Population dynamics and prey composition of Tetragnatha spiders (Araneae: Tetragnathidae) in semi-organic rice fields, Songkhla Province, southern Thailand

Abstract

Tetragnatha spiders are common predators in rice ecosystems. However, changes in their population numbers and availability of prey types at each rice growth stage are poorly understood. Therefore, this study assessed the population dynamics of Tetragnatha spiders and their prey composition during four stages of rice growth, including vegetative, reproductive, ripening, and after-harvesting in semi-organic rice fields in Songkhla Province of southern Thailand. The results showed that species richness and abundance of spiders were significantly higher in the reproductive stage than in other stages. Main prey families captured by Tetragnatha spiders varied with different growth stages. Chironomidae and Corixidae were the main prey in the vegetative and reproductive stages, while Delphacidae was the most common prey in the ripening stage and there was dominant prey in the after-harvesting stage. Overall, the different growth stages provided different rice structures for web attachment and different prey, which influenced both the spider populations and prey composition.

Keywords

• biological control
• long-jawed spider
• generalist predator
• paddy field
• rice growing season