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Resistance rather than tolerance explains survival of savannah honeybees (Apis mellifera scutellata) to infestation by the parasitic mite Varroa destructor

Published online by Cambridge University Press:  22 December 2015

URSULA STRAUSS ,
VINCENT DIETEMANN ,
HANNELIE HUMAN ,
ROBIN M. CREWE  and
CHRISTIAN W. W. PIRK
URSULA STRAUSS
Affiliation:
Department of Zoology and Entomology, Social Insect Research Group, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
VINCENT DIETEMANN
Affiliation:
Department of Zoology and Entomology, Social Insect Research Group, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa Agroscope, Swiss Bee Research Centre, 3003 Bern, Switzerland
HANNELIE HUMAN
Affiliation:
Department of Zoology and Entomology, Social Insect Research Group, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
ROBIN M. CREWE
Affiliation:
Department of Zoology and Entomology, Social Insect Research Group, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
CHRISTIAN W. W. PIRK*
Affiliation:
Department of Zoology and Entomology, Social Insect Research Group, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
*
*Corresponding author: Department of Zoology and Entomology, Social Insect Research Group, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa. E-mail: cwwpirk@zoology.up.ac.za
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Summary

Varroa destructor is considered the most damaging parasite affecting honeybees (Apis mellifera L.). However, some honeybee populations such as the savannah honeybee (Apis mellifera scutellata) can survive mite infestation without treatment. It is unclear if survival is due to resistance mechanisms decreasing parasite reproduction or to tolerance mechanisms decreasing the detrimental effects of mites on the host. This study investigates both aspects by quantifying the reproductive output of V. destructor and its physiological costs at the individual host level. Costs measured were not consistently lower when compared with susceptible honeybee populations, indicating a lack of tolerance. In contrast, reproduction of V. destructor mites was distinctly lower than in susceptible populations. There was higher proportion of infertile individuals and the reproductive success of fertile mites was lower than measured to date, even in surviving populations. Our results suggest that survival of savannah honeybees is based on resistance rather than tolerance to this parasite. We identified traits that may be useful for breeding programmes aimed at increasing the survival of susceptible populations. African honeybees may have benefited from a lack of human interference, allowing natural selection to shape a population of honeybees that is more resistant to Varroa mite infestation.

Keywords

Apis mellifera scutellataVarroa destructorresistancetolerancephysiological costmitereproduction
Type
Research Article
Information
Parasitology , Volume 143 , Issue 3 , March 2016 , pp. 374 - 387
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Copyright © Cambridge University Press 2015 

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