FORAGING ECOLOGY AND ABUNDANCE OF NATIVE POLLINATORS IN BITTER GOURD

Abstract

An experiment is conducted in bitter gourd cropping system at Coimbatore district in India, to study bitter gourd floral character, the foraging ecology of native pollinators and their modes of pollination. Bitter gourd is a monoecious plant bears separate male and female flowers. Male flower blooms early followed by female flowers. Stigma receptivity of pistillate flowers was confirmed on 4th day old flower showed yellowish-green stigma with shining stigmatic exudation. The stigma receptivity lasts up to 24 hours after anthesis. Pollen viability test done with 2 per cent acetocarmine solution indicated that pollen collected during morning hours (06:00 h) were more viable and were deeply stained, whereas pollens collected at evening hours (17:00 h) remained unstained and considered as nonviable. The foraging activities of Apis cerana indica Fabricius and Tetragonula iridipennis begin at 06:00 h and 06:30 h respectively and ceased by evening 17:00 h. T. iridipennis foragers spent more time in pollen collection (31.1 seconds/ flower) and nectar collection (26.14 seconds/ flower) whereas, A. cerana indica spent less time in pollen collection (8.62 seconds/ flowers) and nectar collection (3.56 seconds/ flower) respectively. A total of 17 pollinator species belongs to four orders viz., Hymenoptera, Diptera, Lepidoptera and Coleoptera have been documented and grouped based on their mode of foraging in bitter gourd flowers.