2. Material and methods

#### 2.1. Climate change model selection

In order to select the climate model, out of the 16 models presented on the Climate Change Knowledge Portal created by the World Bank (http://sdwebx.worldbank.org/climateportal/), we used the Taylor diagram technique. This diagram enables to assess how closely a pattern matches observations on the basis of three measures of model quality presented on one chart. These measures are: the correlation (R), the centered rootmean-square-error (RMSE) and the amplitude of the standard deviations (Std) [24]. We compared monthly temperature registered at 16 localities in the period 1986–2005 and the temperatures generated for this period and these locations by the climate models.

#### 2.2. Meteorological data

Korea, Japan, certain areas of the Indian subcontinent, parts of North Africa and the temperate Southern Hemisphere. In Poland, the Colorado potato beetle appeared in 1944 [8]. In 1950, the first great invasion of this species was noticed [9]. Despite the systematic reduction of potato land, the Colorado potato beetle is still a major pest affecting potato crops in Poland [10–12]. Yield losses caused by the feeding of the pest, in the absence of chemical protection, are estimated at 35–40% [13], and in extreme cases, losses can reach 70% of yield [14]. Potato crop losses caused by the Colorado potato beetle are highly dependent on the growth rate of the pest population, which is heavily dependent on meteorological conditions, among which temperature plays a leading role. According to the data from a number of studies, temperature is also the main environmental factor which determines the number of pest generations. The close connection between these two factors indicates the opportunity of using mathematical models expressing relationships between temperature and the rate of Colorado potato beetle development for predicting the influence of climate change on the number of pest generations. This has already been studied in Poland [15], but only for the Wielkopolska region and without considering new emission scenarios termed representative concentration pathways (RCPs) recommended by the international climate modeling community through the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) to be

RCP2.6, RCP4.5, RCP6 and RCP8.5 are four pathways named according to their 2100 radiative forcing level expressed in Watts per meter square. RCP2.6 is a "peak-and-decline" scenario. By mid-century, its radiative forcing level reaches a value of around 3.1 W/m<sup>2</sup> and then decreases to 2.6 W/m<sup>2</sup> by 2100 [17]. RCP4.5 [18–20] and RCP6.0 [21, 22] are stabilization scenarios in which total radiative forcing is stabilized shortly after 2100, following the reduction of greenhouse gas emissions. RCP8.5 is characterized by increasing greenhouse gas emissions over time. This is a representation of scenarios in the literature that lead to high greenhouse gas

The aim of this study was to determine the impact of climate change on the development of the Colorado potato beetle and to identify the region most at risk of increase in the number of pest

In order to select the climate model, out of the 16 models presented on the Climate Change Knowledge Portal created by the World Bank (http://sdwebx.worldbank.org/climateportal/), we used the Taylor diagram technique. This diagram enables to assess how closely a pattern matches observations on the basis of three measures of model quality presented on one chart. These measures are: the correlation (R), the centered rootmean-square-error (RMSE) and the amplitude of the standard deviations (Std) [24]. We compared monthly temperature registered at 16 localities in the period 1986–2005 and the temperatures generated for this period and

used in climate modeling and research [16].

concentration levels [23].

64 Potato - From Incas to All Over the World

2. Material and methods

2.1. Climate change model selection

these locations by the climate models.

generations.

Two kinds of meteorological data were used in the study: first, data were registered in the years 1986–2005 at 16 localities representing the 16 regions of Poland; and second, data obtained after transformation of the recorded data to reflect temperature changes under RCP2.6, RCP4.5, RCP6.0 and RCP8.5 scenarios according to the giss\_e2\_r climate model. Latitudes and longitudes of the analyzed localities are presented in Table 1.

#### 2.3. Simulation of the impact of climate change on Colorado potato beetle development

The study was performed using the NumoGen 2 model, which was developed for the present study based on the earlier version called NumoGen 1 [15]. The main difference between these two models is that NumoGen 2 enables the calculation of differences in the dates of egg laying between regions and years, while NumoGen 1 was only able to consider the changes in temperature triggered by climate changes. But, for all these purposes, the same equation were used, presented by Wójtowicz et al. in [15], describing the relationship between the onset of the egg-laying period and temperature increase.

