Varroa Populations Research Articles

Using safe materials to control Varroa mites with studying grooming behavior of honey bees and morphology of Varroa over winter

Extracts of drone larvae and propolis as safe materials are anticipated to boost the grooming behavior of honey bees against Varroa mites. It is also expected that grooming behavior of bees and morphology of Varroa are stable during the least active period of the year to bee colonies (i.e winter). Sugar syrup alone or mixed with drone larvae extract or propolis extract were examined as potential Varroa control materials to test these hypothesizes. Moreover, percentages of groomed mites along with body lengths and widths of Varroa were studied on weekly basis during winter. The results showed that propolis extract was able to increase the number of fallen mites under field conditions but with lethal impacts on bee workers in the laboratory than extract of drone larvae or sugar syrup. All the treatments were not able to boost the grooming behavior of bees. The results proved that grooming behavior was stable during winter. Therefore, it is better to select colonies with grooming potential against Varroa during winter in selection programs. December was significantly the minimal month in percentage of groomed mites based on the overall means. Means of measured characteristics of Varroa declined significantly over the study period. For beekeepers, using sugar syrup as spray on bees during regularly colony inspection can help managing Varroa populations without harming the bees.

Pyrethroid target site resistance in Greek populations of the honey bee parasite Varroa destructor (Acari: Varroidae)

The mite Varroa destructor is the most serious pest of honey bees worldwide and its control is mainly based on the use of synthetic acaricides, which, in many cases, has led to the development of resistance. In Greece, evidence of resistance to the pyrethroid tau-fluvalinate goes back to the early 1990s. In the present study we examined the presence of resistance mutations at the voltage gated sodium channel (VGSC) gene, encoding the target of pyrethroids. The frequency of resistance mutations was examined by genotyping 113 V. destructor individuals from seven localities in Greece The nucleotide sequencing of the IIS4-IIS5 region of the VGSC gene revealed two amino acid replacements at position 925: a leucine to valine substitution (L925 V) and a leucine to isoleucine substitution (L925I). This is the first report of L925I mutation in European populations of V. destructor that has so far been identified only in USA. No mutations at two other “hot spot” resistance positions, 918 and 929 of the VGSC gene encompassing position 925 were identified. Resistant alleles were predominant (53%) and most of them (83%) corresponded to the L925I substitution. Genotyping results showed the presence of homozygous wild type 925L (44.2%) individuals as well as homozygous resistant 925I (39.8%) and 925 V (7.1%), while heterozygous individuals (925I/L, 925I/V, 925 V/L) were present at low frequency (5.3, 2.7 and 0.9 respectively). Our results clearly show the presence of pyrethroid resistant mutations in high frequency in Greek Varroa populations.

Are Dispersal Mechanisms Changing the Host-Parasite Relationship and Increasing the Virulence of Varroa destructor (Mesostigmata: Varroidae) in Managed Honey Bee (Hymenoptera: Apidae) Colonies?

Varroa (Varroa destructor Anderson and Trueman) are a serious pest of European honey bees (Apis mellifera L.), and difficult to control in managed colonies. In our 11-mo longitudinal study, we applied multiple miticide treatments, yet mite numbers remained high and colony losses exceeded 55%. High mortality from varroa in managed apiaries is a departure from the effects of the mite in feral colonies where bees and varroa can coexist. Differences in mite survival strategies and dispersal mechanisms may be contributing factors. In feral colonies, mites can disperse through swarming. In managed apiaries, where swarming is reduced, mites disperse on foragers robbing or drifting from infested hives. Using a honey bee-varroa population model, we show that yearly swarming curtails varroa population growth, enabling colony survival for >5 yr. Without swarming, colonies collapsed by the third year. To disperse, varroa must attach to foragers that then enter other hives. We hypothesize that stress from parasitism and virus infection combined with effects that viruses have on cognitive function may contribute to forager drift and mite and virus dispersal. We also hypothesize that drifting foragers with mites can measurably increase mite populations. Simulations initialized with field data indicate that low levels of drifting foragers with mites can create sharp increases in mite populations in the fall and heavily infested colonies in the spring. We suggest new research directions to investigate factors leading to mite dispersal on foragers, and mite management strategies with consideration of varroa as a migratory pest.

Population Growth of Varroa destructor (Acari: Varroidae) in Colonies of Russian and Unselected Honey Bee (Hymenoptera: Apidae) Stocks as Related to Numbers of Foragers With Mites.

