J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 Original Research Article Life Table and Survivorship of a Short Horned Grasshopper Exposed to Arsenic Compound under Laboratory Conditions * Susanta Nath and Barnali Roy Post Graduate Department of Zoology Bidhannagar College (Govt. of West Bengal) EB-2, Sector- 1, Salt Lake, Kolkata-700 064, INDIA Received: 13.02.2015; Accepted: 21.07.2015; Published Online: 30.11.2015 ABSTRACT Spathosternum prasiniferum prasiniferum (Walker, 1871), a common short horned grasshopper considered as pest of paddy, mungbean, urd bean, chick bean in India. They were acclimatized in bisexual pairs under laboratory conditions and exposed to various doses of sodium arsenate such as 0.0125mg.l-1, 0.025 mg.l-1, 0.050 mg.l-1, 0.10 mg.l-1, 0.20 mg.l-1 with the aim to find out survivorship, mortality and life expectancy. Sodium arsenate created the variation in their life cycle as well as life span of the insect compared to the control. A convex shaped survivorship curve of both male and female revealed a high mortality in older adult. A sizeable increment in the number of individual presented in the biplot of both male and female grasshopper advocated its ability to use the arsenic efficiently. After slight depression in 0.025 mg.l-1, rapid recoveries signify the insect ability to overcome the initial stress situation and successfully maintained the life cycle with the advancement of doses. Keywords: Grasshopper, Sodium arsenate, Life table, Survivorship curve, Stress, Life expentancy Arseniğe Maruz Bırakılan Çekirgelerin Laboratuvar Şartlarındaki Hayat Tablosu ve Hayatta Kalma Becerileri ÖZ Kısa antenli çekirge Spathosternum prasiniferum prasiniferum (Walker, 1871) Hindistan’da çeltik, maş fasulyesi, siyah mercimek ve nohutun önemli bir zararlısı olarak tanımlanmaktadır. Bireyler laboratuvar şartlarına adapte edildikten sonra değişik dozlarda sodyum arsenata (0.0125mg.l-1, 0.025 mg.l-1, 0.050 mg.l-1, 0.10 mg.l-1, 0.20 mg.l-1) maruz bırakılmış ve bunun sonucunda hayatta kalma becerileri, ölüm oranları ve ortalama yaşam süresi üzerindeki etkileri incelenmiştir. Kontrole göre karşılaştırıldığında sodyum arsenat bireylerin yaşam döngülerinde ve yaşam sürelerinde varyasyonlara neden olmuştur. Erkek ve dişi bireylerde görülen konveks şekilli yaşam eğrisi, yaşlı bireylerde yüksek ölüm oranını ortaya çıkarmıştır. Erkek ve dişi bireylerin biplot tablolarında görülen birey sayılarındaki artışlar, çekirgelerin arseniği verimli biçimde kullanma yeteneklerini desteklemiştir. 0.025 mg.l-1 uygulamasında görülen depresyondan sonra meydana gelen iyileşmeler, böceklerin başlangıçta yaşanan stres koşullarından kurtulabildiği ve yaşam döngülerine devam edebildiğini göstermiştir. Anahtar Kelimeler: Çekirge, Sodyum arsenat, Hayat tablosu, Hayatta kalma eğrisi, Stres, Ortalama yaşam süresi INTRODUCTION In most lifecycle, mortality varies greatly with age in insects as well as in higher organisms. Life tables provides a systematic and complete picture of mortality in a population and a tabular device to describe every particular age of interval (Aziz et al. 2013) and provides precise description of the survivorship, development pattern and life expectancy (Ali and Rizvi 2007; Yazdani and Samih 2012). Pearl and Parker (1921) first introduced the life table into general biology by applying it on Drosophila under the laboratory conditions. Neukirch (1982) has been reported that the life span of worker honeybees