A comparative study of the efficiency of bumble bees and an electric bee in pollinating unheated greenhouse tomatoes

The efficiency of an electric bee in pollinating tomatoes grown in an unhea ted greenhouse was compared with that of bumble bees. Two years of experime nts show that under the moderate climatic conditions of autumn and early wi nter, the two methods had similar effects on fruit set, seed number, fruit size and yield. Under more severe winter conditions, however, bumble bees w ere more efficient than the common agricultural practice of using the elect ric bee 2-3 times a week. Even in the presence of relatively low amounts of pollen grains per flower, a high percentage of fruit set was obtained by t he bees. Under these adverse climatic conditions, flower vibration with the electric bee and with bumble bees achieved equal degrees of fruit set, onl y when the electric bee was operated every day. It may be concluded, theref ore, that bumble bees are efficient pollinators as long as the flower organ s are functional and a minimum number of pollen grains is available. For ac hieving similar pollination efficacy with an electric bee, one should adjus t the frequency of its use according to the circumstances, with daily opera tion under unfavourable conditions.