Abstract

Analysis of Egg Parasitoids of Rice Ecosystem of Intermediate Zone of Sri Lanka

ABSTRACT

Yellow stem borer, white stem borer, rice leaf folder and rice bugs are the main pests in Sri Lanka. Rice is the staple food of Sri Lankans that provides the considerable amount of energy and protein requirement for an average person. In comparison with other crops, rice cultivation demands the control of insect pests in all crop growth stages, thus rice cultivators are not hesitated to apply variety of insecticides. Insecticide application on crop at harvesting stagem creates serious health problems. Therefore, one of the options is implementation of biological control program. Initiation of bio-control program requires some key information such as the availability of egg parasitoids, information on their biology and ecology. Hence, the main objective of this study was to identify and analyze the diversity of egg parasitoids in rice feeding insect in rice field ecosystem. This research was conducted during May-September, 2012 in the Department of Agricultural Biology, Faculty of Agriculture, University of Peradeniya. It included field surveying, characterization and identification of the sampled species. Field survey was conducted in three selected rice fields at Kurunagela and nearby areas. Samples were collected manually using lens and vials. Visual observation was done at the time of sampling. The collected materials were brought to the Entomology Research Laboratory for further processing and identification. Collected eggs were incubated in plastic vials until the emergence of parasitoid adults or host larva. Identification of adult parasitoids was done using taxonomic keys and other available resources. Results and data were used to make an inventory of insect parasitoids in the rice ecosystem, their population fluctuation with time, and possible variation of parasitoids fauna with geographical locations. One Trichogramma species were found parasitizing rice leaf folder and yellow stem borer, one species of gryon nixoni emerged from paddy bug eggs, scelionid wasps emerged from red horn caterpillar eggs.
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