Honey bees are crucial pollinators for agricultural and natural ecosystems, but are experiencing heavy mortality in Korea due to a complex suite of factors. Extreme winter losses of honey bee colonies are a major threat to beekeeping but the combinations of factors underlying colony loss remain debatable. Finding solutions involves knowing the factors associated with high loss rates. To investigate whether loss rates are related to Varroa control and climate condition, we surveyed beekeepers in korea after wintering (2021–2022 to 2022–2023). The results show an average colony loss rate of 46%(2022) and 17%(2023), but over 40% colony loss before wintering at 2022. Beekeepers attempt to manage their honey bee colonies in ways that optimize colony health. Disentangling the impact of management from other variables affecting colony health is complicated by the diversity of practices used and difficulties handling typically complex and incomplete observational datasets. We propose a method to 1) Varroa mite population Control by several methods , and 2) Many nursing bee put in hive before wintering.

The Varroa mite, Varroa destructor is an ectoparasite that parasitizes honey bees. The widespread usage of acaricides, particularly fluvalinate, has resulted in the emergence of resistance in Varroa mite populations all over the world. The goal of this study is to track fluvalinate resistance in Varroa mite field populations in Korea using both bioassay and molecular markers. To accomplish this, a residual contact vial (RCV) bioassay for on-site resistance monitoring was developed. Early mortality evaluation in the RCV bioassay was effective for reliably separating mites with the knockdown resistance (kdr) genotype, but late mortality evaluation was useful for distinguishing mites with additional resistance factors. The RCV bioassay of 14 field mite populations collected in 2021 revealed potential resistance development in four populations. Quantitative sequencing was used as an alternate method to examine the frequency of the L925I/M mutation in the voltage-gated sodium channel (vgsc), which is related with the fluvalinate kdr phenotype. While the mutation was not present in Varroa mite populations in 2020, it appeared in 2021, rose in frequency in 2022, and was practically ubiquitous across the country by 2023. This recent emergence and rapid spread of fluvalinate resistance within a span of three years demonstrate the Varroa mite's significant potential for developing resistance. This situation emphasizes the critical necessity to replace fluvalinate with alternate acaricides, such as fenpyroximate, coumaphos, and amitraz. A few novel vgsc mutations potentially involved in resistance were identified. Potential factors driving the rapid expansion of resistance were further discussed.

The varroa mite, Varroa destructor, is a small ectoparasitic mite which attacks honeybee, Apis mellifera, and also known to harbor small RNA viruses which infect honeybees. To survey the transcriptome of varroa mite, total RNA of female adult mites was subjected to RNA-seq to construct an in silico cDNA library. 2 × 8.3 Gbase of quality filtered paired-end nucleotide sequences were obtained to construct 28,302 of protein-coding contigs by de novo assembly, and subsequent BLAST search revealed the viruses infect honeybee or associated with varroa mites. Six of the contigs showed high sequence identity to Iflavirus, picorna-like virus, rhabdovirus, and macula-like virus were discovered. It implies that the viral flora in varroa mites and honeybees might be more complex than previously studied, and suggests the importance of further virome studies for better understanding of honeybee health.

Varroa destructor is a devastating ectoparasitic mite which attacks Honeybee, Apis mellifera. V. destructor feeds on honeybee hemolymph, and often harbors small RNA viruses such as the deformed wing virus to transmit these viruses in the infested bee hive. To survey the genes of V. destructor, total RNA was subjected to high-throughput transcriptome sequencing to construct in silico cDNA library by using the Illumina HiSeq 2000 platform. Total of 2×107,748,792 paired-end short reads were obtained and quality filtered reads were subjected to Trinity de novo assembler followed by TransDecoder, and CD-HIT program to make a V. destructor reference cDNA library containing 28,023 of clustered contigs with protein coding capacity. These cDNA sequences will help us to understand the molecular biology of V. destructor.

Modeling the complex system often provide better understanding of the behavior of the system given that parameters for the modeling are appropriate. The honeybee mite, Varroa destructor Anderson and Trueman, is one of the most serious pests of honeybees in Korea. Even with vast amount of ecological information of this parasite and its host, Apis mellifera, in the world, limited information is available in Korean environment. This paper provides some basic framework of the varroa mite population dynamics modified from published works in western world to adapt to Korean beekeeping environment. Overall population growth rate was in agreement to those previous published. However the detail behavior was quite different mainly because of splitting honeybee colony during the summer season. Although this framework provide reasonable, logical theoretical linkage to varroa mite population growth, implementation of the results provided from this model is not appreciated mainly because this paper is intended to show the basic framework, not the simulated results. Thus, further incorporation of realistic parameters from honey bee and its parasites in Korean environment would provide better insight of the population behavior and management options. Also, research gaps which need to be filled are further discussed.

Varroa destructor is an ecto-parasite mite and worldwide pest of the honey bee Apis mellifera L. The pyrethroid tau-fluvalinate (Apistan), an acaricide that is tolerated by honey bees, has been used for varroa mite control since the mid 1980s. Even though various resistances to tau-fluvalinate in varroa mites have been reported from Europe, Israel, and USA, the nature of tau-fluvalinate resistance in varroa mites in Korea has never been investigated. To investigate and understand tau-fluvalinate resistance in varroa mites in Korea, we conducted bioassay in several apiaries located different regions in Korea. To understand the molecular mechanisms underlying the difference of tau-fluvalinate resistances in varroa mites, partial genomic DNA fragments of a voltage-sensitive sodium channel gene from varroa mites were cloned and sequenced, since tau-fluvalinate is known to act on the sodium channels directly. Two novel mutations in sodium channels of varroa mites were present in eight apiaries. Two mutations might be a geographical polymorphism of sodium channel of varroa mites in Korea.