Indian Journal of Experimental Biology Vol. 41, April 2003, pp. 376-378

Evaluation of entomopathogenic nematode, Steinernema feltiae against field population of mustard , lug ens proxima (Klug) on radish

K Narayanan Project Directorate of Biological Control, Hebbal, Bangalore 560 024, India and C Gopalakrishnan

Division of Entomology and Nematology, IIHR, Hessargatta, Bangalore 560 086, India Received 19 July 2002; revised 4 February 2003

Mustard sawfly, A. lugens proxima, was found to be highly susceptible to entomopathogenic nematode, S. feltiae under 3 4 5 laboratory condition. Application of three differeIll doses of S. feltiae, viz. 1.1 x 10 , 1.1 X 10 and 1.1 x 10 infective juveniles/ml, at weekly intervals, significantly reduced the field population of mustard sawfly on radish. The mean larval population of A. lugells proxima in all doses of nematode treated plots ranged from 0.42 to 0.48 larvae per plant as against 2.95 larvae / plant in untreated control plots. Similarly, the yield of radish in all the nematode treated plots was significantly higher by way of recording 2.80 to 2.87 tons/ ha as compared to 1.63 tons/ha in the case of control.

The entomopathogenic nematode, Steinernema feLtiae placed in petridishes, moistened with 1ml of sterile (Neoplectana carpocapsae, commonly called DD- distilled water, and then inoculated with 1000 infec­ 136) (Rhabditida: Steinernematidae) has a wide host tive juvenile (IJ) of nematodes in 2 ml sterile distilled range '. This nematode along with its associated gram water. Ten to 15 sixth instar larvae of G. mellonella, negative, non-sporulating entomopathogenic bacte­ were placed in each dish which were then sealed with rium, Xenorhabdus nematophilus, infect many parafilm to prevent desiccation. All treated pests and has considerable promise as a biological were maintained at 25°C. About 7-8 days after the control agent because of its high virulence and repro­ initial exposure to the nematodes, the dead insects ductive potential compatible with other methods. Fur­ were dissected and examined for the presence of ther it is safe to non-target organisms, easy to produce nematodes, using a dissection microscope. The har­ and easy to apply. The mustard sawfly, Athalia Lugens vested infective juveniles were maintained at 10°C in proxima (Tenthridinidae: ) is one of the 0.1 % formalin at a concentration of 1000 nematodes very few serious hymenopteran insect pests on cab­ per ml. New nematode stock was obtained every' 3-4 bage, cauliflower, turnip and radish. Though parasi­ weeks. Nematodes were diluted with water or concen­ 2 toid has been recorded on A. Lugens proxima , no trated by centrifugation as and when needed. pathogens have been reported. The present communi­ Ten to twenty larvae of different. stages (depending cation deals with the effect of entomopathogenic upon the availability) of mustard sawfly, A. [llg ens nematode, Steinernema feLtiae against laboratory and proxima were exposed to 1.1 x 10:' infective juve­ field populations of mustard sawfly, A. lug ens niles/ml. In the case of field trial, three different doses 3 4 5 proxima, on radish. of the nematode, viz. 1.1 x 10 , 1.1 x 10 and 1.1 x 10 The nematode S. feLtiae, (Leningrad strain) culture infective juveniles (IJ)/ml along with Triton x-IOO obtained from erstwhile Common Wealth Inst!tute of (0.01%) was employed. Triton x-100 sprayed alone Biological Control (CIBC), Bangalore, was mass cul­ served as untreated control. The field experiment was tured on the greater wax moth larvae, Galleria mel­ conducted with five replications in a randomized lonelLa in the laboratory as described by Dutky et {f1.3. block design with a plot size of SM x 4M, at Indian Two sterilized Whatman No. I-filter papers were Institute of Horticultural Reseach (I.I.H.R.) Hessara­ ghatta Farm Bangalore. The spraying was done using E-mail: kn_pdbc @rcdiffmail.colll Phonc: 080-351 19R2-40 (0) high volume knap-sack sprayer with the spray fluid of Fax : 080-341 196 i 10.000 liters/ha. The doses were fixed using nematode NOTES 377 counter under stereo zoom microscope. Three rounds mean larval counts of 0.43 and 0.42 larva/plant re­ of nematode sprays at 7 days intervals were given corded in the other two higher concentrations, viz. from the time the insect pest was noticed on the foli­ 1.1 x 105 and 1.1 x 104 IJ/ml tested, respectively age. The nematode spray was given during evening (Table 1). Those radish plants which are not protected hours after 1600 hrs, since solar radiation and ultra­ by the spraying of S. feLtiae showed progressive leaf 4 violet light are detrimental to s. feLtiae . Observations feeding damage caused by Athalia Lugens proxima. on the infestation were based on the number of larvae And at the final stage only the midribs and stems are on ten plants selected at random per plot at weekly left out, in contrast to S. feLtiae treated radish crop. intervals. Counts were taken starting from first appli­ Similarly, the mean yield of 2.80 tons/ha of radish cation. Pre-treatment counts were also taken. Yield obtained in the lowest dose of 1.1 x 103 IJ/ml was sta­ data were recorded for all the treatments including tistically on par with the mean yield of 2.87-2.86 control check. The larval counts were transformed tons/ha obtained in the other two higher concentra­ into --ix + 0.5 as per the method developed by Poisson tions, respectively (Table 2). Thus, the nematode @ 5 3 for statistical analysis . 1.1 x 10 IJ/ml is ideal for getting desired control Nearly all the stages of larvae tested were highly against the insect pest on radish. susceptible. The cadavers of all insects contained Earlier, Narayanan and Gopalkrishnan6 have shown large number of nematodes progeny 7 days after in­ the efficacy of S. feLtiae against pre-pupa, pupa and oculation. Insects infected with Steinernematids were adult of Spodoptera litura. The field efficacy of discoloured with bluish white in contrast to dark col­ S. feLtiae on mustard sawfly was in conformity with oured healthy larvae. The dead insects were flaccid earlier report of Narayanan and Gopalkrishnan 7 who and remained intact. Upon dissection, the tissues had had shown the field efficacy of S. feLtiae on He/i­ a gummy consistency and did not have putrid odour. coverpa armigera and on blister beetle MyLabris pus­ Secondary microorganisms were usually not present tuLata on vegetable pigeon pea. Further, for the nema­ in great numbers because the associated bacterium tode to act on the insect pest, ideal conditions like produces an antibiotic effed. It is well known the moisture and temperature are very essential. Radish nematode needs the association of bacterium for its crop with thick broad leaves close to the ground and growth and development, and the bacterium n·eeds the Table 2 - Effect of 00-136 nematode on radish yield nematodes to invade the host 3. The nematode can kill its host without its associate bacterium but is unable [Values are mean of 5 replications] to reproduce, and the bacterium cannot invade the Treatment Yield (tons!ha) haemocoel of its host without the nematode. 5 I. 00-136 @ 1.1 x 10 Juveniles! ml 2.87 4 There was no significant difference among the 2.00-136 @ 1.1 x 10 Juveniles! ml 2.86 3 three doses of nematodes tested, either in the larval 3. 00-136 @ 1.1 x 10 Juveniles! ml 2.80 counts or in the yield of radish. The mean larval 4. Control 1.63 counts of 0.48 larvae/plant obtained in the lowest dose C.O (P=0.05) 0.44 of 1.1 x 103 IJ/ml was statistically on par with the *Mean of five replications

