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Show Bees Are Factors In Alfalfa Seed Production Article III The benefit from honey bees in seed fields of Utah has been shown in another way. For many vears there has heen an annual movement of migratory colonies of bees from California to the seed areas of Utah. These colonies definitely def-initely augment the number of pollinators in the seed areas, but their numbers have varied widely during the past 23 years, ranging from 1,500 to 15,000 annually. When comparing this traffic with the state seed yields per acre, it is apparent that the yields have tended to vary up and down with the number of incoming colonies. High yields have tended to occur in years of high migratory traffic and low yields when there was less of such traffic. It is surprising surpris-ing that this relationship should be evident through the years in the presence of such other powerful power-ful factors affecting seed yields as injurious insects and weather conditions. This influence of migratory mi-gratory bees on alfalfa seed yields indicate that Utah can use many more bees. In fact, the investigators investiga-tors suggest that for each additional addi-tional 1,000 colonies the state may expect an increase of about 5 lbs. per acre, or about 250,000 pounds on the basis of the 53,000 acres planted to seed in 1949. We recognize the fact that "tripping" "trip-ping" is essential for commercial seed production. In preceding articles ar-ticles we discussed how the flower flow-er was tripped and why, we discussed dis-cussed different methods of pollination pol-lination which included Self and Cross-Pollinization, Methods of Obtaining Ob-taining Pollination, wind- rain-heat rain-heat and humidity-mechanical trip ping- and now we discuss: TRIPPING AND CROSS POLLINATION POLLINA-TION BY INSECTS. At present, the methods of pollination pol-lination previously discussed are of no practical significance in setting a commercial crop of seed. Repeated experiments in which in-seots in-seots have been excluded confirm their importance as agents in the transfer of alfalfa pollen. Replicated Replicat-ed plots of alfalfa from which insects in-sects were excluded produced 14 pounds of seed per acre in contrast con-trast to 198 pounds per acre under I natural conditions where insects , were present. The alfalfa flower is adapted for cross-pollination by insects. When an insect thrusts its head into a flower it releases the sexual sex-ual column and is thereby struck on the head by a mass of sticky pollen and by the receptive area (9tigma) of the female organs. By entering a flower of another plant it receives another load of pollen on the same part of the head and at the same time contributes pollen pol-len from its previous load to the stigma. The seed grower must depend upon the activities of insects in-sects for the tripping and cross-pollination cross-pollination needed for successful seed production along with the activities of the bee. The dependency upon insect pollination pol-lination complicates alfalfa seed production. We might logically inquire in-quire next. What are the factors affecting pollination by insects? Pollination of alfalfa by insects is affeoted both by differences in the insects and differences in the plants. Plant characters possibly significant signif-icant in influencing insect visitation visita-tion include odor, color, nectar, pollen, shape and size of flower, mechanical features, and competition. competi-tion. The bee locates the food and coveys this information to its fellow fel-low workers. However, unless the plant is a wholesome source of food, the bees disregard it. The available food (nectar and pollen) varies from plant to plant within a. group of alfalfa plants and on a broader scale is modified modifi-ed by competition among insect visitors. A large population of one kind of inseot may use all or most of the food, thereby limiting the amount available for another insect in-sect which may be a more efficient pollinator. i Intensive studies in the past few years have shown that in Utah and California honey bees, in spite of their rather low efficiency as individuals are performing most of the pollination of the commercial seed acreage. Material obtained from "Growing "Grow-ing Alfalfa For Seed in Utah" circular cir-cular 125, Utah Agricultural Experiment Exper-iment Station, Logan, Utah. |