Honey Bees as Pollinators of Hybrid Cotton

Honey bees, Apis mellifera L., were frequent visitors to flowers of a male-sterile cotton, a 3-way cross between Gossypium hirsutum L., G. anomalum Wawr. ex Wawra & Peyr., and G. thurberi Todaro, at 1 location in southern Arizona, but the bees made only 1 10 as many visits to cotton flowers at a 2nd location. A good boll set was obtained early at the location with the intense bee activity. The seed set at the 2nd location was adequate, but much slower. Most of the seeds in the bolls set after the 3rd week in August were destroyed by insects. Wild bees appeared too late and in too small numbers to be reliable or adequate pollinators. Honey bees showed a 5 to 3 preference for A-line (male-sterile) flowers over B-line (complete) flowers but crossed readily between the A and B lines; wild bees preferred B-line flowers by a ratio of 3 to 2. Honey bees can set a good crop of cotton seed early in the season in southern Arizona, then they can be moved from the fields so that insecticides can be applied to control harmful insects.