Abstract
Opisina arenosella Walker is a defoliating pest of coconut in Sri Lanka. A firstattempt was made to understand its population dynamics. Analysis of records ofpopulation outbreaks throughout the country from 1965 to 1985 revealed cycles in thepopulation of approximately one generation period, giving the population theappearance of partially discrete generations. There was also evidence for longer cyclesof six-month period. Outbreaks occurred throughout the coconut-growing regions ofSri Lanka, and the numbers of outbreaks per year in different provinces weresometimes correlated, indicating a common, probably climatic, triggering mechanism.Parasitism remained high throughout the outbreaks and there was some evidence thatpupal parasitism increased towards the end of an outbreak. A working hypothesis thatexplains the population dynamics of O. arenosella and the origin of outbreaks ispresented.
Highlights
Opisina arenosella Walker ( = Nephanlis serinopa Meyrick) is an important defoliating, outbreak pest of coconut palms in Sri Lanka
The aim of this paper is to describe a first attempt to understand the population dynamics of O. arenosella based on long-term population monitoring by the Coconut Research Institute (CRI) of Sri Lanka
400 outbreaks of O. arenosella were reported to the CRI on 159 estates between 1965 and 1985
Summary
Opisina arenosella Walker ( = Nephanlis serinopa Meyrick) is an important defoliating, outbreak pest of coconut palms in Sri Lanka. It is recorded from India (Nirula, 1956), Burma (Ghosh, 1924) and Bangladesh (Alam, 1962) (a record from Indonesia (Davis and Sudasrip, 1982) is erroneous). A variety of cultural, biological and chemical control measures have been employed against the pest, and artificial defoliation experiments (Perera, 1987) confirm that moderate to high densities of O. arenosella do cause economic yield loss. Caterpillar infestations are confined to the lower fronds, and it has
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