Diversity, abundance and foraging behaviour of insect pollinators in Radish (Raphanus raphanistrum subsp. sativus L.)

• Published in: Journal of Asia-Pacific entomology Vol. 25; no. 2; pp. 101909 - 5
• Main Authors: Divija, S.D., Kamala Jayanthi, P.D., Varun, Y.B., Saravan Kumar, P., Krishnarao, G., Nisarga, G.S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2022; 한국응용곤충학회
• Subjects: Apis cerana; Apis dorsata; Apis florea; coevolution; Diptera; entomology; flowers; horticulture; India; Lepidoptera; nectar; Nectar robbing; pollen; Pollinator effectiveness; radishes; Raphanus raphanistrum; self-pollination; sporophytes; stigma; Stigma contact; surveys; Tetragonula; Visitation rate; 농학; India; Nectar robbing; Pollinator effectiveness; Stigma contact; Visitation rate
• ISSN: 1226-8615; 1876-7990
• DOI: 10.1016/j.aspen.2022.101909

Some of the insect pollinators observed during the experimentation period [Apis dorsata (a) Apis florea (b) Apis cerana (c) Tetragonula iridipennis (d) Lassioglossum sp. (e) Delta conoideum (f) and Danaus chrysippus (g)] [Display omitted] •Radish is crosspollinated due to sporophytic system of self-incompatibility.•Fifteen insect species, belonging to three orders were found to visit radish.•Species varied in foraging behaviour: visitation frequency and visitation rate.•Nectar robbing of Apis florea reduced their pollination efficiency.•Apis dorsata deposited maximum number of pollen grains per single visit. Insect pollinators and flowering plants have co-evolved together for millions of years, developing a wide array of mutualistic interactions. Several cultivated plant species depend exclusively on insect-mediated pollination services for their subsistence, reproduction and survival. Radish, Raphanus raphanistrum subsp. sativus, a popular edible root vegetable (Family: Brassicaceae) completely depends on pollinators as self-pollination is totally absent due to sporophytic self-incompatibility. The present study was conducted at the experimental fields of the ICAR-Indian Institute of Horticultural Research, Bengaluru, to understand the diversity and foraging behaviour of insect pollinators in R. sativus. Continuous survey during the flowering period revealed that a total of fifteen insect species that belong to three insect orders (Hymenoptera, Diptera and Lepidoptera) were found to visit R. sativus flowers. The most abundant species was Apis florea L., followed by Apis dorsata F., Tetragonula iridipennis (Smith), Apis cerana F., Lassioglossum sp. and Ischiodon scutellaris F. Floral visitors differed significantly in terms of their visitation frequency, with A. florea (0.76 ± 0.22 visits/flower/ min) being the most frequent visitor followed by A. dorsata (0.66 ± 0.21 visits/flower/ min) and T. iridipennis (0.59 ± 0.14 visits/flower/30 min). The maximum visitation rate was recorded for A. dorsata (7.8 ± 1.40 flowers visited/min) followed by A. cerana (6 ± 1.15). The maximum stay time on individual flower was recorded for Lassioglossum sp. (48.2 ± 3.67 sec) followed by T. iridipennis (44.2 ± 4.24 sec). The maximum numbers of pollen grains were deposited by A. dorsata (206.70 ± 56.45) followed by A. cerana (151.20 ± 31.84). All the floral visitors except A. florea made contact with stigma on every single visit (100 %). While, only 53 per cent of total visitation by the Apis florea led to stigma contact. Further, nectar robbing behaviour was majorly exhibited by A. florea and Delta conoideum compared to all other insect pollinators observed. Based on the overall pollinator effectiveness per day A. dorsata was found to be the most effective single pollinator species.