The tobacco caterpillar, Spodoptera Utura F. is one of the most damaging insect pests on several field and vegetable crops. Sex pheromone, ‘litlure’ was used as an attractant in pheromone traps to monitor male moth activity, and to study the relationship between male moth catches in traps and oviposition in field crops at the Crop Research Centre, Pantnagar, India. Pheromone traps effectively monitored population fluctuations and showed seven peaks during 1988 and 1989. Two peaks were observed during the spring/summer season, three in the rainy season and the remaining two peaks in the postrainy season. Few moths were caught during the winter. Significant correlations were found between number of male moths in traps and number of egg masses laid on sugarbeet during spring, on groundnut and soybean during the rainy season, and on cauliflower during the postrainy season. However, there was no oviposition in Kharif sown urdbean and in summer groundnuts. Pheromone traps, therefore, can be used as a monitoring tool to ensure the rational application of insecticide

Sachan, G C

Singh, K N

ICRISAT Open Access Repository

Asessment of the Use of Sex Pheromone Traps in the Management of Spodoptera litura F.K.N. Singh1 and G.C. Sachan2‘ICRISAT, Patancheru, A.P. 502 324, India. 2G.B. Pant University of Agriculture and Technology, Pantnagar263 145, Uttar PradeshAbstractThe tobacco caterpillar, Spodoptera litura F. is one of the most damaging insect pests on several field and vegetable crops. Sex pheromone, ‘litlure’ was used as an attractant in pheromone traps to monitor male moth activity, and to study the relationship between male moth catches in traps and oviposition in field crops at the Crop Research Centre, Pantnagar, India. Pheromone traps effectively monitored population fluctuations and showed seven peaks during 1988 and 1989. Two peaks were observed during the spring/summer season, three in the rainy season and the remaining two peaks in the postrainy season. Few moths were caught during the winter. Significant correlations were found between number of male moths in traps and number of egg masses laid on sugarbeet during spring, on groundnut and soybean during the rainy season, and on cauliflower during the postrainy season. However, there was no oviposition in Kharif sown urdbean and in summer groundnuts. Pheromone traps, therefore, can be used as a monitoring tool to ensure the rational application of insecticides.IntroductionThe tobacco caterpillar, Spodoptera litura F. is an important defoliator, often encountered as a sporadic pest on many crops such as tobacco, cotton, soybean, cabbage, cauliflower, sunflower, castor, groundnut, etc. It has been reported to attack 112 species of plants belonging to 44 families (MoussaandKotbey, 1960). This species has a wide distribution throughout tropical and temperate Asia, Australia and the Pacific basin (Feakin, 1973).In the past it was known to be a major pest of tobacco and chilies. Recently it has attained the status of ‘major pest’ of several field and vegetable crops because of its mismanagement - overdosing with insecticides, the destruction of natural enemies, abandoning cultural control practices, and introduction of high yielding, but pest susceptible crop varieties (Ayyanna et al„ 1982; Mehrotra, 1989; N.J. Armes, Pers. Comm.);The current practice used by Indian farmers is to apply insecticides when larvae are mature and the infestation fairly visible, which is usually 3-4 weeks after adult emergence. Sprays are then applied weekly and at times when they may be least beneficial. However, early instar larvae (1st and 2nd instars) feed gregariously and by virtue of their smaller size are easier to kill with pesticides if applied in time.Although there is a continuing need for pesticides for controlling arthropod pests, the concomitant undesirable effects such as the development of pesticide resistance, effects on non-target organisms and pollution of environment have necessitated and stimulated the exploration of new and more efficient methods for the rationalization of insecticide use. In recent times, one such approach is the