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See detailPhenotyping hygienic behavior and studying diversity in honey bees (Apis mellifera L.): methodological issues and solutions
Leclercq, Gil ULiege

Doctoral thesis (2017)

Honey bees (Apis mellifera L.) are a crucial resource for world agriculture. The global stock of honey bees has increased over the last five decades. In contrast, honey bees have been declining in several ... [more ▼]

Honey bees (Apis mellifera L.) are a crucial resource for world agriculture. The global stock of honey bees has increased over the last five decades. In contrast, honey bees have been declining in several regions, especially in the northern hemisphere. Among the factors responsible for these regional declines, the parasitic mite Varroa destructor plays a central role and is considered as one of the main threats for apiculture. A sustainable solution to the problems caused by V. destructor is to breed Varroa-resistant honey bees. In this context, in Belgium, a research project was developed with the aim of studying the diversity of honey bees in Wallonia, and selecting, within this “local” diversity, Varroa-resistant honey bees. This project required methods to accurately phenotype Varroa-resistance traits, and methods to study the diversity of honey bee populations. In this thesis, we decided to work on these methods, which are a prerequisite for such research project. Two independent objectives were developed: (1) solving the controversy and methodological issues regarding the quantification of hygienic behavior in honey bee colonies, and (2) designing a new method to study the diversity of honey bee admixed populations covering a large-scale area, using pool-based sequencing data. The hygienic behavior of worker bees contributes to the social immunity of honey bee colonies. The manifestation of this behavior consists in detecting and removing unhealthy or dead brood. In this thesis, we reviewed the drawbacks, the benefits, and the methods to test for hygienic behavior, in honey bee colonies. We concluded that, while hygienic behavior was efficient against some brood diseases, it was difficult to draw any definitive conclusion on the efficiency of this behavior against V. destructor. Hygienic behavior likely contributes to Varroa-resistance, but the controversy is fueled by the use of inappropriate bioassays to quantify the hygienic removal of Varroa-infested brood. In our experiments, we showed that a commonly used bioassay, the freeze-killed brood removal bioassay, was unreliable to approximate the benefits arising from the hygienic removal of Varroa-infested brood. As an introduction to the second part of the thesis, we reviewed how human has contributed to reshape the diversity of honey bee populations worldwide, except in Africa. Human management was shown to increase the proportion of admixed populations, sometimes to the detriment of subspecies populations (such as in Belgium). Then, we presented a new approach to study the admixture of hybrid honey bee populations. It was based on a reduced representation of the genome (through genotyping-by-sequencing). In this approach, we enabled the use of pool-based sequencing data by simulating an individual genotype for each pool, sampled from a hybrid colony. Finally, some conclusions and discussion were brought on a few perspectives and research avenues about (1) the phenotyping of hygienic behavior towards Varroa-infested brood, and (2) the study of admixture in honey bee populations. [less ▲]

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See detailHoney bee colony strength - Assessing accuracy of the Liebefeld estimation method
Leclercq, Gil ULiege; Gengler, Nicolas ULiege; Francis, Frédéric ULiege et al

Poster (2014, December 12)

Honey bee colony strength (number of adult bees in a colony) is a crucial character used for both breeding and research. In breeding programs a rough estimate is usually sufficient to select strong ... [more ▼]

Honey bee colony strength (number of adult bees in a colony) is a crucial character used for both breeding and research. In breeding programs a rough estimate is usually sufficient to select strong colonies. On the other hand, the accuracy of this character can deeply affect the quality of several studies in both fundamental and applied research. For example these studies are related to the assessment of low demographic variations following a stress, or the estimate of a host-parasite ratio (e.g. involving the mite Varroa destructor Anderson & Trueman). The “Liebefeld estimation method” is extensively used in these studies while its accuracy remains weakly documented. Our goal is to provide more information on the accuracy of this method. [less ▲]

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See detailLa mortalité de l'abeille domestique : entre communication médiatique et scientifique
Leclercq, Gil ULiege; Francis, Frédéric ULiege; Haubruge, Eric ULiege et al

Conference given outside the academic context (2013)

A l’heure actuelle, plus personne n’ignore que nos populations d’abeilles domestiques subissent de lourdes pertes, chez nous comme dans de nombreux autres pays. Les médias ont axés leur communication sur ... [more ▼]

