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\begin{document}

\title{Climate suitability analyses compare the distributions of invasive
knotweeds in Europe and North America with the source localities of
their introduced biological control agents}



\author[1]{Jeremy Andersen}%
\author[1]{Joseph S  Elkinton}%
\affil[1]{University of Massachusetts Amherst}%


\vspace{-1em}



  
  \date{May 23, 2024}


\begingroup
\let\center\flushleft
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\endgroup





\selectlanguage{english}
\begin{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 \& Chrtkov\selectlanguage{ngerman}á 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.%
\end{abstract}\selectlanguage{ngerman}%



\sloppy


\textbf{Title:} Climate suitability analyses compare the distributions
of invasive knotweeds in Europe and North America with the source
localities of their introduced biological control agents.

\textbf{Authors:} Jeremy C. Andersen, and Joseph S. Elkinton

\textbf{Affiliations:} Department of Environmental Conservation, 160
Holdsworth Way, Room 204 Holdsworth Hall, University of Massachusetts
Amherst, Amherst, MA 01003

\textbf{Running Title:} Climate suitability of knotweed biological
control

\textbf{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
\emph{Aphalaraitadori} (Shinji) (Hemiptera: Pysllidae), each from a
different source locality in Japan, for the biological control of
invasive knotweed species, \emph{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 \emph{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 \emph{R.} \selectlanguage{ngerman}× \emph{bohemica} Chrtek \&
Chrtková and \emph{R. sachalinensis} (F. Schmidt) Nakai predicted no
suitability for this locality compared to other locations in Japan,
while European records for \emph{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.

\textbf{Keywords:} Environmental Niche Modeling, classical biological
control, genotype x environment interactions, \emph{Reynoutria,
Fallopia}

\textbf{Introduction:}

Biological control is a safe and cost-effective approach for the
landscape-wide management of weedy species (Van Driesche et al., 2010).
On numerous occasions, insects and pathogens have been identified and
promoted to reduce the environmental and economic damages of weeds in
locations from across the globe (Van Driesche, 2012). Despite concerns
about the non-target effects of biological control agents (Barratt et
al., 2010; Howarth, 2000; Simberloff, 2012), modern biological control
programs implement a system of safe-guards to reduce unwarranted damage
to non-target species -- particularly when the agent is being introduced
from a novel region through a practice known as classical biological
control (Heinz et al., 2016; Messing, 2001). As a result, the use of
biological control as an alternative to other labor and chemically
intensive methods is increasingly becoming a part of both conservation
and organic management practices (Baker et al., 2020; Van Driesche et
al., 2016)

The control of invasive knotweed species, \emph{Reynoutria} spp. Houtt.
(Caryophyllales: Polygonaceae), has received much attention, with
cultural, mechanical, and chemical control options all being implemented
(e.g., Delbart et al., 2012; Kadlecová et al., 2022; Martin et al.,
2020). Interest has also been directed towards harvesting knotweeds, as
the plants have unique chemical properties (Metli\selectlanguage{polish}č\selectlanguage{english}ar \& Albreht 2022;
Metli\selectlanguage{polish}č\selectlanguage{english}ar et al. 2021) and may themselves be an important source for
biopesticides (Dara et al. 2020). However, for landscape-wide efforts
biological control is likely the most effective strategy, and as such an
international effort was established to identify and promote the natural
enemy, \emph{Aphalara itadori} (Shinji) (Hemiptera: Aphalaridae), which
was observed feeding and causing damage upon wild populations of\emph{R.
japonica} Houtt. on the Japanese island of Kyushu in 2004 (Shaw et al.,
2009). Prior to field releases, a laboratory reared population of the
Kyushu strain of \emph{A. itadori} was then used for host-range testing
and candidate biological control reviews were conducted (Grevstad et
al., 2013; Shaw et al., 2009; Shaw et al., 2011), resulting in the first
approved biological control agent in the European Union (Shaw et al.,
2009). A second population of \emph{A. itadori} , feeding on \emph{R.
sachalinensis} (F. Schmidt) Nakai, was subsequently collected in 2007
near Lake Toya on the Japanese island of Hokkaido, and similarly brought
to the laboratory for host range testing and candidate biological
control review (APHIS, 2020). Both strains were subsequently approved
for release in Europe and North America, and recently a third strain,
the Murakami strain, was identified from near the Japanese city of
Murakami and has been released in the Netherlands against \emph{R.}
\selectlanguage{ngerman}×\emph{bohemica} Chrtek \& Chrtková (Camargo et al., 2022). Review of
the Murakami strain for release in North America is currently underway.

