Potato, Solanum tuberosum Linn., is a world food crop and can be compared only with rice, wheat and maize for its contribution towards securing food and nutrition and avoiding the poverty and hunger especially in the developing world. Thus potato ranks first among vegetables in per capita consumption in many countries and is the second crop in protein production after soya bean (Anonymous, 1990).

 

In India, potato is grown in almost all the states and under very diverse conditions. Among the states, Uttar Pradesh, West Bengal and Bihar accounted for nearly 71% area and 76% production of the country (Chadha, 2002). In West Bengal potato is the most important food crop next to cereals and the state ranks second position in area and production and first position in productivity in the country (Rai, 2003). Potato is infested by more than 100 arthropods from various parts of the world (Simpson, 1977). Among these pests aphids, Myzus persicae (Sulzer) and Aphis gossypii Glover (Aphididae: Hemiptera) is the most important sucking pest, which not only cause direct damage by sucking plant sap, but also transmitting different potato viruses (Khurana, 2000). Therefore to minimize the infestation of aphid, a number of synthetic insecticides are applied randomly, but with limited success. Spraying of the chemicals is responsible for the environmental pollution among man and animals. Thus a field experiment was undertaken to assess the effectiveness of different treatment schedules including chemicals and non-chemicals against aphids on potato with polluting the total ecosystem.

 

Results

In the first year of present study during 2012-13, all the treatment schedules were significantly superior over control (Table 2). Among the seven treatment schedules, only in T₁, which received phorate 10 G@ 1.5 kg a. I/ha at planting followed by spraying of chlorpyriphos 20EC @ 2.5 ml/lit of water at 40 DAP, imidacloprid 17.8 SL @ 1.5 ml/7.5 lit of water at 55 DAP and cartap hydrochloride 50 SP @ 1g/lit of water at 70 DAP, the aphid population never cross the critical level i.e. 20 aphids/100 compound leaves. T₂ and T₃ were also maintained lower population of aphid throughout the crop life by supporting 10.13 and 9.77 mean aphid population per 100 compound leaves as compared to 87.80 in control (T₇). The per cent decrease of aphid population over control was found maximum in T₁ (93.11) which was succeeded by T₃ (88.87), T₂ (88.46), T₅ (85.67), T₆ (82.77) and T₄ (75.93), respectively.

 

In the second year of study during 2013-14, it has been observed that all the treatment schedules were significantly reduced the aphid population throughout the period of crop growth (Table 3). Among the seven different treatments T₁ (Table 1) was found most effective in minimizing the incidence of aphids on potato below its critical level which was followed by T₂, T₃, T₅, T₆ and T₄, respectively than control (T₇). The average aphid population on potato was found minimum in T₁ (7.16 per 100 compounds leaves) which was trailed by T₂ (8.24), T₃ (10.08), T₅ (11.74), T6 (15.05), T₄ (20.66) and T₇ (94.69). Thus T₁ obtained highest percentage of reduction of aphid population (92.44) over control and then in order were T₂ (91.30), T₃ (89.35), T₅ (87.60), T₆ (84.10) and T₄ (78.18), respectively.

 

Discussions

From the results of both years of study, it is evident that among the seven different treatment schedules, T₁ (Table 1) was recorded most effective in reducing the aphid population over control below its economic threshold level  (20 aphids/100 compound leaves) all round the crop season which was succeeded by T₂, T₃, T₅, T₆ and T₄ respectively. T₁ treatment schedule containing only chemical insecticides and maintained the aphid population