was found to be determined by the duration of the hive- period and of the foraging period. Togashi (1990) has been constructed the life table of Monochamus alternatus and analyzed for four consecutive generations within Pinus thunbergii. Grist and Gurney (1995) prepared the model related to the effect of periodic environmental variations on the synchronization of life cycle. A threshold model of outbreak bark beetle population dynamics involved resources assemble during low-density periods and depletion during out-breaks (Okland and Bjornstad 2006). Life table of the Olive leaf moth, Palpita unionalis revealed that the intrinsic rate of population increase depends upon the nature of host plants provided (Kumral et al. 2007). Momen (2011) studied the biology of Proprioseiopsis cabonus in relation to life table and predation * Corresponding author: nathsusanta2012@gmail.com 81 J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 rates of these predatory mites. Whereas, Kakde et al. (2014) reviewed the importance of life table in studying allocation, determination of age and mortality of an organism and individuals. Spathosternum prasiniferum prasiniferum (Walker 1871) a common short horned grasshopper available in India, was considered as a pest of paddy, mungbean and urdbean chickpea (Usmani et al. 2012). Analyses of the mortality are a very useful tool to determine key factors responsible for the highest mortality within population. By calculating the life expectancy of a pest insect we can predict and determine the particular instars within which we get maximum mortality and such idea may be utilized in the management of insect pest at particular time. So the studies were conducted with the aim to find out survivorship, mortality and life expectancy of Spathosternum prasiniferum prasiniferum. MATERIALS AND METHODS To study the life table and mortality rate under laboratory conditions, adults of Spathosternum prasiniferum prasiniferum were collected from a fallow land near Piyali, South 24 Parganas and were kept in bisexual pairs. They were acclimatized under laboratory conditions for 7 days in insectariums. Plastic jars of 10 liter capacity containing 4.0 cm thick sand at the bottom were taken as the rearing cage. The open portion of the cages was covered with nylon net in order to maintain the air supply properly. Conical flask of 50 ml capacity containing food plant was placed in the jar for providing food to the insects (Nath and Rai 2010). Leaves of Cynodon dactylon collected from the institute campus were considered as food plant due to the preference of this grass by this grasshopper. For the control experiments, adults were fed on leaves grown in distilled water. For contamination, arsenic salt (sodium arsenate) was dissolved in distilled water along with food plant (Schmidt & Ibrahim 1994) and kept for twenty four hours. Concentration of 0.0125mg.l-1 (d1), 0.025 mg.l-1 (d2), 0.050 mg.l-1 (d3), 0.10 mg.l-1 (d4), 0.20 mg.l-1 (d5) arsenic salt water were tested respectively. Bisexual pairs were fed upon the contaminated food along with the untreated. After copulation, the female laid eggs in the sand. After approximately 30days of oviposition the first instars hatched out from the eggs. A total number of 1000 newly hatched first instars were taken into consideration. The first instars and their successive stages including the adult insects were also reared following the same procedure. The laboratory mortality