As part of the review prior to introduction in North America, climate
suitability models for the Kyushu strain and the Hokkaido strains were
developed using the software program CLIMEX (Hearne Software, Melbourne,
Australia). These models predicted a strong climate match for both the
Kyushu and Hokkaido strains to potential release locations across North
America (Grevstad et al., 2012). However, despite this predicted climate
match, there have been no documented accounts of establishment of this
species anywhere it has been released. Note: here we use establishment
to indicate a self-sustaining population that is present in a location
for at least three consecutive years without importation or release of
additional individuals. We choose to use this more conservative
definition, though ``establishment'' has historically been reported in
the literature after only one year (see Van Driesche et al. 2008).
Unfortunately to date in locations where the psyllids have been released
and individuals have been observed in the field during post-release
monitoring, neither reduction in plant densities nor biomass have been
observed. We previously suspected that environmental constraints might
be limiting the success of the Kyushu strain in North America (Andersen
\& Elkinton, 2022), and noted a poor climate match to the source
locality of the Kyushu strain based on North American records of\emph{R.
japonica} using a different modeling approach, MaxEnt (Phillips et al.,
2006; Phillips \& Dudik, 2008). The MaxEnt models based on\emph{R.
japonica} records did, however, predicted medium-to-high suitability for
the source localities of the Hokkaido and Murakami strains (Andersen \&
Elkinton, 2022). Therefore, we were curious as to whether climate
suitability estimates conducted in MaxEnt for each target knotweed
species based on records from Europe and North America could help
provide insights into factors influencing the success of\emph{A.
itadori} releases in each region and for each target species of
knotweed.

To address this, we collected public records of all three target
knotweed species from the Global Biodiversity Information Facility
(GBIF) from Europe and North America. Using the MaxEnt software
platform, we estimate climate suitability envelopes based on records
from the invasive regions of each species, and we compared the predicted
suitability of the source locality of each \emph{A. itadori} strain
compared to other localities in Japan for each species of knotweed and
geographic region combination.

\textbf{Materials and Methods:}

The climate suitability analyses presented here follow the methods of
Andersen and Elkinton (2022) using locality records obtained from the
invaded distributions of knotweed species to predict regions in the
native range of these species where candidate biological control agents
might be most successfully established. As per Andersen and Elkinton
(2022), we used host-records (i.e., knotweed records) as a proxy for
their specialist-parasites (i.e., \emph{A. itadori} ), as the records
for hosts are often more readily available in public databases (Andersen
\& Elkinton, 2022; Johnson et al., 2019; Schneider et al., 2022).

Climate suitability analyses were based on the use of published records
for all species of \emph{Reynoutria} (knotweeds) obtained from the GBIF
database (accessed on September 28\textsuperscript{th}, 2022: GBIF
Occurrence Download https://doi.org/10.15468/dl.pdjdh8 ). This dataset
was then filtered to remove all records that lacked geographic locality
information, and then subdivided by focal species, resulting in one
dataset each for \emph{R. japonica} , \emph{R.} × \emph{bohemica} , and
\emph{R. sachalinensis} . The species datasets were then further
subdivided into geographical bins, with separate bins for samples from
North America (those samples located between 0°N, 180°W and 90°N, 20°W)
and from Europe and western Asia (those samples located between 0°N,
20°W and 90°N, 60°E).

