Some Aspects of Flower Biology and Bee Activity on Hybrid Cotton in Arizona, USA

SummaryThe phenology of flowering of male-fertile and genetic-cytoplasmic male-sterile upland cottons was observed and compared in detail, and a descriptive sequence which identifies 5 stages of an thesis is proposed. Phenological differences as well as other differences in availability and relative abundance of extrafloral nectar among cotton lines influenced honeybee (Apis mellifera) visits between cotton lines. In cage studies, cotton pollen-collection activity and flower-visitation movements of both honeybees and bees of an unidentified soil-nesting species were observed and recorded. Both species avidly collected loads of cotton pollen although, in open-field studies, it is unusual to find honeybees collecting cotton pollen. In the cage individual honeybees switched between pollen collection and nectar collection during single foraging trips.