Introduction of Varroa destructor has not altered honey bee queen mating success in the Hawaiian archipelago

Lauren M Rusert,David R Tarpy,Jeffrey S Pettis

doi:10.1038/s41598-020-80525-5

Lauren M Rusert, David R Tarpy + Show 1 more

Open Access

https://doi.org/10.1038/s41598-020-80525-5

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Abstract

Beekeepers struggle to minimize the mortality of their colonies as a consequence of the parasitic mite Varroa destructor in order to maintain a sustainable managed pollinator population. However, little is known about how varroa mites might diminish local populations of honey bee males (drones) that might affect the mating success of queens. As one of the world’s last localities invaded by varroa mites, the Hawaiian Islands offer a unique opportunity to examine this question by comparing queens mated on mite-infested and mite-free islands. We raised queen bees on four Hawaiian Islands (Kaua‘i, O‘ahu, Maui, and Hawai‘i) and subsequently collected their offspring to determine queen mating frequency and insemination success. No significant difference for mating success was found between the islands with and without varroa mites, and relatively high levels of polyandry was detected overall. We also found a significant association between the number of sperm stored in the queens’ spermathecae and the number of managed colonies within the localities of the queens mated. Our findings suggest that varroa mites, as they currently occur in Hawai‘i, may not significantly reduce mating success of honey bee queens, which provides insight for both the reproductive biology of honey bees as well as the apiculture industry in Hawai‘i.

Highlights

Beekeepers struggle to minimize the mortality of their colonies as a consequence of the parasitic mite Varroa destructor in order to maintain a sustainable managed pollinator population
When comparing overall mating success using the first principle component of a Principal Component Analysis (PCA), we found no significant difference between Rounds (F1,24 = 3.43, p = 0.08) or between islands with and without varroa mites (F1,24 = 0.00, p = 0.99; power = 0.054, LSNumber = 2878)
Our results confirm that there is high overall queen reproductive success on the four Hawaiian islands, irrespective of whether or not the varroa mite has been introduced to that sub-population

Summary

Introduction

Beekeepers struggle to minimize the mortality of their colonies as a consequence of the parasitic mite Varroa destructor in order to maintain a sustainable managed pollinator population. Our findings suggest that varroa mites, as they currently occur in Hawai‘i, may not significantly reduce mating success of honey bee queens, which provides insight for both the reproductive biology of honey bees as well as the apiculture industry in Hawai‘i Island systems, such as the Hawaiian archipelago, offer a rare opportunity to study biological invasions and other dynamics of natural- and managed ecosystems. Despite the first detection of the mite to those islands, the other main islands—Maui, Kaua‘i, Moloka‘i, and Lāna‘i—remain free of varroa[10], constituting an intriguing natural laboratory to study the effects of varroa parasitism on honey bees It is unclear if the increased colony losses of feral and managed honey bees as a consequence of varroa mites has led to a decrease in population density[6]. All of these queen reproductive quality measures help to assess the health of queen bees and aid in creating guidelines for overall colony sustainability

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