Editing Varroa destructor (section)

==Management==
Mite populations undergo [[exponential growth]] when bee broods are available, and exponential decline when no brood is available. In 12 weeks, the number of mites in a [[western honey bee]] hive can multiply by roughly 12. Mites often invade colonies in the summer, leading to high mite populations in autumn.<ref>{{cite journal |last1=Frey |first1=Eva |last2=Rosenkranz |first2=Peter |title=Autumn invasion rates of ''Varroa destructor'' (Mesostigmata: Varroidae) into honey bee (Hymenoptera: Apidae) colonies and the resulting increase in mite populations |journal=Journal of Economic Entomology |date=May 1, 2014 |volume=107 |issue=2 |pages=508–515 |doi=10.1603/EC13381 |pmid=24772528 |s2cid=25457602 |doi-access=free }}</ref> High mite populations in the autumn can cause a crisis when drone rearing ceases and the mites switch to worker larvae, causing a quick population crash and often hive death.<ref>{{cite journal |last1=DeGrandi-Hoffman |first1=Gloria |last2=Curry |first2=Robert |title=A mathematical model of Varroa mite (''Varroa destructor'' Anderson and Trueman) and honeybee (''Apis mellifera'' L.) population dynamics |journal=International Journal of Acarology |year=2004 |volume=30 |issue=4 |pages=259–274 |doi=10.1080/01647950408684393 |bibcode=2004IJAca..30..259D |s2cid=84974148 |url=https://www.tandfonline.com/doi/abs/10.1080/01647950408684393 |access-date=1 August 2021 |quote=In the autumn though, brood rearing declines and the number of multiple-infested cells increases.|url-access=subscription }}</ref> Various management methods are used for Varroa mite [[integrated pest management]] to monitor and manage damage to hives.

=== Monitoring ===
Beekeepers use several methods for monitoring levels of Varroa mites in a colony.<ref>{{Cite web|url=https://pollinator.cals.cornell.edu/sites/pollinator.cals.cornell.edu/files/shared/documents/Varroa-mites-monitoring-info-sheet.pdf|title=Varroa mites: A step-by-step guide to monitoring in New York|website=Pollinator Network at Cornell University|date=11 September 2024 }}</ref> They involve either estimating the total number of mites in a hive by using a sticky board under a screen bottom board to capture mites falling from the hive or estimating the number of mites per bee with powdered sugar or an ethanol wash.<ref name="Jack2021"/>

Monitoring for mites with a sticky board can be used to estimate the total number of mites in a colony over 72 hours using the equation:

:<math>p(c)=\frac{3.76-b}{-0.01}</math>

where ''b'' is the number of mites found on the sticky board and ''c'' is the number of estimated mites in the colony. However, the bee population in a colony also needs to be known to determine what population of mites is tolerable with this method.<ref name="Jack2021"/>

Mite counts from a known quantity of bees (i.e., 300 bees) collected from [[brood comb]] are instead often used to determine mite severity. Mites are dislodged from a sample of bees using non-lethal or lethal means. The bees are shaken in a container of either powdered sugar, alcohol, or soapy water to dislodge and count mites. Powdered sugar is generally considered non-lethal to honey bees, but lethal methods such as alcohol can be more effective at dislodging mites.<ref>{{Cite web|url=https://pollinators.msu.edu/resources/beekeepers/varroa-mite-monitoring1/varroa-mite-monitoring/|title=Varroa Mite Monitoring: Using a Sugar Roll to Quantify Infestation of ''Varroa destructor'' in Honey Bee Colonies|last=Milbrath|first=Meghan|date=January 2018|website=Michigan Pollinator Initiative, Michigan State University}}</ref><ref name="Jack2021"/> 3% of the colony being infested is considered an [[economic threshold]] damaging enough to warrant further management such as miticides, though beekeepers may use other management tactics in the 0{{endash}}2% infestation range to keep mite populations low.<ref name="Jack2021"/>

===Chemical measures===
[[File:Beecrystals.PNG|thumb|Honey bee coated with [[oxalic acid]] to protect it from mites]]
Varroa mites can be treated with commercially available [[acaricide]]s that must be timed carefully to minimize the contamination of [[honey]] that might be consumed by humans. The four most common synthetic pesticides used for mite treatments with formulations specific for honey bee colony use are [[amitraz]], [[coumaphos]], and two [[pyrethroids]], [[flumethrin]] and [[tau-fluvalinate]], while naturally occurring compounds include [[formic acid]], [[oxalic acid]], essential oils such as [[thymol]] and beta acids from [[hops]] resin (e.g. [[lupulone]]). Many of these products whether synthetic or naturally produced can negatively affect honey bee brood or queens. These products often are applied through impregnated plastic strips or as powders spread between brood frames.<ref name="Jack2021"/>