To reduce the effects of sampling biases in our analyses we followed the
recommendations of Hijmans and Elith (2021). In the R statistical
language environment (R Core Team, 2022), we used the packages `raster'
(Hijmans \& van Etten, 2012) and `dismo' (Hijmans et al., 2015) to
randomly select one observation per 1 minute x 1 minute grid cell within
each dataset. The final datasets were then used to independently
estimate climate suitability envelopes in MaxEnt v 3.3.3e (Phillips et
al., 2006; Phillips \& Dudik, 2008) based upon the 5-minute resolution
WorldClim v 2.1 dataset (available at https://www.worldclim.org ).
Jack-knife analyses were performed on each dataset to measure the
relative importance of each climate variable, and results were mapped in
ArcGIS v 10.8 (Esri®, Inc., Redlands, CA)

\textbf{Results:}

A total of 249,769 records of \emph{Reynoutria} specimens with locality
information (i.e., latitude and longitude coordinates) were downloaded
from the GBIF database. These included 232,744 records for \emph{R.
japonica} , 11,608 records for \emph{R. sachalinensis} , and 4,377
records for \emph{R.} × \emph{bohemica} . After geographic binning, and
grid-based filtering, the European \emph{R. japonica} dataset included
721 records; the European and North American \emph{R.
sachalinensis}datasets included 432 and 114 records, respectively; and
the European and North American \emph{R.} × \emph{bohemica} included 342
and 92 records, respectively. Model accuracy for the MaxEnt analyses
based on the `area under the receiver-operator curve' (AUC) approach
(Merow et al., 2013), indicated that all models had high AUC scores
(European\emph{R. japonica} AUC = 0.948, European \emph{R.
sachalinensis} AUC = 0.966, European \emph{R.} × \emph{bohemica} AUC =
0.969, North American\emph{R. sachalinensis} AUC = 0.985, North American
\emph{R.} ×\emph{bohemica} AUC = 0.986). In total, 10 of the 18 BioClim
variables provided \selectlanguage{english}[?] 10\% contribution to the MaxEnt model predictions
for at least one of the datasets (Table 1). In Europe, five variables
contributed \selectlanguage{english}[?]10\% to the climate suitability envelope for \emph{R.
japonica} , four variables contributed \selectlanguage{english}[?]10\% to the climate suitability
envelope for \emph{R.} x \emph{bohemica} , and three variables
contributed \selectlanguage{english}[?]10\% to the climate suitability envelope for \emph{R.
sachalinensis} . Two of the 18 variables, Bio 6 (min temperature of the
coldest month) and Bio14 (precipitation of the driest month), were
included in models for all three focal species. In North America, two
variables contributed \selectlanguage{english}[?]10\% to the climate suitability envelope
for\emph{R.} x \emph{bohemica} , and three variables contributed \selectlanguage{english}[?]10\%
to the climate suitability envelope for \emph{R. sachalinensis} . Two of
the 18 BioClim variables, Bio 1 (annual mean temperature) and Bio 19
(precipitation of the coldest quarter) were present in models for both
focal species.

Predictions of climate suitability estimated from the European records
indicated that the source locality of the Kyushu strain had no predicted
suitability based on records for all three focal knotweed species, the
source locality of the Murakami strain had no-to-low predicted
suitability based on records of \emph{R. japanoica} and no predicted
suitability for based on records of \emph{R.} x \emph{bohemica}
or\emph{R. sachalinensis} , and the source locality of the Hokkaido
strain had low-to-medium predicted suitability based on records for all
three target knotweed species (Figures 1-3). A presentation of predicted
climate suitability based on European records across a wider portion of
central and east Asia are presented in Supplemental Figures S1-S3.
Predictions of climate suitability estimated from the North American
records indicated that the source locality of the Kyushu strain had
no-to-low predicted suitability based on records for \emph{R.}
x\emph{bohemica} and no predicted suitability based on records
for\emph{R. sachalinensis} , the source locality of the Murakami strain
had medium-to-high predicted suitability based on records for both
\emph{R.}x \emph{bohemica} and \emph{R. sachalinensis} , and the source
locality of the Hokkaido strain had medium-to-high predicted suitability
based on records for \emph{R. sachalinensis} and low-to-medium predicted
suitability based on records for \emph{R.} x \emph{bohemica} (Figures 4
and 5). A presentation of predicted climate suitability based on North
American records across a wider portion of central and east Asia are
presented in Supplemental Figures S4 and S5.

