Publication JTAFS Issues Archive 1992 Volume 20 No.2 Functional response of the brown planthopper egg parasitoids Anagrus nr flaveolus ( Waterhouse) and Oligosita sp. (Walker)Functional response of the brown planthopper egg parasitoids Anagrus nr flaveolus ( Waterhouse) and Oligosita sp. (Walker)
A. Sivapragasam and T. H. Chua
Abstract
The functional responses of Anagrus nr flaveolus and Oligosita sp., egg parasitoids of the brown planthopper, Nilaparvata lugens, were studied rurder aboratory conditions. One-day-old brown planthopper eggs at densities of 5, 10, 15, 25, 35 and 45 within a rice stem were exposed to a female parasitoid for 24 h at each density. Data were analysed using the Random Parasitoid Equation and estimates of a, the searching efficiency and Th, the handling time, were obtained using the non-linear least square technique. Based on a value, the searching efficiency of A. nr.flaveolus was 3.5 times more than Oligosita sp. However, the handling time (Th ) of the brown planthopper eggs by Oligosita sp. was 1.5 times shorter than that of A. nr flaveolus. The functional response of both parasitoids was adequately described by the Holling's (1959) Type-II model. The potential uses and limitations of the parasitoids as biological control agents of the brown planthopper eggs in the field are discussed.
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