We estimate their potential threat using ecological niche modeling and spatial multi-criteria evaluation protocols to incorporate plant and beetle suitabilities as well as forest stress factors across Mexico. Mexico contains higher climatic and habitat suitability for X. glabratus than for Euwallacea sp. Within this country, the neotropical region is most vulnerable to invasion by both of these species. We also identify a corridor of potential invasion for X. glabratus along the Gulf of Mexico coast where most Lauraceae and native Xyleborus species are present; dispersal of either X. glabratus or Euwallacea sp. into this region would likely lead to major disease spread. However, the overall potential damage that these beetles can cause may be a function of how many reproductive hosts and how many other ambrosia beetles are present, as well as of their capacity to disperse. This work can also alert relevant managers and authorities regarding this threat.

Highlights

Open economies and international trade promote the movement of exotic pests and diseases, creating a threat to agroecosystems and natural ecosystems[1,2]
Of high concern for forest ecosystems in North America is the newly discovered Euwallacea sp. beetle (Polyphagous Shot Hole Borer; Coleoptera: Curculionidae: Scolytinae), which was originally identified as E. fornicatus[16], a native to the region that stretches from Sri Lanka through Vietnam, China, Taiwan and the islands of Okinawa, Indonesia, Philippines and Papua New Guinea (CABI, 2018)
Model transfers were consistent for both thresholding levels; the climate-based transfer for X. glabratus and Normalized Difference Vegetation Index (NDVI)-based transfer for Euwallacea sp. at the 10th percentile from the occurrence points showed a drastic reduction in suitable area compared with the minimum training presence thresholding (Fig. 1)

Summary

Introduction

Open economies and international trade promote the movement of exotic pests and diseases, creating a threat to agroecosystems and natural ecosystems[1,2]. Harr., Fraedrich & Aghayeva, the pathogen causing Laurel Wilt Disease (LWD), was introduced to Georgia, in the east coast of the United States[8], causing major mortality in tree species of the Lauraceae family This fungus is transmitted by the ambrosia beetle Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae;9,10), a species native to Asia that occurs over a broad geographic region from India, Bangladesh and Myanmar, through Japan, and Taiwan[11]. These include Fagaceae (e.g., Quercus agrifolia, Q. robus), Platanaceae (e.g., Platanus racemosa), Magnoliaceae (e.g., Magnolia grandiflora), Euphorbiaceae (Ricinus communis) and Hamamelidaceae (e.g., Liquidambar styraciflua). Mexico presents a large diversity of ambrosia beetle species both in regions where Lauraceae species are abundant as well as in avocado producing states, which could lead to the fungi rapidly spreading[24,25]

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