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Incidence of Fruit Borer (virachola Isocrates F.) on Guava at Khagrachari Hill District

Gobinda Chandra biswas
Scientific officer
HARS, Khagrachari, Hill district

M. Ahmed
Profesor
Department of Entomology, BAU, Mymensingh

Abstract/ Executive Summary:

A research work on the fruit borer, Virachola Isocrates of guava was conducted in Khagrachair Hill District during 1994 to know the incidence, nature and extent of damage, and varietal susceptibility. The infestation began at the marble stage of the fruits (1.5-2. Cm diam.) and the peak infestation was recorded in mid-August to September in all the four guava varieties, kazipiara, kanchannagar, Mukundapuri and Swarupkathi. The highest infestation occurred in Kazipiara resulting in 24.2% fruit damage and 22.7% weight loss, and the lowest in Swarupkathi with 7.8% fruit damage and 6.8% weight loss. The caterpillar damaged 65.6% of the fruit area of Kazipiara and 58.7% of the fruit area of Swarupkathi. Among the four varieties, Kazipiara was highly susceptible and Swarupkathi least susceptible to the fruit borer.

Keywords: Incidence, Fruit borer, Guava

Location: Khagrachari

Start Date: 10-03-1992

End Date: 30-06-1994

Program Area: Pest Management

Commodity: Guava

Objectives:

To know the incidence, nature and extent of damage, and varietal susceptibility of guava to guava fruit borer, Virachola isocrates

Methodology:

The research work on the fruit borer of guava, V. Isocrates was conducted at the Hill Agricultural Research Station (HARS) Khagrachari Hill District in fruit growing season during 1992 and 1994. Four varieties of guava namely Kazipiara, Kanchannagar, Mukundapuri and Swarupkathi were included in this study to know their varietal susceptibility to the fruit borer. The experiment was conducted in randomized complete block design with four varieties as treatment and ten replicates. Ten guava plants,each 6 to 8 years old of each variety, were used for date collected and one plants, served as a replicate. Guava plants were spaced 4m + 4m in contour lines. Data were collected during the harvesting time of guava for the years 1992 and 1994. In 1992,recording of the data was done at weekly interval starting from 2^nd August to 24^th October and from 27^th july to 5^th October, 1994. The harvested fruits were bagged and labelled carefully for each variety and plant and transported to the laboratory where the healthy and infested fruits of each variety and plant were carefully separated ,counted and weighed. The visible damage symptom in an infested fruit was the excreta of the larva of the fruit borer coming out of the entry hole. Sometimes, the anal portion of the larva could be seen through the entry hole. Even single entry hole on the fruit was considered as an infested fruit.The percentage of fruit damage and weight loss was calculated from the number and weight of the infested fruits. The nature and intensity of damage were determined by cutting open the infested fruits through the entry hole made by the fruit borer.Ten plants of each variety were selected and from each plant ten infested fruit were cut open.Per cent damaged area of an infested fruit was determined by eye estimation.Thus, for each variety, 100 infested fruits were used for damaged area estimation. Such damage estimation was done in both the years,1992 and 1994.

Source of Information: Bangladesh Journal of entomology. Vol 5 (1&2),33-39,1995

Article Link (Online Journal):

Funding Source:

1. Government

Budget: 10,000/-

Total Budget (Tk.) : 10,000/-

Achievement/Findings:

The fruit borer (V. Isocrates) infestation in guava begin at the marble stage of the fruits (1.5-2.0 cm diam) and continued through the harvest of the crop. In 1992, mean infestation combining all the four guava varieties ,Kazipiaea , kanchannagar, Mukundapuri and Swarupkathi showed two peaks on August 6 and September 6. ln both the years , the infestation of the individual variety fluctuated and showed no clear cut pattern. In 1992 and 1994, Kazipiara had significantly highest infestation rate and lowest in Swarupkathi (P<0.05). The weight loss among the above four varieties ranged from 7.7-19.6%. Mean infestation levels differed significantly (P<0.001). Kazipiara suffered from maximum infestation of V. iscocrates. But there was no significant difference in infestation between Kanchannagar and Mukundapuri. Swarupkathi suffered the least infestation. In 1994 V, Isocrates damaged guava fruits almost at the same rate as in 1992 and 7.2-26.5 per cent fruits were infested in four varieties. The percentage of fruit damage and weight loss were significantly different from one another (P<0.001). The external and internal symptom of damage in guava is presented in Fig, 4,per cent damage area of the infested fruit of four guava varieties in shown graphically for two years .Although the mean damage intensity of four guava varieties were slightly different from one another ,no significant difference was found in both the years. In both the years, among the four varieties, highest damage was recorded in Kazipiara (65.1%-66.1%) and lowest in Swarupkathi (57.9%-59.6%).

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