"Mite" This Help Bees?

 

Task #1: Describe a problem in your community and explain how it is related to what you are studying in school.

 

Introduction to the Problem: Dramatic Declines in Bee Populations are Hurting Our Food Supply!

 

Imagine a world without blueberry pancakes!

Have you ever thought about how sometimes, the smallest creatures are the most helpful?  This sure holds true for honey bees, which not only provide honey, but pollinate many of our crops, too!  In fact, one-third of our food would be gone without bees.  Some crops that need pollination include almonds, blueberries, cherries, avocado, apples, squash, tomatoes, watermelon, onions, broccoli, peaches, pears, berries -- and that’s only a small part of the long list!  Imagine how bland our plates would look and taste without bees.  The world would be much less healthy from a nutritional standpoint.  So you can see how bees increase crop value by more than 14 billion dollars every year.

 

However, a problem called colony collapse disorder (CCD) is threatening our little black and yellow helpers.  The honeybee population is rapidly diminishing due to CCD.  The number of honeybees has gone from around 6 million in the 1940s to about 2.5 million in 2013.  Over the past 10 years, American and European beekeepers estimate that between 30-50% of their honey bees have disappeared every year. 

 

This disorder has many causes, and since some are more prominent than others in different areas, it’s hard to pinpoint the primary, direct root of the issue.  Most scientists agree, however, that the four main causes are: monocultures (one crop that isn’t pollinator-friendly, covering an expanse of land); neurotoxins (detrimental poisons) in pesticides; diseases; and the Varroa destructor mite.  This last problem is the focus of our project.  

 

 

 

Description of the Problem: The Vicious Cycle

 

The Varroa destructor mite is an arachnid that feeds on bees in their larval, pupal, and adult stages.  Varroa destructor mites are external parasites that attack Western honey bees, and the disease that they inflict is called varroosis.  The adult female mites first attach to worker bees with their claws when they are out of the hive foraging.  These arachnids are colored maroon and are flat, which allows them to hide between the flaps in a bee's abdomen.  Their length ranges from 1.0-1.8 mm and their width from 1.5-2.0 mm.  Mites are able to puncture the soft abdominal tissue of bees and feed on their hemolymph (the circulatory fluid found in most invertebrates).  The mites then ride back to the hive on the worker bees.  

 

In the hive, the honey bees have constructed waxy, hexagonal cells in which the queen bee lays eggs; within a few days, bee larvae emerge from the eggs and begin to develop in the cells.  Mites that have traveled into the hive are attracted to the scent of the brood cells.  The drone (or male bee) brood cells are particularly enticing to the mites, as the drones have a longer brood cycle; the mites' instinct "tells" them that if they head toward the drone brood cells, they will have more time to feed on the young bees and lay eggs.  

 

So, the mites drop off the bees on which they have hitched a ride and crawl into the brood cells (usually drone brood cells) before the cells are sealed by the worker bees.  Each mite then submerges itself under the larvae in the brood food that has been deposited for the bee larvae.  The mite even puts up breathing tubes that allow it to breathe while submerged -- just like a snorkel!  Once the worker bees have sealed the cell, the mite then waits patiently until the bee larva eats its food, which frees the mite.  This is when the mite climbs onto the larva and begins to weaken the young bee by sucking its hemolymph for energy and food.  

 

Soon after, the mite begins to lay eggs.  The first egg is unfertilized and develops into a male.  The remainder of the eggs are fertilized and will develop into female mites.  The young mites hatch around the time the young bee is developing in its pupal stage, but they do not play together nicely as children should!  Instead, the daughter mites and the mother mite share in the tasty feeding on the now developing bee pupa.  The male mite only mates with the females and then dies, never leaving the cell.  The female mites go from egg to adult in about only 1 week!  About 2 female mites will survive to leave a drone brood cell.  (The mother mite dies.)

 

The bee continues to develop into an adult and emerges into the rest of the hive from the brood cell after pupation.  The mites, still attached to the bee, now seize their opportunity to spread to other bees throughout the hive.  New bees become their unwilling hosts, and the cycle starts again.  Varroa destructor mites reproduce about every 14 days, so a hive can be overrun by mites very quickly! 

 

Bees are weakened from mites feeding on the bees' hemolymph.  Even more dangerous to a colony, however, is the efficient transmission of viruses by the mites.  The afflicted bee is exposed to ribonucleic acid viruses, such as deformed wing virus.  These viruses are carried by the mite from one bee host and transmitted directly into the circulatory system of other bee hosts while the mite is feeding, spreading treacherously throughout the colony.  Rapid mite reproduction, combined with the spreading of disease, can wipe out a whole colony or even a set of colonies nearby each other!

