Monarchs and BT Corn
Of the monarch population, it is estimated that 50% originate from the central core of the North American Corn Belt. Monarchs are one of the world’s most beautiful species that are known to us. Initially I will discuss the general information on the monarch. For instance, some general information presented is their scientific name, body segments, and migration patterns. Next, the discussion will lead to BT corn. Most do not know than more than 93% of North American corn is grown in the Corn Belt. About 26% of this is raised as BT corn. Later you will learn why this product was invented, how it is created, and when. After seeing the general information on BT corn, you will then read the effect that monarchs and BT have on one another, both having deadly effects on one another just acting in different ways. Lastly, there are two different opinions of writers, [...] Taverne and Rick Rouse, who have written articles or book reviews on this topic. They both share their ideas, which bring good points to the table that we might not think about everyday.
Background on Monarchs
First, we must understand more about the monarch butterfly. Monarchs are in the class of insecta, order Lepidoptera. A monarch also known scientifically as (Danaus plexippus), have three body segments the head, thorax, and the abdomen. The head contains compound eyes, which are the eyes that are visible to us without a microscope. The compound eyes are really about 12,000 – 17,000 individual optical units that make up one eye. The greater amount of optical units that the butterfly has the better their vision will be. They also have simply eyes found usually with a microscope between their antennae. The simply eyes or ocelli are sometimes hidden by the scales of a butterfly, and they are extremely small that is why they are usually seen with a microscope. The head also contains siphoning mouthparts. The long straw like structure used to suck up pollen and nectar from plants. When they are not feeding, the tube will coil back up into a spiral shape. They also have a pair of antenna. Monarchs will have a pair of clubbed, which describes the way they look. The antennas are used more so by males to detect or smell out pheromones in the females.
The thorax is the part of the body where the large scaly wings are attached. They have two pairs of wings, front wings, shaped like a triangle and hind wings, shaped like a fan. Wings can span up to three to five inches. They also fold their wings vertically over their back while at rest, as opposed to moths whom fold their wings flat over their backs. The thorax also contains six legs for walking when not flying. The abdomen is where the reproduction process begins. The reproduction cycles consists of four steps, egg, larva, pupa, and adult.
The female butterfly will attach her egg to a leaf or branch. Then she will secrete a type of glue like structure over the egg to protect it. After three or five days then the egg will hatch. The baby larva will eat the shell of the egg then milkweed almost immediately. The larva or caterpillar will keep eating until it loses its skin four different times. A caterpillar cannot grow bigger unless it sheds its skin. It is like when your feet when you are a child. When your feet would grow, you would take off your old shoes and buy new ones to fit you better and you do this until they stop growing. When the caterpillar gets about five cm long and has shed four different times, the caterpillar will find a place to pupate. This is when it turns into a pupa. They will find something to hang upside down on and molt (shed skin) for the last time. The pupa will turn green because the new skin has become hard. The pupa will stay in this stage for ten to twelve days until pupa becomes transparent and the butterfly breaks free. Since the wings are wet when it comes out the adult will have to work hard to get the wings to flex. The adult is very vulnerable to predators because it has no way to get protect itself without flight until wings dry. The adult will now continue with the cycle.
The monarch has bright colors to scare away predator in warning. They warn others because it is poisonous from eating the milkweed in the larva stage.
The monarch can live just about anywhere in the world. The monarchs have evolved over time to live in different habitats because of migration. Some migrate from Canada to Mexico where the Tran volcanic mountains are located. The disappointing factor is that one monarch will never make the whole journey in their lifetime. Since their life, spans can range from two weeks to nine months. This time range is dependent upon where they hatched at and if they migrate with a group. It takes at least three generations to complete the migration cycle.
Monarchs have a great impact on us economically. Lepidoptera the order that monarchs are in are the second largest order of insects. Being the second largest order, they have huge impacts when it comes to being destructive. They are probably more destructive to agriculture, crops, and forest than any other groups of insects that are known to us.
