Field evaluation of pumpkin, Cucurbita moschata Duch. ex Poir. cultivars against melon fly, Bactrocera cucurbitae (Coq.) in the foot hills of Himalayas ROSHNA GAZMER, NRIPENDRA LASKAR and GOBINDA ROY Department of Agricultural Entomology, Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal, India-736165 E-mail: roshnagazmer04@gmail.com ABSTRACT: Twenty pumpkin cultivars collected from different sources from all over India have been evaluated against the infestation of melon fly Bactrocera cucurbitae (Coq.) under terai agro-ecological conditions of West Bengal. The cultivars responded variously against melon fly infestation. Intensity of infestation significantly varied from 50 % to 100 % among the test cultivars. Maximum infestation was recorded on cultivar Pumpkin collection, Eluru, followed by Gagan Sardara Para-1, Tripura and Barahmasi, Varanasi, Uttar Pradesh. Minimum percent fruit infestation was observed in cultivars Baidyabati, Debgiri seed, Kolkata, followed by Pumpkin collection, Gagan Sardar Para-2, Tripura, followed by Pumpkin collection, Pasighat-1, Arunachal Pradesh. The variation in melon fly infestation among the cultivars might be due to bio-physical/ biochemical parameters of the fruit. Keywords: Bactrocera cucurbitae, Cucurbita moschata, Pumpkin, melon fly, resistance INTRODUCTION Pumpkin (Cucurbita moschata var Duch. Ex Poir.) is one of the most important cucurbitaceous vegetable crops grown as a sole crop as well as relay crop with potato. Young leaves, flowers, immature and mature fruits of pumpkin are used as vegetable. This cucurbitaceous vegetable suffers intense insect-pest attack due to favourable conditions available for their multiplication and development.the fruit fly, Bactrocera cucurbitae (Coq.) (Diptera: Tephritidae) attacks fruits of the crop and is one of the most important biotic limiting factors. The extent of losses caused by the pest varies from 30-100% depending on cucurbit species and season (Waterhouse, 1993; Dhillon et al., 2005a). Effective management of this dreaded pest is very much difficult due to its concealed feeding habit and typical life history. Efforts in fruit fly management were focused mainly on mature adult including bagging of fruits, field sanitation, bait traps, cuelure and sterile insect technique (SIT) (Hendrichs et al.,2002), spray of protein baits with toxicants, growing fruit fly-resistant genotypes, augmentative releases of biological control agents, and soft insecticides. Conventional insecticides do not work well against the pest, rather, excessive use of pesticides cause development of resistance, resurgence, hazards to non-target organism and environmental pollution. In this perspective, host plant resistance (HPR) is one of the most important and promising aspects of pest management. However, the indigenous cultivars have their innate heritable chemico-physical features to resist the infestation caused by the melon fruit fly. However, information regarding the morphological factors such as skin toughness of fruit, skin thickness of fruit (Dhillon et al., 2005b) and chemical factors such as in moisture level; ascorbic acid, reducing sugar, non-reducing sugar and total sugars, nitrogen, protein, phosphorus and potassium contents (Tewatia et al., 1998) etc. responsible for this variation in different levels of infestations is vital for initiating crop improvement program to develop resistant lines. In the present study an initiative was undertaken to find out the impact of different physical morphological traits of pumpkin fruits on the extent of infestation and field evaluation of pumpkin cultivars against the infestation of melon fruitfly. MATERIALS AND METHOD: The study was conducted at the Instructional Farm, Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal, India (26 19 N latitude and 89 23 E longitude and an altitude of 43 MSL). Twenty varieties of Pumpkin including local accessions, open pollinated, 175
