Climate suitability analyses compare the distributions of invasive
knotweeds in Europe and North America with the source localities of
their introduced biological control agents
Abstract
Climate suitability analyses based on ecological niche modeling provide
a powerful tool for biological control practitioners to assess the
likelihood of establishment of different candidate agents prior to their
introduction in the field. These same analyses could also be performed
to understand why some agents establish more easily than others. The
release of three strains of Aphalara itadori (Shinji) (Hemiptera:
Pysllidae), each from a different source locality in Japan, for the
biological control of invasive knotweed species, Reynoutria spp. Houtt.
(Caryophyllales: Polygonaceae), provides an important opportunity to
compare the utility of climate suitability analyses for identifying
potential climate-based limitations for successful biological control
introductions. Here we predict climate suitability envelopes for three
target species of knotweed in Europe and two target species of knotweed
in North America and compare these suitability estimates for each of
these species to the source localities of each A. itadori strain. We
find that source locality of one strain, the Kyushu strain, has
little-to-no suitability compared to other locations in Japan based on
knotweed records from Europe, supporting an earlier study based on North
American Japanese knotweed records. The source locality of a second
strain, the Murakami strain, was predicted to have medium-to-high
suitability based on records of knotweeds from North America. In
contrast, European records of R. bohemica Chrtek & Chrtková and R.
sachalinensis (F. Schmidt) Nakai predicted no suitability for this
locality compared to other locations in Japan, while European records
for R. japonica Houtt. predicted low suitability. The source locality of
the final strain, the Hokkaido strain, was predicted as having
medium-to-high suitability based on knotweed records of all examined
species from both North America and Europe.