Re: What technique do you see as the future alternative to pesticides?

A really important book to look into is called Silent Spring! It was written when the basic idea to deal with pests was to kill them with chemical warfare using DDT!

I live in Harvest, Alabama. This is only a few miles from Redstone Arsenal where DDT was invented and where it was produced by the millions of tons. Many tons of it were used on local crops. Much more was dumped into Indian Creek on the Redstone Arsenal. It killed the predatory birds by thinning their egg shells.

DDT was banned, and over thirty years later we now have many eagles, hawks and other birds. Wildlife is doing fine now. So to start with we have found many alternatives. You must understand, though, that DDT was an outgrowth of poison gas research for warfare. DDT gave the US Army a great advantage over the Japanese Army during World War II. In Malaysia the Japanese lost some 2 million soldiers to mosquito borne diseases. In Europe it saved millions of lives that would have been lost to diseases. In war more soldiers are killed due to disease than by bombs and guns. (I have a brother who is a Captain US Navy who works in this area of disease control. He is a doctor)

Here in the Southern USA we had millions dying every year due to mosquito- borne diseases and many more sick until DDT. People thought it was a blessing. Here we had a chemical that was so safe that people could be dusted with it and it could be sprayed right over our army and not hurt anyone, and yet it killed these plagues. Malaria, Yellow Fever and many more diseases just disappeared. What is more it allowed the production of food without loss to bugs. Bugs used to eat most of the crops people raised. It made grain safe to store. It was wonderful but as you are learning it had a serious problem.

The alternatives to DDT were coming out as DDT was banned. To this day nothing has been quite as easy or effective in pest control but we have alternatives.

The first generation of alternatives was to turn to organophosphates. These are just weaker versions of poison gas warfare agents. They killed bugs and they degraded pretty fast but they were very dangerous to wildlife and workers who used them. Parathion, endrin and others were used. They are less used now.

A similar group which includes chlordane was developed. It too is a variant of poison gas warfare agent. These are based upon chlorinated compounds. They tend to last a long time and are seldom used. They have been the only effective agents for control of fire ants and termites.

As study went on there was found a set of compounds naturally in plants that kill some insects. These include nicotine (tobacco), pyrithroids (periwinkle plant) and others. The most successful of these have been the pyrithroids. They do not last long and are fairly safe around people though they do have some problems with wildlife. Currently most farmers are using a combination of these and the organophosphates as a backup.

Current research is going on to find more natural pest-resistant plants for breeding, genetic engineering and new pesticide development. Cotton and soya beans now exist that contain pyrithroids by genetic engineering. The problem here is that we do not know all the possible problems. Could you be allergic to pyrithoids and would cotton or margarine now make you sick? Another problem is that all of the weeds get the ability to make pyrithroids too. Then we get resistant pests who can chow down on such plants but now even sprays do not work on them.

There is research on using beneficial insects or insect predators to eat pests. The National Forest Service has bombarded most of the Southeastern USA with billions of ladybugs to control pine beetles. The trouble is that farmer's sprays are killing them too!

Mankind, if he is to have adequate food, must control pests. We are learning to do so without making so many problems. However, every new solution brings with it problems.

Some other new solutions include: bug zappers like are used for controlling flies and mosquitoes, another is literally just spraying soapy water, it drowns the bugs.

Research is going on in use of pheremones which are used to attract the females or males of a pest so that they get trapped and cannot reproduce. This is being used a lot.

One really curious solution which I like is to vacuum up the bugs. A lacewing invasion of California crops was literally sucked up and dumped.

What ever means we use to control pests will have to be based upon understanding the life cycle of the pest and how it interacts with the rest of the world. Nature has been using pesticides for a long time. Oak trees are really devious in their mechanism of defense. Oak trees defend themselves with chemicals which prevent the bugs from completing the pupa stage and becoming adults. But they don't just do it all the time. They wait until the bugs have eaten and bred once then they attack the next generation. Such natural defenses are really quite spectacular.

I am sure you have heard of the Smoky Mountains and the Blue Ridge Mountains. These are called so because of the natural blue haze in the area. The blue haze is part of the natural fight between hardwood and softwood trees. Oaks and nut trees detect the pollen from pines and firs and they emit acids from their leaves to kill these other trees. This, contrary to all the political propaganda, is the primary source of acid rain. US emissions of sulfur compounds and acids is currently at about 15% of the level it was in 1900. About 95% of the Eastern USA acid in the air is from these trees. The reason that there has not been so much in previous years is that the Eastern USA was deforested in the 1930s and is only just now going terminal. This means that the big hardwood trees have taken over and are killing the pines. Naturally their acid also affects fish. (This has happened 6 times in US History.)
[Moderator's note: A different view appears at the end of this document.]

If you want to learn more about the matters of pest control I would suggest that you get in touch with the following sources of information:

All of these should have websites:
US Forrest Service:  Ask about pine beetles and gypsy moths.
US Cooperative Extension Service :  They should have an office near you.
US EPA : They will tell you about rules and pollution control issues.
US Centers for Disease Control : Atlanta Ga.   They will have information on diseases and pesticides.
Monsanto Chemical Corp
Georgia Pacific 
Sierra Club 

Antibiotics are just natural pesticides used by fungi to control bacteria. We are getting resistant bacteria now too.

If you are really curious and want to learn more you may want to study insects or biology. We need people to learn more about what to control and how to control it.

By the way, I use some really simple means to keep bugs out of my fruit trees. I hang red painted blocks of wood sprayed with sticky goo. Another trick is to grow garlic at the base of the trees. I have used marigolds to attract pests to them and keep them off Tomatoes.