Varroa (Varroa destructor Anderson and Trueman) is an external parasite of honey bees (Apis mellifera L.) and a leading cause of colony losses worldwide. Varroa populations can be controlled with miticides, but mite-resistant stocks such as the Russian honey bee (RHB) also are available. Russian honey bee and other mite-resistant stocks limit Varroa population growth by affecting factors that contribute to mite reproduction. However, mite population growth is not entirely due to reproduction. Numbers of foragers with mites (FWM) entering and leaving hives also affect the growth of mite populations. If FWM significantly contribute to Varroa population growth, mite numbers in RHB colonies might not differ from unselected lines (USL). Foragers with mites were monitored at the entrances of RHB and USL hives from August to November, 2015, at two apiary sites. At site 1, RHB colonies had fewer FWM than USL and smaller phoretic mite populations. Russian honey bee also had fewer infested brood cells and lower percentages with Varroa offspring than USL. At site 2, FWM did not differ between RHB and USL, and phoretic mite populations were not significantly different. At both sites, there were sharp increases in phoretic mite populations from September to November that corresponded with increasing numbers of FWM. Under conditions where FWM populations are similar between RHB and USL, attributes that contribute to mite resistance in RHB may not keep Varroa population levels below that of USL.

Migration Effects on Population Dynamics of the Honeybee-mite Interactions

Honeybees are an amazing and highly beneficial insect species that play important roles in undisturbed and agricultural ecosystems. Unfortunately, honeybees are increasingly threatened by numerous factors, most notably the parasitic varroa mite (Varroa destructor Anderson and Trueman). A recent field study showed that migrations of mites into hives on foraging bees greatly contributes to the rapid growth of mite population in colonies, and increases the mortality of honeybees. Motivated by this, we propose a simple two-patch honeybee-varroa model to explore how foraging behavior of honeybees in the presence of varroa mite infestations affect the population dynamics of honeybees and mites, respectively. We provide a full analysis on the local and global dynamics of our proposed two-patch model, which incorporates mite migration generated by honeybee foraging activities. Our analytical and numerical studies reveal the dynamical outcomes of migration including: (a) Mite's extinction cannot be prevented by mite migration when mite population in each patch goes extinct in the absence of mite migration, however, mite migration could drive mite extinct under proper conditions. (b) Under proper conditions, high rates of mite migration could have the following effects: (1) save one honeybee colony from collapsing when both honeybee colonies are going extinct without migration; (2) drive honeybee extinct in at least one patch. (c) Intermediate migration rate could generate multiple locally stable honeybee-mite coexistence equilibria, and drive mite's extinction under proper environments. (d) An increase in migration rate causes a growth of the varroa population, which in return has a negative feedback on the colony population. (e) Increasing mite migration from a healthy patch to a collapsing patch could reduce the extinction time in the collapsing patch. Our results provide novel insights on the effects of foraging and Varroa migration on colony survival.

Morphological Characterization and a Morphometry Map for Varroa Mites from Northwest of Egypt

AbstractVarroa mite,Varroa destructor, is the most destructive factor to western honey bee colonies worldwide. In 1904, Varroa was firstly recorded on honey bees, at the beginning it was hypothesized that Varroa is one species but recently this hypothesis has been considered to be incorrect. In 1983, Varroa mite was recorded in Egypt for first time. So far, a single study was done in Egypt to confirm Varroa species to beV. destructorand notVarroa jacobsonias it was previously thought. Still the exact haplotype of Varroa in Egypt is unknown. This study is a step towards the identification of Varroa in Egypt. Here, morphological investigations were performed on Varroa specimens belong to northwest Egypt (El-Behera governorate). Three characteristics only showed significant differences among districts, namely body width, genital shield width, and genital shield length/genital shield width (ratio II), while the rest of characteristics did not present any significant differences. The correlations among the characteristics were very weak, except body length which correlated significantly (P<0.05) with body width and genital shield width by 0.52 and 0.42, in respect. The study presented additional confirmation thatV. destructoris the current species infesting honey bee colonies in Egypt. Also, Varroa haplotype was identified to be the Korean one. A list of some morphological traits of Varroa mite was provided to enable further comparisons. A morphometry map for Varroa mites was also done using a geographical information system (GIS) to correlate between geographical locations and morphological characteristics. The morphometry map clearly classified studied districts, according to measured characteristics, into three classes as low, moderate and high. This study has a significant importance towards the fully understanding of Varroa populations in Egypt.