\textbf{Discussion:}

Understanding what factors promote and what factors inhibit the
establishment of candidate biological control agents is critical if
biological control is to transition from a reactionary science to a
predictive one (Kimberling, 2004). There has, justifiably, been a major
focus on predicting the potential for non-target impacts (Barratt, 2011;
Barratt et al., 2010), leading to extensive modeling of the potential
extent of a candidate's introduced range based upon its native host's
range (Barton, 2004; Kaser \& Heimpel, 2015; Raghu et al., 2007).
Increasingly, studies are conducting pre-release ecological niche
modeling to identify geographic regions from which candidate biological
control agents might be selected (for some examples see Banerjee et al.,
2019; Manrique et al., 2014; Mukherjee et al., 2011; Zalucki \& van
Klinken, 2006). These types of pre-release comparisons can even help
prioritize the suitability of different strains of biological control
agents (Manrique et al., 2014), thus reducing both the environmental and
political risks of introducing ineffective agents (McClay \& Balciunas,
2005). Of course, these types of models are only estimates and make
numerous assumptions to quantify and reduce complex biological and
ecological processes. For example, models that integrate biological
knowledge in addition to climatic variables produce more accurate models
than those based on climate data alone (Low et al., 2020). In addition,
the choice of climate variables can have important implications on
results (see Booth, 2021). Furthermore, climate variables have been
found to be more closely associated with some species compared to
others, even when the species have overlapping distributions (Shabani et
al., 2016). Most importantly, these approaches fail to account for the
evolutionary potential of species (e.g., Bean et al., 2012, Diamond,
2018). Yet, despite these limitations, ecological niche models can prove
useful as part of a larger discussion of factors that might influence
species distributions (Warren, 2012). Here we find that of the three
strains of the biological control agent \emph{Aphalara itadori}currently
being considered or currently being released for the biological control
of invasive knotweed species (\emph{Reynoutria}spp.), only the Hokkaido
strain is predicted to be suitable in both Europe and North America
based on climate comparisons between the current distributions of
knotweed species in these two regions and the source localities. The
suitability of the other two strains differs by location and target
species and are discussed in more detail below.

In our analyses and the analyses published in Andersen and Elkinton
(2022), the Kyushu strain is found to have no-to-low climate suitability
for any of the target knotweed species in either Europe or North America
(Figure 4 and 5; Andersen \& Elkinton 2022). The lack of climate
suitability of the Kysuhu strain mirrors field observations in North
America, where to date, efforts to establish the Kyushu strain have been
hindered by both biotic and abiotic factors (Andersen \& Elkinton, 2022;
Grevstad et al., 2022; Jones et al., 2021; Jones et al., 2020). In
contrast, our analyses of the Murakami strain shows that this agent has
greater potential, particularly in North America. Analyses, based on the
distributions of all three species of knotweed in North America, suggest
that the Murakami strain has medium-to-high climate suitability in this
region (Figures 4 and 5). In addition, laboratory testing has shown that
this strain is capable of laying eggs on all three target species in a
choice experiment, and that feeding results in significant reductions
for all three species in plant height (8\% total reduction), and rhizome
biomass for \emph{R.} x \emph{bohemica} , and \emph{R.
sachalinensis}(35\% and 50\%, respectively) (Camargo et al., 2022).
Unfortunately, our climate analyses suggest that this strain has
no-to-low suitability based on the distributions of all three target
species in Europe (Figures 1-3). Analyses based on records of the
Hokkaido strain suggest that this agent has at least some climate
suitability based on knotweed records from both Europe and North
America. We should note that this strain has been shown in the
laboratory to have reduced fitness on species of knotweed other than
\emph{R. sachalinensis} (Grevstad et al., 2013); however, it is possible
that additional populations feeding on the other target knotweed species
might be present on Hokkaido as well, and we encourage further
investigations in this region.

In an effort to create datasets with large enough geographic
distributions to be statistically meaningful, these continental-wide
analyses might mask more localized locations where climate suitability
of the different strains might be achieved. For example, despite our
previous findings that the Kyushu strain has no-to-low climate
suitability for most of North America against \emph{R.
japonica}(Andersen \& Elkinton, 2022), in the spring of 2022 we did note
the presence of 15 overwintering adults at one field release site in
western Massachusetts (Andersen \& Elkinton, unpublished data). Similar
reports of small numbers of overwintering adults of the Kyushu strain
were also reported in coastal Rhode Island (Dr. Lisa Tewksbury, personal
communication) and in North Carolina (Dr. Fritzi Grevstad, personal
communication), and individuals of the Murakami strain have been
observed persisting and dispersing in the field in the Netherlands (Dr.
Suzanne Lommen, personal communication), despite our results suggesting
they have no or low climate suitability. While records from several more
years will be necessary before we can consider these localized
populations ``established'', they do suggest that even in areas where
suitability might be predicted to be low based on our analyses, that
persistence and eventually establishment might be possible.