Synthetic compounds often have high efficacy against Varroa mites, but resistance has occurred for all of these products in different areas of the world. [[Pyrethroids]] are used because a concentration that will kill mites has relatively low toxicity to honey bees.<ref name="Jack2021"/> Compounds derived from plants have also been assessed for mite management. Thymol is one essential oil with efficacy against mites, but can be harmful to bees at high temperatures. Other essential oils such as garlic, oregano, and neem oil have had some efficacy in field trials, though most essential oils that have been tested have little to no effect. Essential oil use is widespread in hives with many of those uses being off-label or in violation of pesticide regulations in various countries. Hop beta acids are [[lupulone]]s obtained from hop plants and have been used in products marketed for mite control.<ref name="Jack2021"/>

{| class="wikitable sortable"
|+ Pesticides used for Varroa mite treatment<ref name="Jack2021"/>
|-
! Chemical !! Efficacy !! Notes
|-
| [[Amitraz]] || High (75{{endash}}90%) || Not very affordable; slower occurrence of resistance
|-
| [[Coumaphos]] || Low || Use decreased over time due to low efficacy and resistance
|-
| [[Flumethrin]] || High (73{{endash}}97%) || Negative effects to honey bees less severe than tau-fluvalinate
|-
| [[Tau-fluvalinate]] || Low || Efficacy lost due to resistance; reduced brood survival and queen size
|-
| [[Formic acid]] || High (35{{endash}}75%) || Efficacy varies based on temperature, brood population, and proximity to the chemical within the hive; can cause brood or queen mortality
|-
| [[Oxalic acid]] || High (near 100%) || Used during broodless periods only and increases grooming behavior; no known cases of resistance
|-
| [[Thymol]] || Moderate (50{{endash}}80%) || Similar temperature-based issues to formic acid, not effective under {{cvt|15|°C|°F}}
|-
| [[Lupulone|Hop beta acids]] || Moderate (43{{endash}}88%) || Low toxicity to humans and bees
|}

Resistance to pyrethroids has occurred in the Czech Republic and the UK due to a single amino acid substitution on Varroa mite's genome. Underlying mechanisms for resistance in other pesticides, such as coumaphos, are still unknown.<ref>{{cite journal |last1=Mitton |first1=Giulia A. |last2=Meroi Arcerito |first2=Facundo |last3=Cooley |first3=Hazel |last4=Fernández de Landa |first4=Gregorio |last5=Eguaras |first5=Martín J. |last6=Ruffinengo |first6=Sergio R. |last7=Maggi |first7=Matías D. |title=More than sixty years living with Varroa destructor : a review of acaricide resistance |journal=International Journal of Pest Management |date=1 July 2022 |pages=1–18 |doi=10.1080/09670874.2022.2094489|s2cid=250231123 }}</ref>

===Mechanical control===
Varroa mites can also be controlled through nonchemical means. Most of these controls are intended to reduce the mite population to a manageable level, not to eliminate the mites completely.<ref name="Jack2021">{{cite journal |last1=Jack |first1=Cameron J |last2=Ellis |first2=James D |title=Integrated Pest Management Control of Varroa destructor (Acari: Varroidae), the Most Damaging Pest of ( Apis mellifera L. (Hymenoptera: Apidae)) Colonies |journal=Journal of Insect Science |date=1 September 2021 |volume=21 |issue=5 |page=6 |doi=10.1093/jisesa/ieab058|pmid=34536080 |pmc=8449538 }}</ref>

Screened bottom boards are used both for monitoring and can modestly reduce mite populations by 11{{endash}}14%. Mites which fall from the comb or bees can land outside the hive instead landing on a solid bottom board that would allow them to easily return to the nest.<ref name="Jack2021"/>

Varroa infest drone cells at a higher rate than worker brood cells, so drone cells can be used as a trap for mite removal. Beekeepers can also introduce a frame with drone foundation cells that encourage bees to construct more drone cells. When the drone cells are capped, the frame can be removed to freeze out mites. This labor-intensive process can reduce mite levels by about 50{{endash}}93%, but if trap cells are not removed early enough before mites emerge, mite populations can spike. This method is only viable in spring and early summer when drones are produced.<ref name="Jack2021"/>

Heat is also sometimes used as a control method. The mites cannot survive temperatures near {{cvt|40|°C|°F}}, but brief exposure to these temperatures do not harm honey bees. Devices are marketed intended to heat brood to these temperatures, though the efficacy of many of these products has not been reviewed.<ref name="Jack2021"/><ref name="reuters">{{cite news|url=https://www.reuters.com/article/us-czech-bees-idUSKBN0OD20S20150528|title=Czech teacher battles bee-killing disease with hot hive|date=28 May 2017|newspaper=Reuters}}</ref>

