Nearly half of spring-flying male Andrena bees consume pollen, but less than female conspecifics

Abstract

Despite its potential nutritional benefits, consumption of pollen by adult solitary bees has rarely been quantified. Pollen consumption by adult male bees is usually assumed to be negligible, but few studies have investigated this assumption. Here, we review existing literature on adult male bee pollen consumption and present new data on female and male pollen consumption by 9 species from 5 subgenera of spring-flying Andrena. We dissected and plated full contents of the digestive tract, calculating body-size adjusted pollen volumes for each bee. More females had consumed pollen than males (87% compared to 46%, respectively). Of the bees with pollen, females had consumed over nine times more pollen. However, 10% of males had consumed over 10,000 pollen grains and the highest two exceeded 30,000 grains. Given the large proportion of male bees that consumed pollen, we suggest future work should explore daily/seasonal patterns of consumption and possible fitness implications.