Reproductive Potential Accelerates Preimaginal Development of Rebel Workers in Apis mellifera.

Aneta Strachecka,Michał Woyciechowski,Krzysztof Olszewski,Jerzy Paleolog,Karolina Kuszewska

doi:10.3390/ani11113245

Abstract

Simple SummaryAll female honeybee larvae may develop into workers or queens, depending on the food they receive. During this period, queen mandibular pheromones (QMP) perform a regulatory function in inhibiting ovarian development in adult workers. These pheromones are transmitted (via trophallaxis) by workers to pass information to larvae on the presence or absence of the queen. Queen-less conditions are conducive to the emergence of rebel workers that are set to reproduce, and do not participate in the rearing of successive bee generations in contrast to the sterile, normal workers. We posited that rebels are not only similar to queens in some anatomical features, but also develop in a shorter time in comparison to normal workers. Therefore, the aim of this study was to compare the duration of preimaginal development in rebel and normal workers. Our results confirmed that the workers who develop in a queen-less colony undergo a shorter preimaginal development than those in a queen-right colony.Rebel workers develop from eggs laid by the previous queen, before it went swarming and left the colony orphaned, until the emergence of a new queen. In contrast to normal workers developing in the queen’s presence, rebels are set to reproduce and avoid rearing of successive bee generations. They have more ovarioles in their ovaries, as well as more developed mandibular glands and underdeveloped hypopharyngeal glands, just like the queen. We posited that rebels are not only similar to queens in some anatomical features, but also develop in a shorter time in comparison to normal workers. Therefore, the aim of this study was to compare preimaginal development duration in rebel and normal workers. The results show that rebels, i.e., workers with a higher reproductive potential, had a significantly shorter preimaginal development period (mean ± SD, 19.24 ± 0.07 days) than normal workers (22.29 ± 0.32 days). Our result confirmed that workers who develop in a queen-less colony undergo a shorter preimaginal development than those in a queen-right colony.

Highlights

Honeybees (Apis mellifera), like other holometabolic insects, have three different ontogenetic phases separated by metamorphic moults
Squares represent the mean; the wheels represent the number of section combs (n = 4); the differences between the rebel workers and normal workers are significant at p ≤ 0.05
The boxes indicate the data between the 25 and 75% quartiles, including the median; the whiskers represent the minimum and maximum values; the black squares represent the mean; the wheels represent the number of section combs (n = 4); the differences between the rebel workers and normal workers are significant at p ≤ 0.05 (Mann–Whitney test)

Summary

Introduction

Honeybees (Apis mellifera), like other holometabolic insects, have three different ontogenetic phases (larva, pupa, and imago) separated by metamorphic moults. Female larvae of A. mellifera receive different food to become either queens or workers, i.e., those in queen cells are provisioned with royal jelly, while those in worker cells are provided with worker jelly, which includes pollen [3,4,5,6]. Up to 3 days after hatching, female larvae are totipotent and can develop into queens or workers. The 3rd and 4th day of larval development is the crucial period in female honeybee ontogeny [2,7,8]. An important role in this key period is played by mandibular pheromones (QMP), which have a regulatory function in inhibiting ovarian development in adult workers and suppressing their reproduction [9]

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