Alfalfa (=lucerne) flowers require visiting bees to trip the sexual column, thereby providing pollination and subsequent pod and seed set. Previous studies have compared the pollination values of different bee species solely by the speed with which they handle flowers and the proportion of visited flowers tripped. In this greenhouse study, five species of bees, including the three commercially managed U.S alfalfa pollinators, are likewise compared for their floral tripping frequencies. These bee species are also compared for the pod set and mature seed that results from their single visits to virgin flowers. Regardless of the identity of the pollinating bee, tripped flowers had the same probabilities of pod set and seed set. Thus, differences in the single-visit pollination efficiencies of the various bee species are entirely attributable to the proportion of visited flowers that they trip. Females of the alkali bee, Nomia melanderi Cockerell, and the alfalfa leafcutting bee, Megachile rotundata F, tripped 81 and 78% of visited flowers, respectively. Males of these species are significantly less effective (61 and 51%, respectively), but still significantly superior to the honey bee, Apis mellifera L. (22% of visited flowers tripped). These relationships are supported by field data for tripping frequencies. One candidate pollinator, Osmia sanrafaelae Parker, shows promise (44% tripped), but not the congeneric O. aglaia Sandhouse (13% tripped).
Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.