Pathummal Beevi, SParvathy Meera, KAU2020-10-302020-10-302000171776https://krishikosh.egranth.ac.in/handle/1/5810153981PGA pilot study was carried out with the objective of identification, quantification and comparison of the pest and natural enemy complex present in two different rice ecosystems in Thrissur district of Kerala, viz. non-kole and kole area. The species composition, abundance and relative occurrence of pests, parasitoids and predators collected in sweep net samples from six locations each of non-kole and kole area were studied. Six samples were drawn at weekly intervals from each location starting from 15 days after transplanting till the emergence of panicles and the mean data used for analysis. The species richness, diversity and evenness of all the pests and important natural enemies were also assessed. In situ count of leaf and planthoppers and associated generalist predators were recorded. The extent of natural parasitism on the field collected immature stages of stem borer, leaf folder and gall fly was recorded and identified the important species. In the sweep net samples taken from 12 rice fields, altogether 29 species of phytophages representing 19 families of six insect orders could be identified. Among the 96 species of natural enemies (entomophages) identified, 19 species were predators and 77 were the hymenopteran parasitoids. Except in the case of one or two locations, the occurrence of most common and regular pests and the associated natural enemy fauna were found to be the same in the non-kole and kole area. The entomophages comprising of parasitoids and predators were found to be higher than the phytophages in most of the locations. Homoptera comprising of leaf and planthoppers and Thysanoptera (thrips) were the predominant phytophages. Nephotettix spp. were dominant among the leaf and planthopper while it was Sogatella furcifera (Horvath) among the planthoppers. A significant difference was observed in the mean count of pests as well as natural enemies within the six locations of each situation. Spiders (8 species) cocinellid beetles (3 species), mirid bug (Cyrtorhinus Iividepennis Reuter), damselflies (2 species) and veliid bug [Microvelia douglasi atrolineata (Bergoth)] were the important predators. The predominant predator species were Tetragnatha maxillosa Thorell (Aranae), Cyrtorhinus lividipennis Reuter (Miridae), Micraspis spp. (Coccinallidae) and Agriocnemis pygmea Rambur (Odonata). Highest diversity was noticed in the case of hymenopteran parasitoids and was the single largest group of entomophages. In the non-kole area, spiders were most abundant followed by Odonata, whereas in kole area C. lividipennis was abundant followed by spiders. In the case of phytophages, between the two situations studied, significant difference was noticed only in the case of planthoppers, which was significantly high in kole lands. Spiders, C. Iividipennis and the total predators population were significantly high in kole area, whereas Odonata (damselflies) were significantly high in non-kole area. A highly significant positive correlation existed between the leaf and planthoppers with predators like C. lividipennis and spiders. In situ population count of leaf and planthoppers and their associated natural enemies viz. C. lividipennis and Lycosa indicated a density dependent relationship. From the field collected samples, three species of parasitoids VlZ. Telenomus spp. Tetrastichus spp. and Trichogramma spp. were obtained from the stem borer eggs. The parasitoids emerged from the leaf folder larvae and pupae were Cotesia (=Apanteles) spp. Brachymeria excarinata Gahal, Cardiochilus philippinensis Ashmead, Goniozus spp., Macrocentrus philippinensis Ashmead and Xanthopimpla spp. Only a single species (Platygaster sp.) was obtained from gallfly pupae.EnglishThesis