Lastly, we would like to point out an interesting result from our
analyses. Our climate models, based on the invasive distributions of
each knotweed species, tend to predict low-climate suitability to areas
across much of the Japanese archipelago. On one hand, readers should
interpret this result as an indication that our ecological niche models
are capturing only a portion of the factors that shape the potential and
realized niches of an organism (as reviewed above). On the other hand,
we believe this result highlights the fact that local adaptation has
occurred in this system. Invasive knotweeds have been present in North
America and Europe for nearly 200 years (Conolly 1977), and that during
that time they have successfully adapted to the local environments in
their introduced ranges -- this evolutionary potential is likely one of
the reasons that they are listed amongst worlds 100 most invasive
species (IUCN 2021). Given that coevolutionary forces form the basis of
sustainable biological control services (Holt \& Hochberg 1997), this
potential mismatch between the newly evolved realized niche of an
invasive species and the existing potential niche of the natural enemy
in its native range, such as \emph{A. itadori} , could have profound
implications on the ``success'' of a biological control program if the
target and the natural enemy no longer share the same climatic
constraints.

\textbf{Acknowledgements:}

The authors would like to thank Jennifer Chandler, Ryan Crandall, Rodger
Gwiazdowski, Michelle Labbe, Artemis Roehrig, Dr. Eric Moise, and two
anonymous reviewers for their comments and edits to an earlier version
of this manuscript. This research was funded by a United States
Department of Agriculture Animal and Plant Health Inspection Service
(USDA-APHIS) co-operative agreement (USDA-APHIS-10025-PPQFO000-20-0091)
awarded to J.S.E.

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\textbf{Tables and Figures:}

\textbf{Table 1:} The relative importance of each BioClim climate
variable as predicted by Jack-Knife analyses in MaxEnt for Japanese
(\emph{R. japonica} ), Bohemian (\emph{R.} × \emph{bohemica} ), and
Giant (\emph{R. sachalinensis} ) knotweeds. Variables contributing \selectlanguage{english}[?] 10
to each climate suitability envelope are highlighted.\selectlanguage{english}
\begin{longtable}[]{@{}lllllll@{}}
\toprule
& Europe & Europe & Europe & North America & North America & North
America\tabularnewline
\midrule
\endhead
Variable & Japanese & Bohemian & Giant & Japanese* & Bohemian &
Giant\tabularnewline
Bio1 -- Annual Mean Temperature & 8.6 & 13.8 & 5.9 & 21.2 & 33.3 &
29.7\tabularnewline
Bio2 -- Mean Diurnal Range & 13.7 & 9.8 & 7.6 & 1.3 & 0.4 &
0.4\tabularnewline
Bio3 - Isothermality & 8.3 & 6.8 & 6.7 & 2.2 & 0.2 & 0.2\tabularnewline
Bio4 -- Temperature Seasonality & 0.1 & 2 & 0.2 & 1 & 6.7 &
0.7\tabularnewline
Bio5 -- Max Temperature of Warmest Month & 6.4 & 1.2 & 11.5 & 0.7 & 0 &
0.1\tabularnewline
Bio6 -- Min Temperature of Coldest Month & 15.2 & 11 & 13.5 & 0.7 & 0.9
& 1.1\tabularnewline
Bio7 -- Temperature Annual Range & 1.3 & 0.7 & 2.1 & 6.2 & 2 &
1.6\tabularnewline
Bio8 -- Mean Temperature of Wettest Quarter & 10 & 1.2 & 2 & 0.2 & 0.4 &
0.5\tabularnewline
Bio9 -- Mean Temperature of Driest Quarter & 0.6 & 1.9 & 0.3 & 1.5 & 0.7
& 1.2\tabularnewline
Bio10 -- Mean Temperature of Warmest Quarter & 0.5 & 10 & 7.1 & 1.8 & 3
& 9.1\tabularnewline
Bio11 -- Mean Temperature of the Coldest Quarter & 1.3 & 2.9 & 4.1 &
16.8 & 8.7 & 6.3\tabularnewline
Bio12 -- Annual Precipitation & 0.8 & 0 & 0.2 & 23.8 & 9.5 &
12\tabularnewline
Bio13 -- Precipitation of Wettest Month & 0.3 & 0 & 0.2 & 0 & 0 &
0.2\tabularnewline
Bio14 -- Precipitation of Driest Month & 12.9 & 17 & 28.9 & 0.1 & 0.4 &
0.2\tabularnewline
Bio15- Precipitation Seasonality & 3.5 & 6 & 9.5 & 2.6 & 0.5 &
0.8\tabularnewline
Bio16 -- Precipitation of Wettest Quarter & 0 & 1 & 0 & 1.5 & 0.4 &
0.8\tabularnewline
Bio17 -- Precipitation of Driest Quarter & 15.9 & 13.7 & 0.1 & 6.1 & 5.2
& 0.3\tabularnewline
Bio18 -- Precipitation of the Warmest Quarter & 0.3 & 0.7 & 0.1 & 1.8 &
3.7 & 2.6\tabularnewline
Bio19 -- Precipitation of the Coldest Quarter & 0.1 & 0.3 & 0.1 & 10.7 &
23.9 & 32.4\tabularnewline
\bottomrule
\end{longtable}

