Enhancing Alfalfa (Medicago sativa) Seed Yield: The Effect of Honey Bee (Apis mellifera) Supplementation and Efficiency of Other Pollinators

Alfalfa (<i>Medicago sativa</i>) is an important fodder crop with 16-25% protein and 20-30% fibre content. It requires pollinators for seed development through a process known as "tripping". Honey bees are preferred for their easy management and mass rearing to enhance pollination. In a field experiment, we tested three treatments: two honey bee colonies (moderately supplemented), three honey bee colonies (highly supplemented), and a control with no honey bee colonies. The colonies European honey bee, <i>A. mellifera</i>, were used, starting at the flowering stage. We assessed the abundance, foraging, and tripping behaviour of pollinators, as well as the number of seeds per pod, pod weight, and seed weight. Honey bees were the most abundant in supplemented plots, followed by solitary bees, with increased honey bee visitation in the second year. <i>Megachile cephalotes</i>, <i>M. hera</i>, and <i>A. mellifera</i> were the most efficient pollinators regarding seeds per pod and seed weight. The plot with two honey bee colonies had a higher seed yield than the one with three colonies. Conservation of these pollinators and the introduction of managed <i>A. mellifera</i> colonies can lead to sustainable alfalfa seed production. Our findings suggest that honey bee supplementation, along with conservation efforts for solitary bees, can enhance pollination and seed yield in alfalfa.