First record of resistance to flumethrin in a varroa population from Uruguay

Varroa destructor is the most serious parasitic mite that infests the honey bee Apis mellifera. Different treatments with systemic acaricides are applied to control, but due to the intensive use of these chemicals, resistance to organophosphates and pyrethroids has developed worldwide. Most of the resistance episodes have been registered for fluvalinate, and only in a few cases has flumethrin resistance been reported. In Uruguay, no studies on V. destructor resistance to flumethrin have yet been recorded. High infestation levels of V. destructor are continuously detected in colonies of A. mellifera after treatments with flumethrin. Hence, this study aimed to estimate the possible resistance to flumethrin of a V. destructor population from the Colonia Department. Furthermore, the LC50 baseline levels for flumethrin in two Uruguayan populations were determinated. The LC50 for flumethrin for the population from Colonia Department was 3.8 μg/Petri dish, which means an increase of 34.5 fold when compared to the corresponding baseline, suggesting the development of resistance. These results are the first report of resistance to flumethrin in V. destructor in Uruguay, and extend the knowledge of acaricide resistance in the country.

Integrated varroa control in honey bee (Apis mellifera carnica) colonies with or without brood

Studies were conducted in two apiaries in order to assess the comparative efficacy of oxalic acid (OA), formic acid (FA) and Thymovar® against varroa mites in honey bee colonies. Treatments were performed using 85% FA, and OA consisted of 2.9% OA dihydrate and 31.9% sugar in water. Consecutive short term FA treatments proceeding Thymovar® application, resulted in an average varroa mortality of 11 and 18% respectively. These varroa mortalities were higher than that in the pre-treatment period (p < 0.05). Mortality rates in FA and OA treated colonies were 42 and 34% of the total mite counts. OA treatment in broodless colonies, after caging the queens for 25 days, reduced the varroa population by 11%. Also consecutive OA sublimations reduced varroa populations by 11, 24, and 16% respectively and the final autumn reduction was 77%. In the second experiment using broodless colonies by caging and isolating the queens, initial OA treatments caused 24% varroa mortality, but three additional autumn OA treatments resulted in 97% varroa efficacy. These studies found that consecutive Thymovar® or OA treatments in colonies with brood have a limited effect on reducing varroa mites. Caging queens to obtain broodless conditions was also not sufficient alone for effectively reducing the varroa mites in colonies during summer months. We conclude, however, that a combination of different treatment protocols, using organic means, can ensure an effective varroa control in colonies.

Key management practices to prevent high infestation levels of Varroa destructor in honey bee colonies at the beginning of the honey yield season

Varroa destructor is considered one of the main threats to worldwide apiculture causing a variety of physiological effects at individual and colony level. Also, Varroa mites are often associated with several honey bee viruses presence. Relatively low levels of Varroa during the spring, at the beginning of the honey yield season, can have a significant economic impact on honey production and colony health. Winter treatments against Varroa and certain management practices may delay mite population growth during following spring and summer improving colonies performance during the honey yield season. The aim of this study was to identify risk factors associated with the presence of Varroa destructor in late spring in apiaries from temperate climate. A longitudinal study was carried out in 48 apiaries, randomly selected to evaluate V. destructor infestation level throughout the year. The percentage of infestation with V. destructor was assessed four times during one year and the beekeepers answered a survey concerning all management practices applied in the colonies. We used a generalized linear mixed model to determine association between risk of achieving 2% infestation on adult bees at the beginning of the honey yield season and all potential explanatory variables. The complete dataset was scanned to identify colonies clusters with a higher probability of achieving damage thresholds throughout the year. Colonies that achieved ≥2% of infestation with V. destructor during spring were owned by less experienced beekeepers. Moreover, as Varroa populations increase exponentially during spring and summer, if the spring sampling time is later this growth remains unobserved. Monitoring and winter treatment can be critical for controlling mite population during the honey production cycle. Spatial distribution of colonies with a higher risk of achieving high Varroa levels seems to be better explained by management practices than a geographical condition.

Distance between honey bee Apis mellifera colonies regulates populations of Varroa destructor at a landscape scale

Inter-colony distance of Apis mellifera significantly affects colony numbers of the parasitic mite Varroa destructor. We set up 15 apiaries, each consisting of two colonies. Each apiary pair was assigned an inter-colony distance of 0, 10, or 100 m. Colonies were rendered nearly mite-free, then one colony in each pair was seeded with 300 female mites (mite-donor colony), while the other remained uninoculated (mite-recipient colony). After 4 months of monitoring, a whole-model analysis showed that apiaries in which colonies were spaced 100 m apart contained lower average mite numbers than 0 or 10 m apiaries. There were interactions among colony type, distance, and sampling date; however, when there were significant differences, mite numbers were always lower in 100 m apiaries than 10 m apiaries. These findings pose the possibility that Varroa populations are resource regulated at a landscape scale: near-neighbor colonies constitute reproductive resource for mites in the form of additional bee brood.