Powdered sugar used for estimating mite counts in hives has also been considered for mite management as it or other inert dusts were believed to initiate grooming responses. Long-term studies do not show any efficacy for reducing mite populations.<ref name="Jack2021"/>

===Genetic methods===

====Honey bee genetics====
{{further|Varroa sensitive hygiene}}
The Asian honey bee, is more hygienic with respect to Varroa mite than western honey bees, which is in part why mite infestations are more pronounced in western honey bee colonies. Efforts also have been made to breed hygienic honey bees [[heritable]] behavior traits, such as those with resistance to Varroa mites. Honey bee lines with resistance include Minnesota Hygienic Bees, Russian Honey Bees, and [[Varroa sensitive hygiene]].<ref name="Leclercq">{{cite journal |last1=Leclercq |first1=Gil |last2=Pannebakker |first2=Bart |last3=Gengler |first3=Nicolas |last4=Nguyen |first4=Bach Kim |last5=Francis |first5=Frédéric |title=Drawbacks and benefits of hygienic behavior in honey bees ( Apis mellifera L.): a review |journal=Journal of Apicultural Research |date=8 August 2017 |volume=56 |issue=4 |pages=366–375 |doi=10.1080/00218839.2017.1327938|bibcode=2017JApiR..56..366L |s2cid=90034078 }}</ref><ref>{{cite web|url=http://www.sare.org/Learning-Center/Fact-Sheets/A-Sustainable-Approach-to-Controlling-Honey-Bee-Diseases-and-Varroa-Mites|title=A Sustainable Approach to Controlling Honey Bee Diseases and Varroa Mites|publisher=SARE|access-date=2008-11-18}}</ref><ref>{{cite web | author=Hunt, Greg | author2=Given, J. Krispn | author3=Tsuruda, Jennifer M. | author4=Andino, Gladys K. | title=Breeding Mite-Biting Bees to Control Varroa | url=https://extension.entm.purdue.edu/beehive/pdf/2016_BC_Article.pdf | publisher=Bee Culture | date=April 2016 | access-date=2018-02-18 | archive-date=2018-02-19 | archive-url=https://web.archive.org/web/20180219031344/https://extension.entm.purdue.edu/beehive/pdf/2016_BC_Article.pdf | url-status=dead }}</ref> 

Hygienic behaviors include <ref name="Leclercq"/><ref>{{cite web |last1=Harris |first1=Jeffrey|last2=Danka |first2=Robert|last3=Villa |first3=José |title=Varroa Sensitive Hygiene and Mite Reproduction – Bee Health |url=https://bee-health.extension.org/varroa-sensitive-hygiene-and-mite-reproduction/ |website=bee-health.extension.org|access-date=7 November 2023}}</ref> workers removing pupae heavily infested with mites, which kills both the developing bee and immature mites, and grooming or removal from the brood cell, which increases adult mite mortality.  Mites removed from host pupae are at an incorrect life stage to re-infest another pupa.  An extended [[phoretic]] period in adult female mites has also been noticed.

Hygienic behavior is effective against diseases such as [[American foulbrood]] or [[List of diseases of the honey bee#Chalkbrood|chalkbrood]], but the efficacy of this behavior against mites is not well-quantified; colonies with this behavior alone do not necessarily result in Varroa mite resistant colonies that can survive without [[miticide]] treatments. The efficacy of this behavior can vary between bee lines in comparison studies with Minnesota hygienic bees removing 66% of infested pupae, while Varroa sensitive hygiene bees removed 85% of infested pupae. There are minimal trade-off costs to hives that have this hygienic behavior, so it is being actively pursued in bee breeding programs.<ref name="Leclercq"/>

====Mite genetics====
Researchers have been able to use [[RNA interference]] by feeding honey bees mixtures of [[double-stranded RNA]] that target expression of several Varroa mite genes, such as [[cytoskeleton]] arrangement, transfer of energy, and [[Transcription (biology)|transcription]]. This can reduce infestation to 50% without harm to honey bees and is being pursued as an additional control method for Varroa mite.<ref>{{cite journal |last1=Zotti |first1=Moises |last2=dos Santos |first2=Ericmar Avila |last3=Cagliari |first3=Deise |last4=Christiaens |first4=Olivier |last5=Taning |first5=Clauvis Nji Tizi |last6=Smagghe |first6=Guy |title=RNA interference technology in crop protection against arthropod pests, pathogens and nematodes: RNA interference technology in crop protection against arthropod pests, pathogens and nematodes |journal=Pest Management Science |date=June 2018 |volume=74 |issue=6 |pages=1239–1250 |doi=10.1002/ps.4813|pmid=29194942 }}</ref><ref>{{cite news |last1=Gill |first1=Victoria |title=Genetic weapon against bee killer |url=http://news.bbc.co.uk/earth/hi/earth_news/newsid_9306000/9306572.stm |access-date=31 October 2023 |date=22 December 2010}}</ref>