Population dynamics system of ( integriceps Put.)

BAHRAM TAFAGHODINIA, Iranian Research Organization for Science and Technology #71, Forsat St., Engelab Ave., Theran, . P.O. Box: 15815-3538

MORTEZA ESMAILI Department of Plant Protection, Faculty of Agriculture, University of Tehran, Iran.

GHADIR NOURI-GANBALANI Mohagheg Ardebili University, Ardebil, Iran, P.O. Box: 179

Abstract: - Cereal Sunn pest (E. integriceps) is the most important pest in Iran [6]. Based on horizontal life table method, the population dynamics of this pest was studied. Whereas some life stages of this pest are very small and live in soil cracks and microhabitat, sampling of all life stages are impossible. In this research number of individuals in all life stages were sampled and recorded by some mathematical methods and suppositions. Number of first instar larvae is measured by logical difference of unhatched from 1000 eggs that had been put in field condition. Based on average fecundity, adult density and sex ratio parameters, we supposed that resulted population from 1000 eggs will appear in 6 m2 in wheat field. This continuous recorded data was used to calculate number of life stages based on under-curve area method and was established horizontal life table. Key factor analysis of life table showed the most K-value (mortality index) was related to eggs (0.52) and first nymph (0.58). Survival curve of sunn pest was IV kind and it means most of the mortality is happening at the beginning of life cycle.

Key-Words: - , population dynamics, life table

1 Introduction Life table analysis is one of the best approaches to understand population dynamic system of this pest. The Sunn pest (Eurygaster integriceps Put.) is a very From the basic information contained in the life damaging pest of wheat and in countries table, we are then able to calculate a large number of of West Asia, including , Iran, , interesting statistics that inform us about the life , and , as well as in the Central history of the population. Key factor analysis will Asian republics (, , , find the most important key factor that controls the and ), and and population and then environmentally acceptable IPM [4]. Both nymphs and adults cause damage approaches. The aim of this project involves by feeding on leaves, stems and grains [1]. Yield loss determination of sensitive life stages of sunn pest and is commonly estimated at 20-30% in barley and 50- the factors that suppressing Sunn pest populations. 90% in wheat. Apart from the direct reduction in yield, the also inject chemicals that greatly 2 Materials and Methods reduce the baking quality of the dough. Control of Sunn pest by chemical insecticides is expensive, Whereas some life stages of sunn pest are very small costing over US$ 40 million annually in the countries and live in soil cracks and microhabitat, sampling of concerned, and poses a risk to human health, water all these life stages are impossible. But In this quality and the environment as a whole. The present research individuals number of all life stages were insecticide-based strategies for control of Sunn pest sampled and recorded by some mathematical must be replaced with multi-dimensional integrated methods and suppositions in one m2 units (wooden pest management (IPM) approaches [4]. quadrate). The percent of egg parasitism in field condition was individuals by stage classes and 2) mortality by stage measured by transferring 1000 fresh eggs in active classes. duration of female, into wheat field and recorded number of parasitized eggs daily. The construction of a life table begins by gathering information on survivorship by stage classes [5]. Number of first nymph was measured by logical Fertility and survivorship are put together to form the difference of unhatched (parasitized and other life table for a specific population. (Equations 3-7) factors) from 1000 eggs that had been put in wheat [1]. field (egg trap method). + = l X l ( X +!) (3) Also based on average fecundity, adult density and L X 2 sex ratio parameters, we supposed that resulted population from 1000 eggs will appear in 6 m2 (1). = + + .... (4) T X L X L( X +!) p (1) N = 1000 d × f × r 1000 = d X (5) qX l X

Where N, is number of one m2 units to sampling. p, is the requested population. d, is adult density. f, is = T X (6) average fecundity and r is sex ratio. This continuous eX l X recorded data was used to calculate individual number of life stages based on under-curve area 1000× = 1000 − E p (7) method by equation (2). l2 l1

∑ x = s (2) lx is known as stage-specific survivorship and can be l x thought of as the probability, at birth, of living to a t x specific stage class. Lx is stage-specific survivorship between stage x and x+1. d is the age-specific Where l is individual number of stage x. S is x x x mortality. T is sum of all individual that survive after number of individuals sampled from stage x per day. x stage x in next stages. e is duration that expects t is duration between first and last sampling of stage x individuals survive in stage x. 1000q is mortality x. x speed during stages. It is known as mortality speed of

1000 individual at the beginning of every stage. Developmental time of immature stages in field condition was measured by transferring 10 No matter how the data are gathered, the objective is individuals of all stages into a glass box in wheat to produce a life table based on a theoretical cohort field. of 1000 individuals [8].

