Chem321:DDT and the Biochemical Pesticide Baculovirus

Angela Racine, August 2012

Pesticides

Pesticides are widely used around the world. They are comprised of chemical substances, which are supposed to kill unwanted organisms. Modern pesticide industries aim to control their products so they need less quantities to be effective and won’t ever linger in the environment. These types of pesticides would be considered green. Green pesticides work well with the environment, only killing the pests they are supposed to, but others can harm more than the target, which has a negative impact globally. Many green technologies have influenced pesticide standards and help monitor the control of the environment. They aim to increase sustainability and are better than past “dirty” technologies, which contaminate land systems. The two pesticides to be discussed are DDT and the biochemical baculovirus. Biochemical pesticides, like the baculovirus, are harmless to ecosystems and are part of green technologies. DDT, however, was one of the worst pesticides to wreak havoc on the environment.

DDT

DDT was first synthesized in 1874, but its use as a pesticide wasn’t discovered until 1939. The person who discovered its insecticide use got a Nobel Prize, and this man was Paul Muller. It was banned in the 1970s after Rachel Carson’s Silent Spring had been on the market for a few years, warning people of its negative effects on the environment and human health. Its use spread quickly, both to get rid of insect borne diseases and to help farmers get rid of their crop pests. Over the course of its use in the mid 1900s, it was mainly sprayed on farms, forests, elm trees, and spruce trees. DDT worked well in killing insects that carried diseases and is still used in smaller quantities around the world for this reason. Farmers were able to grow their crops more easily and the plants were able to thrive. It was also used on specific trees for insects, like the aforementioned spruce and elm. The instigator in the spruce tree disease was the quickly spreading budworm. The bark beetle, which thrived in areas only comprising of elm trees, brought about the Dutch elm disease. The less plant diversity in any area, the more the pests can prosper and reproduce. This is true for crops as well. It is because insects can reproduce more easily when similar plant species are around. If trees and crop plants are arranged in alternating orders, it slows the reproduction cycles because the host plants are further apart. DDT was a beneficial pesticide and was able to help many people, but it had many problems linked to it as well.

Problems concerning DDT

Most of these problems with DDT use were linked to environmental and human health. As it is sprayed, it enters the soil or water body, and accumulates with each passing douse. This affects the plants, water systems, and animals around the area. The species on land or in the water are hurt not only from the terrain itself, but also through the food chain. An example would be that the fish eat an affected insect; humans eat the fish, etc. Therefore, it then can harm humans through the food chain, by ingestion of plants or direct contact. If it enters the body of an animal or human, it is stored in fatty organs like the liver, kidneys, and intestines, and eventually it will affect the nervous system. Another negative effect on ecosystems through food chains is on the birds in DDT areas. DDT was used to kill the ravaging fire ant in the mid- U.S., as well as the aforementioned bark beetle on elms. The sprayed areas contaminated earthworms, and birds such as robins were poisoned in large numbers. One college campus in Lansing was considered a “graveyard” for robins. (Carson, 107) This is why Carson named her book Silent Spring, as all the birds in some areas were dying, and there was no music. This problem made many civilians have eerie and uncomfortable feelings relating to the pesticide use. These are the many reasons why DDT was banned. However, science and technology have been working to come up with new ways to control pests in “green” and healthy ways.

Biochemical Pesticides

Biochemical pesticides are one of the technologies used today in place of DDT and other harmful chemicals. They are one of the three types of bio-pesticides, and they control insects with non-toxic techniques while also being naturally occurring. It is difficult to tell if a material meets all of the biochemical criteria, so the EPA formed a special committee to determine such a matter. They are indeed categorized as green pesticides and are un-harmful to the environment, surrounding ecosystems, and human health. This type of bio-pesticide includes viruses, fungi, insect sex pheromones, and scented plant extracts. Most target a specific or related species, and do so in different ways. Viruses and fungi can poison or kill pests once ingested and sex pheromones are sprayed on plants, which interfere with mating and therefore lessen reproduction. The scented plant extracts can attract certain insects to traps that destroy or contain them, also making them a beneficial bio-pesticide.

Baculovirus

As described, there are many types of biochemical pesticides, but the one in focus for this paper will be the baculovirus. The baculovirus is found in 400 living species, the principle one being Lepidoptera butterfly and moths. It is used to control insects in many areas like forests and greenhouses, which are their primary use today. It is also used in fields like cotton against the bollworm pest. Its first successful use as a pest control agent was against the Douglas fir tussok moth in 1984, but it had first been registered as a pesticide in 1975. The baculovirus works because the pests eat the virus through contaminated foliage, and it grows in their systems. As they reproduce, the larvae are also affected and are lethargic. None can survive. The baculovirus is important as a green insecticide because it only harms the target pests, and doesn’t deteriorate other plants or animals in the ecosystem. If protected from light, it can last for many years, and can even be integrated with other biochemical pesticides for a greater advantage. Unfortunately, there isn’t a widespread use for it yet for a couple reasons. The first is that it is slower to kill the pests than other biochemical pesticides, and second is that its production can be costly. Because of its slower deterioration of the insects, the larvae can still feed for a few days, causing some damage. Forests can withstand this damage, but farms are can’t bounce back as quickly. Third, the baculovirus only kills specific insects. While this is good for the environment, it doesn’t help agricultural farmers as much because farms have a variety of pests. This reason limits the areas where the baculovirus is an effective pesticide. Some alternatives are available if one baculovirus spray isn’t enough. For starters, technologies are underway to combine certain types of viruses into one, which will target an array of insects. Another possibility would be the combination of baculovirus with other biochemical pesticides, as mentioned before. Both of these techniques will broaden the number of species that can be affected, making them more successful to farmers.

Future Use?

Biochemical pesticides are definitely good pest control systems from an environmental standpoint. Their presence in the world has a great effect and will definitely have good use in the future, because they are not harmful to ecosystems and are naturally occurring. By this I mean that biochemical pesticides in general are important to the rise in green technologies. In regards to the baculovirus, it is a good technique, but isn’t as widespread and prosperous as the other bio-chemicals. Its use in the future will be present, but I don’t think there will be any serious impact on the world globally if it is used alone. Certain areas like forests and cotton fields will have the greatest benefits, but farms cannot. If new technologies are made which include baculovirus in a combination with other viruses, there will be a greater impact on the future pesticide industry. As for the decline of DDT use, this is positive for the environment and has great impacts on its overall health. It is good to use in small quantities for kill off diseases carried by insects, which is its primary use today, but that should be its only use. Main insect control around the world should be of the bio-pesticide regimes. Anything considered “green” technologies as a whole are much better to use for pest control. They may not be as effective for immediate results like “dirty” pesticides, but they are definitely better for the health of the environment in the long run.

References

• Carson, R. Silent Spring. Boston: Mariner, 2002. Print.

• Murhammer, David W. Baculovirus and Insect Cell Expression Protocols. Totowa, NJ: Humana, 2007. Print. 359-361.

• M, Gavrilescu M. PLANT PROTECTION PRODUCTS AND THEIR

SUSTAINABLE AND ENVIRONMENTALLY FRIENDLY USE. Environmental Engineering & Management Journal (EEMJ) [serial online]. May 2009;8(3):607-627. Available from: Environment Complete, Ipswich, MA.

• "Safe Pesticides?." Ecoworld. Ecoworld Media, 2004. Web. 6 Aug 2012.

• D'Amico, V. "Baculoviruses." Cornell University. N.p., n.d. Web. 8 Aug 2012.