Bees collecting pollen from other bees (Hymenoptera: Apoidea).

Worker honey bees (Apis mellifera) were observed stealing pollen from the scopae of Diadasia enavata and Halictus ligatus on sunflowers. Halictus also rarely stripped pollen from Diadasia scopae. Conditions of occurrence and ramifications of this phenomenon, called cleptolecty, are discussed. Laroca and Winston (1978) described the collection of thistle pollen from the bodies and appendages of male bumble bees by worker honey bees. They reported that honey bees preferentially landed on flower heads oc cupied by bumble bees and that the latter seemed little affected by the activities of the honey bees. Our observations differ in that female bees were seen stealing pollen from the pollen transport apparatuses (scopae) of other female bees. Materials and Methods In autumn 1978 we studied the pollen foraging behavior of bees on the large heads of commercial sunflowers (Helianthus annuus L.) on the Uni versity of California, Davis farm. We recorded our observations with 35 mm macrophotography, 16 mm cinematography and videotape. The principal pollen collecting bees were: Apis mellifera L. , Diadasia enavata (Cresson), Svastra obliqua expurgata (Cockerell), Melissodes spp. , and Halictus li gatus Say. The parasitic Xeromelecta californica (Cresson) and males of Anthophora urbana (Cresson) and Megachile sp. were also present. Results The bees from most to least frequently encountered were Apis, Diadasia, Svastra and Halictus. Female Svastra and Melissodes were the most elu sive and most easily disturbed, while Diadasia and Halictus were the most sedentary and least perturbable on the sunflower heads. The sunflower population declined rapidly during our observations from late September to early October. Bee activity became increasingly concen trated on the heads which still had pollen. We noted many interspecific interactions among the bees on sunflowers at this time. Interactions involving the more skittish females of Svastra or Melissodes usually resulted in a rapid departure of these females. Interactions involving the more sluggish Diadasia and Halictus sometimes resulted in thievery of pollen from their scopae. Received for publication 14 March 1979. This content downloaded from 207.46. 13.113 on Sun, 24 Apr 2016 06:06:30 UTC All use subject to http://about.jstor. org/terms VOLUME 53, NUMBER 1 167 Figs. 1-4. Ap/Aworkers stealing pollen from female bees on sunflower. Fig. 1. Apis hov ering and stealing pollen from scopa of Diadasia while latter raises hind leg in response. Fig. 2. Apis standing on sunflower head while stealing pollen from Diadasia. Fig. 3. Apis hovering and manipulating pollen stolen from Diadasia into its corbicula. Fig. 4. Apis stealing pollen from scopa of Halictus. We noted Apis workers stealing pollen from the well filled scopae of female Diadasia (Figs. 1-3), and occasionally from the scopae of Halictus (Fig. 4). We observed, but rarely, Halictus females thieving pollen from Diadasia. Also we observed a pollen collecting Apis biting at the corbicular pollen load of another Apis worker in an apparent attempt to steal pollen. The victim flew off after an encounter that lasted less than two seconds. Honey bees involved in this thievery approached their hosts lateropos teriorly, orienting toward one of the pollen filled scopae. They used their mandibles and forelegs to scrape with the grain of the scopal hairs of Dia dasia or Halictus. Honey bees robbed pollen while hovering (Fig. 1) or while standing (Fig. 2). After a brief bout of stripping pollen from the scopae of their victims, the honey bees hovered and groomed and transferred the pollen to their corbiculae (Fig. 3). A Diadasia female responded to a raid by elevating the attacked hind leg This content downloaded from 207.46. 13.113 on Sun, 24 Apr 2016 06:06:30 UTC All use subject to http://about.jstor. org/terms 168 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY as if to shake off the pillager (Fig. 1). Only after several repeated attacks would she leave the flower head. When Halictus females were attacked the bouts were usually brief, and the Halictus were sometimes dislodged from the sunflower. Most honey bees exhibited normal pollen collecting behavior on the sun flowers but those which had learned to rob seemed to persist in this behavior at the expense of normal pollen collecting. Robber honey bees continued their attacks on Diadasia and Halictus as long as the victims remained on sunflowers. If her pillaging was disrupted a honey bee hovered in front of available flower heads, but approached only when a bee was on a blossom and then resumed her looting. Pollen thieving by Halictus ligatus females appeared to be a simple dis placement of normal pollen collecting behavior. A female normally stripped pollen from the disk florets with her mandibles and forelegs, often building up a noticeable residue of bright yellow pollen on the apical margin of her clypeus. When the pollen laden scopa of a Diadasia was encountered, the Halictus female stripped pollen from it with the same behavior. Female Halictus were not as persistent as Apis in their thieving behavior. If dis rupted, they would resume normal foraging at the disk florets. They ap peared to take advantage of, but not to search for, opportunities to interact with Diadasia.