Population growth of Varroa destructor (Acari: Varroidae) in honey bee colonies is affected by the number of foragers with mites

Varroa mites are a serious pest of honey bees and the leading cause of colony losses. Varroa have relatively low reproductive rates, so populations should not increase rapidly, but often they do. Other factors might contribute to the growth of varroa populations including mite migration into colonies on foragers from other hives. We measured the proportion of foragers carrying mites on their bodies while entering and leaving hives, and determined its relationship to the growth of varroa populations in those hives at two apiary sites. We also compared the estimates of mite population growth with predictions from a varroa population dynamics model that generates estimates of mite population growth based on mite reproduction. Samples of capped brood and adult bees indicated that the proportion of brood cells infested with mites and adult bees with phoretic mites was low through the summer but increased sharply in the fall especially at site 1. The frequency of capturing foragers with mites on their bodies while entering or leaving hives also increased in the fall. The growth of varroa populations at both sites was not significantly related to our colony estimates of successful mite reproduction, but instead to the total number of foragers with mites (entering and leaving the colony). There were more foragers with mites at site 1 than site 2, and mite populations at site 1 were larger especially in the fall. The model accurately estimated phoretic mite populations and infested brood cells until November when predictions were much lower than those measured in colonies. The rapid growth of mite populations particularly in the fall being a product of mite migration rather than mite reproduction only is discussed.

Comparison of tau-fluvalinate, acrinathrin, and amitraz effects on susceptible and resistant populations of Varroa destructor in a vial test.

The parasitic mite Varroa destructor is a major pest of the western honeybee, Apis mellifera. The development of acaricide resistance in Varroa populations is a global issue. Discriminating concentrations of acaricides are widely used to detect pest resistance. Two methods, using either glass vials or paraffin capsules, are used to screen for Varroa resistance to various acaricides. We found the glass vial method to be useless for testing Varroa resistance to acaridices, so we developed a polypropylene vial bioassay. This method was tested on tau-fluvalinate-, acrinathrin-, and amitraz-resistant mite populations from three apiaries in Czechia. Acetone was used as a control and technical grade acaricide compounds diluted in acetone were applied to the polypropylene vials. The solutions were spread on the vial surface by rolling the vial, and were then evaporated. Freshly collected Varroa females were placed in the vials and the mortality of the exposed mites was measured after 24 h. The Varroa populations differed in mortality between the apiaries and the tested compounds. Mites from the Kyvalka site were resistant to acrinathrin, tau-fluvalinate, and amitraz, while mites from the Postrizin site were susceptible to all three acaricides. In Prelovice apiary, the mites were susceptible to acrinathrin and amitraz, but not to tau-fluvalinate. The calculated discriminating concentrations for tau-fluvalinate, acrinathrin, and amitraz were 0.66, 0.26 and 0.19 µg/mL, respectively. These results indicate that polyproplyne vial tests can be used to determine discriminating concentrations for the early detection of acaricide resistant Varroa. Finally, multiple-resistance in Kyvalka may indicate metabolic resistance.

Erratum to: Differences in Varroa destructor infestation rates of two indigenous subspecies of Apis mellifera in the Republic of South Africa

Varroa destructor Anderson & Trueman (Varroa) is a damaging pest of the Western honey bee, Apis mellifera, in North America, Europe, and Asia. However, Varroa infestations have not produced equivalent colony losses of African subspecies of honey bee throughout Africa and parts of the Americas. We surveyed the Varroa infestation rates (number of Varroa per 100 adult honey bees) in colonies of A. m. scutellata, A. m. capensis, and hybrids of the two subspecies throughout the Republic of South Africa in the fall of 2014. We found that A. m. scutellata colonies had significantly higher Varroa infestations than did A. m. capensis colonies. Furthermore, hybridized colonies of the two subspecies had Varroa infestations intermediate to those of A. m. scutellata and A. m. capensis. This is the first documentation of a clear difference in Varroa infestation rates of A. m. scutellata, A. m. capensis, and hybridized colonies in South Africa. Furthermore, our data confirm that Varroa populations in A. m. scutellata colonies are within the range of populations that are damaging to European honey bees.

