DEVELOPMENT AND LEAF AREA CONSUMPTION RATE OF TWO-COLOUR COCONUT LEAF BEETLE Plesispa reichei ON SELECTED COCONUT LEAF STAGES
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Date
2012
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Uva Wellassa University of Sri Lanka
Abstract
Plesispa reichei is a devastating pest in coconut plantation in Sri Lanka. Being a new pest species, information on its biology and feeding behavior is scarce. This research was conducted to determine some selected parameters on its development and feeding. The egg production was significantly affected by coconut leaf stages; egg hatchability, body length and duration of adult stage. Higher mean number of eggs was observed on first open leaf and second open leaf than on the spear leaf. There was no significant effect of the leaf stage on incubation period of eggs. The egg hatchability was higher on spear leaf and the first open leaf than the second open leaf. Body length of the first-instar larvae was significantly differed among leaf stage; the first open leaf stage had the minimum length. The pupal pro-thoracic length and body length were not affected by the leaf stage. Time taken for adult emergence was longer when they were reared on the spear leaf than on the first open leaf and second open leaf Leaf area consumed by different larval stages was significantly differed with the leaf stage. First and third larval instars fed more on second open leaf stage while second and fourth instars fed more on the spear leaf The fifth larval instar fed more on the first ,-,)pen leaf Field-collected beetles preferred the second open leaf while the labor4 reared beetles preferred spear leaf. Study revealed that the first open leaf and the second open leaf are better than the spear leaf for the development of P. reichei. Therefore, the first open leaf or the second open leaf can be used to mass rear Plesispa beetle.
Key words: Plesispa reichei, coconut, leaf stage, development, larval instar
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Export Agriculture Degree Programme (EAG)