Abstract Individual and colony-level foraging behaviors were evaluated in response to changes in the quantity or nutritional quality of pollen stored within honeybee (Apis mellifera L.) colonies. Colonies were housed in vertical, three-frame observation hives situated inside a building, with entrances leading to the exterior. Before receiving treatments, all colonies were deprived of pollen for 5 days and pollen foragers were marked. In one treatment group, colony pollen reserves were quantita- tively manipulated to a low or high level, either by starving colonies of pollen or by providing them with a fully provisioned frame of pollen composed of mixed species. In another treatment group, pollen reserves were qualita- tively manipulated by removing pollen stores from colo- nies and replacing them with low- or high-protein pollen supplements. After applying treatments, foraging rates were measured four times per day and pollen pellets were collected from experienced and inexperienced foragers to determine their weight, species composition, and protein content. Honeybee colonies responded to decreases in the quantity or quality of pollen reserves by increasing the proportion of pollen foragers in their foraging populations, without increasing the overall foraging rate. Manipulation of pollen stores had no effect on the breadth of floral species collected by colonies, or their preferences for the size or protein content of pollen grains. In addition, treatments had no effect on the weight of pollen loads collected by individual foragers or the number of floral species collected per foraging trip. However, significant changes in foraging behavior were detected in relation to the experience level of foragers. Irrespective of treatment group, inexperienced foragers exerted greater effort by collecting heavier pollen loads and also sampled their floral environment more extensively than experienced foragers. Overall, our results indicate that honeybees respond to deficiencies in the quantity or quality of their pollen reserves by increasing the gross amount of pollen returned to the colony, rather than by specializing in collecting pollen with a greater protein content. Individual pollen foragers appear to be insensitive to the quality of pollen they collect, indicating that colony- level feedback is necessary to regulate the flow of protein to and within the colony. Colonies may respond to changes in the quality of their pollen stores by adjusting the numbers of inexperienced to experienced foragers within their foraging populations. Keywords Apis mellifera · Pollen foraging behavior · Pollen quality · Protein content · Nutrition Introduction Pollen is an extremely important resource that honeybee colonies must collect. It provides them with their only natural source of protein, which is needed for larval development, and fulfils other dietary requirements for lipids, sterols, vitamins, and minerals (Herbert 1992). Nectar is the major energy source of the colony, providing the raw fuel for the activities of all colony members. Not only are nectar and pollen utilized differently by honeybee colonies, but each is collected in a unique way. Colonies typically recruit more foragers to the task of nectar collection than pollen collection, and only a small percentage of foragers collect both resources simulta- neously (Parker 1926; Free 1960; Visscher and Seeley 1982). Behaviors of nectar and pollen foragers also differ: nectar foragers lap nectar from flowers and store it internally, whereas pollen foragers collect pollen externally by grooming it from their bodies and pressing it into their corbiculae (Hodges 1984). As a result, only nectar foragers receive direct qualitative information about the Communicated by R.F.A. Moritz S.F. Pernal ( ✉ ) · R.W. Currie Department of Entomology, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada Present address: S.F. Pernal, Agriculture and Agri-Food Canada, Research Branch, Box 29, Beaverlodge, Alberta, T0H 0C0, Canada, e-mail: pernals@em.agr.ca, Tel.: +1-780-354-2212, Fax: +1-780-354-8171 Behav Ecol Sociobiol (2001) 51:53–68 DOI 10.1007/s002650100412 ORIGINAL ARTICLE Stephen F. Pernal · Robert W. Currie The influence of pollen quality on foraging behavior in honeybees (Apis mellifera L.) Received: 7 February 2001 / Revised: 23 July 2001 / Accepted: 11 August 2001 / Published online: 9 October 2001 © Springer-Verlag 2001