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

Gobinda Chandra biswas
Scientific officer
ORC,BARI,Gazipur

Abstract/ Executive Summary:

Incidence damage estimation and management of hairy caterpillar (Spilarctia obliqua) on sesame were studied in the field and laboratory Oilseed Ressearch Centre, BARI, Joydebpur , Gazipur ,during two consecutive years of March-July, 2000 and 2001. The pest appeared in the sesame crop in the last week of April at the flowering stage at 45-50 days after sowing (DAS) and remained up to third week of June at the pod maturity stage at 95-100 DAS. The peak populations of S. obliqua (3.40-4.50 larvae per plant) and their severe infestation were recorded in the last week of May at the podfilling stage at 60-70 DAS of the crop. The average yield losses of sesame caused by S. obliqua in the treatments 1 spray, 2 sprays, 3 sprays and 4 sprays frequencies with Diazinon 60 EC@2ml/litre were 25.04, 30.86, 35.24 and 37.23, respectively. One spray of the insecticide at the pod formation stage at 50-55 DAS gave the highest benefit cost ratio (4.20).

Keywords: Incidence, Hairy caterpillar, Sesame

Location: BARI, Gazipur

Start Date: 10-07-2000

End Date: 30-06-2000

Program Area: Pest Management

Commodity: Sesame

Objectives:

To know the incidence, damage severity, yield loss and economic management of hairy caterpillar of sesame.

Methodology:

The study was conducted in the field and laboratory of the Oilseed Research Centre, BARI, Joydebpur , Gazipur ,during two consecutive years of March-July,1999 and 2000. The recommended sesame variety T6 was used in this experiment. Seeds of sesame were sown on 10 March in 5 replicated plots measuring 4m x 2m 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 Wahhad 2001). Observations on the population of the larvae of S. obliqua were recorded from 100 randomly selected plants of unsprayed sesame field. Records were taken by visual observations on the standing crop during 0700-1000 HR at weekly intervals starting from 3rd week of April and continued up to 3rd week of June. Five treatments based on frequency 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 spray at 45.55 and 65 DAS and four spray at 40, 50, 60 and 70 DAS and untreated control were used in this trial. Diazinon 60EC @ 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 pets 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 from treated and untreated plots at 80 DAS .Percent population or infestation reduction over untreated control was calculated. Yield data of different treatments were also recorded and BCR was calculated. The avoidable losses or percent increase in yield over untreated control were calculated on the basis of formula (Khosla, 1977) Percent loss= X1-X2/X1 x 100

Source of Information: Journal of Agric. Rural Development 4 (1&2):95-100, 2006

Article Link (Online Journal):

Funding Source:

1. Government

Budget: 12000/-

Total Budget (Tk.) : 12000/-

Achievement/Findings:

Hairy caterpillar (Spilarctia obliqua) larvae on sesame were on sesame crop in the last week of April at the flowering stage at 45-50 days after sowing (DAS) and remained up to third week of June at the pod maturity stage at 95-100 DAS in both 2000 and 2001. The peak populations of S. obliqua (3.40-4.50 larvae per plant) and their severe infestation were recorded in the last week of May at the pod filling stage at 60-70 DAS of the crop. Comparatively high population density per plant and infestation was recorded in 2001 than 2000, which may be due to differences of weather factors and other biotic between the two years. The plant infestation reduction over untreated control of this pest ranged from 49-89% in 2000 and 45-87% in 2001. The pod infestation reduction over untreated control of this pest ranged from 39-85% in 2000 and 38-837% in 2001. About 50% infestation by this pest was reduced in applying one sprayed plot while 83-89% infestation reduction was found in four sprayed plots.The average avoidable yield losses of sesame caused by S. obliqua in the treatments 1 spray, 2 sprays, 3 sprays and 4 sprays frequencies with Diazinon 60 EC@2ml/litre were 25.04, 30.86, 35.24 and 37.23, respectively. One spray of the insecticide at the pod formation stage at 50-55 DAS gave the highest benefit cost ratio (4.20). This findings could be helpful to the farmers for formulating appropriate management techniques and to reduce to insect infestation avoiding misuse of insecticides in this country.

Knowledge Management: Journal