Differences in Varroa destructor infestation rates of two indigenous subspecies of Apis mellifera in the Republic of South Africa.

Varroa destructor Anderson & Trueman (Varroa) is a damaging pest of the Western honey bee, Apis mellifera, in North America, Europe, and Asia. However, Varroa infestations have not produced equivalent colony losses of African subspecies of honey bee throughout Africa and parts of the Americas. We surveyed the Varroa infestation rates (number of Varroa per 100 adult honey bees) in colonies of A. m. scutellata, A. m. capensis, and hybrids of the two subspecies throughout the Republic of South Africa in the fall of 2014. We found that A. m. scutellata colonies had significantly higher Varroa infestations than did A. m. capensis colonies. Furthermore, hybridized colonies of the two subspecies had Varroa infestations intermediate to those of A. m. scutellata and A. m. capensis. This is the first documentation of a clear difference in Varroa infestation rates of A. m. scutellata, A. m. capensis, and hybridized colonies in South Africa. Furthermore, our data confirm that Varroa populations in A. m. scutellata colonies are within the range of populations that are damaging to European honey bees.

Host Specificity in the Honeybee Parasitic Mite, Varroa spp. in Apis mellifera and Apis cerana.

The ectoparasitic mite Varroa destructor is a major global threat to the Western honeybee Apis mellifera. This mite was originally a parasite of A. cerana in Asia but managed to spill over into colonies of A. mellifera which had been introduced to this continent for honey production. To date, only two almost clonal types of V. destructor from Korea and Japan have been detected in A. mellifera colonies. However, since both A. mellifera and A. cerana colonies are kept in close proximity throughout Asia, not only new spill overs but also spill backs of highly virulent types may be possible, with unpredictable consequences for both honeybee species. We studied the dispersal and hybridisation potential of Varroa from sympatric colonies of the two hosts in Northern Vietnam and the Philippines using mitochondrial and microsatellite DNA markers. We found a very distinct mtDNA haplotype equally invading both A. mellifera and A. cerana in the Philippines. In contrast, we observed a complete reproductive isolation of various Vietnamese Varroa populations in A. mellifera and A. cerana colonies even if kept in the same apiaries. In light of this variance in host specificity, the adaptation of the mite to its hosts seems to have generated much more genetic diversity than previously recognised and the Varroa species complex may include substantial cryptic speciation.

Genetic diversity within honey bee colonies affects pathogen load and relative virus levels in honey bees, Apis mellifera L

The evolution of polyandry is one of most highly debated topics in sociobiology. One hypothesis suggests genetic diversity increases resistance against the wide range of parasites and diseases affecting colonies. We investigated effects of manipulating genetic diversity on colony population size, fall Varroa population, Varroa and bee mortality rates, virus prevalence and concentration, and prevalence of Nosema apis Z. and Nosema ceranae F. Sister queens selected for resistance to Varroa were inseminated with either mixed semen from 12 drone sources (genetically diverse colonies, GDC) or single drone inseminated from 12 drone sources (genetically similar colonies, GSC), and colonies from these queens were compared to unrelated queens that were open-mated. When exposed to parasites and pathogens, open-mated colonies (OMC) and GDCs had larger worker populations before winter than GSCs. The bees of GDCs had higher Varroa mortality rates than those of GSCs in the field study. Within the instrumentally inseminated treatments, three pathogens occurred at lower prevalence (acute bee paralysis virus (ABPV) and N. ceranae) or concentrations (deformed wing virus, DWV) in GDCs than in GSCs. Both GDCs and GSCs that had been selected for resistance to Varroa had lower DWV concentration in spring when compared to unselected OMCs. Colonies inseminated by multiple drones and having greater within-colony genetic diversity showed reduced prevalence, concentrations in about a quarter of the pathogens assayed relative to genetically uniform colonies, and the reverse pattern was never observed.

Genome Characterization, Prevalence and Distribution of a Macula-Like Virus from Apis mellifera and Varroa destructor.