Background on BT Corn
BT corn is a product that has been genetically modified. The BT in the BT corn stands for Bacillus Thuringiensis. It is a donor organism that is naturally occurring in soil bacterium. This gene produces a protein found in corn to kill monarchs and other larva. It is made by inserting an unfamiliar DNA strand into the corn plants own DNA. DNA is an acid that contains genetic instructions when developing an organism. Seed companies usually select what traits they wish their seed to posses. There are typically at least three genetic traits inserted into the corn.
First being the protein gene, this is “modified for improved expression in corn, produce Cry proteins. Initial BT hybrids in the United States and Canada include one of three Cry proteins, Cry1Ab, Cry1Ac or Cry9C. Future hybrids may produce other Cry proteins, or proteins from other sources.” The second being the promoter gene which “controls where and how much of the Cry protein a plant produces. Some promoters limit protein production to specific parts of the plant (for example, leaves, green tissue and pollen) whereas others produce protein throughout the plant.” The last being the Genetic marker which “allows seed companies to identify successful transformations. Current examples of markers include genes for herbicide resistance or antibiotic resistance.”(University of Minnesota)
These three genetic packages can be inserted into the plant a variety of ways. Depending on where you insert the protein production may be affected and possible other functions of the corn plant.
The BT idea was created to help protect a variety of plants from pests and other environmental damages. Damages like “toxin sensitivity to UV radiation, heat and desiccation.” The protein cannot completely stop these damages from happening but can help slow down the rapid speed when it does happen. It also helps with the incomplete coverage where feeding sites are located. With older products, this would just be sprayed on or dusted on but now the plants will produce the BT tissue where the larva are going to eat. Since the tissues are produced inside of the plant, it will not be blown off or washed away by rain. Another reason to use BT is so you have a protein that will be present through out all growing season that will protect against new larva, which try to feed off the plant. Therefore, the farm does not have to go back out there and distribute another dose of pesticides to his plants.
BT was thought of by, who is now Novartis Seeds and Mycogen Seeds in 1996. The reason for a product like this was because “losses resulting from European corn borer damage and control costs exceed $1 billion each year. For example, losses during a 1995 outbreak in Minnesota alone exceeded $285 million. A recent four-year study in Iowa indicated average losses near 13 bushels per acre in both first and second generations of European corn borer, for total losses of about 25 bushels per acre.”(University of Minnesota, 2002)
Effects
Research was first done by Cornell University in 1999, “indicated that monarch butterflies under laboratory conditions might be harmed by eating pollen from BT corn plants. That experiment used a small number of caterpillars and gave them no choice about avoiding eating leaves that had been treated with a thick layer of BT corn pollen.” (USDA, 2004) This study can be discredited in many ways though. It does not take into account of weather. In a laboratory there is no weather, there is no change in environment. Environmental factors like wind and rain would have to be considered when doing a study like this because not every leaf will have the exact amount of pollen on it. Things change greatly when put to the test under real world circumstances. Another factor is that the larvae where forced to eat only one food source, well of course they were going to die when fed poison. They would have to be invincible to live through that.
The toxic process begins when the larva eats the pollen that is on the leaf. The next step is protoxin, where the ingested cells activate with the enzymes within the gut. The third step is when the membrane is lined with the toxins, which will then start to cause leaks with in the body. Then the gut just ruptures because the leaking just becomes too much for the body to take. Obviously, this will cause the larva to die quickly. Since insects have more than one brain through out there body, it takes more time to kill the other brains and body segments.
Usually the larva being in their first or second instars stage will be feeding off milkweed leafs which happen to be found in high densities around cornfields within the range of Ontario, to southern Missouri as well as far east as Maryland. It does not take a lot of pollen from BT plants to kill the larvae.
