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2016-08-09 - Colloque/Présentation - communication orale - Anglais - 12 page(s)

Gerard Maxence , De Meulemeester Thibaut, Michez Denis , "Discrimination of haploid and diploid males of bumblebees based on wing shape" in Euro IUSSI , Helsinki, Finlande, 2016

  • Codes CREF : Entomologie (DI3163), Morphologie des espèces [zoologie] (DI3129)
  • Unités de recherche UMONS : Zoologie (S869)
  • Instituts UMONS : Institut des Biosciences (Biosciences)

Abstract(s) :

(Anglais) Being efficient pollinators of many flowering plants, bumblebees are an important group for temperate ecosystems services. Over the last decades they experience a strong decline in Europe because of different primary factors such as habitat fragmentation. These primary factors lead to genetic stresses that can reinforce the decline. This is particularly problematic in haplodiploid species, such as bumblebees, where diploids heterozygous at a single locus sex determination (sl- CSD) are females and haploids are males. Inbreeding can therefore lead to diploids homozygous at the sl-CSD which develop into functionally sterile males, which in turn leads to inbred strain having much lower fitness than outbred colonies. This is known as the “diploid male extinction vortex”. The monitoring of diploid males in wild population is therefore of primary importance for conservation management. Until now, diploid males cannot be morphologically discriminated from haploid males. The present study aims to discriminate diploid males from haploid using wing shape and geometric morphometric methods. Diploid males of Bombus terrestris were produced from sister/brother mating in different colonies, and ploidy was checked by flow-cytometry. Based on wing shape, diploid males are accurately discriminated from haploid males using between-group PCA and LDA (hit ratio of 98% for males correctly attributed). Wing shapes of the other castes were also diagnostic (e.g. hit ratio of 100% for queens). Conservation issues and potential applications are discussed. The morphometric identifiers can be turned into an automated or semi-automated identification tools suitable for field or museum studies. Morphology-based analysis will also facilitate future citizen-science bee monitoring schemes, e.g. involving smartphone or tablet based image analysis.