Field evaluation of methyl eugenol trap for the management of Oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae) infesting mango

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1 Field evaluation of methyl eugenol trap for the management of Oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae) infesting mango O. P. REJI RANI, A. PAUL and T. JIJI Department of Agricultural Entomology, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala , India ABSTRACT : Oriental fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritida), is the most destructive pest of mango occurring in homesteads of Kerala. The IPM developed by Kerala Agricultural University as well as farmers practice were evaluated under the unique homestead farming systems of Kerala. Analysis on percentage of fruits infested under different treatments revealed that the percentage infestation was significantly reduced during the two years with methyl eugenol trap (1.13 and 1.34 % respectively) which was on par with the chemical control. Combination of control measures adopted did not show any superiority. Population of B. dorsalis at different stages of the crop when monitored using bait trap and ME trap, revealed that, the population was minimum at flowering stage increased significantly during fruit set and reached its peak in May - June., at the fruit ripening stage. Keywords: Bactrocera dorsalis, bait Application technique, methyl eugenol trap, MAT INTRODUCTION Among 400 species of fruit flies distributed all over the world, Bactrocera dorsalis (Hendel) is the most destructive pest occurring in homesteads of Kerala (Verghese et al., 2002) causing per cent fruit loss in mango when harvested at the mature ripe stage. The extent of damage may go up to 80 per cent when the pest incidence occurs in an epidemic form (Abdullah et al., 2002, Latif, 2004). Due to this menace, fruits in most of the homesteads in Kerala are being harvested at the immature stage for pickling purpose with an intention to avoid fruit damage which turns serious at maturity. In addition to mango this species attacks guava, sapota and papaya (Jiji et al., 2009). Commercial grows often resort to irrational pesticide use resulting in insecticide residue in fruits and it has been reported that more than 30 percent of fruit samples from Kerala markets were contaminated with pesticides (Beevi et al., 2006). In view of the high export potential of mango for which insecticide free fruit is essential, alternate methods for the control of fruit flies were felt desirable and considerable work has been done for standardizing insecticide free alternate technologies. Stonehouse et al., (2005) reviewed the data generated in a multilocational project on the control of fruit flies viz. Integrated management of fruit flies in India and covering various locations and states spread all over India and recommended the adoption of an integrated practice using Bait Application Technique (BAT), Male Annihilation Technique (MAT) and cultural methods (destruction of fallen fruits and soil raking). He also observed that BAT and MAT reduced the crop losses each by 50 percent with little interaction between them. Thus MAT using traps with methyl eugenol as attractant has been reported as very effective against B. dorsalis in different locations in India and abroad (Ravi Kumar and Virakthamakth, 2007). Kerala being unique for its homestead farming system needs a thorough evaluation of components of the above integrated approach. The existing Kerala Agricultural University recommendations as well as the farmers practice for the management of fruit flies were compared with the above components during 2007 and Population build up of the pests during different crop stages were also monitored based on the number of flies caught in the trap. MATERIALS AND METHODS The work was carried out in the homesteads of Kottarakkara block, Kollam district, Kerala. The period of investigation was from flowering season of mango in Kerala (December January) to the period of fruit maturity (April to May) for two years 2007 and Methyl Eugenol Trap (MET), Jaggery Bait Trap (JBT), Kerala Agricultural University package (KAU practice) as well as Farmers practice (FP) was evaluated under homesteads having an area of 0.25 ha. 19