 

below its critical level throughout the crop life. T₂, in which the seeds were treated with imidacloprid 17.8 SL @ 1.5 ml/7.5 lit of water at the time of planting, followed by spraying of acephate at 40 DAP, imidacloprid at 55 DAP and chlorpyriphos + cypermethrin at 70 DAP and T₃ in which received soil application of phorate 10 G at planting, and then spraying of chlorpyriphos at 40 DAP, azadirachtin at 55 DAP and Bacillus thuringiensis var. Kurstaki at 70 DAP, also achieved better control of the pest. But among these two treatment schedules, T₂ was quite better (88.46-91.30%) in decreasing the aphid population over control than T₃ (88.87-89.35%). This is due to the fact that in the former schedule, only chemical insecticides were used and the second and third treatments were done with systemic insecticide (acephate and imidacloprid) which were sprayed at the time of aphid population development, but in later schedule, only phorate was applied as systemic insecticide along with two bio-pesticides. For the same reason, T₅ was quite effective (85.67-87.60% decrease of aphid population over control) than T₆ (82.77-84.10% decrease of aphid population over control) in controlling the pest of potato. These results are in line with the findings of Konar and Chettri (2003), Konar et al. (2003), Paul and Konar (2004), Paul et al. (2005) who evaluated the efficacy of single component against aphid, but not in a schedule of different insecticides throughout the crop life. The marketable tuber yield (t/ha) during 2012-13, was found maximum in T₂ (26.28), followed by T₅ (26.25), T₁ (22.92), T₃ (21.67), T₆ (20.14), T₄ (18.19) and control, T₇ (15.69), respectively (Table 4). T₅ recorded highest additional benefit (Rs. 29,040 per ha) over control, while it was lowest in T₄ (Rs. 6,875 per ha). Maximum gain (Rs/ha) in income was also found from T₅ (Rs. 27,597) and then in order were T₂ (Rs. 25,015), T₁ (Rs. 18,169), T₃ (Rs. 14,980), T₆ (Rs. 11,072) and T₄ (Rs. 5,805) respectively. Similar trend was also observed when the cost-benefit ratio (CBR) was considered and these were in T₅ (1:19.12), T₂ (1:18.43), T₁ (1:10.61), T₃ (1:10.22), T₆ (1:9.50) and T₄ (1:5.42), respectively.

 

During 2013-14, the highest marketable yield (t/ha) of potato tuber was achieved in T₂ (26.80) which was succeeded by T₅ (26.67), T₃ (23.33), T₁ (23.19), T₄ (19.44), T₆ (19.17) respectively than control, T₇ (14.17). Increased production (t/ha) over control was found maximum from T₂ (12.63), which was followed by T₅ (12.50), T₃ (9.16), T₁ (9.02), T₄ (5.27) and T₆ (5.00) respectively (Table 4). Hence the added benefit (Rs. /ha) over control was recorded highest in T₂ (Rs. 36,627) and lowest in T₆ (Rs. 14,500). Thus T₂ was most economical as it produced maximum net profit per ha and CBR (Rs. 35,270 and 1:25.99 respectively) succeeded by T₅ (Rs. 34,807 and 1:24.12), T₃ (Rs. 25,099 and 1:17.13), T₁ (Rs. 24,445 and 1:14.27), T₄ (Rs. 14,213 and 1:13.28) and T₆ (Rs. 13,335 and 1:11.45), respectively.

 

From the results of two consecutive potato growing seasons during 2012-13 and 2013-14, it may be concluded that amongst the seven different treatment schedules T₅ (Table 1) and T₂ (Table 1) were much better in increasing the marketable tuber yield of potato and net return over control than other treatments. The present results support the findings of Tripathi et al. (2003).

 

Materials and Methods

The present field experiment was undertaken to work out the bio-efficacy of different insecticidal treatment schedules including control against aphids on potato for two consecutive rabi seasons from November to February in 2012-13 and 2013-14, respectively at Adisaptagram Block Seed Farm, Hooghly, West Bengal. The seed tubers of potato cv. Kufri chandramukhi were planted by end November in the plots having 3.6m x 2m area. Each plot had 6 rows with 10 tubers or plants/row, i.e. 60cm x 20cm spacing between row to row and plant to plant, respectively was maintained. All standard agronomic practices, recommended for this region, were strictly followed during raising the crop. The crop was dehaulmed at an age of 85 days and 10 days after dehaulming it was harvested from the field.

