The alfalfa leafcutter bee, Megachile rotundata: a potential pollinator for some annual forage clovers

TLDR: The arrowleaf, berseem and crimson clovers were essentially self-sterile and produced very little seed when bees were excluded, whereas about one-third of the Persian clover flowers were self-pollinated.

Abstract: SUMMARYThe effectiveness of the alfalfa leafcutter bee (Megachile rotundata) as a pollinator of arrowleaf clover (Trifolium vesiculosum), berseem or Egyptian clover (Trifolium alexandrinum), crimson clover (Trifolium incarnatum) and Persian clover (Trifolium resupinatum) was evaluated over a 3-year period at Lethbridge, Canada. Treatments consisted of plants caged to exclude all pollinators, plants caged (cages were 40 × 20 × 2 m) with a shelter containing 30 000 leafcutter bees, and plants exposed to all pollinators present, including honey bees, bumble bees and leafcutter bees. The arrowleaf, berseem and crimson clovers were essentially self-sterile and produced very little seed when bees were excluded, whereas about one-third of the Persian clover flowers were self-pollinated. Only for crimson clover was there a significant difference in the percentage seed set between plants caged with leafcutter bees (50.5 ± 2.5%) and those exposed to resident pollinators (70.4 ± 1.1 %). However, the seed yield of pl...