A l’heure actuelle, plus personne n’ignore que nos populations d’abeilles domestiques subissent de lourdes pertes, chez nous comme dans de nombreux autres pays. Les médias ont axés leur communication sur des messages très simples. On en retient surtout que les pesticides tuent nos abeilles. La conclusion au problème est dès lors évidente : il faut interdire les pesticides. Mais cette problématique est-elle si simple ? Ce message est-il le même que celui communiqué par les scientifiques ? Cette conférence permettra de faire le point sur les pertes en colonies d’abeilles domestiques. On s’intéressera plus particulièrement aux pertes de ces dernières années en Belgique, cartes et chiffres à l’appui. On y verra aussi comment chacun, qu’il soit citoyen, apiculteur, agriculteur,… peut aider à enrayer cette mortalité effrayante. [less ▲]

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See detailGenetic variability of the mid-infrared prediction of lactoferrin content in milk for Walloon Holstein first-parity cows
Leclercq, Gil ULiege; Gengler, Nicolas ULiege; Soyeurt, Hélène ULiege et al

in Livestock Science (2013), 151(2-3), 158-162

The objective of this study was to assess the genetic variability of the mid-infrared prediction of lactoferrin content in milk (pLF) in Holstein first-parity cows. Variance components were estimated by ... [more ▼]

The objective of this study was to assess the genetic variability of the mid-infrared prediction of lactoferrin content in milk (pLF) in Holstein first-parity cows. Variance components were estimated by Average Information Restricted Maximum Likelihood using a single-trait test-day random regression animal model. The dataset included 395,287 test-day records from 67,178 cows in 1190 herds from the Walloon Region of Belgium. Average pLF was 164.89. mg/L and the standard deviation was 76.07. mg/L. Frequency distribution for pLF was slightly asymmetrical, and pLF seemed to increase almost linearly all along the first lactation after a sharp decrease in early lactation. Genetic variance of pLF increased with days in milk within lactation while the permanent environmental variance was the highest in early lactation, then decreased to become lower than genetic variance at 50 days in milk, and finally increased in the last lactation stages. The pLF was a moderately heritable trait. Daily heritability of pLF was the lowest at 5 days in milk (0.19), then increased to reach a maximum at 260 days in milk (0.44), and finally decreased for the last stages of lactation (0.35 at 365 days in milk). Results from this study indicated that pLF is variable and heritable over the lactation and therefore it could be changed by genetic selection. © 2012 Elsevier B.V. [less ▲]

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See detailDiversité de l’abeille & sélection de souches tolérantes à Varroa destructor
Leclercq, Gil ULiege; Francis, Frédéric ULiege; Haubruge, Eric ULiege et al

Conference given outside the academic context (2012)

Présentation des 2 volets de recherche du projet "Selapis" (D31-1280) : la diversité de l'abeille et la sélection de souches tolérantes au Varroa

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See detailEvaluation of the genetic diversity of honey bees, Apis mellifera L. in the Walloon Region and selection of strains tolerant to the mite Varroa destructor Anderson and Trueman
Leclercq, Gil ULiege; Nguyen, Bach Kim ULiege; Gengler, Nicolas ULiege et al

Poster (2012, February 10)

For more than a decade, high losses of honey bee colonies have been noticed in several countries, including Belgium. Currently often the mite Varroa destructor is considered a main threat for beekeeping ... [more ▼]

For more than a decade, high losses of honey bee colonies have been noticed in several countries, including Belgium. Currently often the mite Varroa destructor is considered a main threat for beekeeping. In view of the inefficiency of the current chemical treatments, one of the solutions is to select honey bees tolerant to this parasite using genomic selection. To reach this objective the genetic diversity of honey bees needs first to be studied using mainly ‘Single Nucleotide Polymorphisms’ (SNP). Records and samples will be collected all over the Walloon Region in order to create an informative phenotypic and genomic data base that will be used for ‘Genome Wide Association Studies’ (GWAS) to detect associations between SNPs and tolerance, and to select bees tolerant to Varroa destructor. [less ▲]

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See detailGenetics of the mid-infrared predicted lactoferrin content in milk of dairy cows
Bastin, Catherine ULiege; Leclercq, Gil ULiege; Soyeurt, Hélène ULiege et al

in Book of Astracts of the 63rd Annual Meeting of the European Federation of Animal Science (2012)

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See detailGenetics of the mid-infrared prediction of lactoferrin content in milk for Holstein first-parity cows
Bastin, Catherine ULiege; Leclercq, Gil ULiege; Soyeurt, Hélène ULiege et al

in International Journal of Dairy Science (2012), 95, Suppl. 2

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