Population genetics and host specificity of Varroa destructor mites infesting eastern and western honeybees

Abstract

In a globalized world, parasites are often brought in contact with new potential hosts. When parasites successfully shift host, severe diseases can emerge at a large cost to society. However, the evolutionary processes leading to successful shifts are rarely understood, hindering risk assessment, prevention, or mitigation of their effects. Here, we screened populations of Varroa destructor, an ectoparasitic mite of the honeybee genus Apis, to investigate their genetic structure and reproductive potential on new and original hosts. From the patterns identified, we deduce the factors that influenced the macro- and microevolutionary processes that led to the structure observed. Among the mite variants identified, we found two genetically similar populations that differed in their reproductive abilities and thus in their host specificity. These lineages could interbreed, which represents a threat due to the possible increased virulence of the parasite on its original host. However, interbreeding was unidirectional from the host-shifted to the nonshifted native mites and could thus lead to speciation of the former. The results improve our understanding of the processes affecting the population structure and evolution of this economically important mite genus and suggest that introgression between shifted and nonshifted lineages may endanger the original host.

The first steps toward a global pandemic: Reconstructing the demographic history of parasite host switches in its native range

“…Recent work has shown experimentally that gene flow between can occur between V. destructor populations on the two hosts in the native range [20]. This observation, together with migration between host species detected in this study provides a mechanism by which gene flow occursthrough occasional co-infestations by females from different populations.…”

“…mellifera belonged to the Korean K1 lineage, which was also found in one A. cerana sample (Figure 1B). We found three additional K1 mitotypes in China that were not previously reported on A. mellifera [20] (Table S1). We confirmed that the SNPs differentiating these K1 mitotypes were not artifacts of base calling by manually checking the read alignments.…”

The first steps toward a global pandemic: Reconstructing the demographic history of parasite host switches in its native range

“…Throughout our Asian sampling sites, all V. destructor mitotypes on the new host (A. mellifera) belonged to the Korean K1 lineage and was also found in one original host colony (Apis cerana) sample (Figure 1b). We found three additional K1 mitotypes in China that were not previously reported on A. mellifera (Lin et al, 2021) (Table S1). We confirmed that the SNPs differentiating these K1 mitotypes were not base-calling artefacts by manually checking the read alignments.…”

“…Recent work has shown experimentally that gene flow can occur between V . destructor populations on the two hosts in the native range (Lin et al, 2021). This observation, together with migration between host species detected in this study, provides a mechanism by which gene flow occurs—through occasional co‐infestations by females from different populations.…”

Molecular Detection and Differentiation of Arthropod, Fungal, Protozoan, Bacterial and Viral Pathogens of Honeybees

“…Accordingly, by concatenating mitochondrial haplotype sequences, 18 haplotypes of V. destructor could be assigned to six haplogroups of V. destructor infesting A. mellifera and/or A. cerana . Recently, 14 additional haplotypes and three additional haplogroups (K2, J2, and C4) were identified in A. mellifera and/or A. cerana in China [ 64 ]. Due to a bottleneck event where a host switch from A. cerana to A. mellifera occurred, some variants of haplogroups K1 and J1 are exclusively identified in A. mellifera (e.g., K1-1/2, K1-4, K1-5, J1-1, and J1-6).…”