Quantities of pollen on the bodies of insects visiting apple blossom.
The amount of pollen of the appropriate species borne on the body of an insect is presumed to be an important factor in assessing its value as a pollinator. Some 700 insects of more than 70 species were collected from the blossoms of apple trees at different times and at various phases of blossom and in varying weather, in 1969 and 1970. Estimates were made of the quantities of pollen carried on their bodies, excluding that in the corbiculae of bees. A table lists the species in descending order of the geometric mean number of fruit pollen grains on the body. Females of Andrena haemorrhoa and A. coitana and workers of Bombers terrestris and B. lucorum bore over 15 000 grains of fruit pollen, considerably more than worker honeybees (mean ca. 4000), a number of other wild bees, and some of the larger and hairier Syrphidae. Insects with significantly less fruit pollen than this group included a few wild bees and the majority of Syrphidae. A number of small or smooth insects, including various Diptera and Coleoptera, bore very few pollen grains.D.A. Kendall