data of Spathosternum prasiniferum prasiniferum were used to construct life tables and survivorship curves. Explanation of symbols used in the life table (Ricklefs & Miller 1999; Dash 2005; Smith and Smith 2007): x = age in days. nx = number of individuals from the original cohorts that are alive at the specified age x. lx = the probability at birth of surviving to any given age. dx = number of individuals out of lx who die before completing age x+1. sx = survival rate (proportion of individuals of age x surviving to age x+1). mx = mortality rate (proportion of individuals of age x surviving to age x+1). Lx = number of individuals alive between ages x and x+1. Tx = total number of days lived by the cohort after age x days. In fact, this is the total future life time of the lx individual (until all of them die off). qx = mortality rate for an age interval. ex = expectation of further life of individuals of age x. kx = –loge sx , the exponential mortality rate between age x and x+1. 82 J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 RESULTS AND DISCUSSION Spathosternum prasiniferum prasiniferum, a short horned grasshopper exposed to various doses of sodium arsenate results in disturbance in their life cycle, which results in the significant changes in the life span of the insect compare to the control. Percentage of mortality of first instar in control was 17.5 per cent (Table 1), which was maximum 25 percent in grasshopper exposed to 5d (Table 6). Second instars had 9.09 percent mortality, and showed a maximum of 14.40 per cent exposed to d2 (Table 3). The third instars had maximum mortality 23.12 percent at 4d (Table 5) and significant change in the mortality of the same instar at d2 (Table 3), d3 (Table 4) and d5 (Table 6) in compare to the untreated grasshoppers. Table 1. Life tables of control (untreated) S. prasiniferum prasiniferum. Stage lx dx dx as % of lx Ist instar 1000 175 17.5 IInd instar 825 75 9.09 IIIrd instar 750 75 10 IVth instar 675 175 25.92 Vth instar 500 0 0 Adult female 175 Adult male 125 Female X(days) nx lx dx Sx mx Lx Tx qx 175qx ex Kx 0 175 1 25 0.857 0.143 162.5 600.5 0.143 25 3.43 0.15 5 150 0.857 27 0.82 0.18 136.5 438 0.18 31.5 2.92 0.19 10 123 0.703 33 0.73 0.27 106.5 301.5 0.268 46.95 2.45 0.31 15 90 0.514 23 0.74 0.26 78.5 195 0.255 44.72 2.16 0.30 20 67 0.382 23 0.65 0.35 55.5 116.5 0.343 60.0 1.74 0.43 25 44 0.251 21 0.52 0.48 33.5 61 0.477 83.52 1.38 0.65 30 23 0.131 12 0.47 0.53 17 27.5 0.521 91.3 1.19 0.75 35 11 0.063 6 0.48 0.52 8 10.5 0.545 95.45 0.95 0.73 40 5 0.028 5 0 1 2.5 2.5 1.00 175 0.5 - Male X(days) nx lx dx Sx mx Lx Tx qx 125qx ex Kx 0 125 1 25 0.96 0.04 122.5 422.5 0.2 25 3.38 0.04 5 120 0.96 5 0.95 0.05 117.5 300 0.04 5.2 2.5 0.05 10 115 0.92 30 0.73 0.27 100 182.5 0.26 32.6 1.58 0.31 15 85 0.68 53 0.37 0.63 58.5 82.5 0.62 77.9 0.97 0.99 20 32 0.25 24 0.25 0.75 20 24 0.75 93.75 0.75 1.38 25 8 0.06 8 0 1 4 4 1 125 0.5 - 83 J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 Table 2. Life tables of 0.0125mg.L-1treated S. prasiniferum prasiniferum . Stage lx dx dx as % of lx Ist instar 1000 63 6.3 IInd instar 937 63 6.72 IIIrd instar 874 63 7.21 IVth instar 811 62 7.64 Vth instar 749 0 0 Adult female- 375 Adult male - 374 Female X(days) nx lx dx Sx mx Lx Tx qx 375qx ex Kx 0 375 1 0 1 0 375 1673.5 0 0 4.46 0 5 375 1 0 1 0 375 1298.5 0 0 3.46 0 10 375 1 63 0.832 0.168 343.5 923.5 0.17 63 2.46 0.18 15 312 0.83 112 0.641 0.359 256 580 0.29 134.6 1.85 0.44 20 200 