Predicting the Development of Critical Biological Stages of Sunn Pest, Eurygaster Integriceps Put

Turkish Journal of Agriculture and Forestry Turk J Agric For (2016) 40: 577-582 http://journals.tubitak.gov.tr/agriculture/ © TÜBİTAK Research Article doi:10.3906/tar-1511-64 Predicting the development of critical biological stages of Sunn pest, Eurygaster integriceps Put. (Hemiptera: Scutelleridae), by using sum of degree-days for timing its chemical control in wheat* 1, 2 3 Celalettin GÖZÜAÇIK **, Abdurrahman YİĞİT , Ziya ŞİMŞEK 1 Department of Plant Protection, Faculty of Agriculture, Iğdır University, Iğdır, Turkey 2 Department of Plant Protection, Faculty of Agriculture, Mustafa Kemal University, Hatay, Turkey 3 Department of Forest Engineering, Faculty of Forestry, Çankırı Karatekin University, Çankırı, Turkey Received: 14.11.2015 Accepted/Published Online: 23.03.2016 Final Version: 14.06.2016 Abstract: This investigation was carried out for possible use of sum of degree-days (total effective temperatures) in order to predict the critical biological stages in chemical control of Sunn pest, Eurygaster integriceps Put. (Hemiptera: Scutelleridae), in 28 wheat fields of Adıyaman, Diyarbakır, and Şanlıurfa provinces from 2007 to 2010, and in climate chamber conditions. Development threshold temperature (°C) of Sunn pest in terms of the life span, starting from egg to new generation of adults, was found as 13.30 °C. Sums of degree-days starting from 1 January to appearance of the eggs, first-stage nymphs (n1), second-stage nymphs (n2), and fourth-stage nymphs (n4) were found with the averages of 44.6, 84.4, 123.3, and 223.1 degree-days, respectively. The results from the field studies reflected that developmental biological data on sum of degree-days as a predictive tool could be useful in better decision making to start chemical applications as soon as the appearance of n1 until n4 for Sunn pest control. Key words: Sunn pest, Eurygaster integriceps Put., development threshold, sum of degree-days 1. Introduction Eurygaster integriceps has a univoltine life cycle, with Sunn pest, Eurygaster integriceps Put. (Hemiptera: diapause occurring at the adult stage. The life cycle develops Scutelleridae), is one of the most harmful insect pests of in two biotopes. Growth and development take place in wheat and barley from West Asia (Near and Middle East), wheat, whereas diapause (estivation and hibernation) including many of the newly independent states of Central occurs in a different habitat, such as oak-forest litter in Asia, to East and South Europe and North Africa as well as Europe or in bushes of Artemisia spp., Acantholimon spp., in Turkey (Lodos, 1961; Schuh and Slater, 1995; Javahery or Astragalus spp. in the mountains of Asia. The insects et al., 2000; Kazzazi et al., 2005). migrate to the wheat fields in the spring and the diapause Severe crop losses in quality and quantity occur when sites in the summer (Paulian and Popov, 1980; Lodos, control measures for the pest are ignored, especially 1982; Koçak and Babaroğlu, 2005). in wheat production. Yield loss has been expected at Control attempts of Sunn pest were performed by 50%–90% in wheat and 20%–30% in barley. Sunn pest physical, chemical, and biological methods from 1927 to sometimes causes a low yield in large wheat production areas. Especially the nymph stages, as well as the adults of 1954, but integrated pest management (IPM) practices Sunn pest, damage these crops by sucking on leaves, stems, have been gradually applied since 1955 in Turkey. and grains. During feeding, they also inject enzymes that In Turkey, wide areas where Sunn pest was controlled degrade gluten proteins, and thus the baking quality of by agrochemical pesticides have different topographical flour made from damaged wheat is greatly reduced (Rajabi, and ecological features. Pesticide applications must be 2000). If 2%–3% of the grain is damaged, entire lots may timed precisely to improve efficiency of pest control be ruined because the flour will be unpalatable and bread because of the fact that an accurate prediction of insect will not rise. development is essential for effective pest management. * Presented at the 4th Plant Protection Congress of Turkey, 28–30 June 2011, Kahramanmaraş, as a poster presentation. ** Correspondence: [email protected] 577 GÖZÜAÇIK et al. / Turk J Agric For Therefore, based on the pest’s biology, starting dates of (°C) and thermal constant (Th. C.) values of each biological pesticide applications vary based on years and locations. stage (eggs, nymph stages, and new-generation adults Improperly timed applications result in not only (NGAs)) in climate chambers were studied. insufficient levels in efficacy but also cause decreases in For this purpose, Sunn pest cultures were set up in populations of natural enemies. Insects emerge earlier plastic boxes (29 × 21 × 21 cm), the top surface of which generally in warm years or localities than in cool ones. was covered with cheese-cloth and kept at 25 and 30 ± Since insect development is dependent on temperature, 1 °C and 65 ± 5% relative humidity with