Roshna Gazmer et al. hybrids were taken for study. The varieties taken for the study were as follows- V1: Pumpkin collection, Eluru, Andhra Pradesh V2: Baidyabati Kumra, Krishi Mangal Vegetable Seeds, Kolkata V3: Pumpkin collection, Pantnagar-2, Uttarakhand V4: Baidyabati, Debgiri seed, Kolkata V5: Pumpkin collection, Pasighat-1, Arunachal Pradesh V6: Pumpkin collection, Pundibari Local-1, West Bengal V7: Pumpkin collection, Pantnagar-1, Uttarakhand V8: Pumpkin collection, Pundibari Long Variety, West Bengal V9: Arka Suryamukhi, IIHR, Bangalore V10: Pumpkin collection, Phek, Nagaland V11: Pumpkin collection, Gagan Sardar Para-2, Tripura V12: Pumpkin collection, Trivendrum, Kerala V13: Pumpkin collection, Gagan Sardar Para-1, Tripura V14: Pumpkin collection, Pasighat-2, Arunachal Pradesh V15: Pumpkin collection, Komatapalli, Andhra Pradesh V16: Pumpkin collection, Pundibari Local-2, West Bengal V17: Pumpkin collection, Ambalavayal, Kerala V18: Pumpkin collection, Pundibari Local-3, West Bengal V19: Barahmasi, Varanasi, Uttar Pradesh V20: Pumpkin collection, Pundibari Local-4, West Bengal The test materials were planted on raised beds of 6m x 3m with a plant-to-plant spacing of 3m and row to row distance at 3m in December (winter season) of 2014 and February (summer season) of 2015. The experiment was replicated thrice arranged by following randomized block design (RBD). In each bed five plants were tagged randomly for recording observation. The winter season crop fruited in April-May and the summer season crop during June-July. Recommended agronomic practices were adopted to raise the crop except chemical control of insect pests. Marketable sized fruits were picked at three days interval and brought to the laboratory for recording observation regarding physical characteristics and percent fruit infestation. The infested fruits were counted and the percent fruit infestation was calculated both in number and weight basis % fruit infestation was determined as follows: The genotypes were grouped by following the rating system, given by Nath (1966) for the fruit damage as immune (no damage), highly resistant (1 10%), resistant (11 20%), moderately resistant (21 50%), susceptible (51 75%) and highly susceptible (76 100%). The infested fruits were cut open to count the number of maggots of melon fly fruit. Healthy fruits were used to observe Skin toughness and skin thickness of fruits by using texture analyser (TA.XT. Plus Texture analyser Serial No- 41439, AOAC guidelines). The data, thus obtained were analyzed statistically using INDOSTAT and Microsoft Excel package of statistical analysis. The percentage data were transformed using angular transformation. The significance of differences between the cultivars was judged by F-test, and the treatment means were compared by the LSD (least significant difference) at p=0.05. The data on percentage fruit infestation and physical characteristics such as skin toughness and skin thickness were also subjected to correlation, regression analysis to see the impact and association of morphological traits on resistance/susceptibility reaction to melon fruit fly infestation. RESULTS AND DISCUSSION Significant differences in percent fruit infestation were observed among the test cultivars in both the seasons of study (Table 1). Percent fruits infested by the melon fly varied significantly from 11.39% to 58.44% being lowest infestation in Baidyabati, Debgiri seed, Kolkata (V4) and highest in Pumpkin collection, Eluru, Andhra Pradesh (V1). Maximum percent fruit infestation were observed in cultivars Pumpkin collection, Eluru, Andhra Pradesh (V1), followed bypumpkin collection, Gagan Sardar Para-1, Tripura (V13), followed by Barahmasi, Varanasi, Uttar Pradesh (V19), followed by Pumpkin collection, Pasighat-2, Arunachal Pradesh (V14), followed by Baidyabati Kumra, Krishi Mangal Vegetable Seeds, Kolkata (V2). Minimum percent fruit infestation were observed in cultivars Baidyabati, Debgiri seed, Kolkata (V4), followed by Pumpkin collection, Gagan Sardar Para-2, Tripura (V11), followed by Pumpkin collection, Pasighat-1, Arunachal Pradesh (V5), followed by Pumpkin collection, Komatapalli, Andhra Pradesh (V15), followed by Pumpkin collection, Pundibari Local-1,West Bengal (V6) etc. Other varieties showed moderate percent fruit infestation. Percentage fruit infestation increases with an increase in fruit length and diameter as reported by Jaiswal et al. (1990) and Tewatia et al. (1997). 176
Evaluation of pumpkin against melon fly Maximum fresh yield was observed in Pumpkin collection, Gagan Sardar Para-2, Tripura (V11) i.e. 18.77 tonnes/ha, followed by Pumpkin collection, Pundibari Local-1,West Bengal (V6) i.e. 17.89 tonnes/ha, followed by Pumpkin collection, Ambalavayal, Kerala (V17) i.e. 17.36 tonnes/haetc. Minimum fresh yield was observed in Pumpkin collection, Pasighat-2, Arunachal Pradesh (V14) i.e. 7.56 tonnes/ha followed by Barahmasi, Varanasi, Uttar Pradesh (V19) i.e. 8.02 tonnes/ha followed by Pumpkin collection, Gagan Sardar Para-1, Tripura (V13) i.e.. 8.50 tonnes/ha etc.maximum infested yield was observed in Pumpkin collection, Eluru, Andhra Pradesh (V1) i.e.13.66 tonnes/ha followed by Pumpkin collection, Pantnagar-1, Uttarakhand (V7) i.e.12.03 tonnes/ha, followed by Barahmasi, Varanasi, Uttar Pradesh (V19) i.e, 11.44 tonnes/ha etc. Minimum infested yield was observed in Baidyabati, Debgiri seed, Kolkata (V4) i.e., 2.22 tonnes/ha, followed by Pumpkin collection, Pasighat-1, Arunachal Pradesh (V5) i.e., 4.12tonnes/ha, followed by Pumpkin collection, Komatapalli, Andhra Pradesh (V15) etc. Total yield was highest in Pundibari Local-1, West Bengal (V6) i.e.24.53 tonnes/ha and lowest in Arka Suryamukhi, IIHR, Bangalore (V9) i.e. 16.50 tonnes/ha. Skin toughness of fruits Significant variation in skin toughness of fruits of different cultivars was also recorded (Table 1). Toughness of skin varied from 221.87g/mm 2 to 522.73g/mm 2 being lowest in Baidyabati, Debgiri seed, Kolkata (V4) and highest in Pumpkin collection, Eluru, Andhra Pradesh (V1). Minimum toughness was observed in cultivars Pumpkin collection, Eluru, Andhra Pradesh (V1) followed by Pumpkin collection, Gagan Sardar Para-1, Tripura (V13) followed bybarahmasi, Varanasi, Uttar Pradesh (V19). Maximum skin toughness were observed in cultivars Baidyabati, Debgiri seed, Kolkata (V4) followed by Pumpkin collection, Gagan Sardar Para-2, Tripura (V11), followed by Pumpkin collection, Pasighat-1, Arunachal Pradesh (V5). Skin toughness was associated negatively and significant with percent fruit infestation (r=-0.83) i.e, tougher the fruit less was the infestation. The interaction between plant and herbivore is influenced by several morphological traits that interfere with feeding and oviposition by the insects (De Ponti, 1977). Identification of physico-chemical factors involved in host plant selection by insects is an important step in selecting resistant genotype (Maxwell and Jennings, 1980). Chelliah and Sambabdam (1971) observed that egg laying by the melon fly was 17.77% in fruits having tough rind in Cucumis callosus when compared with 87.33% of the fruits of susceptible variety. Thick and tough rind fruits of genotypes resistant to melon fly were earlier reported by Pal et al. (1984). Skin thickness of fruits Significant variation in skin thickness of fruits of different cultivars was also recorded (Table 1). Thickness of skin varied from 4.63 mm to 5.00 mm being highest in Pumpkin collection, Pundibari