0.53 63 0.685 0.315 168.5 324 0.31 118.1 1.62 0.37 25 137 0.36 62 0.668 0.332 106 155.5 0.45 169.7 1.13 0.40 30 75 0.2 63 0.16 0.84 43.5 49.5 0.84 315 0.66 1.83 35 12 0.03 12 0 1 6 6 1 375 0.5 - Male X(days) nx lx dx Sx mx Lx Tx qx 374qx ex Kx 0 374 1 0 1 0 374 1674 0 0 4.47 0 5 374 1 0 1 0 374 1300 0 0 3.47 0 10 374 1 0 1 0 374 926 0 0 2.47 0 15 374 1 149 0.60 0.4 299.5 552 0.39 149 1.47 0.5 20 225 0.6 125 0.44 0.56 162.5 252.5 0.55 207.7 1.12 0.82 25 100 0.26 60 0.4 0.6 70 90 0.6 224.4 0.9 0.91 30 40 0.10 40 0 1 20 20 1 374 1 - 84 J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 Table 3. Life tables of 0.025mg.L-1treated S. prasiniferum prasiniferum. Stage lx dx dx as % of lx Ist instar 1000 222 22.2 IInd instar 778 112 14.40 IIIrd instar 666 0 0 IVth instar 666 0 0 Vth instar 666 0 0 Adult female- 222 Adult male- 111 Female X(days) nx lx dx Sx mx Lx Tx qx 222qx ex Kx 0 222 1 0 1 0 222 1179 1 0 5.3 0 5 222 1 0 1 0 222 957 1 0 4.3 0 10 222 1 21 0.90 0.1 211.5 735 1 21 3.3 0.1 15 201 0.9 16 0.92 0.08 193 523.5 0.9 17.67 2.6 0.08 20 185 0.83 45 0.76 0.24 162.5 330.5 0.83 54 1.78 0.27 25 140 0.63 42 0.7 0.3 119 168 0.63 66.6 1.2 0.35 30 98 0.44 98 0 1 49 49 0.44 222 0.5 - Male X(days) nx lx dx Sx mx Lx Tx qx 111qx ex Kx 0 111 1 0 1 0 111 394.5 0 0 3.5 0 5 111 1 12 0.89 0.11 105 283.5 0.108 12 2.5 0.1 10 99 0.89 19 0.8 0.2 89.5 178.5 0.19 21.3 1.8 0.2 15 80 0.72 31 0.61 0.39 64.5 89 0.38 43.0 1.1 0.49 20 49 0.44 49 0 1 24.5 24.5 1 111 0.5 - 85 J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 Table 4. Life tables of 0.050mg.L-1treated S. prasiniferum prasiniferum. Stage lx dx dx as % of lx Ist instar 1000 167 16.7 IInd instar 833 0 0 IIIrd instar 833 0 0 IVth instar 833 168 20.04 Vth instar 665 0 0 Adult female- 333 Adule male- 332 Female X(days) nx lx dx Sx mx Lx Tx qx 333qx ex Kx 0 333 1 0 1 0 333 1904.5 0 0 5.7 0 5 333 1 3 0.9 0.1 331.5 1571.5 .009 3 4.7 0.1 10 330 0.99 15 0.95 0.05 322.5 1240 0.04 15.14 3.75 0.05 15 315 0.94 31 0.9 0.1 299.5 917.5 0.09 32.7 2.9 0.10 20 284 0.85 35 0.87 0.13 266.5 618 0.12 41.0 2.2 0.14 25 249 0.74 82 0.67 0.33 208 351.5 0.32 109.6 1.4 0.4 30 167 0.5 107 0.36 0.64 113.5 143.5 0.64 213.3 0.85 1.02 35 60 0.18 60 0 1 30 30 1 333 0.5 - Male X(days) nx lx dx Sx mx Lx Tx qx 332qx ex Kx 0 332 1 0 1 0 332 1792 0 0 5.39 0 5 332 1 0 1 0 332 1460 0 0 4.39 0 10 332 1 5 0.98 0.02 329.5 1128 0.015 5 3.39 0.02 15 327 0.98 28 0.91 0.09 313 798.5 0.08 28.4 2.44 0.09 20 299 0.90 67 0.77 0.23 265.5 485.5 0.22 74.39 1.62 0.26 25 232 0.69 128 0.45 0.55 168 220 0.55 183.2 .95 0.79 30 104 0.31 104 0 1 52 52 1 332 0.5 - 86 J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 Table 5. Life tables of 0.10mg.L-1treated S. prasiniferum prasiniferum. Stage lx dx dx as % of lx Ist instar 1000 125 12.5 IInd instar 875 62 7.08 IIIrd instar 813 188 23.12 IVth instar 625 62 9.92 Vth instar 563 0 0 Adult female- 375 Adult male- 188 Female X(days) nx lx dx Sx mx Lx Tx qx 375qx ex Kx 0 375 1 0 1 0 375 1874.5 0 0 4.99 0 5 375 1 0 1 0 375 1499.5 0 0 3.99 0 10 375 1 53 0.832 .168 348.5 1124.5 0.14 53 2.99 0.18 15 322 0.85 25 0.92 0.08 309.5 776 0.07 29.1 2.40 0.08 20 297 0.79 125 .599 0.401 242 466.5 0.42 157.8 1.57 0.51 25 187 0.49 85 0.54 0.46 144.5 224.5 0.45 170.4 1.20 0.61 30 102 0.27 73 0.28 0.72 65.5 80 0.71 268.4 0.78 1.27 35 29 0.07 29 0 1 14.5 14.5 1 375 0.5 - Male X(days) nx lx dx Sx mx Lx Tx qx 188qx ex Kx 0 188 1 0 1 0 188 817.5 0 0 4.34 0 5 188 1 0 1 0 188 629.5 0 0 3.35 0 10 188 1 53 .72 0.28 