J./Jiol. COlllrol. 8 (]), 59-60, 1994 Influence of Lablab Bean Varieties on The Nuclear Polyhedrosis Virus Mortality in Larvae of Helicoverpa armigera (Hbn.)* M.MUTHUSWAMI, R.I. RABINDRA and S. JAYARAI Departmen t of Agricultural Entomology Tamil Nadu Agricultural University Coimbatore - 641 003 The nuclear polyhedrosis virus (NPV) has batore. From each variety, three shoots con­ heen found to be effective in the control of tainingbuds, flowers and young pods were Helicoverpa armigera (Hbn.) on several crops treated by dipping in the virus suspensions. The (Jayaraj et at., 1989) including lablab been shoot ends were kept immersed in water taken (Jayaraj et ai., 1987). Studies on the influence in 100 mt conical flasks. After shade drying of of varieties of host plants on the activity of the treated shoots, 10-12 second ins tar larvae NPV are rather limited. Rabindra et ai. (1992) of H.armigera were released per shoot for each studied the effect of different chickpea treatment. There were three replications. After varieties on the NPV - control of H. armigera. 24 h of feeding, the larvae were transferred The present study was carried out to find out indi vidually to vials containing semi- synthetic the influence of lablab bean Dolichos lab lab (L.) diet. Observations on mortality were recorded varieties on the mortality caused by NPV in lar­ daily for ten days. vae of H.armigera. The mortality data showed that there were Mass culturing of the larvae was carried out significant differences on NPV mortalities in the in the laboratory following standard methods different varieties of lablab on all the three days (Shorey and Hale, 1965; Rabindra and Jayaraj, of observation. NPV + adjuvants gave significant­ 1988). The NPV used in this study was obtained ly higher mortality than NPV applied alone in all from the stock maintained in the Department of the three periods of observation (Table 1). Agricultural Entomology. The virus was The 10th day data showed that the virus propagated by inoculating either late fourth or mortality was significantly highest in Co 5 and early fifth instarlarvae with the NPV con­ lowest in Co 3. This difference between Co 5 centration of 108 POB/m) following the and Co 3 was seen in the 5th and 7th days also. methods of Rabindra and Jayaraj (1986). Dis­ The interaction between treatments and eased larvae were homogenized in distilled varieties was significant only in the 10th day. water, filtered through a cheese cloth and semi­ On all the varieties, addition of adjuvants sig­ purified by differential centrifugation. The nificantly enhanced the mortality due to NPV. strength of polyhedral occlusion bodies (POB) was assessed using an improved Neubauer The difference in moralities may largely be haemocytometer. attributed to differences in feeding rates. Fee­ ding preference of larvae may influence the Varietal influence of seven lablab bean NPV mortality in insects. Larvae feeding on varieties on NPV mortality of H. armigera was host plants supporting better growth are more studied under laboratory conditions. The virus susceptible to virus. High food quality and was tested at a dose of 104 POB/ml either alone good insect growth were positively correlated or in comhination with cotton seed kernel ex­ with increased mortality due to GmNPV in Gal­ tract IO<}(, + crude sugar 1O'/(!. The lahlab hean leria l1lellonella L. larvae (Schultz and Keat­ varieties (Co 2. Co 1, Co 5. Florika field, Pan­ ing, I (}9\). Level of resistance in the crop thai Avarai J No. I. J>usa prolific and Kanus­ varieties to the insect may also influence the ward) were raised in Pulses Brcl'din g Station