illumination of monitoring degree-days accumulation is a valuable tool 1500 lx for 16 h of light per day in climate chambers. The for predicting pest activity (Herms, 2004). Thus, the culture was started with 10 overwintered adults (5 ♀, 5 monitoring system can be more accurate compared to the ♂) per box, which were collected on 23 March 2011 from calendar method for estimating insect development and Karacadağ Mountain, Diyarbakır. The experiment was timing management strategies. set up with 10 replications and initiated with 10 fresh egg Thermal constant (Th. C.), sum of degree-days (total masses. Duration of egg and nymph stages of Sunn pest effective temperatures), and lower development threshold were observed and recorded twice a day from eggs to values are more convenient for predicting development NGAs. Wheat plants were given as food to both adults and time of insect populations over a range of biologically nymphs. The plants were renewed when necessary. The significant temperatures. The right decision on the development threshold (°C) and thermal constant (Th. usability of control measures will be dependent upon C.) of Sunn pest were calculated according to the equation factors like the level of damage or the life stage of the given below (Sanderson and Peairs 1913): insect, because the wheat kernel is especially susceptible Th. C. = t (T – C), to the early nymph stages’ (n1–3) damage. Treatment, if where Th. C. is the species (or stage-specific) thermal decided upon, would be timed to correspond with some constant of a poikilothermic organism, which is expressed point within the sum of the degree-days range. Therefore, as the number of degree-days (in °C) and provides an predicting the appearance of the eggs and the early nymph alternative measure of the physiological time required for stages, which are critical biological stages of Sunn pest, the completion of a process or a particular developmental is inevitable for successful chemical control in different event; t is development duration (days); T is temperature wheat areas where surveys need to be carried out by “Sunn (°C); and C is developmental threshold or baseline (°C), pest teams” in millions of acres within a limited period. All the minimum temperature at which insects first start these activities are time-consuming and costly. to develop. The base temperature is that which below Developmental characteristics of E. integriceps have not the insect does not develop (also called “threshold been documented in detail on wheat with the exception of temperature”). The growth rate of the insect increases with the studies of Ionescu and Mustatea (1973), Şimşek and temperature above the developmental threshold. Growth Yılmaz (1992), and Kıvan (2008). Hence, this study was and development are closely related to daily temperature carried out during the years 2007–2010 in order to solve mean accumulations above the developmental threshold. the problem mentioned above by predicting the proper The thermal constant (Th. C.) provides a measure of time for chemical control of Sunn pest, regarding the the physiological time required for the completion of development of critical biological stages of the pest by using a developmental process and is measured in degree- sum of degree-days in wheat growing areas of Adıyaman, days (Önder, 2004; Damos and Savopoulou-Soultani, Diyarbakır, and Şanlıurfa provinces in Southeastern 2012; Kansu, 2012). By using the relationship between Anatolia, where the largest Sunn pest chemical control temperature and rate of development, when insects will application area of Turkey is located. pass through certain stages can be predicted. This method of estimating time is called the degree-day method. A 2. Materials and methods degree-days is the same as an average of one degree over The study was conducted both in insecticide-free wheat the threshold temperature for a 24-h period. The ability of fields in Adıyaman, Diyarbakır, and Şanlıurfa provinces of these models to predict insect development depends partly the Southeastern Anatolia region of Turkey during 2007– on the accuracy of the data used in determining degree- 2010 and in laboratory conditions. days (Bessin, 2016). The degree-days were calculated Predicting the proper application time for chemical using the simple formula given below for the average control of Sunn pest regarding the development of n1 to n4, daily temperature, calculated from the daily maximum which are critical biological stages of the pest, by using sum and minimum temperatures, minus the developmental of degree-days in the field and the development thresholds threshold (Herms, 2004; Murray, 2008). 578 GÖZÜAÇIK et al. / Turk J Agric For Appearances of the first eggs, the early stage nymphs, When the findings were evaluated together, it was and the NGAs of Sunn pest were surveyed and detected understood that the Sunn pest began to lay eggs by the once a week in 28 wheat fields in Adıyaman, Diyarbakır, first half of April and continued until the first week of May, and Şanlıurfa provinces.

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