ISSN: 0974-0376 NSave Nature to Survive : Special issue, Vol. VI: 175-180: 2014 AN INTERNATIONAL QUARTERLY JOURNAL OF ENVIRONMENTAL SCIENCES www.theecoscan.in SEASONAL INCIDENCE OF FLEA BEETLE (PHYLLOTRETA SPP.) INFESTING TOMATO (LYCOPERSICON ESCULENTUM L.) AND THEIR SUSTAINABLE MANAGEMENT B. Subba et al., KEYWORDS Tomato Flea beetle Incidence Sustainable management Proceedings of National Conference on Harmony with Nature in Context of Environmental Issues and Challenges of the 21 st Century (HORMONY - 2014) November 28-30, 2014, Udaipur, organized by Department of Environmental Sciences, Faculty of Earth Sciences M. L. Shukhadia University, Udaipur - 313 001 (Rajasthan) in association with National Environmentalists Association, India www.neaindia.org 175
NSave Nature to Survive QUARTERLY B. SUBBA 1 *, S. K. GHOSH 1, K. RAVI KUMAR 2 AND B. CHHETRI 3 1 Department of Agricultural Entomology, 2 Department of Pomology and Post Harvest Technology, 3 Department of Agronomy, Uttar Banga Krishi Viswavidyalaya (University), Pundibari, Coochbehar - 736165, West Bengal, INDIA e-mail: bikashsubba545@gmail.com ABSTRACT Incidence of flea beetle (Phyllotreta spp.) and its botanical management in tomato was assessed by Randomized Block Design for two consecutive rabi season (2011-2013) at Uttar Banga Krishi Viswavidhyalaya, Pundibari, Coochbehar, West Bengal. The lower population level was recorded during 38 th standard week to 9 th standard week and 19 th standard week to 20 th standard week. Higher population level was maintained during 10 th standard week to 20 th standard week and peak population (1.11/plant) was recorded on 23 rd standard week. Abiotic conditions such as relative humidity (maximum, minimum and average) had significant negative influence on Phyllotreta spp. while non-significant negative correlation with weekly total rainfall. In case of temperature (maximum, minimum, and average), non-significant positive correlation was observed. The highest mortality was recorded from neem and Spilanthes against flea beetle providing 53.84% suppression, closely followed by neem pesticides providing 44.97% suppression and least morality was recorded from garlic extracts providing 30.37% suppression. The overall result of remaining biopesticide revealed that insecticidal action of Spilanthes, Polygonum plant extracts, acetamiprid, tobacco extracts and Garlic extracts gave moderate results, recording about 37.06%, 35.05%, 34.91%, 30.10%, and 28.05% suppression respectively. The lowest yield was recorded from control plots i.e. 18.32 t/ha and highest yield, 30.15 t/ ha were recorded from acetamiprid treated plots followed by neem + Spilanthes (27.55 t/ha) Spilanthes extract (26.67 t/ha) and Polygonum extract (26.32 t/ha) which are significantly different from yield of other treated plots. Other than control plots, the lowest yield were recorded from garlic treated (23.11 t/ha) plots closely followed by tobacco extract (24.02 t/ha) treated plots. *Corresponding author INTRODUCTION Tomato (Lycopersicon esculentum Mill.) is one of the most popular and widely grown vegetables throughout the world ranking second in importance after potato in India (Jatand, 2013). It is attacked by number of insect pests in which flea beetles are among the most injurious insect pests of young tomato plants (Gentile et al., 1968). Flea beetle is one of the most difficult-to-manage pests in seedlings of tomatoes. There are various genera and species of flea beetles, all members of the Chrysomelidae family. Symptoms of flea beetle feeding are small, rounded, irregular holes; heavy feeding makes leaves look as if they had been peppered with fine shot (Metcalf and Metcalf, 1993). The main damage is caused by the adults which kill or severely stunt small plants by feeding on the leaves and growing points (Batiste, 1970). They typically begin to become active during warm days in midspring but may straggle out over several weeks (Fact Sheet No. 5.592). Flea beetles are most common on early plantings. They apparently fly into tomato fields from weed hosts where they overwintered. In one study of 12 fields of tomato seedlings 50% of the plants were fed upon by flea beetles (Ag Alert, 1991). Botanical pesticides recommended for controlling flea beetles include neem, rotenone, pyrethrin, sabadilla, and formulations of these in some combination (Ellis et al., 1992). Botanical pesticides, neem (Azadirachta indica) are being widely used and several formulations thus containing the active component azadirachtin are commercially available (Kumar et al., 2003; Anis Joseph et al., 2010). Other sources suggest that garlic sprays are useful (Rateaver et al., 1993). The evidences abound that botanical pesticides are generally safe and effective (Emosairue and Ubana, 1998; Okrikata et al., 2008). Hence, the present study was taken to determine the seasonal abundance of pestiferous flea beetle populations during susceptible stage and to evolve a technically feasible, environmentally sound and economically viable safe pest management strategy of tomato crops against flea beetle. MATERIALS AND METHODS Studies were conducted in the Instructional Farm of Uttar Banga Krishi Viswavidyalaya at Pundibari, Coochbehar, West Bengal, India for two consecutive years rabi season (2011-13). The experimental area is situated in the sub-himalayan region of north-east India. This terai zone is situated between 25º57 and 27ºN latitude and 88º25 and 89º54 E longitude. To study the population fluctuation and seasonal incidence of flea beetle and also the influence of prevailing weather conditions on the population dynamics, Pusa Ruby variety was taken to raise in two different season. The fertilizer doses of 120:60:60 NPK kg per ha was given for normal crop growth as well as other agronomic practices was followed as per schedule. The experiment was conducted in Randomized Block Design in three replications. The data for seasonal incidence on tomato plant were recorded at seven days interval. Three plants were randomly selected and tagged from each replicated plot 176
SEASONAL INCIDENCE OF FLEA BEETLE (PHYLLOTRETA SPP.) for each observation. The number of flea beetles were counted per plant basis. The seasonal incidence of pest and important weather parameter viz., temperature, relative humidity and rainfall were worked out, to find out the influence of pest population fluctuation on important environmental parameter. In management trial, eight treatments were taken viz., T 1 tobacco 7.5%(75ml/L), T 2 garlic 5%(50ml/L), T 3 Polygonum 5%(50ml/L), T 4 Spilanthes 5% (50ml/L), T 5 neem pesticide (2.5ml/L), T 6 neem + Spilanthes (1.5ml+40ml/L), T 7 acetamiprid (1g/3L), T 8 untreated control. The botanicals were extracted in methanol by filtering through whatman 42 filter paper, except tobacco in which water was used for extraction. Observations of pests to find out the efficacy of botanical extracts were recorded at 3, 7 and 11 days after each spraying. In these also, three plants were randomly selected from each replicated plot and flea beetles were counted as number per plant basis. The data thus obtained was computed on the percentage of insect population suppressed and analyzed statistically. For the purpose of studies on comparative efficacy, percentage of incidence was converted into percentage protection (Efficacy) by adopting the following formula (Abbott, 1925). Po Pc Pt = 100 100 Pc Where, Pt = Corrected mortality, Po = Observed mortality and Pc = Control mortality. Temperature ( C) and RH (%) 100 90 80 70 60 50 40 30 20 10 0 Temp. C RH % Flea/plant 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Standard