Queen-Signal Modulation of Worker Pheromonal

Queen-signal modulation of worker pheromonal

composition in honeybees

Tamar Katzav-Gozansky1

, Raphae¨ l Boulay2, Victoria Soroker3

and Abraham Hefetz1

1Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel

2Estacion Biologica de Don˜ana, CSIC, Apdo. 1056, 41013 Sevilla, Spain

3Department of Entomology, ARO, The Volcani Center, Bet Dagan, 50250, Israel

Worker sterility in honeybees is neither absolute nor irreversible. Whether under queen or worker control, it

is likely to be mediated by pheromones. Queen-specific pheromones are not exclusive to queens; workers

with activated ovaries also produce them. The association between ovarian activation and queen-like pheromone

occurrence suggests the latter as providing a reliable signal of reproductive ability. In this study we

investigated the effect of queen pheromones on ovary development and occurrence of queen-like esters in

workers’ Dufour’s gland. Workers separated from the queenright compartment by a double mesh behaved

like queenless workers, activating their ovaries and expressing a queen-like Dufour’s gland secretion,

confirming that the pheromones regulating both systems are non-volatile. Workers with developed ovaries

produced significantly more secretion than sterile workers, which we attribute primarily to increased ester

production. Workers separated from the queenright compartment by a single mesh displayed a delayed

ovarian development, which we attribute to interrupted transfer of the non-volatile pheromone between

compartments. We suggest that worker expression of queen-like characters reflects a queen–worker arms

race; and that Dufour’s gland secretion may provide a reliable signal for ovarian activation. The associative

nature between ovary development and Dufour’s gland ester production remains elusive.

Keywords: Dufour’s gland; Apis mellifera; pheromones; worker reproduction

1. INTRODUCTION

Reproductive skew,...