Tropilaelaps mercedesae Anderson and Morgan, 2007 (Acari: Laelapidae) is a serious ectoparasite of the brood of several honey bee species. Among the four recognized species of Tropilaelaps, Korean population was renamed as T. mercedesae from T. clareae on the basis of morphological evidences and genetic data. In this study, we report the complete mitochondrial genome (mitogenome) sequence of T. mercedesae. The 15,119-bp long mitogenome has an identical gene arrangement to that of Chinese sample reported previously. Comparison of two geographic samples showed COII, ND5, ND4, ND6, CytB, and ND1 to have higher number of variable sites than COI, which is often used for population-level study, suggesting these genes to have potential usefulness for population genetic study. The mitogenome sequence of T. mercedesae from Korea could be useful for species identification for geographic samples, trace of the origin of local populations, and illustration of evolutionary distinction among Tropilaelaps species either using part of or whole genome.

Tropilaelaps mercedesae is an ectoparasite of immature honey bees belonging to the genus Tropilaelaps (Acari: Laelapidae). T. mercedesae has become a major threat to the Western honey bee Apis mellifera in Asia, including Korea, and is expanding its geographical range to northern regions due to global warming. To establish gene resources of T. mercedesae, the whole transcriptome was analyzed by RNA sequencing. An mRNA-focused library was generated from total RNA extracted from the mixed stages using the TruSeq RNA Library Preparation kit and sequenced using the HiSeq 2000 platform. A total of 6.0 Gb reads were obtained with 85% Q30 value. Trimmed sequence data were de novo assembled using the CLC Assembly Cell v 4.2. A total of 64,868 non-duplicate contigs were finally obtained and annotated by the Blast2GO using the NCBI nr database. The most abundant species in the resulting 14,336 Blast hits (22.1%) was Metaseiulus occidentalis, a predatory mite, followed by Ixodes scapularis and Tribolium castaneum, suggesting that the T. mercedesae transcriptome matches well with closely related other arthropod species, including mites and ticks. In order to provide basic information for efficient control and monitoring of potential resistance in T. mercedesae, acaricide target genes were annotated and characterized. One voltage-sensitive sodium channel gene encoding the molecular target of fluvalinate, a pyrethroid acaricide most widely used for the control of T. mercedesae, was identified and its molecular properties were investigated. In addition, other acaricide target genes, including acetylcholinesterase and glutamate (or GABA)-gated chloride channel, were identified and characterized.

Varroa destructor and Tropilaelaps mercedesae mites are ectoparasitic to honey bee having similar life cycle and damage symptoms. Both invade into the last instar larval cell and reproduce during capped brood period of honey bee development. Female adult mites escape from the comb cell on the back of the emerging adult bee (phoretic period) and invade another cell for reproduction. Objective of this study was to study the effect of competitive interaction on each parasitic mite species population. We assessed population monitoring of host and parasitic mites. Honey bee population was monitored by approximating sealed brood and adult bees based on the coverage of the combs. Parasitic mites were monitored by detection technique like sugar shake, stick board, and sealed brood. This monitoring continued at weekly interval during 2008, 2014, and 2015. Additionally Invasion distribution of each species was checked. We calculated carrying capacity, population growth rate, and competition parameter from population monitoring data. Single parasitic mite, Varroa occurred and infestation increased continuously throughout the year in 2008. Co-occurrence of Varroa and Tropilaelaps in honey bee colonies was studied in 2014 and 2015. Carrying capacity was higher in single parasite infesting honeybee than parasites in co-occurrence. While using sugar method, carrying capacity of Varroa alone was found higher than in its co-occurrence with Tropilaelaps. Population growth rate of Varroa when tested alone was higher than its co-occurrence with Tropilaelaps in sugar method. Population growth rate of Varroa and Tropilaepas was higher in sticky method than sugar methods when they were tested in co-occurrence. Population growth rate is higher in Tropilaelaps (0.09) than Varroa (0.05) when both are tested in co-occurrence. We calculated competition parameter of Varroa and Tropilaelaps which was 1.9 and 0.53, respectively. Negative effect on regulation of carrying capacity and population growth rate is due to interspecies competition. Varroa population was higher than Tropilaelaps because there was high intraspecies competition among Tropilaelaps. Single Varroa or its co-occurrence with Tropilaelaps both can destroy honeybee colonies.