Weed control is another curious one. In China they use geese to weed the crops. They have to eat the geese every year or the geese will eat the crops the next year. We are starting to use geese here in the USA. They eat the bugs too! I have used Guinea Pigs to weed Tomatoes. In South America they raise the Guinea Pigs for food. I just used my pets. They fertilize them too! The list of ideas to manage crops is just beginning.

The US TVA has planted special fish in their lakes to eat the weeds. Unfortunately the weeds grew so fast that all they got was lots of really fat fish.

I guess the real answer to all of this is to realize that in every problem there is an opportunity.

Have fun with this one. Just don t panic over every current emergency. I remember strip mines which were never going to recover and they have most all recovered. Care about things but learn the entire story.

Several countries in southern Asia banned DDT because of the book you are reading. They wound up with millions of cases of Malaria. We need to be careful to look at the whole picture. The environment will become a larger and more complex problem as human populations increase. The greatest issues will be the disposal and recycling of ionic nutrients from human waste. Other great issues will be bacteria and control of disease.

Sincerely
Paul Noel
ltree@ro.com

A different opinion about the causes of acid rain:

The extent to which acid rain is natural is a subject of controversy. Over the years I have seen various amounts of the total acid load attributed to natural vs anthropogenic sources (anthropogenic is caused by pollution from human activities). The figure you mentioned of 95% coming from trees is at the very low end of the estimates of human contribution. At the other end, Environment Canada estimates that 90 to 95% is of human origin. Industry groups tend to cite numbers minimizing the human contribution, while environmental groups tend to cite numbers maximizing human influence. The consensus among most scientists in the field (those not working for coal and oil companies anyway) is that the actual amount is closer to the high end estimates.

The reason for the controversy is that in most areas now affected by acid rain there is not enough background data from before the problem started to tell exactly how much more acid there is now. Published estimates of anthropogenic acid loads are based on the amount of emissions of sulfur dioxide and nitrogen oxides, the measured sulfate and particulate levels in air monitoring, the amount of sulfate and acidity in rainwater, and historic changes in stream water chemistry.

Natural (unpolluted) rain is actually slightly acidic due to dissolved carbon dioxide, which forms carbonic acid. Neutral pH is 7.0, but natural rainfall has a pH of around 5.6. This is the same as distilled water in equilibrium with the air. Organic compounds from vegetation can lower the pH further. This is one reason why rainfall in areas with wet climate tends to have slightly lower pH than rainfall in arid areas. In some tropical rainforests, vegetation can lower the pH substantially, but this is unusual and does not occur to such an extent in temperate areas. If no pollution were occurring, rain where I live in West Virginia could probably be expected to have a pH between 5.0 and 5.6. As it is, however, it averages 4.5 in the valleys and 4.0 on the ridges. These are averages, so while sometimes rain pH will be above 5.0, at other times it is closer to 3.0. Remember that pH is a logarithmic scale, with acidity increasing by a factor of ten for each point lower on the scale. So if the average pH has been lowered from 5.0 to 4.0 it is 10 times more acidic than natural, and at times when it approaches 3.0 it can be as much as 100 times more acidic.

Other natural sources of atmospheric acidity are volcanoes, geothermal areas and forest fires. Eruptions and fires are episodic events that do not account for trends that last over years and decades. Volcanic eruptions can spew large volumes of sulfuric acid and sulfur dioxide into the atmosphere and can cause very low pH rain in local downwind areas. Some of the acid ends up in the stratosphere, where, although it can travel long distances, it does not greatly affect the pH of precipitation in areas far from the volcano.

In summary, the evidence for pollution as the source of acid rain is:

1. Spatial correlation: Areas receiving the worst acid rain are in the prevailing downwind directions from the major sources of SO2. In addition, the areas that have the lowest rainfall pH correspond to the areas having the highest sulfate concentrations in rainfall, indicating that the two are related as sulfuric acid, and that SO2 emissions are the cause. Particulates associated with SO2 emissions also have a similar relationship with acid rain.

2. There is no similar correlation with vegetation. Vegetation and forest cover are approximately the same in the southern and northern Appalachians, but acid rain is considerably worse in the north. Also, if the primary source of acid rain was compounds released from trees there should be an improvement in pH in the winter months, especially in the north. This does not occur, however. The average pH of winter snow is the same as summer rain.

3. The timing of stream degradation in the Appalachians generally coincided with the widespread building of taller smokestacks to alleviate pollution in cities, industrial areas and around power plants. These sent pollutants higher into the atmosphere, where they traveled longer distances than they had previously. Ironically, a measure intended to fix an air pollution problem ended up only shifting it elsewhere.

4. USGS data show that recent reductions in SO2 emissions have resulted in less acidic rainfall in areas downwind from the sources.

That acid rain is primarily the result of pollution has been pretty well established and is now accepted by a consensus of the scientific community. The extent to which it is causing damage is, however, a different argument that is not yet resolved.

Some sources on the source of acid rain:
NAPAP: National Acid Precipitation Assessment Program, a ten year study, report published in 1991 with updates since then, titled "Acidic Deposition: State of Science and Technology"
Journals: "Water Resources Research", and "Water, Air and Soil Pollution".

Some sources of info on the web:

EPA Acid Rain Program

Environment Canada "Primer on Environmental Citizenship"
go to section 3 - The Biosphere, acid rain begins at Q3.49.

Well, I hope I cleared the air a little bit on this subject. Best regards,

---- Sean Sherlock