 

Seven different insecticidal treatment schedules including control were assessed against aphid in a RBD (Randomized Block Design) and each schedule was replicated thrice. The schedules were consisting of both chemical and non-chemical insecticides as mentioned in table 1. During the crop season, weekly observations were recorded on the population of aphids. Aphid population was counted by 100-leaf index method detailed by Simpson (1940), i.e. the population of aphid was observed from one upper, one middle and one lower compound leaves of randomly selected 33 plants and one leaf from 34 plant (Aphid population was noted from 100 compound leaves). The weights of healthy and damaged tubers in each plot for each treatment were also taken during harvesting and thereafter, the data were analyzed after converting them into necessary forms. The cost-benefit ratio (CBR) for respective treatment schedules was computed and analyzed with the help of market value of insecticides as well as potato tubers.

 

Data analysis

All the data were analyzed by different statistical analysis.

 

Author’s contributions

BK designed the draft of the manuscript with the help of other authors and institutional supports.

PM helps in draft corrections.

AK gives the idea of the experiment.

 

Acknowledgement

The authors are grateful to the Farm Manager, Adisaptagram Block Seed Farm, Hooghly, West Bengal for providing various facilities including land to conduct the present field trial.

 

References

Anonymous, 1990, FAO Production Yearbook, Food and Agricultural Organization of the United Nation, Rome, pp.45-60

 

Chadha K.L. (eds.), 2002, In: Handbook of Horticulture, ICAR, New Delhi, pp. 8-10

 

Chourasia N., Mandal S., and Konar A., 2004, Efficacy of synthetic insecticides and bio-pesticides against potato aphids, Myzus persicae (Sulzer) and Aphis gossypii Glover in eastern gangetic plains, J. Ent. Res., 28(4): 1-3

 

Khurana S.M.P. (eds.), 2000, In: Diseases and Pests of potato- A Manual, CPRI, Shimla, HP. pp. 41-66

 

Konar A., and Chettri M., 2003, Effectiveness of synthetic insecticides, bio-pesticides and azadirachtin against potato aphids, J. Indian Potato Association, 30(3-4): 331-334

 

Konar A., and Paul S., 2005, Comparative field efficacy of synthetic insecticides and bio-pesticides against aphids on potato, Annuals of Plant Protection Science, 13(1): 34-36

 

Konar A., Paul S. and Chettri M., 2003, Efficacy of synthetic insecticides, bio-pesticides and azadirachtin against aphids on potato in West Bengal, Abstract of the National Symp. on “Assessment and Management of Bio-resources”, Univ. North Bengal, pp. 30

 

Paul S., and Konar A., 2004, Aphid management for virus free potato seed tuber production in eastern gangetic plains of West Bengal, The Horticultural Journal, 17(3): 253-258

 

Paul S., Konar A. and Mandal S., 2003, Efficacy of synthetic pesticides and bio-pesticides against potato aphids in eastern gangetic plains of West Bengal. Proceedings of National Symp. on “Frontier Areas of Entomological Research”, IARI, New Delhi, pp.155-156

 

Rai M., 2003, Role of potato in food and nutritional security in developing countries with special reference to India, Proceeding of National Symp.”Potato Research towards National Food and Nutritional Security”, CPRI, Shimla H.P., pp.28-30

 

Simpson S.W., 1940, Aphid and their relation to the field transmission of potato viral diseases in north-east Marine, Naive Agricultural Experiment-Statistical Bulletin, pp 403

 

Tripathi D.M., Bisht R.S., and Mishra P.N., 2003, Bioefficacy of some synthetic insecticides and biopesticides against black cutworm, Agrotis ipsilon infesting potato (Solanum tuberosum) in Garhwal Himalaya, Indian J. Ent., 65(4): 468-473