week Figure1: Incidence of Flea beetle by influence of temperature and RH 1.20 1.00 0.80 0.60 0.40 0.20 0.00 Flea beetle/plant %reduction in treatment %reduction in control % reduction over control = 100 100 %reduction in control Data were analyzed by using INDO-STAT- software for analysis of variance following Randomized Block Design (RBD) treatment means were separated by applying CD Test (critical difference) at 5% level of significance. The tomato fruits were harvested at frequent intervals when they reached marketable size. The yield of marketable produce was calculated in different years separately on the basis of fruit yield per plot and converted to quintal per hectare. RESULTS AND DISCUSSION Trend of incidence of flea beetle tomato during 2011-12 and 2012-13 crop seasons is depicted in Fig. 1. The pooled data on flea beetle incidence for the two years showed that flea beetle was not very active all throughout the year. Lower population level was notice during 38 th standard week to 9 th standard week that is during 3 rd week of September to last week of February and 19 th standard week to 20 th standard week that is during 1 st week of May to last week of May. Higher population level was maintained during 10 th standard week to 20 th standard week that is during 1 st week of March to 2 nd week of May and highest population (1.11/plant) was recorded on 23 rd standard week that is on 3 rd week of March. This result is similar to factsheets on vegetable. According to this factsheet, flea beetles become active and begin to leave their overwintering sites and seek acceptable host plants with warmer temperatures (>5OºF) in late April and May. (www.nysipm.cornell.edu/factsheets/vegetables/misc/fb.pdf.). Correlation studies (Table 1) between flea beetle population and environmental parameter revealed that flea beetle population had a significant negative correlation with relative humidity (maximum, minimum and average). On the other hand non-significant negative correlation found between flea beetle population and weekly total rainfall while non-significant positive correlation with temperature (maximum, minimum, and average). This indicates that activity of flea beetle population decrease with the rise of relative humidity and population increase with the rise of temperature. Ghosh (2014) reported that in lady s finger the flea beetle population showed significant positive correlation (p = 0.05) with average temperature, relative humidity, whereas significantly negative correlation with rainfall. The different treatments and their persistence at different days after application varied significantly Table 1: Correlation co-efficient between flea beetle and environmental parameters Environmental parameter Correlation co-efficient (r) Co-efficient of determination (R 2 ) Regression equation Temperature C Maximum 0.284 0.081 Y= 3.663X+28.766 Minimum 0.068 0.004 Y= 1.314X+16.101 Difference 0.231 0.053 Y= 2.336X+12.673 Average 0.158 0.025 Y= 2.464X+22.450 Relative Humidity (%) Maximum -0.656** 0.431 Y=-22.145X+84.238 Minimum -0.712** 0.507 Y= -34.141X+73.848 Average -0.718** 0.516 Y= -28.143X+79.043 Rainfall(mm) Weekly total -0.119 0.014 Y= -17.99X+22.860 *Significant at 5% level of significance, ** Significant at 1% level of significance 177