161.5 441.5 0.28 53 2.35 0.33 15 135 0.71 35 0.74 0.26 117.5 280 0.25 48.7 2.07 0.30 20 100 0.53 25 0.75 0.25 87.5 162.5 0.25 47 1.62 0.28 25 75 0.39 75 0 1 75 75 1 188 1 - 87 J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 Table 6. Life tables of 0.20mg.L-1treated S. prasiniferum prasiniferum. Stage lx dx dx as % of lx Ist instar 1000 250 25 IInd instar 750 0 0 IIIrd instar 750 0 0 IVth instar 750 0 0 Vth instar 750 0 0 Adult female- 500 Adult male-250 Female X(days) nx lx dx Sx mx Lx Tx qx 500qx ex Kx 0 500 1 0 1 0 500 2997 0 0 5.9 0 5 500 1 0 1 0 500 2497 0 0 4.9 0 10 500 1 0 1 0 500 1997 0 0 3.9 0 15 500 1 0 1 0 500 1497 0 0 2.9 0 20 500 1 75 0.85 .15 462.5 997 0.15 75 1.9 0.16 25 425 0.85 103 0.75 0.25 373.5 534.5 0.24 121.2 1.3 0.28 30 322 0.64 322 0 1 161 161 1 500 0.5 - Male X(days) nx lx dx Sx mx Lx Tx qx 250qx ex Kx 0 250 1 0 1 0 250 1332 0 0 5.32 0 5 250 1 0 1 0 250 1082 0 0 4.32 0 10 250 1 0 1 0 250 832 0 0 3.32 0 15 250 1 0 1 0 250 582 0 0 2.32 0 20 250 1 43 0.83 0.17 228.5 332 0.17 43 1.32 0.18 25 207 0.83 207 0 1 103.5 103.5 1 250 0.5 - Table 7. Rate of metamorphosis (%) in S. prasiniferum prasiniferum. -1 -1 -1 -1 -1 Grasshopper Control 0.0125mg.l 0.025mg.l 0.050mg.l 0.10mg.l 0.20mg.l (dose1) (dose2) (dose3) (dose4) (dose5) Male 12.5 37.4 11.1 33.2 18.8 50 Female 17.5 37.5 22.2 33.3 37.5 25 Adult 30.0 74.9 33.3 66.5 56.3 75 Among the instars the fourth one of untreated grasshopper showed highest mortality 25.92% (Table 1) which was zero in d2 and d5, whereas fifth instars showed zero mortality in untreated grasshopper and maintained almost similar trend in all the treated insects. When treated grasshopper was concerned, first instars showed highest mortality at d5 and lowest at d1, second instar have highest mortality at d2, third instars highest at d4 and lowest in rest of the doses except d1. Fourth instars showed highest mortality in d3 and lowest in d2 and d5, whereas, treated 5th instars revealed a zero mortality rate in treated as well as untreated grasshopper studied. Life table of adult female and male were found significant variation when treated with different doses of arsenic. The average life span of normal female was 40 days which reduced to 30 in d2 and d5 treated grasshopper, but in d4 the life span was 35 days. Whereas, male have normal 25 days life span which increased to 30 days in d1 and came down in 20 days in d2. Again an increase up to 30days was available when the grasshopper was treated with d3. Life expectancy (ex) of treated grasshopper was observed significant difference from that of control male and female. Untreated female have ex of 3.43 (Table 1) whereas it ranged between 4.46 and 5.9 in treated one. Untreated zero days old male have ex of 3.38 which was ranged between 3.5and 5.39 in arsenic treated male grasshopper. When survival rate (sx) was concern, it was found almost significantly high throughout the life span in grasshopper exposed to d5 (table-6). Whereas other treated grasshopper almost maintained a similar trend of sx in comparison to untreated. 88 J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 Survivorship curve of both male and female revealed a convex shape which indicates a high mortality in older adult. 30% of the untreated grasshopper were converted into adult, whereas, such metamorphosis was comparatively higher in treated grasshopper. Highest conversion was more than 70% in d1 and d5. 