* Results for Japanese knotweed in North America are reprinted from
Andersen and Elkinton (2022) with permission.

\textbf{Table 2:} Climate suitability of candidate strains for each
target species as determined by the presence or absence of suitable
habitat in the geographical vicinity of the source locality for each
candidate strain of \emph{A. itadori} against each target species of
knotweed (Japanese = \emph{R. japonica} , Bohemian = \emph{R.}
\selectlanguage{ngerman}×\emph{bohemica} , and Giant = \emph{R. sachalinensis} ).\selectlanguage{english}
\begin{longtable}[]{@{}llll@{}}
\toprule
& Kyushu & Murakami & Hokkaido\tabularnewline
\midrule
\endhead
Europe & Europe & Europe & Europe\tabularnewline
Japanese knotweed & No Suitability & No/Low Suitability & Low/Medium
Suitability\tabularnewline
Bohemian knotweed & No Suitability & No Suitability & Low/Medium
Suitability\tabularnewline
Giant knotweed & No Suitability & No Suitability & Low/Medium
Suitability\tabularnewline
All North American Records & All North American Records & All North
American Records & All North American Records\tabularnewline
Japanese knotweed* & No Suitability* & High Suitability* & Medium/High
Suitability*\tabularnewline
Bohemian knotweed & No/Low Suitability & Medium/High Suitability &
Low/Medium Suitability\tabularnewline
Giant knotweed & No Suitability & Medium/High Suitability & Medium/High
Suitability\tabularnewline
\bottomrule
\end{longtable}

* Results for Japanese knotweed in North America are summarized from the
analyses presented in Andersen and Elkinton (2022).

\textbf{Figure Captions:}

\textbf{Figure 1.} Climate suitability analysis results based on
publicly available records of Japanese knotweed (\emph{R. japonica} )
from Europe in the GBIF database as estimated in MaxEnt. Orange circles
represent the localities of samples used to construct the climate
envelope. Stars represent the source localities of each of the strains
of \emph{A. itadori} released, or under review for knotweed biological
control.

\textbf{Figure 2.} Climate suitability analysis as per Figure 1 based on
publicly available records of Bohemian knotweed (\emph{R.}
\selectlanguage{ngerman}×\emph{bohemica} ) from Europe.

\textbf{Figure 3.} Climate suitability analysis as per Figure 1 based on
publicly available records of Giant knotweed (\emph{R. sachalinensis} )
from Europe.

\textbf{Figure 4.} Climate suitability analysis as per Figure 1 based on
publicly available records of Bohemian knotweed (\emph{R.}
×\emph{bohemica} ) from North America.

\textbf{Figure 5.} Climate suitability analysis as per Figure 1 based on
publicly available records of Giant knotweed (\emph{R. sachalinensis} )
from North America.

\selectlanguage{english}
\FloatBarrier
\end{document}

