Efficacy of Biobit Against Teak Defoliator, Hyblaea Puera Cramer*

Karnataka J. Agric. Sci., 21 (1): (134-136) 2008

Efficacy of Biobit Against Teak Defoliator, Hyblaea puera Cramer*

Bacillus thuringiensis (B.t) Berliner is one of the few larval mortality was calculated for each instars at different doses available broad spectrum and ecologically safe insect control tested. The data were subjected for ANOVA test by adopting agents ( Burges and Hussay, 1971). Chemical as well as biological C.R.D. The total mortality corrected for control by adopting methods have been tried in the past to control the teak defoliator, Abbott”s formula (1925) as follows. Hyblaea puera (Singh, 1980, Nair et al. 1995), but none have been found satisfactory. In forests, the scope of chemical control % test mortality -% control mortality is limited because of environmental concern, but biological Percent corrected mortality=______control using naturally occurring pathogens is found 100 -% control mortality satisfactory. Currently scientists have been concentrating more on the use of pathogens for pest management as these have The effects of commercial formulation of Biobit tested potentialities over the conventional spraying of chemical at laboratory conditions revealed that, Biobit expresses its action pesticides. Bacillus thuringiensis is one among commercially after 10-15 hours of the larval feeding on the sprayed leaves and available control agents that has long range of host killing ability. with clearly visible symptoms after 24 hours of feeding. The B. thuringiensis and its toxins have been reported to be highly results on the efficacy tests demonstrated the effectiveness of effective against H. puera ( Kalia and Lall, 2000 ). As for as the Biobit on all the larval instars in causing larval mortality. It use of different commercial products is concerned, few reports caused 100 per cent mortality in first to third instars with in 72 hr. are available (Singh and Misra, 1978, Loganathan and David, of treatment. The larval mortality was reduced to 29.5 and 51.5 2000 and Senguttuvan et al., 2000) Therefore present study was per cent in fifth and fourth instars, respectively, and was undertaken to test the conventional commercial products of statistically found significant in causing larval mortality (Table- Biobit (B.t ) at different concentrations against the larvae of 1). H.puera. during 2004 in the college of forestry Sirsi. Among the different concentrations of Biobit tested, Commercial formulation of B.thuringiensis, BiobitÒ 0.5, 1.0 and 1.5 g/l. dose, proved to be effective against larvae was evaluated for its pathogenicity against larvae of teak of H. puera and caused 78.5, 80.1 and 78.5 per cent mean larval defoliator, H. puera. The product was diluted with distilled mortality, respectively and were significantly superior over the water and tested at the doses of 0.1, 0.2, 0.5, 1.0 and 1.5 g/l. per cent larval mortality recorded at 0.1 and 0.2 g/l. However, the Larvae were collected from the foliage of teak and reared in the laboratory by providing fresh leaves of teak as food. The per cent larval mortality by Biobit used at 0.1 and 0.2 g/l. was different larval instars were separated before the initiation of statistically on par with each other (Table 1). the experiments. Food supply was stopped a day prior to the The data summarized on per cent larval mortality by starting of the experiment so as to starve the larvae. To find out Biobit (B.t) against different larval instars indicated that the the efficacy of Biobit on the third, fourth and fifth instars larvae, mortality caused by Biobit was higher at higher concentrations different doses of Biobit was sprayed on two years old teak especially against early instars larvae compared to later instars. seedlings by hand sprayer. Ten twenty four hours old starved This shows that the target pest is highly susceptible to Biobit larvae of third, fourth and fifth instars were released separately and the present findings are in agreement with the observations in wire mesh cage (35x30x30 cm hxbxl) and the treated leaves of Loganathan and David (2000), Senguttuvan et al. (2000) and were plucked and provided as food for feeding. Kalia and Lal (2000) who have reported that B. t is effective on To assess the susceptibility of first and second instars the early instars larvae than the later instars. larvae of H. puera, tender leaves of teak were collected from the The action of B. t starts at 10-15 hours after the larval field, washed with tap water and cut into circles of 10 cm diameter feeding on the sprayed leaves and symptoms were clearly visible and the leaf discs were dipped in different doses of Biobit for one minute and the dipped leaf discs were later placed on the after 24 hr of feeding. The larvae at first, develop light brown agar media to keep turgidity of the leaf and maintained in plastic colour, shrink in size and finally turn dark brown with concomitant cups. Ten larvae of first and second instars were allowed to feed larval death. Kalia and Lal (2000) showed that paralysis of the in each leaf disc for 24 hr. After 24 hr. of feeding larvae were midgut occurs within 15- 20 minutes after the ingestion of the separated and tender teak leaf was provided separately for Bacillus followed by general paralysis of the entire body within feeding. The experiment contained three replications having 7 hr. leading to fatal septicemia. It has also been reported that ten larvae in each replication. The water spray remained as spraying of B. t on host plants is more effective in killing the control. The observation on the number of dead larvae due to larvae than spraying directly on the target pest (Roychoudhury B.t infection was recorded at 24, 48 and 72 hr and per cent total et al., 1994; Kalia et al., 1997, Kalia and Lal 2000).

