Relationships Among Insect Pollinators, Micro-environmental Factors and Fruit Settings of Teak (Tectona grandis L.F.) in Seed Orchards, Thailand

Abstract

The ecological effects of insects in the tropics have been studied generally in terms of its impact on species diversity and abundance. However, the information is very limited regarding the interrelationship of insects on ecological processes such as insect pollinators, environmental variables and fruit settings of teak. All data were studied at five main teak seed orchards in Thailand. Observations were carried out by walking on line transects and air-flight malaise traps from tree canopies in each site during the peak flowering season of teak. A total of 63 species in 17 families and three orders (Hymenoptera, Lepidoptera and Diptera) of flower visitors were found. The relationships between insect pollinator composition and environmental factors among the teak seed plantations were significantly different in species composition and some environmental variables. The results of this study showed that micro-environmental factors (temperature and photosynthetic active radiation) significantly affected species diversity and abundance of insect pollinators, especially in their foraging behavior responses to the photosynthetic active radiation variable. We thus concluded that some pollinators have different responses to environmental variables that affect their visiting behavior on flowers and also fruit set, and this was associated with visiting periods and habitats.

Keywords: insect pollination, visitor, teak, microclimate, tropical forest