use of synthetic insect sex pheromones. Female sex pheromone of S. litura has been identified and named ‘litlure’. It is a mixture of 9Z, 11E, tetradecadienyl acetate and 9Z, 12E, tetradecadienyl acetate in a ratio of 9:1 (Tamaki et a l, 1973).Experiments were carried out to assess the use of sex pheromones to monitor S, litura populations, and to study the correlations between male moth catches in traps and levels of oviposition in the field. Such information would help in estimating the capture threshold of this insect which in turn will assist in timely application of control measures.Materials and MethodsThe studies were conducted at the Crop Research Center (CRC), G.B. Pant University of Agriculture and Technology, Pantnagar, Nainital, Uttar Pradesh, India (29°N, 79.3°E) during 1988 and 1989. The pheromone trap used was an ICRISAT standard type, comprising a single white plastic funnel trap8 K.N. Singh and G.C. Sachan(Ranga Rao et al., 1991). The trap was fixed with a nut and bolt to an angular metal support pole. The sex attractant, 1 mg impregnated into a white polyethylene vial, was obtained from the Natural Resources Institute (N.R.I.), U.K. through the International Crops Research Institute for the Semi- Arid Tropics (ICRISAT), Patancheru, India. The pre-baited pheromone vial was hung above the trap funnel from an aluminum plate into the centre of the trap. The trap was fixed 1 m above the ground level and each pheromone vial was replaced with a new one after an exposure of 4 weeks, as no reduction in trap catch occurs over this period (Ranga Rao et al., 1991).Four pheromone traps were operated through out the year to monitor the population of S. litura. Traps were operated from January to May in sugarbeet fields, March to mid November in groundnuts, July to October in soybean, and mid November to December at the sides and parallel to the main approach road. Traps were placed 200 m apart to reduce the possibility of inter-trap interference (Ranga Rao et al., 1991). Captured moths were counted daily, and averaged for each standard week (each calendar year is divided into 52 standard weeks; 1 January to 7 January is week one; in leap year the week no. 9 will be 26 February to 4 March i.e. 8 days instead of 7; and last week will have 8 days, 24 to 31 December) to facilitate the analysis and interpretation of the data.Influence o f Environmental Factors on Pheromone Trap CatchesData on maximum temperature, minimum temperature, wind velocity, and rainfall werecollected from the meteorological centre, CRC, Pantnagar. To study the relationship between moth catches and weather factors, the calendar year was divided into four seasons, summer (March-May), rainy (June-August), postrainy (September - November) and winter (December-February). The relationship between weather factors and the moth catches in the pheromone baited traps were, established using correlation analysis.Relationship Between Pheromone Trap Catches and OvipositionTo determine the correlation between male moth catches in pheromone baited traps and oviposition, the number of egg masses were counted thrice in a week on differentcrops (Table 1) from 30randomly selected sites of 1 m each selected in a diagonal transectacross the field. Mean weekly moth catches and numbers of egg masses laid in individual crops were correlated.Results and DiscussionMonitoringFigure 1 shows the mean population catches of male S. litura in pheromone baited traps during 1988 and 1989. A total of seven population peaks were recorded in a year. Only a few moths were caught during winter (December-February). Moth catches during the rainy season (June-August) were relatively low compared to that in summer (March- May) and postrainy (September-November) seasons.The first peak of male S. litura which occurred in 13 th standard week (26 Mar-1 Apr) was of high magnitude, followed by four smallerpeaks in weeksTable X. Schedule of weekly crop surveys for Spodoptera litura F. egg masses (1988 and 1989)MonthStandard week number Crop(s) surveyedMarch 10-13 SugarbeetApril 14-18 Sugarbeet, GroundnutMay & June 19-26 GroundnutM y 27-31 Groundnut, SoybeanAugust & 32-39 Groundnut, Soybean, UrdbeanSeptemberOctober 40-44 Groundnut, Soybean, CauliflowerNovember 45-48 CauliflowerNo. of male moths trapped/week/irap Temperature °C / Wind velocity Km/hrAssessment of the Use of Sex Pheromone Traps 9Standard weeksFig. 