17.5% adult female and 25% adult male were metamorphosed in case of untreated grasshopper, whereas, this rate was ranged between 22.2 and 37.5 per cent and 11.1 to 50 per cent in arsenic treated female and male grasshopper respectively (Table 7). The study of life table in Spathosternum prasiniferum prasiniferum indicated the impact of arsenic on nymph as well as adult mortality was different when their life span was concerned. The mortality rate was higher in the nymph of the studied grasshopper in comparison to the adult grasshopper. Such nymphal mortality i.e. early death in the population more or less counter balances the effect of reproduction in most animal population. So pre reproductive death rate helps to hold a population in check which obviously depend on the reproductive capacity of the species (Nath and Rai 2010) It is demonstrated in the present study that Spathosternum prasiniferum prasiniferum possessed a resistance when exposed to arsenic infection. Though the metamorphosis rate in male was come down in d2 but it recovered and went up to 50 present at 0.20mg.l-1 , which was also observed in female. Adult male maintained a steady life span in various doses of arsenic. Life span of adult female slightly reduced than untreated but maintained distinct survival rate in younger adult. High metamorphosis rate in both the sexes also emphasized its ability to recover from the detrimental effect of arsenic at various doses. It was designated that organisms, those subject to different stresses of toxic substances in the ecosystems have their own mechanism to decontaminate various toxic substances (Migula 2000). In many cases arsenic have been acted as an essential trace element for the normal growth and development of experimental animals (Schwarz 1977; Anke et al. 1980). Present study advocated the ability to use the arsenic efficiently as presented in the biplot of both male and female grasshopper (Figure 1). Cohort life table helps to estimate the parameters related to growth potential and suitable to study dynamics of insect population (Aziz et al. 2013). After slight depression in d2, rapid recoveries signify the insect ability to overcome the initial stress situation and successfully maintained the life cycle with the advancement of doses. 89 J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 BIPLOT OF FEMALE lX (axes F1 and F2: 95.64 %) 3 2 1 0 40 Normal 150 35 0.0125 0.1 0 00..0052 5 15 0.2 30 20 -1 25 -2 -3 -5 -4 -3 -2 -1 0 1 2 3 F1 (87.53 %) BIPLOT OF MALE lX (axes F1 and F2: 92.42 %) 2 25 20 1 0.2 0.1 0 0.05 0.025 35 15 1500 Normal 0.0125 30 -1 -2 -3 -4 -3 -2 -1 0 1 2 3 F1 (85.31 %) Figure 1. Biplot showing the effect of various doses of arsenic on Spathosternum prasiniferum prasiniferum female and male. 90 F2 (7.10 %) F2 (8.10 %) J. BIOL. ENVIRON. SCI., 2015, 9(26), 81-91 CONCLUSIONS The studies were conducted with the aim to find out survivorship, mortality and life expectancy of Spathosternum prasiniferum prasiniferum exposed to arsenic compound. Result demonstrated a rapid recovery from initial effect of arsenic and able to maintain a steady rate of life cycle with further increase of doses. Authors are also grateful to Prof. Samiran Chakraborty, University of Kalyani, India, for help in preparing this manuscript. ACKNOWLEDGEMENTS Authors are thankful to University Grants Commission, New Delhi for providing financial support as Major Research Project to Dr. Susanta Nath for this work. REFERENCES Ali, A. and Rizvi, P.Q. 2007. Age specific survival