 

Once a bee colony is affected by mites, there is little that can be done to stop the cycle.  Though the mites are roughly only about the size of a pin head, Apis mellifera are totally defenseless against them (excepting a few genetically modified strains).  The number of mites in a hive can multiply by about 12 times in just 12 weeks!  Mite populations can multiply by 12 times in hives that have brood for half a year and by 800 times in hives that have brood for the full year!  In a 2007 study in Canada of about 400 bee colonies, almost 30% of them collapsed, and 85% of the collapses were due to the Varroa destructor mite.  Many treatments have been tried to prevent the mites, but mites often become resistant and/or immune to them.  In addition, the honey bees themselves can be harmed by the treatments for the mites! 

 

The Varroa destructor mite didn't originally attack Apis mellifera (the Western honey bee); it actually is native to Asia.  However, the Asian Apis cerana (the Eastern honey bee) seems to have developed a resistance against the mite.  Beekeepers and entomologists have observed that Apis cerana has developed behaviors and traits to prevent mite infestations!  Though the practices of the Eastern honey bee aren't totally understood, they seem to work well enough to keep colonies up and running.  However, Apis mellifera doesn't have such tolerance.  Only when the Western honey bee was brought to Asia, giving mites access to this vulnerable species, did people realize how devastating the Varroa destructor mite could be.  The mites' change in host was gradual and may have taken 50-100 years; during that time, the Varroa destructor mite population spread throughout much of the world.

 

 

 

Relevance to Our Team:  "Bee-friend" the Bee!

 

The attack by Varroa destructor mites, the decline of bee populations, and the resulting concern with crop growth affect people around the world.  Here in Davis, CA, we are surrounded by agriculture, as we are located in the northern part of the Central Valley, which is known for its fertile land.  All around us, we see fields and orchards full of almonds, peaches, pears, tomatoes, sunflowers, and more; all of these crops require pollination in order to support the food supply and the economy.

 

We are enrolled at the Davis School for Independent Study, which means that we have personalized learning through our homes, but also a strong community of other families and teachers through our school district.  We have been working on an ongoing science project on how to support bee populations.  Last year, two of us created a school science fair project on native mason bees and how they can help to supplement the declining honey bee population.  We also researched how to grow bee gardens, by finding out which native plants support bee nutrition and how to set up a bee-friendly environment.  Using this information, we now have planted organic bee gardens in our front yard, our back yard, at the Davis School for Independent Study, and at another school in Davis.

 

We currently are also getting organized to hold a yard sale in order to raise money for more bee-friendly plants, so that we can implement bee gardens elsewhere in the community.  (Our yard sale hopefully also will give people a chance to check out our bee garden in the front yard -- good publicity!)  One of our team members even designed a board game called "Bee" a Survivor, that educates people on declining bee populations.  

 

Two of our team members also created a website called Bokashi to Bees, which is a broader environmental project involving the cycle of using all food scraps to strengthen the growth of plants, which get pollinated by bees, which provide food for humans, who create food scraps..., and the cycle continues.  (See logo in margin.) We also have made a presentation on Bokashi to Bees that teaches and encourages others to: (a) use this method of utilizing food scraps; and (b) protect and grow bee populations.  This presentation has been given at two elementary schools, one third and fourth-grade classroom, and the University of California, Davis' Student Farm.  However, this project with ISTF is the first time we have researched the threat of the Varroa destructor mite to the honey bee, so this information and design process is very new for us.  

 

All of this relates to units that we have been studying in science on Living Systems, Food Production, and Plant Parts.  Living systems of people and non-human animals are strongly connected.  We have been studying what plants need in order to grow and how agriculture needs to be sustainable in order to keep producing food.  We have to be aware of how our food gets created, from the health of the plants that grow our food to a food's arrival at our homes.  With awareness, we can help to protect the environment that produces our food.  Bees are one critical part of this connection.  Their pollination ensures the production of our food!

 

 

 

Task #2:  Pick a technical application from the National Critical Technology (NCT) list.  Tell how your team thinks this technical application could be used to fix the problem.

 

Our technical category from the National Critical Technologies list is Living Systems. Our sub-category is Sustainable Agriculture Production, and the technical application is Ecosystem Management.  Since Varroa destructor mites need bees in order to live, but bees can't survive with the mites in their midst, these creatures have a living system that needs to be studied; so Living Systems is an appropriate category for this project.  Bees are necessary to sustainable agriculture through their pollination, so this sub-category also fits.  We chose Ecosystem Management as our technical application to help solve the mite problem, since our design attempts to manage, or change, a small part of the ecosystem in which the bees and mites exist.  

 

Many solutions have been attempted in order to reduce the harm that mites cause to bee colonies.  However, many of them cause other problems.  For instance, when chemicals are used to kill the mites, the mites often build up resistance and/or become immune to the chemicals.  Also, some products end up killing or harming the bees, as well.  Finally, pesticides can harm plants and animals in the nearby area of the hive.  