B. SUBBA et al., Table 2: Effects of different treatment schedules of plants extracts against flea beetle (Phyllotreta spp.) on tomato plants during 2011-2012 to 2012-2013 Treatments Spray conc. % Suppression of flea beetle population on different days after treatment (DAT) Season-I (2011-2012) Season-II (2012-2013) Pre Days after treatment Pre Days after treatment treatment 3 7 11 Mean treatment 3 7 11 Mean cont. cont T 1 (Tobacco extract) 7.5% (75ml/L) 0.89 39.25(38.74) 31.41(34.07) 23.65(29.09) 31.44(33.97) 0.56 35.62(36.62) 24.73(29.77) 25.93(30.61) 28.76(32.33) 2 T (Garlic extract) 5% (50ml/L) 1.01 32.91(35.01) 28.76(32.42) 29.93(32.68) 30.53(33.37) 0.78 29.71(33.01) 27.48(31.60) 23.65(29.09) 25.57(31.23) 3 T (Polygonum extract) 5% (50m/L) 0.77 37.52(37.77) 33.30(35.24) 28.76(32.42) 33.19(35.14) 0.72 42.37(40.42) 35.65(36.65) 32.71(34.85) 36.91(37.31) 4 T (Spilanthes extract) 5% (50ml/L) 0.87 42.45(40.60) 37.08(37.41) 31.00(33.83) 36.84(37.28) 0.67 44.38(41.75) 36.49(37.16) 30.94(33.79) 37.27(37.57) 5 T (Neem pesticides) 2.5 ml/l 1.12 54.71(47.70) 40.86(39.73) 37.08(37.51) 44.22(41.65) 0.44 55.78(48.32) 46.82(43.17) 34.52(35.74) 45.71(42.41) 6 T (Neem + Spilanthes ) (1.5ml+ 40ml)/L 1.01 56.18(48.55) 49.11(44.49) 47.59(43.62) 50.96(54.55) 0.48 65.56(54.07) 54.28(47.46) 50.33(45.19) 56.72(48.71) 7 T (Acetamiprid) 1g/3L 0.67 39.14(38.73) 29.02(32.59) 31.95(34.35) 33.37(35.23) 0.89 34.95(36.24) 35.91(36.81) 38.46(38.33) 36.44(37.13) 8 T (Untreated control) - 0.56 0.00(4.05) 0.00(4.05) 0.00(4.05) 0.00(4.05) 0.42 0.00(4.05) 0.00(4.05) 0.00(4.05) 0.00(4.05) SEm ± - - 2.32 2.91 2.41 2.55-1.92 1.75 2.44 2.04 CD (5%) - NS 6.91 8.65 7.18 7.58 NS 5.72 5.21 7.18 6.04 Figure in the parenthesis are angular transformed values, DAT = Days after treatment, NS = Not significant in their suppression of flea beetle populations (Table 2 and Table 3). Among the seven pesticides evaluated (Table 3) under the present investigation, neem + Spilanthes was found most effectively against flea beetle providing 53.84% suppression, closely followed by neem pesticides providing 44.97% suppression. From over all observation it was revealed that extracts of Spilanthes, Polygonum plant extracts, acetamiprid, tobacco extracts and garlic extracts gave moderate results, recording about 37.06%, 35.05%, 34.91%, 30.10% and 28.05% flea beetle suppression respectively. Least effectiveness against flea beetle was recorded from garlic extracts providing 30.37% suppression. Ghosh (2014) reported that azadirachtin and extracts of Polygonum plant gave moderate to higher flea beetle control, recording more than 50% mortality and produced higher yield. Three days after spraying, neem + Spilanthes and neem pesticides was found most effectively against flea beetle providing 60.87% and 55.25% suppression respectively. Remaining treatment viz., Spilanthes extracts, Polygonum extracts, tobacco extracts, acetamiprid, garlic extracts and were found to be moderately effective providing 43.42%, 39.95%, 37.44%, 37.05%, 32.91% mortality respectively. Similarly after seven days, neem + Spilanthes and neem pesticides were also found to be superior insecticide by suppressing population by 51.70% and 43.84% respectively. Spilanthes extracts, Polygonum extracts, acetamiprid, garlic extracts and tobacco extracts show moderate result against flea beetle providing 36.79% and 34.48%, 32.47%, 28.12% and 28.07% suppression respectively. Similar results were supported by Subedi and Vaidya, 2003; Rateaver et al., 1993 to control flea beetle in different crops. In case of after eleven days of spraying, neem + Spilanthes was found to be most efficient (48.96%) against flea beetle closely followed by neem pesticides (35.81%) and acetamiprid (35.21%). The fairly effective insecticides were Spilanthes extracts, Polygonum extracts, garlic extracts and tobacco leaf extracts against flea beetle providing 30.97%, 30.74%, 26.79% and 24.79% prevention respectively. The results were conformity with Sharma et al., 2012. Anon. (1998) reported that the garlic extracts are successful in suppressing flea beetles, but efficacy may trail off later in the season. From the overall observations it was revealed that neem and Spilanthes was found to be most effective against flea beetle providing more than 53% suppression however neem pesticides gave a satisfactory result i.e., 44% control. Both