Community structures and population dynamics of rice arthropods in irrigated ricefields in the Philippines
1994
Barrion, A.T. | Aquino, G.B. | Kong Luen Heong (International Rice Research Inst., Los Banos, Laguna (Philippines). Entomology and Plant Pathology Div.)
Four guilds-phytophages, predators, parasitoids, and scavengers/tourists constituted the arthropod community structure of five irrigated rice ecosystems in Luzon Island, Philippines. The phytophages and predators were most preponderant in all sites. Suborder Homoptera were the dominant phytophage represented mainly by three major genera of sap-sucking pests of rice-Nephotettix, Nilaparvata, and Sogatella. Three Heteroptera or true bugs - Microvelia (Veliidae), Mesovelia (Mesovellidae), and Cyrtorhinus (Miridae), and four Araneae-Pardosa (Lycosidae) and three species of Tetragnatha (Tetragnathidae) were the most common predators. The major parasitoids were Gonatocerus spp.(Mymaridae), undetermined Diapriidae, and Megaselia (Phoridae). The population dynamics of key pests and predators in all sites were compared. The cicadellids, dephacids, and ephydrids were abundant in the first 40 days after transplanting followed by the predators-spiders and semiaquatic bugs thereafter. Species richness and diversity of arthropods were determined and a total of 240 species were encountered in all sites. In general, species richness increased with crop age. Diversity, on the other hand, differed across sites. The order of diversity was Los Banos (12.75)Bayombong (10.65)Kiangan (10.08)Banaue (5.70)Cabanatuan (4.70). Foliar sprays of pyrethoid insecticides disorganized the arthropod guilds. Both phytophages and natural enemies responded differently to the spray. Knowledge of the community structures and temporal dynamics of arthropods in rice ecosystem and the factors affecting them can be valuable tools in developing pest management strategies
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