The leafcutting bee, Megachile rotundata (F.): a potential pollinator for red clover

The use of the leafcutting bee, Megachile rotundata (F.) as a pollinator of single-cut, diploid red clover, Trifolium pratense L. was investigated in the Peace River region of northern Alberta over a 5-year period, 1983 to 1987 inclusive. Average seed yield with the use of this pollinator was 410 kg/ha as compared to 291 kg/ha for the control where the leafcutting bee was not used. Furthermore, in four of the five years of study, provision of leafcutting bees was associated with higher seed production. Reproduction of leafcutting bees pollinating red clover was comparable to that obtained on alfalfa. For each crop, about 96 percent of the cells produced were viable. Also, about 32 percent of these cells were females, i.e., a 2:1 ratio of males to females. It should be noted however, that the ratio of cell increase was generally lower in bees pollinating red clover than in those pollinating alfalfa but that the lowest increase obtained was 1.5, i.e., there was no bee loss, only a minimum gain of 50 percent. The results of the present study indicate that management of the leafcutting bee as a pollinator of red clover merits further investigation. Zusammenfassung Die Blattschneiderbiene Megachile rotundata (F.): ein potentieller Bestauber fur Rotklee Die Verwendung von Megachile rotundata als Bestauber des diploiden Rotklees, Trifolium pratense, wurde in der Peace River-Region (N-Alberta) 1983–1987 untersucht. Die mittlere Samenernte nach Einsatz dieser Blattschneiderbiene betrug 410 kg/ha gegenuber der Kontrolle (291 kg/ha). Die Reproduktion von Rotklee bestaubenden Blattschneiderbienen war jener der Alfalfa bestaubenden vergleichbar. Bei jeder der zwei Kulturpflanzen waren etwa 96% der Megachile–Brutzellen lebensfahig. Rund 32% der Zellen ergaben Weibchen, was einem Geschlechterverhaltnis von 2:1 zugunsten der Mannchen entspricht. Der Zuwachs an Zellen war allgemein bei den Rotkleebestaubern geringer als bei den Alfalfabestaubern, betrug jedoch zumindest 1,5. Das heist, das es keinen Verlust an Bienen gab, sondern mindestens einen Gewinn von 50%. Die Ergebnisse zeigen, das die Frage eines Managements von Blattschneiderbienen als Rotkleebestauber weitere Untersuchungen verdient.