1. Influence of abiotic'factors on S. litura catches in sex pheromone trap for the year 1988 and 1989.Rainfall (mm)10 K.N. Singh and G.C. SachanTable 2. Correlation coefficients (r) between weekly pheromone trap catches of Spodoptera litura F. and weather factors in different seasons (1988 and 1989)SeasonsSummer Rainy Post-rainy WinterWeather factors (Mar-May) (Jun-Aug) (Sep-Nov) (Dec-Feb)Maximum temperature 0.01 0.67* 0.12 0.32Minimum temperature -0.12 -0.28 -0.22 0.57*Wind velocity 0.15 0.62* -0.42 -0.32Rainfall -0.08 -0.05 -0.37 -0.22* Significant at P = 0.05.21 (21-27 May), 24 (11-17 June), 27 (2-8 July) and 33 (13-19 Aug). The sixth and seventh peaks occurred in 37 (10-16 Sept) and 44 weeks (29 Oct- 4 Nov) were of high magnitude. From December, moth catches begun to decline and only a few moths were trapped during the winter.Influence o f Weather Variables on Trap CatchThe mean weekly moth catch of S. litura and the corresponding maximum temperature, minimum temperature, wind velocity and rainfall for the years 1988 and 1989 are given in Fig. l .I t  is evident that during winter, when temperature dropped to <10°C, moth catches in traps declined sharply and only few moths were caught. There was a significant positive correlation between trap catches and the minimum temperature (0.57). An increase in moth catches was observed in March with an increase in temperatures, and for peak moth catch observed in week 13, the corresponding maximum and minimum temperatures were 29.9°C and 12.5°C, respectively. Intherainy season,significantpositive correlation existed between trap catches and maximum temperature, and wind velocity (Table 2). In general, when heavy rainfall occurred moth catches decreased; however, slight to moderate rainfall during spring/summer seasons in the previous week (week 12) probably enhanced insect emergence as evidenced by peak of moths in standard week 13.Oviposition/Trap Catch CorrelationsFrom Fig. 1 it is evident that there were 7 adult peaks during the year. Crops were surveyed and number of egg masses found in different crops in 1988 and 1989 were correlated with mean weekly moth catches (Table 3). During spring/summer, peak moth activity between weeks 12-15 coincidedwith egg laying on sugarbeet. The correlation coefficients were significant in both years (0.90, 1988; 0.83,1989). Smaller peaks in weeks 21,24, 27 and 33 in both years were not followed by egg laying. However, peak moth activity in September (weeks 36-39) coincided with egg laying in groundnut and soybean. The correlation coefficients were significant during 1988 in groundnut (0.87) and soybean (0.87), but no significant correlation existed during 1989. The nextpeak was between- weeks 40-43, but no egg laying was found either in groundnuts or soybean. However egg masses were recorded on cauliflower grown in nearby fields. Correlation coefficients were significant in both years(0.96,1988; 0.75,1989). However, there was no oviposition in Kharif urdbean and summer groundnuts in both years.Monitoring of S. litura male moths with sex pheromone baited traps at Pantnagar, Uttar Pradesh, India indicated seven population peaks in a year. However, at the ICRISAT farm, PatanCheru, Spodoptera appears to be present continuously throughout the year and 10 peaks were reported (RangaRaoef al., 1991a). Trials conducted through the All India Coordinated Research Project on Oilseeds (AICORPO) had shown the major moth activity in August at Dharwad, late September at Jalgaon, July at Junagadh, and 3rd week of June through November at Ludhiana (Annual Kharif Oilseeds Workshop, 1987). Miyaharaef a/. (1977) observed 5 generations of this species in a year in Japan. The first peak was observed in late March or early April and adults were active until mid- December. Five peaks of this insect in a year have also been reported by Shin et al. (1987) in South Korea. The