Specialization on pollen or nectar in bumblebee foragers is not associated with ovary size, lipid reserves or sensory tuning.
Foraging specialization allows social insects to more efficiently exploit resources in their environment. Recent research on honeybees suggests that specialization on pollen or nectar among foragers is linked to reproductive physiology and sensory tuning (the Reproductive Ground-Plan Hypothesis; RGPH). However, our understanding of the underlying physiological relationships in non-Apisbees is still limited. Here we show that the bumblebeeBombus terrestrishas specialist pollen and nectar foragers, and test whether foraging specialization inB. terrestrisis linked to reproductive physiology, measured as ovarian activation. We show that neither ovary size, sensory sensitivity, measured through proboscis extension response (PER), or whole-body lipid stores differed between pollen foragers, nectar foragers, or generalist foragers. Body size also did not differ between any of these three forager groups. Non-foragers had significantly larger ovaries than foragers. This suggests that potentially reproductive individuals avoid foraging.
Department of Biological Sciences, George Washington University , Washington , DC , United States.
Adam R
AR
Smith
Department of Entomology, University of California, Riverside , Riverside , CA , United States.
Peter
P
Graystock
School of Life Sciences, University of Sussex , Brighton , United Kingdom.
William O H
WO
Hughes
Division of labor; Foraging specialization; Reproductive ground plan hypothesis