and fecundity table of Coccinella septempunctata L. (Coleoptera:Coccinellidae) on different aphid species. Annals of Plant Protection Sciences, 15, 329-334. Anke, M., Groppel, B., Grun, M., Henning, A. and Meissner, D. (1980). The influence of arsenic deficiency on growth reproductiveness, life expectancy and health of goats. In: Spurenelement Symposium. pp. 25-32 Aziz, M. A., Ayesha, I and Hanif , M., 2013.Life table studies of Trilocha virescence (Bombycidae: Lepidoptera) on Ficus nitida. Asian Journal of Agriculture and Biology, 1(1),2-7. Dash, M.C. 2005. Fundamentals of Ecology. 2nd Edn. Tata McGraw-Hill Publishing Co. Ltd. New Delhi. pp.260. Grist, E.P.M. and Gurney, W.S.C. 1995. Stage specificity and the synchronization of life-cycle to periodic environmental variations. Journal of Mathematical Biology, 34 , 123-147. Kakde, A.M., Patel, K.G. and Tayade, S. 2014. Role of Life Table in insect Pest Management-A Review. IOSR- JAVS. 7(1) , 40-43. Kumral, N.A., Kovanci, B. and Akbudak, B. 2007. Life Tables of the Olive leaf Moth, Palpita unionalis (Hubner) (Lepidoptera: Pyralidae), on different host plants. Journal of Biological and Environmental Sciences, 1(3), 105-110. Migula, P. 2000. Relationships between enzymatic response and animal population demography in polluted environments. In: kammenga, J., Laskowski, R. (ed.) Ecotoxicology in Demography. John Wiley and Sons Ltd, New York. pp: 219-240 Momen, F. M. 2011. Life tables and feeding habits of Proprioseiopsis cabonus, a specific predator of Tydeid mites (Acari: Phytoseiidae and Tydeidae) Acarina 19, (1), 103–109. Nath, S. and Rai, A. 2010. Study of life table of Ceracris nigricornis Laeta (Orthoptera: Acrididae) in laboratory conditions. Romanian Journal of Biology-Zoology , 55, 159-165 Neukirch, A. 1982. Dependence of the life span of the Honey bee (Apis melifica) upon flight performance and energy consumption. Journal of Comparative Physiology, 146, 35-40. Okland, B. and Bjornstad, O.N. 2006. A resource depletion model of forest insect outbreaks. Ecology, 87, 283-290. Pearl, R. and Parker, L.J. 1921. Experimental studies on the duration of life : introductory discussion of the duration of life in Drosophila. Amer. Nat., 55, 481-509. Ricklefs, R.E., Miller G.L. 1999, Ecology. 4th Edn. W. H. Freeman And Company, New York, pp. 292-293. Schmidt, G.H., Ibrahim, N.M.M. 1994. Heavy metal content (Hg+, Cd+, Pb+) in various body parts: Its impact on Cholinesterase activity and binding glycoprotein in grasshopper Aiolopus thalassinus adults. Ecotoxicology and Environmental Safety, 29,148-164. Schwarz, K. 1977. Essentiality versus toxicity of metals. In: Clinical Chemistry And Chemical Toxicology Of Metals. S.S.Brown(ed.). Elsevier, New York. Smith, T.M. and Smith, R.L. 2007. Elements of Ecology. 1st Edn. Pearson Education Inc. India. pp 209-217. Togashi, K. 1990. Life table for Monochamus alternates (Coleoptera, Ceramkycidae) with in dead trees of Pinus thunbergii. Japanese Journal of Entomology,58(2), 217-230. Usmani, M.K., Nayeem, M.R. and Akhtar, M.H. 2012. Field observations on the incidence of Grasshopper fauna (Orthoptera) as a pest of Paddy and pulses. European Journal of Experimental Biology, 2(5), 1912-1917. Yazdani, M. and Samih, M. A. 2012. Life table attributes of Clitostethus arcuatus (Coleoptera: Coccinellidae) feeding on Trialeurodes vaporariorum and Siphoninus phillyreae (Hemiptera: Aleyrodidae). Journal of Asia Pacific Entomology , 15, 295–298. 91