Here are the steps the plant must go through in order to pollinate. The growth stages of a corn plant start at about the middle of April. Once the seed is planted, it will not take long before germination will begin. Then after about five days, it will emerge from the soil. After it emerges then leaf growth begins for about forty-five days. Then the reproductive phase of growth starts. This stage includes flowering emergence or tassel emergence. Then after about two weeks, this is when the plant will start to pollinate. Pollen is shed usually in mid-July to the middle of August. It does not shed the whole time just for one to two weeks somewhere in that time frame. This is the ideal time for pollen to start to fly through out the countryside because this is when they thrive. The weather conditions are ideal for growth for both plant and insect.
Another question brought to mind is so how about the plant? What effect do the larvae have on the plants? Are they even serious enough to kill off this species of insects? Well the larvae start on the leaves of milkweed, which grow next to cornfields. A larva will have a better chance of living longer if it eats a BT plant without pollen on the leaves then a milkweed plant with pollen on the leaves. This is true because the pollen is more lethal then a leaf with out pollen. The larvae might move over to corn plant since the two plants grow so close to each other. So the larvae will eat away to stabilize growth. Then they work their way towards the stalk or ears of corn. In some cases if the ear of corn is damaged then the product cannot be sold, usually only with sweet corn does this happen. Once the larvae have made into the ear then they eat away at the product that we use. It also is not healthy at all for the plant to be damaged by hungry larvae. It makes it harder for the plant to put more energy into growing back leaves when they should be putting energy into growing its product. You can decide now whether these effects by the larvae are enough to kill of some of the species.
Opinions of Others
The first writer I chose was [...] Taverne. He works to promote the “evidence-based approach to scientific issues.” In his article, he talks about the following, “The past few decades have witnessed a growing influence of 'green' activists who approach environmental issues with a semi-religious zeal and seemingly little regard for evidence. The increasing prominence of these viewpoints in the media and in political circles is a significant cause for concern; it imperils not only the future of the biotech enterprise but also the health of society as a whole.” As you can see, [...] understands not everyone is for the idea of biotechnology, which poses a problem for biotechnology in the future. Biotechnology is the use of living organisms or other biological systems in the manufacture of drugs or other products or for environmental management. In this statement, “The scientists are cautious, emphasize the need to judge each issue case by case and avoid generalization; the opponents make wild generalizations that do not stand up to critical analysis.” He makes the point that each study is different and no one really knows what will come of this new wave of technology. article link1
The next writer was writing to review a book. Rick Rouse reviewed the book, Dangerous Liaisons: When Cultivated Plants Mate with their Wild Relatives. In his review, he brings up some very valuable points that people sometimes forget to think about. He states, “The ecological effects of genetically modified (GM) crops remain controversial, despite evidence of the crops' agricultural benefits, such as reduced pesticide use, fewer human poisonings and increased net incomes for farmers. Their most ardent critics argue that GM crops lead to the rapid evolution of resistance in pests, harm non-target species and soil organisms, and create 'superweeds' by introducing transgenes into wild plant populations.” In this statement, he introduces ideas of a possibility by using genetically modified product such as BT corn too much could lead to plants like super weeds. Super weeds are weeds that have adapted or evolved to the herbicides. The same thing could happen to insects, they could evolve around pesticides. This would make it almost impossible to control weeds and insects and could lead to outbreaks. As he goes on, he talks about how this has not transpired at this point in time but could happen in the near future. article link 2
Conclusion
In conclusion, monarchs are a beautiful and delicate creature that needs to be protected during migration through the Corn Belt of North America. BT was created in the nineties by Novartis Seeds and Mycogen Seeds, to control all larvae and to stop them from eating away at the plant. Since a big percentage of farmers do use BT products that do affect the population of monarchs. However, monarchs affect plants so much that the plant may have a reduced yield when it comes to harvest time. When economics comes into view, then most would pay to kill a pest like monarchs then take the hit at the bank. We must also think about how studies are done with biotechnology and if they are accurate, an idea passed on to us by [...] Taverne. Another idea that we should also think about is what kind of effects could develop over time to pest and weeds from genetically modified organisms.
References
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