sentences:  However, Western honey bee colonies may suffer protein stress when working alfalfa only, because alfalfa pollen protein is deficient in isoleucine, one of the amino acids essential in the diet of honeybee larvae.Today, the alfalfa leafcutter bee ("Megachile rotundata") is increasingly used to circumvent these problems.As a solitary but gregarious bee species, it does not build colonies or store honey, but is a very efficient pollinator of alfalfa flowers.