Efficacy of certain new insecticide molecules against groundnut defoliator, Spodoptera litura (Fab.) (Noctuidae : Lepidoptera)

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1 Efficacy of certain new insecticide molecules against groundnut defoliator, Spodoptera litura (Fab.) (Noctuidae : Lepidoptera) T. Murali Krishna*, K. Devaki, K. Raja Reddy and U. Venkateswarlu Regional Agricultural Research Station, Tirupati , Chittoor Dist. A.P. India * murali_tirupati@rediffmail.com ABSTRACT Evaluation of five insecticide molecules along with two microbial formulations were carried out against groundnut defoliator, Spodoptera litura (Fab.) at Regional Agricultural Research Station, Tirupati, Andhra Pradesh, India during and Results showed that Novaluron 10% 1ml/lt was found to be the best treatment with lowest incidence (20.99 %) of S. litura followed by Chlorfenapyr 10% 2ml/lit and Thiodicarb which were on par with each other. Highest pod yield was recorded from Thiodicarb treated plot, which was on par with Novaluron and Chlorfenapyr. Bt treated plots also recorded considerable yield indicating that it can be recommended and integrated as one of the IPM components. With respect to Benefit Cost ratio, Thiodicarb recorded highest net returns with 1.43 followed by Novaluron with KEYWORDS: Groundnut, insecticides, Spodoptera litura INTRODUCTION Groundnut is one of the most important oil seed crops grown in India and contributes about 30% of the total domestic supply of oil. In India groundnut is mainly grown as rainfed crop by resource poor farmers. Though India ranks first in area under groundnut cultivation, the productivity is quite low (1000Kg/ha) compared to that of USA (3000 Kg/ha), China (2600 Kg/ha), Argentina (2100 Kg/ha) and Indonesia (1550 Kg/ha) (Annual Reports, 2005, NRCG, Junagadh). The reason for low productivity of groundnut is due to biotic and abiotic stresses during crop growth. Pests and diseases are the major biotic stresses for groundnut production. Groundnut crop is attacked by about 173

2 90 species of insect pests and among them nine are considered to be economically important. The key insect pests are root grub, red hairy caterpillar, tobacco caterpillar, gram caterpillar, leaf webber, leaf miner, thrips (as vectors of viral diseases), aphids and jassids. In recent years tobacco caterpillar, Spodoptera litura (Fab.), Noctuidae: Lepidoptera has emerged as a major pest of groundnut in India particularly Andhra Pradesh. The farmers of Eastern mandals of Chittoor district in Andhra Pradesh are applying 4-5 rounds of insecticide interventions to manage this pest during post rainy season (Rabi). This pest has acquired resistance to many of conventional and currently available insecticides. Hence there is a need to search for an alternate insecticide, which can fit in to farmer s budget as well in Integrated Pest Management (IPM) programme. MATERIALS AND METHODS The field experiment was conducted at Regional Agricultural Research Station, Tirupati (situated at 13" 27 o N latitude, 79" 36 o longitude and 182.9m above MSL) Andhra Pradesh, India in late Kharif/early Rabi from September/October to January/February for two consecutive seasons from to Groundnut variety (Narayani) released by ANGRAU which is popularly grown in Southern Zone of Andhra Pradesh, was raised in 5 x 5m 2 plot area with 22.5 x 10 cm spacing. Normal agronomic practices were followed for raising the crop. The trial was laid with eight treatments replicated thrice viz., Thiodicarb 75 1g/lt, Spinosad 0.25ml/l, Chlorfenapyr 2ml/l, Quinalphos 2.0ml/l, 1ml/l, Bt 0.1% 1g/l, 250 LE/ha and unsprayed control. Periodical observations viz., pre- treatment, post-treatment data at 3, 7 and 10 days after treatments were recorded on the percent damage caused by Spodoptera litura. The data were analyzed statistically and necessary conclusions were drawn. Pod yield was recorded at the time of harvest and from each treatment, net returns and cost benefit ratio was calculated. 174

