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Population Dynamics and Management of Thrips in Bulb Onion Using Vegetable Intercrops

M.M. Hossain
Scientific Officer
Spices Research Centre, BARI, Shibganj, Bogra, Bangladesh

K.M. Khalequzzaman
Senior Scientific Officer
Spices Research Centre, BARI, Shibganj, Bogra, Bangladesh

M.A.A. Mamun
Assistant Professor
Department of Soil Science, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh

M.J. Alam
Program Officer
Mennonite Central Committee, Bangladesh

R.N. Ahmed
UAO (LR)
DAE, Khamarbari, Dhaka, Bangladesh

Abstract/ Executive Summary:

The field experiment was conducted at Spices Research Centre, Shibganj, Bogra during Rabi season of 2014-15 to study the population dynamics and to evaluate the effectiveness of intercropping Carrot, Tomato and French bean with onion for the management of thrips attacking onion. Variety BARI Piaz-1 was intercropped with each of the vegetables and insecticide Imidacloprid was used as a standard check. The treatments were five including control. Infestation of onion thrips was started from the first week of February and it become gradually increases upto first week of April then it was declined. Thrips populations were positively correlated with temperature and negatively with relative humidity and rainfall. Thrips incidence and damage severity were determined at 7 days interval with damage severity being estimated on a scale of 1-5. Total and marketable bulb yield were determined at physiological maturity. Intercropping onion with carrot, tomato and insecticide Imidacloprid significantly reduced thrips population over control up to 52.42, 48.84 and 58.97%, respectively, but French bean had no significant effect. The three vegetable intercrops significantly reduced damage severity, with insecticide Imidacloprid showed the greatest damage reduction up to 23.81% followed by carrot (21.04%) and tomato (11.90%). Intercropping onion with tomato and carrot showed significantly lower onion bulb yield (6.6 t/ha and 7.54 t/ha, respectively) but statistically comparable to that of French bean (8.62 t/ha). The effect of Imidacloprid on yield (11.24 t/ha) was statistically higher. The reduction in bulb yield was compensated by the yield from the vegetable intercrops and, therefore, no loss was incurred in carrot and tomato showing higher MBCR (12.55 and 17.90, respectively) compared to Imidacloprid (5.52). This study showed that Carrot or Tomato intercrop may be utilized as intercrop for the management of onion thrips.

Keywords: Population dynamics, Management, Thrips, Intercrops, Bulb onion

Location: Spices Research Centre, BARI, Shibganj, Bogra

Start Date: 00-11-2014

End Date: 00-04-2015

Program Area: Pest Management

Commodity: Insects

Objectives:

To study the population dynamics and to evaluate the effectiveness of vegetable intercrops in the management of thrips in bulb onions

Methodology:

The study was conducted at Spices Research Centre, Shibganj, Bogra during Rabi season of 2014-15 to study the population dynamics of onion thrips and to evaluate the effectiveness of intercropping carrot, Tomato and French bean with onion for the management of thrips attacking in onion. The experimental plot was prepared with five ploughings and cross ploughings followed by laddering. The weeds and stubbles of previous crops were removed from the soil. The unit plot size was 4 m × 1.80 m and the spacing was 15 cm × 10 cm for onion, 45cm × 50 cm for tomato, 45cm × 10cm for carrot and 45 cm × 15 cm for French bean. The treatments were Onion intercropped with carrot; Onion intercropped with tomato; Onion intercropped with French bean; Spraying Imidacloprid (Admire 200SL) @ 0.5ml/L (as standard check) and an untreated control. Treatments were arranged in a randomized complete block design with three replications. Variety BARI Piaz-1 was used as main crop whereas unknown cultivar of carrot, BARI Tomato-9 and BARI Zhar Sheem-2 were used as intercrop for this trial. The seedlings of onion were transplanted on 28 December 2014. On each plot where intercropping was used, one row of intercrop was alternated with three rows of onion. Cowdung at 5 t/ha, fertilization with N₁₂₀P₄₀K₇₅S₃₀ kg/ha were applied. The entire amount of cow dung, TSP and ½ of N and K were applied during final land. The rest N and K was applied in two equal splits as top dress at 25 and 50 days after transplanting (DAP). Three weeding were done at 25, 50 and 75 DAP. To control purple blotch disease, the crop was sprayed three times with Rovral 50 WP @ 2g/l of water at 35, 45 and 55 DAP. Three irrigations were done at 10-20 days interval during vegetative growth stage. On the maturity, the crop was harvested on 12 April 2015. Thrips population was counted at 7 days interval starting from the first appearance of infestation. Number of thrips (both nymphs and adults) was recorded from 20 randomly selected plants in each plot by keeping a white sticky paper below the plant and then shaking the plants with finger. Silvery patches characteristically caused by thrips on onion leaves were considered to assess thrips damage on a weekly basis from the fourth week after transplanting to physiological maturity of the crop. Incidence of thrips damage was determined by counting the number of damaged plants over the total number of plants per plot. Thrips damage severity was determined by randomly sampling ten plants from the inner rows of each plot. The percentage of leaf surface showing thrips damage was assessed based on a scale of 1-5 (Smith et al. 1994) where 1 = no damage, 2 = up to 25%, 3 = 26-50%, 4 = 51-75% and 5 = >75% damage. The Minolta SPAD 502 chlorophyll meter was used for the measurement of onion leaf color. Harvesting was done by hand at physiological maturity when 50-80% of the foliage had fallen over and then the tops and roots were cut off. The bulbs from each plot were weighed and the marketable bulbs that were greater than 3 cm diameter separated and graded into non-split or non-double bulbs according to HCDA. The bulb yield for each onion-vegetable intercrop treatment was extrapolated into ton per hectare. Another data were recorded on plant height at 85 DAT, SPAD (CCI) value at 85 DAT, bulb diameter, bulb weight and yield at harvest. The recorded data were analyzed and mean values were adjusted and means were separated by Duncan’s Multiple RangeTest (DMRT).

Percent thrips population reduction over untreated control was calculated using following formula:

Percent thrips population reduction over untreated control = (Mean of control – Mean of treatments) ÷ Mean of control X 100

Source of Information: Int. J. Sustain. Crop Prod. 10(3):8-15, (2015)

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

It may be concluded that carrot or tomato intercrop may be utilized for the management of thrips infesting onion with higher economic return.

Knowledge Management: Journal