Pollination of Brassica campestris (Cruciferae) by Andrena savignyi (Andrenidae: Hymenoptera): Female vs. Male Pollination

Abstract

Female and male solitary bees usually differ in their behavioral and morphological attributes and consequently in their pollination effectiveness. The current study was carried out at the research farm of The Islamia University of Bahawalpur, Pakistan, to compare the foraging behavior and pollination efficiency of female and male Andrena savignyi Spinola, 1838 on Brassica campestris. The impact of different environmental factors (temperature, relative humidity, light intensity and wind speed) on foraging behavior was also studied. Andrena savignyi was the most abundant floral visitor of B. campestris and comprised 52.17% of the floral visitors. Female individuals fed on both nectar and pollen while male fed on nectar. Visitation frequency, visitation rate, pollen harvest and pollen deposition of females were significantly higher than that of males because of their larger size and more dry weight. The maximum abundance of females was recorded at 12:00 pm followed by a sharp decline until 4:00 pm whereas males attained their maximum abundance at 2:00 pm. The female pollinated flowers resulted in greater pod weight, pod length, number of seeds per pod, seed weight per pod and germination percentage than the males. Our results suggest that females of A. savignyi deliver better pollination of B. campestris than males in terms of its reproductivesuccess and germination percentage. Future studies should emphasis on exploring the biology and ecology of A. savignyi with special focus of its artificial nesting.