Local-1, West Bengal Baidyabati, Debgiri seed, Kolkata (V4) and lowest in Pumpkin collection, Eluru, Andhra Pradesh (V1). Minimum skin thickness were observed in cultivars Pumpkin collection, Eluru, Andhra Pradesh (V1), followed by Pumpkin collection, Gagan Sardar Para-1, Tripura (V13), followed by Barahmasi, Varanasi, Uttar Pradesh (V19). Maximum skin thicknesswere observed in cultivars Baidyabati, Debgiri seed, Kolkata (V4) followed by Pumpkin collection, Gagan Sardar Para-2, Tripura (V11) followed by Pumpkin collection, Pasighat- 1, Arunachal Pradesh (V5). Skin thickness was associated negatively and significant with percent fruit infestation (r=-0.79) i.e., thicker the fruit less was the infestation. Fig. 1. Effect of skin toughness of fruits on melon fly infestation in pumpkin Fig. 2. Effect of skin thickness of fruits on melon fly infestation in pumpkin 177
Roshna Gazmer et al. Table 1.Extent of fruit fly infestation in relation to fruit skin characters Variety Yield (tones/ha) Infestation (%) Skin thickness Skin toughness Fresh Infested Total (mm) (g/mm 2 ) V1 9.90 13.66 23.34 58.44 (49.86) 4.63 221.87 V2 9.34 11.44 20.78 54.95 (47.84) 4.59 290.93 V3 12.10 10.25 22.53 45.41 (42.36) 4.76 394.27 V4 16.33 2.22 18.47 11.39 (19.72) 5.00 522.73 V5 15.42 4.12 19.54 20.99 (27.27) 4.97 494.77 V6 15.38 5.06 20.39 24.69 (29.79) 4.89 486.53 V7 12.75 12.03 24.52 48.99 (44.42) 4.83 396.27 V8 12.09 10.78 22.80 47.17 (43.38) 4.45 462.70 V9 9.57 6.99 16.50 42.19 (40.51) 4.94 459.37 V10 10.87 10.02 20.81 48.11 (43.91) 4.75 319.57 V11 18.77 3.89 22.60 17.10 (24.43) 4.89 510.70 V12 12.48 11.02 23.46 46.94 (43.25) 4.56 465.20 V13 8.50 11.39 19.78 57.48 (49.30) 4.62 238.20 V14 7.56 9.34 16.85 55.31 (48.05) 4.78 337.83 V15 15.62 4.43 20.01 22.04 (28.00) 4.96 485.43 V16 17.89 7.00 24.53 27.15 (31.40) 4.91 478.63 V17 17.36 5.98 23.29 25.59 (30.39) 4.97 486.10 V18 11.15 9.50 20.42 45.55 (42.45) 4.68 457.43 V19 8.02 10.54 18.53 56.77 (48.89) 4.63 289.40 V20 10.58 9.45 23.34 47.17 (43.38) 4.62 284.87 Mean 12.58 8.46 21.12 40.17 4.77 404.14 S. Em (±) 0.03 0.07 0.08 0.25 0.05 10.01 LSD (5 %) 0.10 0.22 0.24 0.73 0.15 28.68 *Figures in the parenthesis are arc-sine (angular) transformed values Infestation of pumpkin by melon fly has been found to influence much by the morphological traits of fruit. The cultivars having higher tough skin of fruit and thicker skin of fruit to be selected so as to lessen melon fly infestation. The traits can also be utilized for developing melon fly resistant cultivars in future breeding programme. ACKNOWLEDGEMENTS The authors are thankful to Prof. A. K. Singha Roy, Dean Faculty of Agriculture, Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal, India for his co-operation, suggestion and providing necessary facilities for conducting the experiment. REFERENCES Chelliah, S. and Sambandam, C. N. 1971. Role of certain mechanical factors in Cucumis callosus (Rottl.) Cogn. In imparting resistance to Dacus cucurbitae. Auaru 3: 48-53. De Ponti, O. M. B. 1977. Resistance in Cucumis sativus L. to Tetranychus urticae Koch. I. The role of plant breeding in integrated control. Euphytica, 26: 633. Dhillon, M. K., Singh, R., Naresh, J. S. and Sharma, H. C. 2005a. The melon fruit fly, Bactrocera cucurbitae: A review of its biology and management. Journal of Insect Science., 5: 40. Dhillon, M. K., Singh, R., Naresh, J. S., Singh, R. and Sharma, N. K. 2005b. Influence of physico- chemical traits of bitter gourd, Momordica charantia L. on larval density and resistance to melon fly, Bactrocera cucurbitae (Coq.). Journal of Applied Entomology, 129(7): 393-399. Hendrichs, J., Franz, G. and Rendon, P. 1995. Increased effectiveness and applicability of the sterile insect technique through male-only releases for control of 178
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