They outnumbered honeybees and bumblebees, the second and third most frequent foragers, EMR scientist Michelle Fountain told delegates attending the EMRA/HDC tree fruit day last month.
The survey was carried out as part of a research project looking at ways in which growers can boost insect pollination in fruit crops.
"Often pollination is not something that's highlighted in best practice," said Fountain. Prior to the study there was a lack of evidence to show which insects visit the fruit blossom, she added.
The research involved monitoring visitors to plants each hour in six orchards, including a hectare of apples, a hectare of pears and a blackcurrant plantation.
"Andrena dorsata and A. haemorrhoa were common solitary bees on all three crops," said Fountain. The term "solitary" is misleading because they are communal insects, she added. "Each bee is providing for its own eggs - they are just nesting in the same place."
Fountain advised growers that solitary bees like to nest in undisturbed, south-facing, sparsely vegetated ground with loose, crumbly soil not susceptible to waterlogging.