of mortality due to NPV. In chickpea. H.annigera TamilNadu Agricultural 11nivcrsity, COiHl- Part of rcscarrh work 1IIIlllnl hy U.S,n.A. through \lSIF (PI ,IXO) scheme 60 MUTHUSWAMI et al. Table 1. Varietal influence of lablab bean on the mortality caused by HaNPV in second instar larvae 4 of H.armigera at a dose of 10 POB/ml % Larval mortality days after inoculation 5 7 10 Varieties NPV + NPV+ NPV+ NPV Mean NPV Mean NPV adjuvants Mean adjuvant* adjuvants Co 2 3.33 26.67 15.00 13.33 40.00 26.67 20.00 60.00 40.00 (6.14) (30.99) (18.57) (21.14) (39.14) (30.14) (26.56) (50.76) (38.66) Co 3 3.33 23.33 13.33 6.67 36.67 21.67 10.00 56.67 33.33 (6.14) (28.78) (17.46) (12.29) (37.22) (24.75) (18.43) (48.84) (33.64) CoS 16.67 36.67 26.67 33.33 56.67 45.00 40.00 66.67 53.33 (23.85) (37.22) (30.53) (35.21) (48.84) (42.03) (39.23) (54.78) (47.00) Florika field 13.33 33.33 23.33 26.67 46.67 36.67 33.33 60.00 46.67 (21.14) (35.21) (28.78) (30.99) (43.07) (37.03) (35.21) (50.76) (42.99) Panthal A varai J 13.33 33.33 23.33 23.33 50.00 36.67 30.00 56.67 43.33 No 1 (21.14) (35.21) (28.78) (28.18) (45.00) (36.89) (33.21) (48.84) (41.02) Pusa Prolific 13.33 30.00 21.67 23.33 50.00 36.67 33.33 56.67 45.00 (21.14) (33.21) (27.17) (28.78) (45.00) (36.89) (35.21) (48.84) (42.03) Kanusward 10.00 23.33 16.67 13.33 40.00 26.67 16.67 60.00 38.33 (15.00) (28.78) (21.89) (21.14) (39.14) (30.14) (23.85) (50.76) (37.31) Mean 10.48 29.52 20.00 45.71 26.19 59.52 (I 6.36) (32.77) (25.47) (42.49) (30.24) (50.51) C.D. for varieties 7.51 ** 5.62** 3.00** C.D. for treatments 4.01 ** 3.00** 1.60** C.D. for interaction NS NS 8.77** * Cotton seed kernel extract 10% + Crude sugar 10% Figures in the parentheses indicate angles corresponding to percentages larval mortality due to NPV was found to be RABINDRA, R.J.and JAYARAJ, S. 1986. Multi­ significantly higher on Heliothis- susceptible plication and use of nuclear polyhedrosis viruses for the control of important crop pests. varieties (Shoba and Annigeri) than on the In ; S.Jayaraj (ed.) Pest and Disease Manage­ resistant accessions (ICC 506 and ICC 10817) ment : Oilseeds, Pulses, Millets and Cotton. pp. (Rabindra et at., 1992). 51 - 61. Tamil Nadu Agric. Univ., Coimbatore. RABINDRA, R.J. and JAYARAJ, S. 1988. Evalua­ KEYWORDS: Lablab bean, NPV, Helicoverpa tion of certain adjuvants for nuclear polyhedro armigera sis virus (NPV) of Reliothis armigera (Hbn.) on chickpea. Indian J. Exptl. Bioi., 26, 60 - 62. REFERENCES RABINDRA, R.J., SATHIAH, N. and JAYARAJ, S. JAYARAJ, S., RABINDRA, R.J. and 1992.Efficacy of nuclear Polyhedrosis virus NARAYANAN, K. 1989. Development and use ~gainst Helicoverpa armigera (Hbn.) on of microbial agents for control of Retiothis spp. Reliocoverpa- resistant and susceptible varieties (Lepidoptera: Noctuidae) in India. In: E.G.King of chickpea. Crop Prot.,ll (8),320 - 322. and R.D. Jackson (eds.). Proceedings of the workshop on Biological control of Reliothis : SCHULTZ, J.C. and KEATING, S.T. 1991. Host­ Increasing the effectiveness of natural enemies. Plant Mediated interactions bctween the gypsy pp. 483 - 503. November 11 - 15, 1985. New moth and a baculovirus, In: P.Barbosa, Delhi, India. V.S.Krishchide and C.G. Jones (cds.) Microbial Mediation of Plant Herbi vore Interacti Oil s. pp. JA YARAJ, S., RABINDRA, R.J.and SAN­ 489 - 504. John Wiley & Sons, Inc. THARAM, G. 1987. Control of Retiothis ar­ migera (Hubner) on chickpea and Lablab bean SHOREY, H.H. and HALE, R.L. 1965. Mass rcaring by nuclear polyhedrosis virus. Indian J. agric. of the larvae of nine noctuid species on a simple Sci., 57,738 -741. artificial medium. J. Econ. Entomol.. 58. 422 - 524. .