By: Charlie Vanden Heuvel
This article originally appeared in the Spring 2021 issue of BEEKeeping Your First Three Years
Minimizing or reducing environmental risks to humans, plants and insects reduces costs while effectively mitigating the pest problem (Agriculture and Natural Resources). Essentially, insects are divided into two categories: 1) harmful, and 2) beneficial. Out of the nearly million known insects, somewhere between 1 % and 3% are considered harmful. Types of insects that are considered ‘beneficial’ include:
•Preying – spiders devour insects for nourishment. Beetles, flies, true bugs, and lacewings also are predators to insects.
•Parasitizing – wasps lay their eggs inside insects.
•Birds and bats – feed on pest insects.
Integrated Pest Management (IPM) concept entails the softest method be used first progressing up the pyramid to the most aggressive (Agriculture and Natural Resources) (Hood).
•Biological – natural enemies such as predators, parasites, pathogens, and competitors are the first step.
• Cultural – practices intended to reduce pest’s establishment, reproduction, dispersal, or survival. Reducing root disease or supporting weed production through a change in irrigation.
•Mechanical / Physical – use of traps, mulch for weed control, soil management through steam sterilization, or screens as barriers keeping birds out.
•Chemical – pesticides should only be used as needed and in combination with lessor management practices. Through the use of selective pesticides directed to specific pests rather than a broad spectrum application.
In the past, agricultural practices focused on the eradication of pests, all pests, consider DDT. As the effects to the environment became known, alternatives were sought to effectively control the known pests but also to reduce costs. Use of chemical intervention does eliminate the pest, but has the added disadvantage of ridding all insects and unfortunately effecting biological processes.
Farmers shifted their management practices toward an Integrated Pest Management regime. The first step, Cultural, entails creating good sanitation in the surrounding area. Pests need specific habitat to thrive. As research shifted toward expanding knowledge in this arena, the view of ‘beneficial’ insects came to light (National Pest Information). Yellow Jackets are a great example. Humans despise these aggressive insects, yet they are terrific in ridding the area of insects in their thirst for protein nourishment.
Agricultural practices have taken a dramatic shift in recent years as identification of the pest culprit becomes the first step prior to chemical applications. For the home garden separating the beneficial from the unwanted becomes paramount. Trap one or more for your local Extension Service to identify.
A few pests in the garden may be tolerable while an overwhelming number need tending. Dousing the few eliminates food needed in support of ‘beneficial’ insects. Allowing Yellow Jacket nests to thrive within the agricultural space yet away from any BBQ event goes a long way toward reducing pesty infestations.
Cultural Controls include using Varroa Resistant Queen stock (Connor, 2015) or creating a brood break. Selecting stock demonstrating grooming behavior, hygienic, enhances the removal of mites from the bees within the colony. Two major categories of grooming behavior in honey bees are: 1) auto-grooming or self-grooming and 2) inter-bee grooming (Pritchard).
Inter-bee grooming, called allogrooming, is evidenced by one-on-one nestmates cleaning other bees within the colony. Some workers evolve into allogrooming specialists for the majority of their lifespan.
Creating a break in the honey bee brood cycle as the Varroa reproduction is closely associated or interlinked with the honey bee reproduction. The Varroa destructor mite’s Foundress, mother, is reliant on the honey bee brood cell capping where she enters just prior to the cap being creating in order to deter detection by worker bees. Interrupting the queen’s egg laying thus prevents the mite from also reproducing.
Creating colony splits serves several purposes: 1) increase apiary number of hives, and 2) create a brood break. In terms of Varroa control, it is the brood break which prevents the Foundress (mother) mite to produce thus reducing the percent of infestation. Numerous methods exist in the splitting of honey beehives. The natural hive behavior of swarming effectively splits the hive while creating a break in the brood production. Until the swarmed hive’s queen has mated, the hive experiences a period of bloodlessness. Captured swarms should be assessed for mite infestation. It becomes an opportunity to chemically treat, for instance Oxalic Acid Dribble, the colony in the absence of brood where the Varroa reside under the brood capping, thus precluding most miticides from being effective.
Sequestering the Queen, or setting her in a cage, preventing egg laying from occurring becomes another management practice frustrating the mother Varroa from producing new brood.
Sequestering or caging the queen creates another brood break scenario simultaneously frustrating the Varroa Foundress (Jack, van Santen, & Ellis, 2020). Sequestering the Queen, or setting her in a cage, preventing egg laying from occurring becomes another management practice frustrating the mother Varroa from producing new brood.
Mechanical Controls of reducing or eliminating Varroa destructor mites from honey beehives may entail several choices. Drone Brood removal through the use of Drone Frames. These frames are entirely plastic, stamped with the cell design size for the larger drone cell directing worker bees to create drone comb in which the queen lays drone eggs. The Drone Frame is placed at the edge of the honey bee brood oval. In a typical Langstroth hive, the central frames within the box are used by the queen for egg laying. Selecting the outer edge or frame location for placement of the Drone Frame encourages Workers to build drone comb. As the Drone life cycle from egg to hatching is a bit longer than the Worker, by four days, it allows the Varroa brood to mature from egg to mated adult producing two daughters versus one in the Worker brood. Removing the Drone Frame once the Brood is capped, decapping all the cells, freezing the entire frame, and finally defrosting it to be used again reduces mite loads (Gross, 2018).