peaks were reported in early May, mid J une, late J uly, late August, and mid- late September.Assessment of the Use of Sex Pheromone Traps 11Table 3. Weekly pheromone trap catches of Spodoptera litura F. and egg mass counts in two successive years, 1988 and 19891988 1989Standard weeksMoths caught per trapEgg masses per 30 m2Moths caught per trapEgg masses per 30 m2Sugarbeet (Spring/summer season)10 126 0 18 011 193 0 33 012 419 1 193 013 1371 7 1185 314 642 6 1182 1015 273 1 858 816 77 0 392 117 284 0 181 018 328 0 319 0Mean 412.6 1.7 484.6- 2.4S.D. 396.4 2.8 467.9 3.9“r” 0.90** 0.83**Groundnuts (Rainy season)34 56 0 29 035 69 0 97 036 513 12 622 637 852 17 487 1238 391 2 97 239 J72 0 283 140 413 0 488 0Mean 352. 4.4 300.4 3.0S.D. 283.2 7.1 234.6 4.5“r” 0.87* 0.59Soybean (Rainy season)34 59 0 52 035 66 0 100 236 501 5 548 437 881 6 467 238 314 2 98 139 271 2 242 040 376 0 377 o-Mean 352.6 2.1 269.1 1.3S.D. 282.3 2.5 197.6 1.5“r” 0.87** 0.56Cauliflower (Post-rainy season)40 395 0 433 041 360 0 764 042 563 2 608 143 1129 6 905 544 1550 12 772 445 1118 7 593 246 683 3 419 047 485 0 424 048 50 0 185 0Mean 703.7 3.3 567.0 1.3S.D. 471.3 4.2 224.6 1.9“r” 0.96** 0.75*“r” correlation coefficient. *, ** significant at P = 0.05, and P = 0.01, respectively.12 K.N. Singh and G.C. SachanThe<iistribution and abundance of S. litura is influenced by both abiotic and biotic factors. Temperature is probably the one which can most influence the population dynamics of S. litura. Temperature is known to influence the rate of development of the eggs, larvae, and pupae of S. litura with the optimum temperatures for survival between 25-28°C (Ranga Rao et al., 1989). The temperatures at Pantnagar during winter dropped to <10°C and this may have reduced the rate of larval development, decreased the larval survival, and delayed pupal development. Thus only a few moths were caught during winter (December- February). When weather conditions became conducive in late March, moths emerged soon after.High temperatures may also affect growth, development, and survival of S. litura (Ranga Rao et al., 1989). High temperatures experienced in Pantnagar (above 37°C) during summer may cause a decline in moth numbers due to decrease in survival.The feeding preference of S. litura has been studied by Prasad and Bhattacharya (1975). One or the other preferred host plant(s) for oviposition and larval feeding is available throughout the year at CRC farm, viz., sugarbeet, groundnuts, mungbean, urdbean, maize, castor, soybean, sunflower, and some wild host plants after the onset of the monsoons, and winter cauliflower and cabbage grown in nearby fields. In the present study, the majormothpeak during spring/summerin sugarbeet and during postrainy in groundnuts, soybean and cauliflower coincided with the egg laying. Females emerged 2-3 days earlier than the males when reared under laboratory conditions (Singh, 1990). Male moths were probably first attracted towards the virgin females rather than to the synthetic pheromone source. Probably because of this fact, maximum trap catches coincided with the oviposition peak. Similar observations were reported by Oyama and Wakamura (1976) for S. litura and by Kehat et al. (1985) for S. littoralis where they found that males were attracted to, and mated with, virgin females before orientation towards pheromone baited traps. Peak trap catches occur very near to, or after harvest of Kharif groundnuts and soybean, which suggests the possibility of dispersal of emerging moths, leadingto oviposition on the preferred hosts such as cauliflower. This hypothesis is supported by Ranga Rao et al. (1991b) who found changes in flight pattern of S. litura during die cropping periods of groundnut and maximum moths were caught at4 m height, after the groundnut harvest showing emigration of emergent moths.Thepresentfindings have shown the importance of sex pheromone traps to monitor the population changes of 5. litura, and have indicated significant relationship between moth catches in traps and oviposition in the fields. However, oviposition/ trap catch correlations were not consistent between fields, seasons and years. Information on these factors, therefore, could be used as indicators to pin-point when to make crop inspections for possible larval infestation to ensure the rational application of insecticides.AcknowledgementsSubmitted as Journal Article no. 1349 by the International CropsResearch Institute for the Semi- Arid Tropics (ICRISAT).ReferencesDirectorate of Oilseeds Research. 