What is there to mimic?

Have you ever tried to mimic something? All I can think of is going hunting. When you go hunting you dress in clothes that have patterns of leaves that are brown and green. You mimic the coloration of the forest around you to blend in. You don’t want to be seen by your prey, so you camouflage yourself. Lots of organisms use camouflage as well. They use it to hide from predators. For example, insects can camouflage themselves as plant material. The leafhopper below is mimicking a thorn on a bush. If something was walking by, it might not even notice the insect that is there. Not only do insects mimic plants but they also mimic each other. They do this by matching the color patterns of another.

http://www.painetworks.com/previews/fr/fr2269.html

Most insects that aren’t palatable show warning coloration. When one of these insects is eaten, it allows the predator to learn that this certain coloration isn’t too yummy to munch on. Other insects that are tasty mimic the same warning coloration. This is called Batesian mimicry. There is another type of mimicry called Mullerian.  Mullerian mimicry is when two or more unpalatable insects have the same coloration. They are mimicking each other. By doing this it allows for the protection of both individuals.

 A study at Cat Tien National Park in Vietnam showed a species of cockroach that was identified mimicking a beetle. This was the first roach to have been thought of as showing this type of behavior. The undescribed roach from the family Blattinae mimics the coloration of a carabid beetle. The species of beetle is Craspedophorus sublaevis. The roach not only has two yellow spots like the C. sublaevis, but it also has two little orange spots at the front of the pronotum. These two orange spots are thought to mimic the ectoparasitic Laboulbeniales. This ectoparasitic is often found on the elytra of C. sublaevis and other carabids. The mimicry shown between the beetle and roach is thought to be Batesian because the roach doesn’t seem to show that it is unpalatable.

http://derstandard.at/1339639101960/Mimikry-Neue-Schabenart-taeuscht-mit-Kaeferkostuem-ihre-Feinde

It is hard to say if their conclusion is right or wrong. To really see if Batesian mimicry is occurring a bioassay of some kind would have to be created to test the hypothesis. One would have to see if a predator finds that the roach is tasty and the beetle is not. It makes sense why the researches support Batesian. This is because Carabids have pygial glands that secrete chemical compounds that aren’t attractive to predators. So many insects mimic their coloration. But because it is not known if the roach also is unpalatable you can’t rule out Mullerian mimicry yet.

After reading this article and looking up the different types of mimicry I thought, which would be best? Would it be better to just camouflage a piece of foliage or mimic another individual? Personally I would go for camouflaging a piece of foliage. I would rather be walked passed and not seen, than out in the open pretending to be another individual. What would you chose?  

Article Link : http://onlinelibrary.wiley.com/doi/10.1111/j.1479-8298.2012.00529.x/full

Heres another interesting article on mimicry: http://www.hindawi.com/journals/psyche/2012/168549/

Genetics to the Rescue...

http://en.wikipedia.org/wiki/Varroa_destructor
Varroa destructor

In the bee keeping industry there is a problem with a mite called Varroa destructor. As the name implies this mite does some real damage to honey bee colonies. The mite feeds on the haemolymph (blood) of adult and larvae stages of the honey bee. By feeding on the bee it causes many effects. These effects include introduction of viruses, decreased body weight, reduction of life, deformed wings and many more. Colonies that become infested with Varroa usually die within six months to two years unless steps are taken to reduce the infestations.  Chemical treatments can be used to reduce infestations, but it is not a sustainable way to limit the population in years to come do to the mite's ability to become resistant. Because of this fact people are looking towards breeding for hygienic behavior in bees.

At this moment research is being conducted to help the bees become tolerant to Varroa. The plan is to selectively breed the honey bees to increase their hygienic behavior.  Dr. Hunt and his colleagues did a study to try and find the gene that underpins increased mite-grooming behavior. Their objectives were to genotype individuals DNA and then locate candidate genes by using quantitative trait loci (QTL) mapping.  Individuals were chosen from their performance in a behavioral study. In the assay, a single Varroa mite was placed on the thorax of a honey bee that was inside an observation area. Two individuals then observed and timed how long it took the bee to respond by using grooming behavior. Grooming behavior in this assay was defined as “swiping motions in the direction of the mite with the front two pairs of legs.” Each colony that was tested had a phenotype estimated by the average reaction time of 40 workers.

http://beelebanon.wordpress.com/2011/05/11/
colony-collapse-disorder-and-resistant-pests-create-demand-for-new-treatments/

From the many colonies that were tested only two were choose to be backcrossed to create the population of bees that would be genotyped. The backcross breeding method takes the F1 (hybrid) individual (the queen) and crosses her back to one of the parental lines. The new populations of backcrossed workers were then tested on the same behavioral assay as above. From the recorded data, the top and bottom 98 bees for reaction time were chosen. The results from this study show that they were able to locate 27 candidate genes, but not able to find the specific gene that has the major impact on grooming behavior.

Can you imagine what this will mean if the gene is located?
By finding this gene it will make breeding so much easier. You wouldn’t have to go through the trouble of picking queens only based on observations of their workers productively against these mites. You would be able to genotype their DNA and figure out if the queen carries the right gene for the trait. Once this gene is found it will be a step in the right direction to make honey bees tolerant to the dreaded Varroa destructor.

Although this finding will help, more needs to be done to make the honey bee tolerant, one thing isn't enough to cause the change!

           

If you would like to read the paper:

 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0047269

           

References:     

 Goodwin, Mark, and Eaton Cliff Van. Control of Varroa: A Guide for New Zealand Beekeepers. Wellington, N.Z.: New Zealand Ministry of Agriculture and Forestry, 2001. Print.

They Have Found a Weak Spot!

There are many animals, insects, and mites that feed on plants. From learning about herbivorous insects, I thought mites also feed by sticking their stylet, needle like mouthparts, into the leaves and sucking up the nutrients. I was surprised to find out from reading, Herbivore Exploits Chink in Armor of Host, that some mites and insects actual feed through the stomata opening on the leaves. It had never occurred to me that this feeding behavior could happen.

http://www.sciencephoto.com/media/374168/view

This unique feeding behavior had been observed in certain insects, but never mites. Research was being done on Raoiella indica, also known as the red palm mite to discover why the mite was able to produce such large and dense populations on a single palm plant. To find the answer to this question, researchers used low-temperature scanning electron microscopy to examine the mites feeding on their host. It was found that R.indica, at all active stages, were inserting their stylet between the guard cells of the stomata opening. The mites were able “to actively bypass the mechanical defenses by exploiting a series of structural weakness in the architecture of their host.”

The affect of the R.indica feeding from the stomata of the plant is still unknown. If the mites do cause damage to the guard cells during feeding it will affect the plant. Stomata regulate the exchange of gases and water in and out of the plant. Once the guard cells are damaged the plant is no longer able to control the opening and closing of the stomata. This results in a loss of regulation and also leaves the internal plant tissue open to attack from the outside world. Some examples of harmful sources that can enter the plant include pathogens and fungi. To understand how this feeding behavior is affecting the plant more research needs to be completed. The research could show the advantages and disadvantages to this type of feeding compared to other herbivore feeding behaviors. 

http://www.reportapest.org/pestlist/raoind.htm

From reading about this feeding behavior, it makes me wonder… why don’t more insect pests feed in the same way. If it really is a so called “Chink” in the armor of the plant, why aren’t more things taking advantage of it?

            

Link to Article:          http://www.ars.usda.gov/SP2UserFiles/person/333/Herbivore%20Exploits%20Chink%20in%20Armor%20of%20Host.pdf

Another article for more information on the mite:
http://www.bioone.org/doi/full/10.1653/024.092.0212