Diversity and abundance of insect pollinators on Allium cepa L.
Sunita Devi, Rachna Gulati, Kanika Tehri and Asha
Field experiment was conducted at CCS Haryana Agricultural University, Hisar during 2009-10 to investigate the diversity and abundance of insect pollinators on Allium cepa L. and correlate their incidence in relation to the abiotic environmental factors. Hymenopterans were found to be the most abundant (60%) followed by Lepidoptera, Diptera and Coleoptera. Variation in abundance was recorded over time and space. Irrespective of different day hours, significantly maximum number of Apis dorsata was recorded from onion umbels (5.24 bees/m2/5 min.) followed by A. mellifera (4.05 bees/m2/5 min.), A. cerana (2.93 bees/m2/5 min.) and A. florea (1.79 bees/m2/5 min.) (CD=0.51; p=0.05). Fluctuation in visits of insect pollinators on different days was observed. The visits were low at the time of commencement and cessation of flowering but remained high during mid-flowering period. The study revealed that among abiotic factors, maximum and minimum temperature and relative humidity play a significant role in the foraging population on onion umbels.
Fig.: Abundance of different insect pollinators on onion (A. cepa) umbels