Assessment of Apis mellifera and Other Insect Pollinators in Augmenting Seed Yield of Onion (Allium cepa. L).

Abstract

To identify the pollinator community of insects and its role in onion (Allium cepa L.) pollination, an investigation was carried out at the vegetable research field of SKUAST-K, Shalimar at two hourly basis from 8:00hr-18:00 hr in the bloom period of crop during the year 2021-2022. The observations on diversity of pollinators showed that large number of insect pollinators were found visiting onion bloom. The insect pollinators were found active during the blooming period, however the foraging activity differs significantly at different time intervals of the day, that too among the different insect pollinators. It was also concluded that the insect visitors may not necessarily be the potential pollinators as well. Out of seven insect species visiting onion bloom Hymenopterans (Apis mellifera, Apis cerana and Vespa spp) were the main visitors, but the foraging activity of Syrphids was highest, followed by Apis mellifera, Apis cerana and others. The highest foraging activity of syrphids (6.88) was observed at 1000-1200 hr followed by (5.72) at 1200-1400 hr, whereas, in case of Apis mellifera highest foraging activity (4.86) was observed at 1200-1400hr followed by (4.30) at 1000-1200 hr. The impact of managed pollination on the yield and quality of onion seeds was assessed by using four treatments: plants enclosed in nets without pollinators (T1), plants enclosed with honey bees (Apis mellifera) as the sole pollinator (T2), plants enclosed with syrphids as the sole pollinators (T3), and plants exposed to all pollinators (T4). The number of umbels produced per plant was not influenced by pollination. However, both honey bee pollination and open pollination resulted in 232.14 seeds/umble and 227.60 seeds/umble and 3.95 and 3.87 as 1000 seed weight/gm respectively, and seed yield of 568.22 and 590.98 kg/ha honey bee as pollinator and open pollination conditions, respectively. Pollination by honeybees showed better performance followed by open pollination and least performance in the yield and yield attributing parameters were observed in pollination exclusion treatment