3 RESULTS AND DISCUSSION The pooled data analysis indicated that, incidence levels of S. litura before treatment varied from to per cent among treatments and there was no statistical difference between different treatments. However, the incidence levels one week after treatment varied from to per cent. The treatment with Novaluron 1ml/lt was found to be the best treatment with lowest incidence of per cent followed by Chlorfenapyr 2ml/lit with per cent and Thiodicarb with per cent damage which were on par with each other. The next best treatment, Quinalphos 2ml/lit recorded per cent defoliation. NPV 250LE/ha (29.25 %) and (30.63 %) were on par with each other and superior over Spinosad 0.25ml/lt (33.55%) and untreated control (40.56%). Regarding yield and economics, highest yield was recorded from Thiodicarb 1g/lit with (25.67 q/ha) which was on par with Novaluron 1ml/lt (25.25 q/ha) and Chlorfenapyr 2ml/lit (24.83 q/ha). The next best treatments, (23.08 q/ha) and NPV 250LE/ha (21.83 q/ha) were on par with each other and Quinalphos 2.0ml/l(22.92 q/ha). Highest net returns were obtained from Thiodicarb 1g/lit with 1.43 C:B followed by Novaluron 1ml/lt(1.29). In the present study, Novaluron was highly effective against Spodoptera litura on groundnut when compared to other insecticides. Since Novaluron belongs to benzoyl phenyl urea class of chitin synthesis inhibitors, it is known to kill the insects by inhibiting or interfering with chitin deposition (Wellinga et al.,1973). The results of present study are in conformity with Chatterjee and Sarkar (2007), as they reported that 75g a.i /ha and 50 g a.i /ha recorded lowest fruit damage due to S. litura in chilli and highest yield of 1.67 and 18.9q/ha; 1.71% and 18.75q/ha followed by 400 g a.i/ha (2.20% and q/ha) as against control (16.88 % and 11.10q/ha). Similarly, Venkateswarlu, 2004 reported that at LD 90 level, Novaluron was 4.94, 4.14, 1.65 times relatively toxic than Quinalphos, Fenvalerate and Chlorpyriphos, respectively at 24 hours after treatment against third instar larvae of S litura. 175

4 Chlorfenapyr is derived from a natural product dioxapyrrolomycin produced from a culture of Streptomyces fumanus and it acts by disturbing the proton gradient across mitochondrial membranes and prevents mitochondria from producing ATP. The loss of energy production results in cell disfunction and subsequent death of the affected pest organisms. Thiodicarb, a carbamate insecticide was also found effective which was on par with Novaluron and Chlorfenapyr in reducing foliar damage due to, S. litura, because of its activity on nervous system of insect. This was also observed in earlier studies against some noctuid pests (Joyce et al., 1986), Heliothis virescens (Campanhola and Plapp. 1980) and Plusia includens (Hall et al., 2000). The efficacy of Bt was comparatively low on S. litura in the present study, which may be attributed to its slow action. David (1982) reported that, larvae of S. litura itself are immune to B.t.k because of its low gut ph. This result was similar to the studies of Rao (1995), who reported through his studies that Bt at a concentration of 0.15% gave a moderate level of S. litura control (20-30%). On the contrast, Wang et al (1989) reported higher efficacy of Bt at 0.1% against Pieris rapae (90%), Dacus indica (62.5%) and S. litura (82.4%). The treatment with SlNPV was found to be superior over untreated control in the present study, which was similar to the findings of Dhandapani and Babu ( 1995), who reported that two applications of nuclear polyhedrosis 250LE/ha was found to be effective in reducing defoliation by S.litura on groundnut and increased yields over untreated control. Kamala Jayanthi and Padmavathamma (2001) also reported higher efficacy of bioagents like nuclear polyhedrosis 1 x 10 7 PIBs/ ml, Bacillus thuringiensis subsp. 1 x 10 spores/ ml and Beauveria 1 x 10 7 spores/ml against S. litura than the recommended doses of chemical insecticides like 0.005% and 0.025% 176

5 In the present study Spinosad was found to be ineffective against S. litura. This is in agreement with Venkateswarlu (2004), who reported that the LD 50 (23.6 µg/larva) and LD 90 (31.97 µg/larva) values of spinosad were very high and was found less toxic than all the insecticides to which this pest has developed resistance. Rame gowda and Basavana goud (2001) reported that among new molecules like spinosad, polytrin C and profenophos, spinosad showed less efficacy against resistant population of S. litura. On contrary higher field efficacy of spinosad 45SC was found against S. litura on groundnut with 61.8 per cent larval mortality compared to acephate (55.34%), SlNPV, B. bassiana and N.rileyi (Srinivas and Nagalingam, 2005). CONCLUSIONS The studies on management of tobacco caterpillar, Spodoptera litura on groundnut with certain newer insecticides revealed that Novaluron 10% 1ml/lt was found to be best treatment with lowest incidence of per cent followed by Chlorfenapyr 10% 2ml/lit (22.26%) and Thiodicarb (23.83%) which were on par with each other. Highest pod yield of q/ha was recorded from Thiodicarb 1g/lit which was on par with Novaluron 10% 1ml/lt (25.25 q/ha) and Chlorfenapyr 2ml/lit (24.83 q/ha). Bt treated plots recorded 23.08q/ha indicating that Bt can also be recommended as one of the IPM components. Thiodicarb 1g/lit recorded highest net returns with 1.43 Benefit Cost ratio followed by Novaluron 1ml/lt with ACKNOWLEDGEMENTS The authors are thankful to Associate Director of Research, RARS, Tirupati and ANGRAU, Hyderabad for providing necessary facilities to conduct the experiment. REFERENCES Adamczyk J J Jr Leonard B R and Graves J B Toxicity of selected insecticides to fall army worms (Lepidoptera: Noctuidae) in the laboratory bioassay studies. Florida Entomologist, 82(2):