*Part of Ph. D. thesis submitted by the senior author to the University of Agricultural Sciences, Dharwad - 580 005, India. 134 Karnataka J. Agric. Sci., 21 (1): 2008 Mean otal T 100.0 100.0 100.0 100.0 100.0 100.0 ------15.0 17.5 32.5 29.5 - 24 48 72 CV % 10.53 - - otal 62.5 35.0 20.0 30.038.0 60.0 51.5 T 100.0 100.0 100.0 100.0 100.0 100.0 ------22.5 38.0 - 24 48 72 -40.0 Cramer under laboratory condition otal CD at 0.01% 11.47 T 100.0 100.0 100.0 100.0 100.0 100.0 Dose (g/l) Hyblaea puera ------20.0 12.5 32.5 37.5 22.5 60.0 - - 24 48 72 Per cent larval mortality after (hr) ferent larval instars of otal 32.5 T 100.0 100.0 100.0 100.0 100.0 100.0 SEm ± 1.11 4.64 1.37 5.13 3.06 (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) on dif - 7.5 15.0 20.0 WP)Ò -- -- 5.0 2.5 25.0 (9.1) - - 24 48 72 97.5 Berliner (Bio-bit otal Factor Instar Concentration Interaction 25.0 73.5 70.5 78.5 80.1 78.5 T 100.0 100.0 100.0 100.0 100.0 (59.0) (57.0) (62.4) (63.5) (62.4) - - - 5.0 0.1 0.2 0.5 1.0 1.5 Bacillus thuringiensis 5.0 20.0 20.0 22.5 42.5 (26.5) (12.9) (30.0) (12.9) (22.8) (26.6) (26.6) (20.7) (34.7) (38.1) (38.1) (22.8) (24.7) (34.7) (32.9) (26.5) (28.3) (40.7) (30.0) (15.9) (34.7) (37.7) (28.3) (50.7) (39.3) (28.3) (52.2) (36.3) (26.5) (33.2) (50.7) (45.9) ficacy of - - 24 48 72 95.0 90.0 10.0 85.0 15.0 (77.0) (12.9) (90.0) (80.9) (71.5) (18.4) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (67.2) (22.7) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) (90.0) able 1. Ef T Lar- val instar Mean V I II III IV Figures in the parentheses are arc sine transformed values 135 Efficacy of Biobit (Bt) Against......

Department of Forest Protection JAVAREGOWDA Forestry College, Sirsi, India L. KRISHNA NAIK (Received: August, 2007)

References

Abbot, W.S., 1925, A method of computing the effectiveness of an (Lepidoptera: Hyblaeidae) using insect parasitoids, problems insecticides. J. Econ. Ent.,18 : 265-267. and prospects in: Biological Control of Social Forest and plantation crops insects.1995, Ed. Ananthkrishnan, T.N. Burges, H.D. and Hussay, N.W., 1971, Microbial Control of Insects Oxford and IBH Publishing Company Private Limited, New and mites 1971. Academic Press, New york, pp. 861. Delhi. 75-95.

Kalia S., Joshi, K.C. and Pant, N.C., 1997, Effectiveness of three Roy Choudhury, N., Joshi, K.C., Sambath, S. and Pande, 1994, toxins of Bacillus thuringiensis against shisham defoliator Effectiveness of three varietal toxins of Bacillus thuringiensis plecoptera reflexa. J. App. Zool. Res., 8 : 115-116. against teak leaf skeletonizer, Eutectona machaeralis walker (Pyraliadae). My forest, 30: 57-60. Kalia,S and Lal, R.B., 2000, Efficacy of three varietals toxins of Bacillus thuringiensis tested against some important forest insect pests Senguttuvan, T., Chinniah, C., Varma, R.v. And Nair, K.s.s., 2000, of multipurpose forest tree species. Indian Forst., 126: 62-66. Knockdown toxicity of insecticides and B.t. formulations on larvae of teak defoliator, Hyblaea puera. Indian J. Fort., 23: Loganathan, J. and David, P. M. M., 2000, Laboratory and field 160-163. evaluation of Bacillus thuringiensis Berliner products against Singh, P., 1980, Aerial spraying of chemicals to control teak defoliators. the teak defoliator Hyblaea puera Cramer. Insect Sci. Appl.,20: Proc. of the 2nd For. Conf. DehraDun, India, 901-907. 61-65. Singh, P and Misra., R.M, 1978, Bio-assay of thuricidae, microbial Nair, K.S.S., Mohandas, K. and Sudheendrakumr, V. V., 1995, Biological insecticides, against important forest pests. Indian For., 12: control of the teak defoliator, Hyblaea puera Cramer 836-842.

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