Around 14 distinct virus species-complexes have been detected in honeybees, each with one or more strains or sub-species. Here we present the initial characterization of an entirely new virus species-complex discovered in honeybee (Apis mellifera L.) and varroa mite (Varroa destructor) samples from Europe and the USA. The virus has a naturally poly-adenylated RNA genome of about 6500 nucleotides with a genome organization and sequence similar to the Tymoviridae (Tymovirales; Tymoviridae), a predominantly plant-infecting virus family. Literature and laboratory analyses indicated that the virus had not previously been described. The virus is very common in French apiaries, mirroring the results from an extensive Belgian survey, but could not be detected in equally-extensive Swedish and Norwegian bee disease surveys. The virus appears to be closely linked to varroa, with the highest prevalence found in varroa samples and a clear seasonal distribution peaking in autumn, coinciding with the natural varroa population development. Sub-genomic RNA analyses show that bees are definite hosts, while varroa is a possible host and likely vector. The tentative name of Bee Macula-like virus (BeeMLV) is therefore proposed. A second, distantly related Tymoviridae-like virus was also discovered in varroa transcriptomes, tentatively named Varroa Tymo-like virus (VTLV).

Heterotrophic bacteria associated with Varroa destructor mite

Varroa bee hive attack is a serious and common problem in bee keeping. In our work, an ecto-microflora of Varroa destructor mites was characterised as a potential source of bacterial bee diseases. Using a cultivation approach, a variable population of bacteria was isolated from the body surface of Varroa mites with frequency of about 150 cfu per mite individual. Nine studied isolates were classified to four genera and six species by a combination of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF)- and 16S ribosomal RNA (rRNA)-based methods, suggesting relatively low diversity of Varroa mite-associated ecto-microflora. The Varroa mite-associated bacterial population was found to be dominated by Gram-positive bacteria of Bacillus and Microbacterium genera. Gram-negative bacteria were represented by members of Brevundimonas and Rhizobium genera. Most of the identified species are not known to be associated with Varroa mite, either honey bee or honey up until now and some of them are probably representatives of new bacterial taxa.

Impact of Varroa destructor on honeybee (Apis mellifera scutellata) colony development in South Africa.

The devastating effects of Varroa destructor Anderson & Trueman on European honeybee colonies (Apis mellifera L.) have been well documented. Not only do these mites cause physical damage to parasitised individuals when they feed on them, they also transmit viruses and other pathogens, weaken colonies and can ultimately cause their death. Nevertheless, not all honeybee colonies are doomed once Varroa mites become established. Some populations, such as the savannah honeybee, A. m. scutellata, have become tolerant after the introduction of the parasite and are able to withstand the presence of these mites without the need for acaricides. In this study, we measured daily Varroa mite fall, Varroa infestation rates of adult honeybees and worker brood, and total Varroa population size in acaricide treated and untreated honeybee colonies. In addition, honeybee colony development was compared between these groups in order to measure the cost incurred by Varroa mites to their hosts. Daily Varroa mite fall decreased over the experimental period with different dynamics in treated and untreated colonies. Varroa infestation rates in treated adult honeybees and brood were lower than in untreated colonies, but not significantly so. Thus, indicating a minimal benefit of treatment thereby suggesting that A. m. scutellata have the ability to maintain mite populations at low levels. We obtained baseline data on Varroa population dynamics in a tolerant honeybee over the winter period. Varroa mites appeared to have a low impact on this honeybee population, given that colony development was similar in the treated and untreated colonies.

Population growth of Varroa destructor (Acari: Varroidae) in commercial honey bee colonies treated with beta plant acids.

Varroa (Varroa destuctor Anderson and Trueman) populations in honey bee (Apis mellifera L.) colonies might be kept at low levels by well-timed miticide applications. HopGuard® (HG) that contains beta plant acids as the active ingredient was used to reduce mite populations. Schedules for applications of the miticide that could maintain low mite levels were tested in hives started from either package bees or splits of larger colonies. The schedules were developed based on defined parameters for efficacy of the miticide and predictions of varroa population growth generated from a mathematical model of honey bee colony–varroa population dynamics. Colonies started from package bees and treated with HG in the package only or with subsequent HG treatments in the summer had 1.2–2.1 mites per 100 bees in August. Untreated controls averaged significantly more mites than treated colonies (3.3 mites per 100 bees). By October, mite populations ranged from 6.3 to 15.0 mites per 100 bees with the lowest mite numbers in colonies treated with HG in August. HG applications in colonies started from splits in April reduced mite populations to 0.12 mites per 100 bees. In September, the treated colonies had significantly fewer mites than the untreated controls. Subsequent HG applications in September that lasted for 3 weeks reduced mite populations to levels in November that were significantly lower than in colonies that were untreated or had an HG treatment that lasted for 1 week. The model accurately predicted colony population growth and varroa levels until the fall when varroa populations measured in colonies established from package bees or splits were much greater than predicted. Possible explanations for the differences between actual and predicted mite populations are discussed.