Question

“We should investigate further. Maybe something new about Colony Collapse Disorder has been found,” Mark said. He was worried, not only because of the effects this was having on the emotional and economic standing of his family, but for what this meant for pollinating honeybee colonies all over the United States.

Tanya entered the room reading an article titled “Solving the Mystery of the Vanishing Bees” that she had found inScientific American.

“Look at this excerpt from an article by Diana Cox-Foster and Dennis vanEngelsdorp, the top CCD researchers,” said Tanya.

... no single culprit has been identified. Bees suffering from CCD tend to be infested with multiple pathogens, including a newly-discovered virus, but these infections seem secondary or opportunistic much the way pneumonia kills a patient with AIDS. The picture now emerging is of a complex condition that can be triggered by different combinations of causes.

“This makes sense. There were no signs of Varroa mites on our remaining bees. The mites feed on hemolymph, and their small dark bodies can be seen on the bees under close inspection. I noticed the presence of Nosema. The parasitic fungus infects a bee’s gut after the bee ingests its spores. The spores damage the bee’s digestive tract, cause dysentery, and can expose the bee to other viruses and parasites. But honeybees are infected by them every spring, and the mites did not seem to overwhelmingly harm the bees in the past.”

Mark commented, “I have always been nervous about letting our colonies pollinate genetically engineered crops. I looked into that right away, but have not found any conclusive data yet. Most studies say that the toxin caused by the bacterium Bacillus thuringiensis (Bt) that is inserted into the crop as an insecticide does not affect pollinators such as bees. However, a study done in Germany noticed that bees used in their study that were fed a concentrated Bt poison feed were more susceptible to parasites than those that were not.”

Dave added, “But look at places like Illinois. They use genetically modified crops all over the place and they are
not having as many issues with CCD. What I am worried about are all of the pesticides and chemicals we have used on the bees ourselves. The mites and fungi gain resistance faster than chemical companies can keep up. Consider neonicotinoids.”

“Neonicotinoids?” Tanya asked. “Those pesticides were banned in some places in Europe, right?”

“Yes, they were,” Dave responded. “They mimic the effects of nicotine, which is what tobacco plants use as a defense against some insects. Some people do not think these would hurt bees but the pesticide can enter the pollen and nectar of the plant, thereby affecting honeybees. Neonicotinoids affect honeybees’ learning and memory, which in turn affects the bees’ ability to find both the plants it pollinates and its way back to the hive.”

Tanya interjected, “Look at these studies I just found. In colonies with highly concentrated amounts of neonicotinoids, no larva or young bees died, but worker development was delayed. Good thing we stayed away from them.”

“Ugh,” Mark muttered. “There are so many possibilities. How are we ever going to figure this out?”

“Wow! This is something new!” Dave exclaimed. “The Israeli acute paralysis virus, or IAPV, was found in almost all of the colonies suffering from CCD. Within two weeks of being infected, honeybees begin dying while having paralytic seizures, most often while away from the hive. This strong correlation means that IAPV could be a marker, or even the cause, of CCD.”

“A new virus makes more sense as a cause of CCD,” said Tanya. “We all know how to keep our bees healthy, and we know the signs of disease or infection. This was something entirely new.”

Dave commented, “Now that scientists know IAPV is involved with CCD, they can create a vaccine to help colonies like ours.”

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

“The Buzz about Colony Collapse Disorder” by Oster and Wood Page 2

“No, Dave,” said Mark. “Bees do not have the same immune system as vertebrates. Because they don’t have the ability to produce antibodies the way we do, a vaccine would not work.”

Tanya added, “I read that researchers do not think IAPV is the only cause. Do you guys think that poor nutrition and stress are causing CCD?”

“What?” Dave asked. “We feed our bees protein supplements to make sure we are covering all of the bases.”