1987.30th Annual Kharif OilseedsWorkshop ofGroundnut, Sesame, Niger andSunflower, 22-27 April, 1987, Akola. Directorate of Oilseeds Research, Hederabad, A.P. pp. 367-421.A yyanna, T ., A rju n a ra o , P ., S u b b a ra tn a m , G.V., K rishnam urthy Rao, B.H. and Narayana, K.L. 1982.Chemical control of Spodoptera I itura (Fabricius) on groundnut crop. Pesticides 16:19-20.Feakin S.D. (ed.), 1973. Pest Control in Groundnuts. PANS ManualNo.2. Centre for Overseas PestResearch, London, U.K. 197 pp.Kehat, M., Gothilf, S., Dunkelblum, F., Shavit, N.B. and Gordon, D. 1985. Night observations on the cotton leafworm, Spodoptera littoralis: Reliability of pheromone traps for population assessment and efficacy of widely separated pheromone dispensers for mating disruption. Phytoparasitica 13: 215-220.Mehrotra, K.N. 1989. Pesticide resistance in insect-pests Indian scenario. Pesticides Research Journal 1:95-103.Miyahara, Y. Shimazu, M. and Wada, T. 1977. Seasonal occurrence of Spodoptera litura (F.) as measured by a virgin female trap. Japanese Journal of Applied Entomology and Zoology 21:59-65.Moussa, M.A. and Kotbey, F A . 1960. Abundance of cotton leaf-worm Prodenia litura (F.) (Lepidoptera: Agrotidae) in relation to host plants. 1. Host plants and their effect on biology. Bulletin of Society of Entomologie of Egypte 44:241 -251.Assessment of the Use of Sex Pheromone Traps 13O y a m a . M. and W akamura, S. 1976. Influence of the wild population density and environmental conditions on recapture of the released males Spodoptera litura F. (Lepidoptera: Noctuidae) using sex pheromone traps. Japanese Journal of applied Entomology Zoology 20: 151-156.Prasad, J . and Bhattacharya, A.K. 1975. Growth and development of Spodoptera littoralis (Boisd.) on several plants. Zeitschrift fur Angewandte Entomologie 79: 34-48.Ranga Rao, G.V., Wightman, J.A. and Ranga Rao, D.V. 1989. Threshold temperatures and thermal requirements for the development of Spodoptera litura (Lepidoptera: Noctuidae). Environmental Entomology 18: 548-551.Ranga Rao, G.V., Wightman, J.A. and Ranga Rao, D.V. 1991a. Monitoring Spodoptera litura (F) (Lepidoptera: Noctuidae) using sex attractant traps: effect of trap height and time of the night onmoth catch. Insect Science and its Application 12: 443-447.Ranga Rao, G.V., Wightman, J.A. and Ranga Rao, D.V. 1991b. The development of a standard pheromone trapping procedure for Spodoptera litura (F) (Lepidoptera: Noctuidae)population in groundnut (Arachis hypogaea L) crops. Tropical Pest Management 37: 37-40.Shin, H.Y., Kim, C.H., Park, C.G. and Lee, Y.S. 1987.Biology of tobacco cutworm,Spodoptera litura F. (Lepidoptera: Noctuidae). I. Seasonal occurrence of tobacco cutworm in Southern Korea and larval development, pupal period, adult longevity and oviposition on the differentfood sources. Research Report, Rural Development Administration, Korea Republic, Plant Environment, Mycology and Farm Products Utilization. No.29: 301-307.Singh, K .N , 1990. Population Monitoring and Resistance in Groundnut to Spodoptera litura (Fabricius) With Reference to Losses from Insect Pests. Ph. D. Thesis, G.B. Pant University of Agriculture and Technology, Pantnagar 263 145, India. I l l  pp.Tamaki, Y., Noguchi, H. and Yushima, T. 1973. Sexpheromone of Spodoptera litura (F.) (Lepidoptera: Noctuidae): Isolation, identification and synthesis. Applied Entomology Zoology 8: 200- 203.Received: 3.7.1992. Revised: 12.8.1993.

Asessment of the use of sex pheromone traps in the management of Spodoptera litura F.

http://oar.icrisat.org/6876/1/IJPP_21_1_7-13_1993.pdf

Asessment of the use of sex pheromone traps in the management of Spodoptera litura F.

Abstract

Similar works

Full text

Available Versions

ICRISAT Open Access Repository