2 Reji Rani et al. Treatment description JBT Malathion (0.1%) and jaggery (20 g -1 l) in coconut shell, replaced at weekly intervals at the rate of 4 traps per tree. MET The trap was designed using a ply wood block of 5x5x1cm 3 impregnated with 6:4:1 mixture by volume of ethyl alcohol, methyl eugenol and malathion 50EC (Stonehouse et al., 2002). The block was soaked in the solution in a glass jar for seven days after attaching a plastic twine on the top middle part of each block with the help of a small nail. The blocks were then dried under shade for two days and were suspended in transparent plastic bottles (250ml) punched with four circular windows of 3 cm diameter along its central circumference. Each bottle with a block was tied to mango trees at the canopy level at a height of 2 m from ground, away from reach of children and animals. Traps were installed at the rate of 1per 0.1 ha at flower stage, and were replaced with freshly prepared ones after 75 days and maintained till harvest. The food bait trap was prepared using jaggery (20g) dissolved in water (100ml) poisoned with 0.5 ml malathion. The bait was taken in coconut shell and hung on the trees at canopy level at Table 1. Percentage of infested fruits at harvest during 2007 and 2008 Traps Fruit infestation (%) JBT (25.69) (32.68) MET (4.98) (5.60) JBT + MET (7.72) (14.86) MET + KAU practice (6.46) (10.58) FP (43.88) (3.73) Control (43.88) (36.76) CD Figures in paranthesis are values after arc sin transformation the rate of 4 traps per tree. Traps were replenished at weekly intervals KAU Practice The University recommendations consisted of malathion (0.1%) spray at monthly intervals, leaves of Ocimum sanctum (20g) crushed and mixed with carbofuran(5g) taken in coconut shells and hung at the canopy level of mango tree at the rate of four traps per tree and collection and destruction of fallen fruits. Farmers Practice Spraying malathion (0.1%) at monthly intervals. Each treatment was replicated five times and data were subject to analysis using Randomized Block Design. Observations were recorded on weekly catch of flies in the trap, percentage of fruits damaged in each treatment and average yield of the homestead. RESULTS AND DISCUSSION Fruit fly infestation Analysis on percentage of fruits infested under different treatments (Table1) revealed that the infestation was significantly reduced during the two years with ME trap (1.13 and 1.34 per cent respectively). Its combination with KAU package as well as with JBT also reduced the infestation levels (1.29, 2.89 KAU practice; 1.83, 6.69 JBT). In farmers practice where chemical measures alone were used, infestation was low (1.74, 0.74) and on par with ME trap and its combinations. But JBT alone could not reduce the infestation levels. However the infestation levels were reduced to as against 48.4 per cent in control plots. Since the combination of control measures adopted did not show any superiority compared to ME trap when used singly, it may be inferred that ME trap alone is sufficient to manage the pest. Jiji et al., (2009) also observed significant reduction in infestation of mango fruit fly in farmers field where ME traps were kept. During the second year, even though the fruit loss was highest (29.33%) in plots treated with bait trap, it was significantly lower (36.76%) than that in the control plots. This indicates repeated trapping is essential to reduce infestation in the subsequent year. Nasiruddin et al., (2008) has highlighted that continuous trapping create cumulative negative effect on population build up of fruit fly resulting in higher yields. They have also reported that baiting effectively reduced fruit infestation when compared to non baited fields. 20

