Agriculturally beneficial arthropods for conservation and augmentation had been studied in dipterocarp reforested plots at Lainan Research and Technology Transfer station, Wiang Sa district, Nan Province, and in yard-long bean cultivation in organic demonstration plot at Chulalongkorn Land development project, Kaeng Khoi district, Saraburi province. Hand collection, vacuum, and beating sheet were used for arthropod sampling. The beneficial arthropods found in both studies were predatory spiders, particularly in families Salticidae and Oxyopidae. In dipterocarp reforested plots, leaf-rolling weevils, Apoderous notatus, were dominant pest, and praying mantis and assassin bugs were negatively affected from bird and bat predation. In yard-long bean plots, the main pests were bean aphid, Aphis craccivora, with oxyopid spiders as the major predetors of these aphids. The study of population dynamics of predatory arthropods will elucidate in conservation and augmentation of these beneficial arthropods.
