Journal of Pest Science (2018) 91:523–538
Considering biology when inferring range‑limiting stress mechanisms
for agricultural pests: a case study of the beet armyworm
· Darren J. Kriticos
· Natalia Kirichenko
· Noboru Ota
Received: 26 October 2016 / Revised: 10 August 2017 / Accepted: 20 November 2017 / Published online: 17 January 2018
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
Reliable niche models are a cornerstone of pest risk analyses, informing biosecurity policies and the management of biologi-
cal invasions. Because species can invade and establish in areas with climates that are diﬀerent from those that are found in
their native range, it is important to accurately capture the range-limiting mechanisms in models that project climate suitabil-
ity. We examined a published niche model for the beet armyworm, Spodoptera exigua, to assess its suitability for bioeconomic
analyses of its pest threat, and identiﬁed issues with the model that rendered it unreliable for this purpose. Consequently, we
reﬁtted the CLIMEX model, paying close attention to the biology underpinning the stress mechanisms. This highlighted the
necessity of carefully considering how the diﬀerent stress mechanisms operate, and to select mechanisms which align with
knowledge on the species’ biology. We also identiﬁed the important role of irrigation in modifying habitat suitability. The
reﬁtted model accords with both distribution data and our understanding of the biology of this species, including its seasonal
range dynamics. The new model identiﬁes establishment risks to South America, Africa, the Middle East and Asia, and
highlights that under current climate, Europe is only climatically suitable during warm seasons when crops are available.
The modelling exercise reinforced the importance of understanding the meaning of a location record (e.g. persistent versus
ephemeral populations) and of carefully exploring the role of habitat-modifying factors, such as irrigation, in allowing spe-
cies to persist in otherwise inclement localities.
Keywords Bioclimatic modelling · CLIMEX · Niche modelling · Pest risk · Spodoptera exigua
We reﬁt the existing CLIMEX model of this species by
explicitly considering how diﬀerent stress mechanisms
work to restrict range distribution.
Robust niche models demand the simultaneous consid-
eration of species’ distributions and their biology in rela-
tion to climatic range-limiting factors.
The new model emphasizes the critical role of irrigation
in extending the potential range of Spodoptera exigua
into xeric environments, and the role of migration in
extending the threat into seasonally suitable habitats.
The potential distribution and biosecurity risk of this pest
extend signiﬁcantly beyond its current distribution.
Communicated by B. Lavandero.
Electronic supplementary material The online version of this
article (http s://doi.org/10.1007 /s103 40-017-0938 -9) contains
supplementary material, which is available to authorized users.
* Tania Yonow
* Darren J. Kriticos
HarvestChoice, InSTePP, University of Minnesota, St. Paul,
MN 55108, USA
CSIRO, GPO Box 1700, Canberra, ACT 2600, Australia
Forest Zoology Department, Siberian Branch of the Russian
Academy of Sciences, Sukachev Institute of Forest,
Akademgorodok 50/28, Krasnoyarsk, Russia 660036
Siberian Federal University, 79 Svobodny Pr., Krasnoyarsk,
CSIRO, Private Bag 5, Wembley, WA 6913, Australia