Sticky boards placed under a Screened Bottom Board in the hive captures mites that have fallen off. In the absence of the sticky board, these wayward mites merely wait for another passerby bee to jump on continuing in the mite’s effort to survive. Through the use of the Sticky Board, the mites are unable to reengage bees, thus eliminating their food source and viability to survive. Another method of eliminating Drone Brood is through the use of medium size frames within the deep Langstroth Hive. Bees have a tendency to construct Drone Cells on the medium frame in the space between the bottom of the frame and the box below. This free hanging comb can easily be chopped off.
Screened Bottom Boards become another mechanical means of reducing Varroa within a colony. Honey bees in the natural grooming cause Varroa to fall off the bee’s body. With the screen the Varroa falls out of harm’s way disallowing the critter to reenter the hive.
Biological Controls are a focus on research. To date, no promising natural enemies of Varroa have been identified. The search includes predatory mites, parasitoids and entomopathogens (nematodes, protozoa, viruses, Bacillus thuringiensis, rickettsiae, and fungi (Chandler, Sunderland, Ball, & Davidson).
Chemical Controls are separated into two categories: 1) biorational pesticides and 2) conventional pesticides. A helpful reference is located at the Honey Bee Health Coalition website where three opportunities are provided. 1) Tools for Varroa Management Guide – an excellent source of information about Varroa, monitoring techniques, and control methods. 2) Varroa Videos demonstrating monitoring and treatment techniques. 3) Varroa Management Decision Tool – provides a quick means to identify the most appropriate treatment given the season, colony status and other particulars. These can be accessed at: https://honeybeehealthcoalition.org/varroa/.
Biorational pesticides relates to pesticides that relatively cause no harm to humans, animals, or has little effect to the environment. Examples of these miticides approved for use by the EPA are formic acid, oxalic acid, Api Life Var, and Apiguard.
Examples of conventional pesticides include amitraz, terramycin, tylosin, and fumagillin.
Whether the beekeeper falls within the commercial, sideliner, or backyard arena; colony management should incorporate effective means while maintaining expenses at their lowest level. A proactive stance is wise, while the use of chemicals in the absence of pest or disease identification leads to increased costs as well as potential side effects to the colony being managed .
Be proactive through inspections! Brood assessment in determining diseases on a minimum of monthly basis along with a Varroa sampling become prudent.
References:
Chandler, D., Sunderland, K. D., Ball, B. V., & Davidson, G. (n .d .). Prospective Biological Control Agents of Varroa destructor n.sp., an Important Pest of the European Honeybee, Apis mellifera. Retrieved November 04, 2020, from https://www.tandfonline.com/ doi/ abs/ 10.1080/09583150120067472
Chapman, N. (2020, September 18). Screened bottom boards. Retrieved November 02, 2020, from https://extensionaus.com.au/ professionalbeekeepers/screened-bottom-boards/
Connor, L. (2015, December 10). Integrated Pest Management of Varroa in North America. Retrieved November 02, 2020, from https: / / americanbeejoumal.com/ integrated-pest-managementof-varroa-in-north-america/
Gross, B. (2018). Drone Brood Removal: A bee-utiful form of Varroa control and source of edible insect protein (Tech.). Wooster, OH: Department of Environmental Studies lndependent Study Thesis.
Integrated pest control for Varroa mites in honey bees . Various example of this observed. (n.d.). Retrieved November 04, 2020, from https://beekeep.info/a-treatise-on-modem-honeybee-management/managing-diseases-and-pests/varroa-shorthistory/ integrated-pest-management-for-varroa/
IPM Action Plan for Honey Bees. (2019, July 12). Retrieved November 02, 2020, from https://schoolipm.tamu.edu/forms/pest-managementplans/ipm-actlon-plan-for-honey-bees/ (Texas A&M, 2019)
Jack, C., Van Santen, E., & Ellis, J. (2020, January 07). Evaluating the Efficacy of Oxalic Acid Vaporization and Brood Interruption in Controlling the Honey Bee Pest Varroa destructor (Acari: Varroidae). Retrieved November 04, 2020, from https:/ /academic.oup.com/jee/article/ 113/2/582/5697464
National Pest Information. (n.d.). Beneficial Insects. Retrieved November 02, 2020, from http://npic.orst.edu/envir/beneficial/index.html
Pritchard, D. (n.d.). Grooming by honey bees as a component of varroa resistant behavior. Retrieved November 04, 2020, from https:/ /www.tandfonline.com/ doi/ abs/ 10.1080/00218839.2016.1196016
What Is Integrated Pest Management (IPM)? (n.d.). Retrieved November 02, 2020, from https://www2.ipm.ucanr.edu/What-is-IPM/ What Integrated Pest Management Means For Today’s Beekeeper. (n.d.). Retrieved November 02, 2020, from https://www.clemson.edu/extension/beekeepers/fact-sheets-publications/pest-managementpublication.html
