Infestation Patterns of The Coconut Mite (Eriophyes Guerreronis) and Resulting Yield Loss in The South Western Region of Bangladesh

Abstract

A study on infestation patterns of the coconut mite on coconuts and resulting yield loss in the south western region of Bangladesh was carried out during the period from April, 2011 to February, 2012. Coconut was collected randomly from Khulna, Satkhira and Bagherhat districts of Bangladesh and graded into five categories. Three fruits were collected from each grade. After this subsequent operation was done in Germplasm Centre and Molicular Horticulture Laboratory of Agrotechnology Discipline, Khulna University, Khulna. The factorial experiment was laid out in Completely Randomized Design with three replications. The experimental treatments consisted of three locations (L1 Khulna, L2 = Bagherhat and L3 = Satkhira); two varieties (V1= Green and V2= Brown) and five grades on the basis of mite infestation which are Go nuts with no mite damage, G1 = nuts with 1-29% surface area damage, G2 = nuts with 30-59% surface area damage and less than 20% reduction in size, G3 = nuts with 60-80% surface area damage, 20-30% reduction in size and G1 = nuts with over 80% surface area damage with 30% reduction and often greatly deformed. The data on fresh weight (g), length (cm), equatorial circumference (cm) of fruit, kernel length (cm), kernel equatorial circumference (cm), kernel weight with water (g), kernel weight without water (g), copra weight (g), dry weight of copra (g), moisture (%) and yield loss have been studied. From the study it was found that most of the cases highest values were recorded from Go and the lowest values were recorded from G1. It was found that the dry weight of copra was significantly varied among the different grades. The highest dry weight (164.33g) was recorded from Go and the lowest (386.94g) from G4. Variety was not significantly varied due to mite infestation. Among the location, the fruits collected from Khulna and Satkhira gave highest values and the lowest value was recorded from the fruits of Bagherhat districts. From the experiment it was found that water loss was observed about 0, 5.5, 34.19, 50 and 62.59% in damage categories Go, G1, G2, G3 and G4, respectively. For the copra yield considerable loss was occurred that ware 0, 13.22, 24.90, 38.00 and 52.72% in damage categories Go, G1, G2, G3 and G4, respectively. Observed coconut shell losses were 0, 7.28, 15.32, 24.42, and 37.17% corresponding to damage categories Go, G1, G2, G3 and G4, respectively. Due to mite infestation about 37.17% coconut shell loss, 62.59% water loss and 52.72% copra yield loss was occurred when nuts with over 80% surface area damaged with 30% reduction of size.