3 Methyl eugenol trap for mango fruit fly Table 2. Mean number of B. dorsalis per catch at weekly intervals 21

4 Reji Rani et al. Fruit fly catch in different traps Population of B. dorsalis at different stages of the crop when monitored using MET and JBT, from flowering to fruit ripening (Table 2) revealed that, the population was minimum in January i.e, at flowering stage, increased significantly during fruit set and reached its peak in May - June, at the fruit ripening stage. The catches in ME trap were always significantly higher when compared to those in bait traps, throughout the monitoring period. Using MET, minimum catch was at flowering (January) and maximum at fruit maturity (April-May). But at ripening a declining trend was observed (86.40). In homesteads where both bait and ME traps were used, population build up started in January (59.00) gradually increased at fruit set (150.6), declined during tender fruit stage in March (120.00), reached maximum at development stage (252.00) and declined significantly at ripening (27.2) June. When KAU practice was adopted, even though the catch was significantly high during the fruit setting stage (248.00) there after, a decline was observed during fruit development stage (81.20), peak in maturity stage (151.20) and decreased significantly to its minimum at ripening (73.80). At the end of the monitoring period in all the treatments, population reduction was observed indicating the efficacy of control measures adopted in time. The decline in population during the ripening stage when monitored using ME trap separately and in combination, reflects the efficacy of the ME trap in controlling the population. This finding is in accordance with the findings by Ishaq et al., 2004, Stonehouse et al., 2005, Jiji et al., 2009 who reported that among the various management strategies tested ME trap + Bait was the most effective technique. The declining trend during the tender fruit stage observed in these treatments might be an indication of efficacy of the trap in controlling the population and not the deterioration of field performance of the trap which is indicated by the peak catch that was observed during the fruit maturity stage (April- May). The study by Lutap et al., (2009) also revealed a peak population of fruit flies during May- June, when monitored using ME trap. Population reduction observed during the end of the monitoring period may also be attributed to the fact that the crop was nearing to the end of harvesting stage in all the experimental plots irrespective of the treatment. Cost factor analysis Popularity of any plant protection measure depends not only on the control obtained but also on the benefit derived from its use. Cost benefit ratio determines the economic viability of any plant protection measure. According to the package of practice recommendations of the Kerala Agricultural University, chemical spray of malathion (0.1 %) is to be given at monthly intervals from initial fruit set to harvest (3 sprays). In addition to this oscimum + carbofuran trap at the rate of 4 traps per tree is also recommended. For protecting one tree from fruit fly 30 ml malathion is required (100ml malathion cost Rs.50). Cost of malathion is Rs. 9. Labour cost for three spraying is Rs.150. Cost of carbofuran (200 g) required for one tree per season is Rs.15. Thus pesticide application per tree per season works out to be Rs. 174/ - Where as cost of methyl eugenol trap is Rs.100 per homestead not exceeding 0.25 ha and does not involve labour cost. Hence methyl eugenol trap is cost effective when compared to chemical control. Sapkota et al., (2010) also concluded that spraying insecticides for the management of fruitflies is worthless. Fruit fly being a menace to mango growers world wide, deserves much attention to formulate an effective eco friendly pest management practice. This study substantiates the suitability of ME trap for the management of fruit flies being safe and cost effective. Wide area adoption of this technology by farmers can bring more encouraging results. ACKNOWLEDGEMENT The authors are grateful to Indian Council of Agricultural Research and Kerala Agricultural University for providing necessary facilities to carry out the study. REFERENCES Abdullah, K., Akram, M. and Alizai, A. A Non traditional control of fruit flies in guava orchards in D. I. Khan. Pakisthan Journal of Agricultural Research, 17(2) : Ishaq Mohammad, Usman Muhammad, Asif Muhammad and Khan, A Integrated Pest management of mango against mealy bug and fruit fly. International journal of Agriculture and Biology, 6: Jiji, T., Suja, G and Verghese, A Methyl Eugenol traps for the management of fruit fly Bactrocera dorsalis Hendel in Mango. Proceedings of the 21 st Kerala Science Congress, January 2009 pp Latif, A Integrated management of fruit flies (Diptera:Tephritidae) in Pakisthan. Annual report, Agricultiral Linkages programme. PAARC, Islamabad

5 Methyl eugenol trap for mango fruit fly Lutap, L. A., Barroga, S. F. and Atis M. I Mango fruit fly: Population fluctuation and effectiveness of bait trap for its control. Ilocos Agriculture and Resources Research and Development Consortium. Nasiruddin, S. N., Alam, M., Korsheduzzaman, M., Jasmine, A. N., Karim, M. R. and Rajotte, E Online publication on http// vt.edu/ipmcrsp/ communication/ammrepts/annreppoz/bangladesh/ bang-topic. Ravikumar, P. and Virakthmath, S Attraction of fruit flies to different colours of Methyl Eugenol Traps in guava and mango orchads. Karnataka Journal of Agricultural Science, 20 (4) : Sapkota, R., Dahal, K. C. and Thapa, R. B Damage assessment and management of cucurbit fruit flies in spring-summer squash. Journal of Entomology and Nematology, 2(1): Stonehouse, J. M., Mahmood, R., Paswal, A., Neemford, J. D, Baloch, K. N, Chaudhary, Z. M, Makdum, A. H., Mustafa, G. and Huggett, D Farm field assessments of fruit flies (Diptera: Tephritidae) in Pakistan: Distribution, damage and control. Crop Protection, 21: Stonehouse, J. M., Verghese, A., Mumford, J. D., Thomas, J., Jiji, T., Falerio, R., Patel, R. K., Shukla, R. P., Singh, H. S., Satpathy, S., Singh, A. and Sardana, H. R Research Communications and recommendations for the on farm IPM of tephritid fruit flies in India. Pest management in Horticultural Ecosystems, 11(2): Verghese, A., Nagaraju and Sreedevi, N. N Pre and post harvest IPM for management of mango fruit fly Bacterocera dorsalis( Hendel). Proc.of seventh Int. Sym. On Fruit flies of Economic Importance, September 2006, Salvador, Brazil MS Received : 27 May 2012 MS Accepted : 25 June