are bio pesticides which is non-toxic, so there is no possibility to contaminate tomato fruits with the toxic chemicals. Plant extracts are of biological origin having low or no hazardous effect on health and environment and so can be incorporated in IPM programme against flea beetle in tomato plants. Yield was directly related to the efficacy of the insecticides (Ghosh, 2012). Yield is the ultimate output to the farmer which makes them content. In this view, comparison has done for yield in order to find out effectiveness of botanical pesticide over tomato pests. Here over all yields is taken for evaluation (Table 4). The lowest yield was recorded from control plots i.e. 18.32 t/ha (Madhusudan, 2011). Highest yield (30.15 t/ha) was recorded from acetamiprid treated plots followed by neem + Spilanthes (27.55 t/ha), Spilanthes extract (26.67 t/ha) and 178
SEASONAL INCIDENCE OF FLEA BEETLE (PHYLLOTRETA SPP.) Table 3: Overall efficacy of plants extracts against flea beetle (Phyllotreta ssp.) on tomato plants (Grand Mean of 2011-12 and 2012-13) Treatments Spray conc. % Suppression of flea beetle population on different days after treatment (DAT) Season-I (2011-12) and Season-II (2012-2013) Pre treatment cont. Days after treatment 3 7 11 Mean T 1 (Tobacco extract) 7.5% (75ml/L) 0.73 37.44(37.68) 28.07(31.92) 24.79(29.85) 30.10(33.15) T 2 (Garlic extract) 5% (50ml/L) 0.90 32.91(34.01) 28.12(32.01) 26.79(30.89) 28.05(32.30) T 3 (Polygonum extract) 5% (50m/L) 0.75 39.95(39.10) 34.48(35.95) 30.74(33.64) 35.05(36.23) T 4 (Spilanthes extract) 5% (50ml/L) 0.77 43.42(41.18) 36.79(37.29) 30.97(33.81) 37.06(37.43) T 5 (Neem pesticides) 2.5 ml/l 0.78 55.25(48.01) 43.84(41.45) 35.81(36.63) 44.97(42.03) T 6 (Neem + Spilanthes ) (1.5ml+ 40ml)/L 0.75 60.87(51.31) 51.70(45.98) 48.96(44.41) 53.84(51.63) T 7 (Acetamiprid) 1g/3L 0.78 37.05(37.49) 32.47(34.70) 35.21(36.36) 34.91(36.18 T 8 (Untreated control) - 0.49 0.00 (4.05) 0.00 (4.05) 0.00 (4.05) 0.00 (4.05) SEm ± - - 2.12 2.33 2.43 2.30 CD(5%) - NS 6.32 6.93 7.18 6.81 Figure in the parenthesis are angular transformed values, DAT = Days after treatment, NS = Not significant Table 4: Yield potentiality in different treatments (2011-12 and 2012-2013) Yield/t/ha Treatment Spray conc. 2011-12 2012-13 Mean T 1 (Tobacco extract) 7.5%(75ml/L) 24.52 23.52 24.02 T 2 (Garlic extract) 5%(50ml/L) 22.24 23.98 23.11 T 3 (Polygonum extract) 5%(50m/L) 25.07 27.57 26.32 T 4 (Spilanthes extract) 5%(50ml/L) 29.29 24.05 26.67 T 5 (Neem pesticides) 2.5ml/L 26.79 24.33 25.56 T 6 (Neem + Spilanthes) (1.5ml+ 40ml)/L 27.99 27.11 27.55 T 7 (Acetamiprid) 1g/3L 28.15 32.15 30.15 T 8 (Untreated control) - 16.46 20.18 18.32 SEm ± - 1.57 1.64 1.49 CD (5%) - 4.76 5.01 4.53 Polygonum extract (26.32 t/ha) which are significantly different from yield of other treated plots. Other than control plots the lowest yield were recorded from garlic treated (23.11 t/ha) plots closely followed by tobacco extract (24.02 t/ha) treated plots. From whole observation acetamiprid treated plots gave satisfactory yield but it is harmful as it is consumed by human being and it also contaminated the environment there by causing health hazard to other plant and animals. So, it is advisable to use neem + Spilanthes as a safety measure. ACKNOWLEDGEMENT Authors are very thankful to Department of Agricultural Entomology, UBKV, for providing laboratory, field and financial assistance for this study. REFERENCES Ag Alert. 1991. Large populations of flea beetles can be troublesome in tomatoes. Anon. 1998. Flea Beetle IPM. IPM Practitioner. September. p. 16. Batiste, W. C. 1970. Insecticidal control of the tobacco flea beetle on seedling tomatoes in Northern California. J. Economic Entomology. 63: 1339-1341. Ellis B. W. and Marshall, B. F. 1992. 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