Analyzing climate impacts on insect pests using 
phenology modeling and geographic information system 
implemented in the 
Insect Life Cycle Modeling (ILCYM) software Tropentag 2013
The Challenge The pest damage potential of the potato tuber moth may ISTRC
“Agricultural 
Climate change will precariously affect agricultural production and progressively increase in all regions where the pest prevails deSvelyopmmepnt owisthinu thme 
the livelihood of farmers in developing countries by unpredictably today with an excessive increase in warmer cropping regions of
changing the abundance of insect pests. On average, 30 to 50% of rural-urban continuum”
the tropics and subtropics (Fig. 3).
the yield losses in agricultural crops are caused by pests despite the Economic damage starts to occur when >4 generations
application of pesticides to control them. Climate, especially September 17 - 19, 2013,
develop/year. Today, >4 generations are developed on 30.2%
temperature, has a strong and direct influence on insect develop- (5.9 million ha) of the total potato production area worldwide; Stuttgart-Hohenheim
ment and is considered under climate change the dominant abiotic this can potentially increase to 42% (8.3 million ha).
factor directly affecting herbivorous insects. Early predictions of pest Jürgen Kroschel1
risks could help to adapt to climate change by developing and North America: Europe: Asia:
supporting farmers with adequate pest management strategies. 15.87% (280,180 ha) 10.14% (1,115,432 ha) 15.29% (5,246,319 ha) Henri E. Z. Tonnang1,2
Henry Juarez1
Our Approach B. Le Ru2
The International Potato Center (CIP) developed the Insect Life R. Hanna3
Cycle Modeling (ILCYM) software as an open-source computer tool South America:
which supports the development of pest phenology models and to 13.11% (530,116 ha) 1Agroecology/IPM
map and quantify changes on global and regional scales under Integrated Crop and Systems 
current and future climates. Research Program, 
Africa: Oceania: International Potato Center, 
ILCYM Modeling Concept 2.87% (1,113,966 ha) 26.05% (42,465 ha) P.O. Box 1558, Lima 12, Peru
Insects require a certain amount of heat to develop from one j.kroschel@cgiar.org
Figure 3. Change in the abundance (damage potential) (%, ha) of the potato tuber
developmental stage to another in their life-cycle. Besides moth, Phthorimaea operculella, in potato production systems worldwide according
development, other processes that determine an insect species’ life to model predictions, using the generation index for the years 2000 and 2050 and 2icipe, Nairobi, Kenya
history, such as survival and reproduction, are also strongly the absolute generation index change. 3IITA, Ibadan, Nigeria
influenced by temperature. The relationship between insect
development and temperature is best described by process-based (B) The case of the spotted stem borer
phenology models. The conceptual framework of ILCYM is based The spotted stemborer, Chilo partellus (Lepidoptera: Crambidae)
on the application of temperature-dependent nonlinear relationships is an invasive cereal pest with origin in India (Fig. 4).
for representing all insect life cycle processes. It has three main
modules: the model builder, the validation and simulation module, F. igure 4. The spotted stemborer, 
and the potential population distribution and risk mapping module. Chilo partellus, causes damage 
on maize and sorghum leaves 
Life table parameters and stems; its center of origin is 
ILCYM calculates: the net reproduction rate R India, but today the pest  occurs 
0(♀/♀), mean
generation time T (days), intrinsic rate of increase rm; finite rate in most lowland areas in East and  
Southeastern African countries, 
of increase erm and the doubling time Dt = Ln(2)/rm.
Risk indices
From life table parameters, three indices are estimated: The Under future temperature scenarios the spotted stem borer will
establishment risk index (EI), the generation index (GI) and the potentially disappear from most dry lowland areas of East Africa
activity index (AI). and expand into most higher elevated areas in East and
Southeastern African countries (Fig. 5A, B).
Temperature inclusion in the phenology model
Using cosines approximation of temperature, the risk indices can
be mapped under present and projected SRES emission
scenarios (e.g., SRES-A1B) for predicting responses to present
and future climates.
Predictions of global risks 2000 - 2050
(A) The case of the potato tuber moth
The potato tuber moth, Phthorimaea operculella (Lepidoptera: Figure 5. Change in establishment of the spotted stem borer, Chilo partellus, in
Gelechiidae) is an invasive potato pest with origin in South Africa according to model predictions, using the establishment risk index for the
America (Fig. 1). years 2000 and 2050.
FFi
Model predictions indicate a potential increase in the number of
Fgiiguguruerree 11.1.. TThThehee ppopotoattataottoo tuttububebererr mmmootohtth,h,,
PPPhhthhtthohoroirmriimmaaeaeaeaa oopopeperecrrucculuellelelalllla,a,, caccauausuesseses spotted stem borer generations in the year 2050, which indicates
s
ddadamammaagagegee(m((mminiinenese)ss))oononnppopotoattataottoolelleaeavaevvesessaanandndd that higher pest infestations and yield losses may occur (Fig.
tuttububeberesrrss(;A(A)i;t)s;itsitcsceecnententerterorofof fooorriirggigiinninisiissSSSoououtuhtthh 6A, B).
AAAmmmeereircriiacca,a,b, bubututttottododadayayythttheheeppepesetssttoococccuccurusrrssiniinn
mmmooroerreethtthahanann990900coccouoununtnrtitreriiesesswwwoorolrdrlldwdwwidiidedee(B.(B).).
A potential range expansion into temperate regions of the
northern hemisphere as well as in tropical mountainous regions References
is predicted for the potato tuber moth (Fig. 2). Kroschel, J., M. Sporleder, H.E.Z. Tonnang, H.
Juarez, P. Carhuapoma, J.C. Gonzales & R.
Simon (2013): Predicting climate change
Europe: Asia: caused changes in global temperature on
North America: 2.73% (234,404 ha) 8.3% (699,680 ha) potato tuber moth Phthorimaea operculella
4.21% (32,873 ha) (Zeller) distribution and abundance using
Figure 6. Change in the number of generations/year of the spotted stem borer, phenology modeling and GIS mapping.
Chilo partellus, in Africa according to model predictions, using the generation risk Journal of Agricultural and Forest
Meteorology 170: 228-241.
index for the years 2000 and 2050. Sporleder M, H.E.Z. Tonnang, P. Carhuapoma,
J.C. Gonzales, H. Juarez, J. Kroschel (2013):
Insect Life Cycle Modeling (ILCYM) software
– a new tool for regional and global insect risk
South America: Conclusions assessment under current and future climate
11.9% (109,666 ha) • ILCYM is proposed as a very helpful software and tool in pest change scenarios, CABI Publishing; pp 412-
427.
risk assessments and for adaptation planning in integrated pest
management.
Africa: Oceania: • The software supports the analysis of life table data and the Funded by: 
1.01% (11,605 ha) 13.67% (7,314 ha) development of phenology models for a wide range of insect
pests and natural enemies of different orders and families.
Figure 2. Change in establishment and future distribution (%, ha) of the potato • Currently, we investigate climate impacts on 22 pests of
tuber moth, Phthorimaea operculella, in potato production systems worldwide
according to model predictions, using the establishment risk index for the years cassava, maize, potato, sweetpotato, fruits and vegetables
2000 and 2050. Indices of >0.6 are associated with permanent establishment. and 12 related parasitoids used in biological control.
The ILCYM software and manual can be downloaded from www.cipotato.org/ilcym