From experiments conducted in the Wielkopolska region at WinnaGóra in the years 2003–2005 when Colorado potato beetle egg laying was noticed in the first decade of June, it was decided to perform simulations of the pest development with the use of meteorological data collected in Poznan in 2005 starting from 27 May to 15 June. This covers the period from 5 days before the start to 5 days after the first decade of June. The start of simulations performed with the use of data collected in Poznań in 1986–2004, as well as those registered at the other 15 localities in the period 1986–2005 and virtual data generated by the giss\_e2\_r model were obtained with


Table 1. Latitude and longitude of localities analyzed in the study.

the use of an equation describing the relationship between onset of the egg-laying period and temperature increase [15].

NumoGen 2 simulates the development of colorado Potato Beetle from the occurrence of egg clusters until meteorological conditions or photoperiods prevent further development of the pest. The model was developed from information presented in scientific reports. The development of the pest from egg to adult was based on information presented by Łarczenko [25]. The dates of egg laying by female beetles of succeeding generations were estimated according to data presented by Alyokhin and Ferro [26]. The beginning of the winter diapause was determined from data reported by Tauber et al. [27], who found that all females reared at a photoperiod between 10:14 and 14:10 (L:D) entered diapause. This information was used to determine the dates of diapause based on day length at the 16 localities analyzed in the study. Information about day length was found on the internet at: http://www.timebie.com/sun/.

For each locality, 20 simulations were performed. Each simulation generated information about CPB development based on meteorological data registered in the 20 years, 1986–2005, and data obtained after transformation of the recorded data to reflect temperature changes under four scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) and four periods (2020–2039, 2040–2059, 2060–2079 and 2080–2099) according to the giss\_e2\_r climate model.

Additionally for each locality, a model was developed to estimate the minimum temperature increase, in relation to 1986–2005, that ensured the emergence of the second generation of CPB.

The models were developed based on meteorological data (registered and obtained after transformation of the recorded data to reflect the temperature changes under four RCP scenarios) and simulation results describing the probability of the occurrence of CPB second generation. The models were developed with the use of the exponential function:

$$\text{SCCPBP} = \mathbf{a} + \exp\left(\mathbf{b} + \mathbf{c} \times \mathbf{T}\right) \tag{1}$$

worst conditions were noted in the northern and north-eastern parts of Poland (Table 3). Out of the four RCP scenarios, three (RCP4.5, RCP6.0 and RCP8.5) generated the greatest acceleration of egg laying in the period 2080–2099. But, according to the RCP2.6 scenario, the earliest egg laying is expected in the period 2020–2039 (Table 2). Comparison of meteorological data registered in 1986–2005 revealed that the differences between the earliest and the latest day of

Figure 1. Taylor diagram illustrating the statistics of the comparison between observed and 16 model estimates of air temperature at 16 localities in 1986–2005. Bcc\_csm1\_1, bcc\_csm1\_1\_m, ccsm4, cesm1\_cam5, csiro\_mk3\_6\_0, fio\_esm, gfdl\_cm3, gfdl\_esm2m, giss\_e2\_h, giss\_e2\_r, ipsl\_cm5a\_mr, miroc\_esm, miroc\_esm\_chem, miroc5, mri\_cgcm3, noresm1\_m:

Simulations of Colorado Potato Beetle Development in Poland Based on Four Climate Change Scenarios

http://dx.doi.org/10.5772/intechopen.70777

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Simulations performed on real data, except for Białystok (95.8%), Gdańsk (85%) and Olsztyn (99.3%), as well as on transformed data showed a 100% probability of the appearance of the first generation of CPB (Figure 3). Simulations performed on real data revealed that the average number of days needed for the development of the first generation of CPB was 56. Use of transformed data resulted in a shortening of the first generation development of the

egg laying ranges from 12 at Białystok to 16 at Opole (Table 3).

Model names used in the study.

where SGCPBP is the probability of the occurrence of CPB second generation; T the temperature increase for the temperature registered in 1986–2005; a, b and c are the equation coefficients.
