Research Note: Abundance and prey spectrum of web spiders in rice agroecosystems of Pangasugan, Leyte, Philippines

the cultivation of tropical Asian rice, which may have originated 9,000 years ago, created an agricultural ecosystem of unrivalled ecological complexity. A complex arthropod communitiy is inhabiting in the rice ecosystem, including pest and beneficial species. Concerning beneficials, the spiders are among the very commonly encountered species. A study was conducted in the irrigated tropical rice fields of Leyte, Philippines on the abundance and their potential for natural biological control. the objective of this study was to record, identify and count individuals of selected web building spider species and evaluate the prey spectrum at different stages of rice growth. It was observed that abundance of spiders in the rice ecosystems occurred only starting at the tillering stage when the preferred host plant stage for the prey species was reached. the most dominant species of spiders encountered were Tetragnatha species. However, in the latest stage of rice development, Argiope species were the most dominant spiders. Prey species included mainly the pest species of the rice plants, such as the hoppers, rice bugs and other smaller insects and in addition the other predatory species such as the coccinellid beetles, dragonflies and parasitic hymenopterans were also observed. The web building spiders showed more activity in the late afternoon than in early morning.