Hibernation of Adult is in mountain [3]. To measure The life table is used to construct the survivorship the winter mortality, 100 numbers of adults of sunn curves. In a survivorship curve, stage, as an pest were collected, marked and observed in independent variable, is graphed against mountain habitat weekly. survivorship. The y-axis may be on a straight

arithmetic scale; however, may authors prefer a log We considered 1000 eggs as a cohort of individuals (base 10) scale for survivorship [7]. all born at the same time, and followed the survivorship of these individuals until the last member of the cohort died. In order to predict population growth with distinct 10stage classes, it is necessary to know: 1) the current distribution of

3 Results and conclusion The life table of E. integriceps is showed in table 1. Ten classes were considered to instruction of life The curve for population variations is showed in table. First class (A) is egg stage with 67.7% figure 1. The result showed the first individual of mortality and 0.49 as K value. Second class (B) is second nymph was observed in 18th of May and its first nymph stage that was not sampled, but was highest level in 4th of June. The population of third, calculated based on egg trap method. This class has forth and fifth nymph stages reached to its highest highest mortality (72.8%) with K value equal 0.58. level in 7th, 12th and 21st of June. The first adult of Third until seventh classes (C-G) are second nymph new generation was observed in 19 June and reached until adult of new generation. The second nymph has to its highest level in 1st July. Fast reduction of Adult highest mortality between these classes (52%) with K population after its highest level indicates the value equal 0.22. The eighth class (H) is aestivation immigration to mountains. of adult in mountain with 1.1% mortality.

Table 1 - Life table of E. integriceps A B C D E F G-H I J

400 ∑ sx - - 3070 1709 1391 1182 975 - -

350 tx 11.5 5.5 9.5 11 11.5 14.5 - - -

300 lx 1000 - 323 155 121 82 76 65 61 d 677 - 168 34 39 6 11 4 61 250 x Total 67.7 22.6 16.8 3.4 3.9 0.6 1.1 0.4 6.1 200 mortality density 150 Stage 67.7 72.8 52 21.9 32.2 7.3 14.5 6.2 100 mortality 100

Lx 662 - 239 138 102 79 71 63 31 50 Tx 1385 - 723 484 346 244 165 94 31 0 1.39 - 2.23 3.1 2.85 2.97 2.17 1.45 0.5 1 4 7 10131619222528313437404346495255 ex

days 1000qx 677 - 520 219 322 730 145 620 1000 nymph2 nymph3 nymph4 nymph5 adult sum Log lx 3 - 2.51 2.19 2.08 1.91 1.88 1.81 1.79 Fig 1- stage frequency data of E. integriceps K 0.49 0.58 0.32 0.11 0.17 0.03 0.07 0.02 -

The curve of egg parasitism variations is showed in The ninth class (I) is hibernation of adult in figure.2. The result showed, egg Parasitism started mountain. Mortality of different factor in this class is one day after ovipozition. The egg parasitism showed in table 2. The last class (J) is fertilized adult declined at the end duration of ovipozition with that come back to wheat field. average of 69.4%. Table 2 – Mortality in hibernation

120 Mortality Alive Died percent Log x K factor number number

100 Fly 65 8 12.3 1.76 0.05 Lost 57 3 5.3 1.73 0.03 80 fungi 54 6 11.1 1.69 0.04

60

number ofeggs 40 The survival curve of sunn pest is type IV. This is

20 illustrated most dramatically in Figure 3, using the arithmetic scale for survivorship. This kind of curve 0 1 2 3 4 5 6 7 8 9 1011121314151617181920 applies to the vast majority of biological populations. days In this curve, there is very high morality among the

releazed parazitized juvenile stages while adult survivorship is relatively

Fig 2 – number of released and parasitized eggs of high. E. integriceps 1200 2. E. S. Brown, Researches on the ecology and biology of Eurygaster integriceps Put. (, 1000 ) in the Middle East countries, with

800 special reference to over wintering period, Bull. Entomol. Res. 53: 3-9 (1962) 600 density 3. E. S. Brown, Notes on the migration and direction 400 of flight of Eurgaster and Aelia spices (Hemiptera, 200 Pentatomidae) and their possible bearing on invasions of cereal crops, Ecology, 34: 93- 0 eggs nymph nymph nymph nymph adult 1 adult 2 adult 3 107 (1965) 2 3 4 5 life stages 4. El-Baoushssni, Integrated pest management of Fig 3 – survival curve of E. integriceps sunn pest in Asia. Natural resource institute, (2003)

5. B. F. Manly, Stage-structured population It means juvenile stages are very sensitive and apply (sampling, analysis, simulation), Chapman & Hall, a farmer acceptable and participatory approach to (1990) support of mortality factors of these stages is an IPM method to control sunn pest. 6. G. Rajabi, Pre harvest of wheat for sunn pest control in Iran, Proceeding of sunn pest conference, Tehran University, (1993) References: 7. A. Sherov, Quantitative population ecology, 1. T. S. Bellows, R. G. Vandriesche, and J. S. www.gypsymouth.ento.edu, (1996) Elkinton, Life table analysis construction and analysis in the evaluation of natural enemies, Ann. 8. T. R. E. Southwood, Ecological methods, London Rev. Entomol. 37: 587-614 (1992) Methuen 2 co Ltd, (1966)