 

We are suggesting that we change a minor part of the ecosystem where the bees and mites live in order to manage the problem - Ecosystem Management.  We want to try luring the mites off of the bees with a scent that naturally attracts them; this should make it less likely that the mites become immune to our solution, and it wouldn't use any chemicals harmful to the bees.  So our idea involves channeling bees through special entrances to the hives.  These entrances would contain deceptive drone brood scents (to lure the mites off the bees) and decelerating structures (to slow down the bees); the mites would think they were going into a real drone brood cell, but actually these special hive entrances would prompt the mites to drop off the bees and into a trap!  Here are the specifics of how it would work:

 

Bees normally enter their hive via an alighting board (the term used for where the bees usually land outside the hive).  After landing, the bees crawl into an entrance next to the alighting board that is a small opening in the side of the hive.  

 

Our design would extend the alighting board and the entrance out from the hive, using 4 funnels attached to each other, that are about 15 cm each in length.  At the narrow end of the funnels, the circle would be about 1.5 cm in diameter, and at the wide end, the circle would be about 5.0 cm in diameter.  These funnels would repeatedly slow down the bees at each narrow part of the funnels.  The wide ends of the funnels would close onto the next funnel so that the bees wouldn't be able to exit them.  Only the funnel farthest away from the hive would be open to allow the bees to enter and exit.  The funnels would be made out of a metal mesh with openings through which only creatures as small as Varroa mites could fall.  

 

Below the funnels, there would be a removable tray inside of a box that would be attached to the side of the hive.  This tray would be covered in a sticky gelatin coating with the scent of drone brood cells.  This coating would attract the mites, as the real scent does in the hive; as the bees slowed down, the mites would catch wind of the drone-brood-cell-scent, scramble off the bees, and fall into the trap, freeing most bees of mites.  This way, the bees wouldn't come in contact with any chemical, and the mites simply would think that they are entering a brood cell, so the possibility of mites becoming immune shouldn't be an issue.  When the tray became filled with mites, the beekeeper would need to remove the tray, dispose of the mites, refill the tray with the scented, gelatin coating, and put the tray back in the box.  Our Design Screen illustrates and labels this suggested solution, to give a clearer description of the design.  

 

To make an artificial drone scent, we need to know how real drones scents are made.  Both larvae and pupae release a pheromone, which helps nurse bees (which nurture the brood) distinguish drones from other bees.  This pheromone is made of fatty acid esters and changes based on the life stage of the bee.  An artificial brood pheromone was created by a team of French researchers in 1996.  The chemical contents of actual brood pheromone were taken from a hive and analyzed so that researchers knew what percentage of each component was needed to make their own brood pheromone in a laboratory.  They did this in order to study behavior during bee development.  So we believe that the exact make-up of the drone brood pheromone could be created in this way, or modified from the artificial pheromone already created, to use for our design.  

 

 

 

 

Task #3:  Use the internet to find another community that has the same problem your team chose.  Name the community, describe its problem and tell what it is doing to fix the problem.

 

Varroa destructor mites are a problem for honey bees around the world.  So beekeepers in a wide range of communities are trying to find solutions to their collapsing colonies.  We found a beekeeper online in Grass Valley, CA (a town northeast of us, but still in California) with a mite control problem common to the beekeeping community.  When the mites first struck, he lost almost all of his 250 hives!  Even in less severe years, beekeepers in the California Central Valley told him that they lost about a third of their hives due to mites.

 

A company that focuses exclusively on apiary care has developed a plastic beehive strip that is used for mite control, and this Grass Valley beekeeper has conducted experiments on its effectiveness.  The beehive strips are placed inside the hives so that the strips' vapors can be directed toward Varroa mites as they feed inside the honey bee brood cells.  The beehive strips are made from a biodegradable polymer, which is filled with miticide formic acid in a plant sugar formulation.  It controls the release of the vapors of its formic acid, which penetrates the brood cell cap and knocks out the Varroa mites before they have a chance to reproduce.   

 

The Grass Valley beekeeper ran numerous experiments to test the beehive strips and communicated with beekeepers in the California Central Valley who also were trying the strips.  There were issues early in the testing with the formic acid affecting the bees, such as loss of brood, not enough ventilation for the bees, and death of plants around the hive.  But overall, the beehive strips reduced the number of mites so that the hive could survive.  Many other communities around the world are also developing other ways to repel and/or kill the mites, but the mites are proving to be very resilient and difficult to manage.  

 

 

 

Task #4:  Describe at least three differences between your solution and the solution used by the community you found.

 

1. Our project focuses on redesigning an entrance to the hive, rather than placing a product into the hive.  We are trying to prevent the mites from entering the hive at all.  Also, this approach should be less intrusive to the colony, as no product has to get put into the hive or be removed from the hive.  

 

2. Our design would have a drone brood scent that attracts the mites into a trap, rather than the vapor of an acid that kills them.  The Varroa destructor mite has shown a remarkable ability to develop resistance to the various treatments and chemicals that beekeepers and apiary researchers have developed to try to get rid of the mites.  With our method, mites shouldn't become immune, because we are using a scent that attracts them.  

 

3. Our design should not kill any plants around the hive, as the formic acid in beehive strips can, since we would be using the scent of a drone brood cell.