Haplotype diversity and Varroa destructor infestation patterns in commercial beekeeping operations across Southwestern Saudi Arabia

The honey bee subspecies native to Saudi Arabia, Apis mellifera jemenitica Rutter, is currently being threatened by genetic pressure from exotic subspecies imported by commercial beekeepers. Uncontrolled interbreeding between native and exotic subspecies could dilute advantageous adaptations and give rise to new haplotypes that are not well suited for Saudi Arabia’s harsh climate. In this study, we analyzed the mitochondrial haplotypes and parasitization patterns by Varroa destructor mites in commercial beekeeping operations across Southwestern Saudi Arabia. We sampled 300 workers from five randomly chosen colonies at each of the eleven apiaries from December 2022 to February 2023. We extracted DNA from two workers per colony for analysis of the mitochondrial COI-COII region and assessed the remaining workers for mite infestation levels. We also haplotyped a subgroup of mites. All 55 colonies analyzed belonged to the A. m. jemenitica subspecies, which is part of the Z subgroup of the A lineage. Mitochondrial genome analysis revealed ten distinct haplotype sequences at four of the eleven locations. The average (± SEM) number of mites per 100 workers across all sites was 1.95 ± 0.96 and was below a 3% infestation threshold at nine of the eleven locations. All tested mites belonged to the Korean haplotype. The Al-Riyan, Al-Radha, and Khaitaa apiaries had both, no novel haplotypes, and the lowest Varroa mite infestation levels. This study could ultimately inform a colony selection process for the implementation of a breeding program aimed at improving honey bee productivity in Southwestern Saudi Arabia.