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Incidence and Management of Hairy Caterpillar (spilarctia Obliqua Walker) on Sesame

G. C. BISWAS
Oilseed Research Centre, Bangladesh Agricultural Research Institute, Gazipur, Bangladesh

Abstract/ Executive Summary:

Incidence and management of hairy caterpillar, Spilarctia obliqua (Walk.) on sesame were studied in the field and laboratory of the Oilseed Research Centre, BARI, Gazipur, during March to July, 2000 and 2001, respectively. The pest appeared in the sesame crop in the fourth week of April at the flowering stage at 45-55 Days After Sowing (DAS) and remained up to third week of June at the pod maturity stage at 90-95 DAS. The peak populations of S. obliqua (4.00 – 4.50 larvae per plant) and their severe infestation (100% plant) were recorded in the fourth week of May, at the pod filling stage at 60-70 DAS of the crop. The yield reduction of sesame caused by S. obliqua in the treatments 1 spray, 2 sprays, 3 sprays, and 4 spray frequencies with Diazinon 60 EC @ 2 ml/litre were calculated 25.00, 30.86, 35.24 and 37.23 percent, respectively. One spray of Diazinon 60 EC applied at the pod formation stage at 50-55 DAS gave the highest benefit cost ratio (4.20).

Keywords: Incidence, Hairy caterpillar, Sesame, Infestation, Management

Location: Oilseed Research Centre, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur

Start Date: 00-00-2000

End Date: 00-00-2001

Program Area: Pest Management

Commodity: Sesame

Objectives:

Therefore, the present research work was conducted to know in details the incidence, severity of damage, yield loss and economic management of S. obliqua.

Methodology:

The study was conducted in the field and laboratory of the Oilseed Research Centre, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur, during two consecutive years of March to July, 2000 and 2001, respectively. Seeds of sesame (Variety -T6) were sown on 10th March of each year of 2000 and 2001 in 5 replicated plots measuring 4m X 2m each following randomized complete block design. The plants were spaced 30 cm between rows and 10 cm between plants. Recommended agronomic practices were adopted to raise the crop properly (Mondal and Wahhab, 2001). Observations on the populations of the larvae of S. obliqua were recorded from 100 randomly pre selected plants of unsprayed sesame field. Records were taken by visual observations on the standing crop during 0700 - 1000 HR and 4.00 - 6.00 HR at weekly intervals starting from 3rd week of April to 3rd week of June, 2000 and 2001, respectively. Their nature of damage was also observed. The number of larvae attacked in sesame plants was counted. Five treatments based on frequencies of spray namely, one spray at the flowering and pod formation stage at 50 days after sowing, two sprays at 45 and 55 DAS, three sprays at 45, 55 and 65 DAS, four sprays at 40, 50, 60 and 70 DAS and untreated control were used in this trial. Diazinon 60 EC @ 2ml/litre of water was applied in treated plots at vegetative, flowering, pod formation and pod pre-maturity stages of the crop with the help of a Knapsack sprayer (Asha) at 10 days intervals. Only tap water was sprayed in untreated plots. The population density per plant of S. obliqua was recorded at 75 DAS by observing 10 randomly selected plants in treated and untreated plots in both the years. Percent plant infestation due to this pest was calculated by counting infested and healthy plants from 10 randomly selected plants at 75 DAS in different replicated plots. Percent pod infestation was calculated by counting the infested and healthy pods from randomly collected 100 pods in treated and untreated plots at 80 DAS. Percent population or infestation reduction over untreated control was calculated. The yield data (kg/ha) were recorded from insecticide treated and untreated plots. The difference between the weight of seed yield in treated and untreated plots was considered as loss. The avoidable losses or percentage of increased in yield over untreated control were calculated on the basis of formulae (Khosla 1977) as given below: i) Per cent loss or increased in yield = {( X1 – X2/X1) x100}.

Source of Information: J Agric Rural Dev 4(1&2), 95-100, June 2006 ISSN 1810-1860

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The present study revealed that S. obliqua damaged the sesame crop seriously at the pod filling stage (60-70 DAS) and only one spray of Diazinon 60 EC @ 2ml/litre of water applied at this vulnerable stage gave the highest BCR (4.20). This finding could be helpful to the farmers for formulating appropriate management techniques and to reduce insect infestation avoiding indiscriminate use of insecticides in this country.

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