Comparison of insect invasions in North America, Japan and their Islands

Abstract

Among the various animal taxa that are have established outside their native ranges, invasions by insect species are the most numerous worldwide. In order to better understand the characteristics of insect species that make them more invasion prone, the characteristics of habitats that make them more susceptible to invasions and to understand the pathways that facilitate invasions, we compared the compositions of the native and non-native insect communities among five Pacific regions: North America, the Hawaiian Islands, mainland Japan, Ogasawara and Okinawa Islands. These regions comprise both island and mainland habitats and have historically been subjected to varying activities affecting insect movement. Among the five regions, the oceanic islands, Hawaii and Ogasawara, appear to be the most prone to invasions. Specific insect orders such as the Blattodea, Siphonaptera, Thysanoptera and Hemiptera are disproportionally represented in the non-native insect fauna compared to the native fauna in all regions. A large fraction of the non-native insect species in North America (9.4 %) and Hawaii (13.2 %) were introduced intentionally, as part of biological control programs, which were historically pursued more vigorously in those regions than in Japan. Dominance by individual insect orders within invaded communities can be explained by the historical importance of invasion pathways, some of which were likely similar among regions (e.g., movement on live plants), while other pathways appear more region specific. Translocation of insect species among world regions appears to be affected by climatic similarity, 123Biol Invasions (2015) 17:3049-3061 DOI 10.1007/s10530-015-0935-y host plant similarity and propagule pressure, though these effects are often confounded.

Depletion of heterogeneous source species pools predicts future invasion rates

“…For example, of the ~90 000 insect species native to North America, only 55 have successfully invaded Japan (Yamanaka et al . ). Despite the seemingly endless supply of species in source regions, there is reason to believe that depletion of species pools has had at least some effect on rates of species establishment.…”

Evolutionary history predicts high‐impact invasions by herbivorous insects

“…We censused non‐native insects, using published lists (Aukema et al, ; Yamanaka et al, ), and identified 58 conifer specialists currently established in North America that feed on hosts in Cupressaceae, Pinaceae, and/or Taxaceae (Table A1). For each conifer specialist, literature and online searches were conducted (March 2016–July 2017) to find: (a) values of 15 potentially relevant insect life history traits including fecundity and voltinism, (b) the highest level of plant damage described in published literature, (c) all documented North American host trees (excluding conifers outside their native range in North America), and (d) all host trees from the insect's native range.…”

“…We censused non-native insects, using published lists (Aukema et al, 2010;Yamanaka et al, 2015), and identified 58 conifer specialists currently established in North America that feed on hosts in Cupressaceae, Pinaceae, and/or Taxaceae (Table A1) High-impact insects were defined as those reported to cause tree mortality at the population or regional level (Figure 1), whereas species that directly or indirectly caused only individual tree mortality or minor damage were not considered to be high impact (Table 1). A binary impact response variable was considered useful for decisionmaking (high impact or not), avoided the subjectivity of multiple impact levels, and eliminated the potential effect of time since introduction.…”

Thysanoptera-Terebrantia of the Hawaiian Islands: an identification manual

“…For these, the country in which they originally evolved is probably of limited importance when considering invasion pathways. Such species could have reached Hawaii from any part of their disrupted distribution, although Yamanaka et al (2015) appeared to assume that each invasive species had entered Hawaii from the area in which it had evolved. Despite this, an invasion pathway from the Americas is indicated by the 15 species that are found otherwise only in North America, and a second pathway is indicated by the five species shared only with the Neotropics.…”