Genetics and human management in Varroa destructor parasitism Público
Dynes, Travis (Summer 2018)
Abstract
European honey bee colonies have experienced widespread losses in the past decades, a particular concern due to the importance that honey bees play in agricultural services critical in both economic terms and to human health. In the first half of the 20th century the obligate ectoparasitic mite Varroa destructor made a sustained host switch from the Asian honey bee to the European honey bee. Since that time V. destructor has spread around the world and become the largest pathogenic threat currently facing the beekeeping industry.
When Varroa arrived in the United States in the 1980’s beekeepers were able to effectively treat Varroa infections with miticides. However, the mites quickly developed resistance to these miticides. This was unusual considering Varroa is characterized by a lack of genetic diversity. Our research was able to show that there was more genetic diversity at fine scales than would have been predicted. This implies that there was also more transmission of mites between colonies than would have been predicted. Human management of honey bee colonies places colonies in densities that more than three orders of magnitude greater than would be found in feral colonies. This increased density has implications for parasite transmission, colony health and survival. We found that increased density leads to more potential for disease transmission, decreased colony health and productivity, and increased winter mortality.
According to the virulence-transmission theory, Varroa populations evolving under these different management intensities (from feral to heavily managed) may face different selection pressures for population growth and virulence. Our research was consistent with this hypothesis for population growth. However, our virulence results suggest that there are genotype by genotype interactions that are occurring.
Table of Contents
Chapter 1
1.1 Introduction 1
Chapter 2: Fine scale genetic structure of Varroa destructor, an ectoparasitic mite of the honey bee (Apis mellifera)
2.1 Introduction 6
2.2 Materials and Methods 8
2.3 Results 11
Table 2.1 Population (apiary) pairwise FST values 13
Table 2.2 AMOVA analysis 14
Figure 2.1 Fine scale allelic diversity compared to global allelic diversity 15
Figure 2.2 Allelic diversity in ten apiaries using a rarefaction approach 16
Figure 2.3 AMOVA change in source of population variation over time 16
2.4 Discussion 17
2.5 Supplementary Materials 22
Table 2.S1 Observed and expected heterozygosity levels within apiaries 25
Table 2.S2 Observed and expected heterozygosity levels within colonies 26
Table 2.S3 SMOGD alternative estimates of population differentiation 27
Figure 2.S1 Boxplot of Garza-Williamson Index values 28
Chapter 3: GRAPHITE: A graphical environment for scalable in situ video tracking of moving insects
3.1 Introduction 29
3.2 Experimental Setup 32
Figure 3.1 Camera housings 33
3.3 Modules and Editor 34
Figure 3.2 Analysis pipeline 35
Figure 3.3 Active region 36
Figure 3.4 Tag detection from a single video frame 38
Figure 3.5 Tag tracks 41
Figure 3.6 Graphical user interface 42
3.4 Evaluations 43
3.5 Conclusions and Future Directions 44
3.6 Supplementary Material 45
Figure 3.S1 Tagged bees 45
Figure 3.S2 Editor 45
Chapter 4: Reduced density and visually complex apiaries reduce parasite load and promote overwintering survival in honey bees
4.1 Introduction 46
4.2 Materials and Methods 49
Figure 4.1 Scale representation of apiary arrangement from above 50
4.3 Results 55
Figure 4.2 Honey production over time 56
Figure 4.3 Mite count by sticky board 57
Figure 4.4 Mite levels in brood 58
Figure 4.5 Survival curves and winter survival 59
Figure 4.6 Representation of drift within each of the apiaries 60
4.4 Discussion 61
Chapter 5: Assessing virulence of Varroa destructor mites from different honey bee management regimes
5.1 Introduction 67
5.2 Materials and Methods 70
Table 5.1 Mite inoculation sources within each apiary 71
5.3 Results 76
Figure 5.1 Measures of mite abundance by treatment 76
Figure 5.2 Number of frames of brood by treatment 78
Figure 5.3 Survival curves by mite treatment 78
5.4 Discussion 79
Chapter 6
6.1 Dissertation Conclusion 85
Bibliography 88
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Primary PDF
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Genetics and human management in Varroa destructor parasitism () | 2018-07-13 14:39:16 -0400 |
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Supplemental Files
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GRAPHITE environment (a demonstration of the GRAPHITE program) | 2018-07-13 14:39:12 -0400 |
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Tag tracker (a demonstration of tag tracking with GRAPHITE) | 2018-07-13 14:39:14 -0400 |
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