“They might not be enough. Look at the almond fields,” said Mark. “The bees are surrounded entirely by almonds, without any weeds. Compare a natural habitat to apple orchards, pumpkin fields, or even suburban lawns. One plant doesn’t meet all of their nutritional needs, so agricultural fields do not have the variety of plants bees require for proper nutrition. Could this result in a weakened immune system in the bees?”

Tanya chimed in, “Other honeybees, or moths that usually take over an abandoned hive, will not inhabit a hive infected with CCD. This points to some contaminant or disease still present in the hive itself.”

Questions

1. As a class, list possible causes of CCD that Mark, Dave, and Tanya read about.

2. How do Varroa mites and Nosema spores damage honeybee health? What are the disadvantages of using pesticides or fungicides against the mites and spores?

3. How do neonicotinoids affect a honeybee’s learning and memory?

4. Do you think genetically modified (GM) crops could contribute to symptoms of CCD?

5. Why don’t scientists think Israeli acute paralysis virus (IAPV) is the only causative agent of CCD?

6. What changes in agricultural practices could improve the environments of the honeybees?

Answer 1

1. POSSIBLE CAUSES OF COLONY COLLAPSE DISORDER (CCD):

CCD seems to be a complex and a result of multiple factors. The causes Mark, Dave and Tanya read are:

* Honeybees infested with multiple pathogens including newly discovered virus are seen highly affecting with CCD.

* Varroa mites and Nosema spores losses in bees.

* Israeli acute paralysis virus is new and found in almost all colonies of bees suffering with CCD.

* Weak immune system could be a cause.

* Poor nutrition and stress can cause CCD as one kind of plants does not meet all nutritional requirements of bees.

VARROA MITES AND NOSEMA SPORES DAMAGING HONEYBEE'S HEALTH:

* Varroa mite is an external parasite that attacks honeybees. These Varroa mites feed on hemolymph of bees and weaken the bee.

* Nosema is a parasitic fungus producing spores. Nosema infects bee's guts after the bee ingests spores. These spores damage the digestive tracts of bees causing dysentry. This leads to bee's exposure to other viruses and parasites.

DISADVANTAGES OF USING PESTICIDES AND FUNGICIDES AGAINST MITES AND SPORES:

* By a study in Germany it is known to increase the susceptibility to parasites.

* Bees when fed with insecticides like Bacillus Thuringiensis were more susceptible to parasites than those that are not.

* The mites and fungi gains resistance faster to these pesticides and insecticides.

* Pesticides can enter pollen and nectar of plant thereby affecting honeybees

* Pesticides can have adverse affects in development, learning abilities of bees.

NEONICOTINOIDS AFFECT ON LEARNING ABILITY AND MEMORY OF HONEYBEES:

* Neonicotinoids mimics the effects of nicotine.

* Neonicotinoids affect affect honey bee's learning and memory resulting in inability of bee's to find the plants it pollinates and its way back to the hive.

* Also development of worker bees gets delayed due to neonicotinoids.

* They hurt bees by entering into pollen and nectar of plants.

GM CROPS CONTRIBUTING SYMPTOMS OF CCD:

Genetically Modified crops could have a moderate impact contributing CCD.

GM crops are infected with bacterium like Bacillus Thuringiensis. When bees are fed on these GM crops, they lose their resistance to parasites becoming susceptible to various spores and mites.

IAPV ONLY CAUSE OF CCD?

Scientists don't think IAPV as the only cause of CCD because there are various other factors contributing CCD in honeybees. They are as follows:

* Increased losses due to Varroa mites.

* Pesticides poisoning

* stress to bees due to management practices.

* Changes in habitat.

* Poor nutrition

CHANGES IN AGRICULTURAL PRACTICES TO IMPROVE ENVIRONMENTS OF HONEYBEES:

* Important practice to be done is to plant garden with nutritional rich and bee friendly plants.

* Finding healthier and clean space to beehiving.

* Helping to protect swarms.

* Training programs should be provided to allow enthusiasts to master beekeeping.