Table I - Effect of 00-136 nematode on larval population of mustard sawfly, Athalia lugens proxima on radish [Values are mean of 5 replications] Trea tment Before spray After spray I count " count III count Means 5 I. 00-136 @ l.l x 10 Juveniles! ml 0.55 0.90 0.35 0.05 0.43 (1.51 ) ( 1.19) (1.20) (0.46) (0.95) 4 2.00-136 @ 1.1 x 10 Juveniles! ml 0.60 0.80 0.45 0.00 0.42 (1.51 ) ( 1.78) (1.35) (0.31) (1.15) 3 3. 00-136 @ 1.1 x 10 Juveniles! ml 0.65 0.90 0.50 0.05 . 0.48 (1.61 ) ( 1.90) ( 1.43) (0.46) ( 1.26) 4. Control 0.65 5.55 2.50 0.80 2.95 (1.63) (4.68) (2.99) (1.81 ) (3.16) C.O (P=0.05) NS 0.64 0.42 0.28 0.45 Figures in parenthesis are arc sine transformation values NS: Non significant 378 INDIAN 1 EXP BIOL, APRIL 2003 also irrigation of the crop, twice or thrice a week, Athalia proxima Klug. by Apanteles glomerotus. Linnaeus. provide ideal condition for the nematode to act on the Bull. Entomol, 33 (1992) 155. 3 Outky S R, Thompson 1 V & Cantwell G E, A technique for insect pest. Since radish is a short duration crop, use the mass propagation of the 00-136 nematode, 1. Insect. of insecticide may lead to accumulation of residues in Pathol, 6 (1964) 417. the storage part of the crop and hence the use of 4 Gaugler R & Boush G M, Effects of ultraviolet radiation and nematode for the control of A. lugens proxima on sunlight on the entomogenous nematode, Neoaplectana cmpo­ capsae, 1. Invertebr. Pathol, 32 (1978) 29l. radish can be recommended as a safe biological con­ 5 Snedecor G W & Cochran W G, Statistical methods. (Iowa trol method in future. State Univ. Press, Ames.) 1957,593. The authors are thankful to the Director, I.I.H.R. 6 Narayanan K & Gopalakrishnan C, Effect of entomogenous for the facilities. nematode, Steinernema feltiae (Rhabdidae: Steinernematidae) to the prepupa, i3upa and adult of Spodoptera litura F. (Noc­ tuidae: Lepidoptera), Indian 1. Nematol, 17 (I 987a) 273. References 7 Narayanan K & Gopalakrishnan C, Integration of Heliothis Poinar G 0 Jr, Nematodes for biological control of insects: nuclear polyhedrosis virus with 00-136 nematodes for the (CRC Press. Inc. Boca Raton,Florida) 1979. control of pests on vegetable pigeon pea. Proc. "National 2 10hri R, Pandey U K, Pandey N 0 & 10hri P K, Influence of Symposium on Integrated Pest Control-Progress and Perspec­ host plants on the parasitisation of grubs of mustard sawfly, tives". Trivandrum, (l987b) 32.