6 Annual Reports, NRCG, Junagadh Campanhola C and Plapp FW Jr Pyrethroid resistance in the tobacco bud worm (Lepidoptera: Noctuidae). Insecticide bioassays and field monitoring. Journal of Economic Entomology, 82(1): Chatterjee M L and Sarkar M A Management of Chilli fruit borer (Spodoptera litura) with novel and non-conventional pesticides. National seminar on Indian Spices; Research Advances and utilization 6 th to 8 th, March, 2007, BCKV, Kalyani, Nadia, West Bengal. David B V Elements of Economic Entomology, Popular Book Depot, Madras PP: 301. Dhandapani N and Babu, P C S Efficacy of nuclear polyhedrosis virus against Spodoptera litura on groundnut in different locations of Tamil Nadu. Madras Agricultural Journal, 82:9-10, Hall T S, Leonard B R, Boethel D J, Gore J, Dugger P (ed.) and Richter D Proceedings of Beltwide cotton conferences, Sanantonio, U.S.A., 4-8 January (2): Joyce J A, Ottens R J, Herzog G A, Bass M H A laboratory bioassay for Thiodicarb against the tobacco budworm, bollworm, beet worm and fall army worm. Journal of Agricultural Entomology, 3(3): Kamala Jayanthi P D and Padmavathamma K Joint action of microbial and chemical insecticides on Spodoptera litura (Fab.) (Lepidoptera: Noctuidae). Journal of Tropical Agriculture, Vol 39, No 2. Kostyukovsky M and Trostanetsky A The effect of a new chitin synthesis inhibitor, Novaluron, on various developmental stages of Tribolium castaneum (Herbst). Journal of Stored Products Research, 42(2) : Ramegowda G K and Basavanagoud K Management of insecticide resistance in Spodoptera litura (Fabricius) by microbial agents and newer molecules. Karnataka Journal of Agricultural Sciences, 14(4): Rao B M Evaluation of baits with selected insecticides against Spodoptera litura (Fabricius). M.Sc.(Ag). Thesis submitted to ANGRAU, Hyderabad. 178

7 Srinivas M S and Nagalingam B Influence of certain microbial agents on Spodoptera litura (Hubner) and coccinellids in groundnut. Journal of Entomological Research, 29(1): Venkateswarlu.U. 2004, Assessment of Insecticide Resistance and Management of Spodoptera litura (Fab.) on Cotton in Guntur and Prakasam districts of Andhra Pradesh, MSc (Ag) Thesis submitted to ANGRAU, Hyderabad. Wang A.I, Huang J N and Hah P E A Study on the control of insects on vegetables with preparation of Bacillus thuringiensis. Zhejiarg Agricultural Science, 2: Wellinga K, Mulder R and Dallen J V A Synthesis and laboratory evaluation of 1- (2, 6-disubstituted benzyol) 3- phenyl ureas, a new class of insecticides. Journal of Agricultural Food Chemistry, 21:

8 Pooled data of Bio-efficacy of New Insecticide Molecules against Spodoptera litura in Groundnut during Late Kharif / Early Rabi, & Treatments Pretreatment T1 Thiodicarb 75WP 1g/lit (34.55) T2 Spinosad 45%SC ml/lt (34.70) T3 Chlorfenapyr 10%SC ml/lit (34.10) T4 Quinalphos 25%EC ml/lit (34.90) T5 Novaluron 10%EC ml/lt (34.13) T6 NPV 250LE/ha (37.42) T7 Bt 1.0g/lt (37.54) T8 Control (35.21) (% Foliar damage) Posttreatment Yield (Q/ha.) C:B (29.21) (35.39) (28.14) (30.99) (27.25) (32.72) (33.59) (39.55) SEM CD (0.05) Figures in parentheses are arc sine transformed values Disclaimer: Statements, informations, scientific names, spellings, inferences, products, style, etc. mentioned in Current Biotica are attributed to the authors and do in no way imply endorsement/concurrence by Current Biotica. Queries related to articles should be directed to authors and not to editorial board. 180