Date: Mon, 10 Apr 1995 14:04:09 GMT

In article lowell@cybergate.com wrote:
In article aquilla@salus.med.uvm.edu (Tracy Aquilla) wrote:

LOWELL: Before addressing this issue, I'd like to state my opinions so as to avoid anyone jumping the gun and possibly flaming me. First, I think eradication programs are a huge waste of time and money. It is impossible to eradicate an insect; at least it has never been done before, as far as I know.

Tracy - I generally thought of you as a knowledgeable person.. but here you fall short. Many insect pests have been eradicated from certain geographic locations.

TRACY: Thanks for (previously?) thinking of me as knowledgeable. While I have had no direct personal experience with cotton, I am quite familiar with numerous eradication programs. Furthermore, since you question my knowledge in this area, I guess I should point out that I have several years of training and research under my belt and hold advanced degrees in entomology and genetics from the entomology department at UC Riverside. I am not just speaking as a "knowledgeable person" but as a professional trained in the field of agricultural pest control. There are a few rare cases where eradication programs have been deemed "successful" by bureaucrats. However, entomologists in the field disagree on whether or not these programs have been successful. Some entomologists may try to convince you that eradication is cost effective, but these are usually the guys who earn their living from these programs. Certainly the pests in question have not been completely eliminated from the the areas in question, and even with constant monitoring and occasional necessary insecticide applications, these pest populations frequently return to economic levels. If an eradication program is discontinued, the insect returns to pest status very quickly. In nearly every case it is debatable whether the annual cost of the eradication program is offset by the benefits. There may be one or two exceptions.

LOWELL: >I'm no expert in this but I know that the screw fly in the desert >southwest has been eradicated - and very clearly the boll weevil has been >eradicated from large areas of the southeast.

TRACEY: Speak to an entomologist in one of these areas and they'll tell you that these species are found occasionally in areas from which they've supposedly been "eradicated". Since the screw-worm eradication program began (in the early 60s?), there have been several rather serious outbreaks of screw-worms in the southern US. Even with constant vigilance, there are infrequent small outbreaks; this pest has not really been eradicated (see eradicate in your dictionary). In order to maintain control the program must be ongoing, meaning it costs lots of money every year. Even if they were to be completely eradicated, they would soon be re-introduced. The case of the Med fly is another example that is often touted as a success. We've been trying to eradicate this pest for over fifty years and it's still here.

LOWELL: >The reason the boll weevil can be eradicated is because of its very >limited host range. essentially cotton. If you can control it in cotton >you will eradicate it. If you lose the battle on even one field you lose >the war.

TRACEY: This last statement is exactly why eradication generally doesn't work. There are no insecticides that will kill 100% of the field population, even when exceeding the application rate listed on the label. In fact, the boll weevil is a particularly tough case for chemical control, since the pest burrows into the squares and bolls, making it difficult to hit with insecticides. Complete eradication is not only unattainable, such attempts are extremely wasteful of valuable resources that could be used much more effectively elsewhere. In the US we have been battling this pest for nearly a century. The idea that we can win this war with nature is absurd! Will we never learn?

LOWELL: >It it has been shown conclusively that non-chemical methods do not work!

>Organic farmers are deillusional if they think otherwise.

TRACY: Now you've really stepped in it! First, in regard to the scientific method, a negative experimental result generally does not provide conclusive evidence of anything. Secondly, THE most successful eradication program of the century is that of the screw-worm in the southern US (east and west). The success of this program is directly due to the ongoing annual release of sterile male flies, NOT insecticide applications. I'd say non-chemical methods are the ONLY ones that DO work! Even this pragram doesn't have 100% penetrance.

Hasn't eradication of the boll weevil been attempted before in Texas; why would anyone expect it to work this time around? When calcium arsenate didn't work in the first half of the century, chlorinated hydrocarbons were used. Boll weevils developed such a level of resistance to these insecticides that many safe and effective organochloride compounds were deregistered. Next the second and third generation compounds were used (i.e. organophosphates and carbamates). Some of the most toxic compounds synthesized by man have proven to be ineffective at eradicating this pest. Therefore, it seems clear that attempts at complete eradication are pointless, and in fact, complete eradication is unnecessary. It is only necessary to reduce the pest population to a stable level below the economic threshold. Finally realizing this, we turned to our last resort: cultural control. I think the success of the eradication program in the southeastern US can mostly be attributed to cultural control. Pheromone trapping, early planting, using early-maturing varieties, and other similar cultural methods are really what have allowed us to continue producing cotton in the cotton belt of the US. These are all non-chemical methods of pest control, and they work fairly well.

Concerning your second statement above, I think many classical biocontrol programs have proved to be much more successful at maintaining a stable sub-economic pest population than any eradication program ever conceived. I'm not convinced that IPM couldn't solve this problem more effectively and more economically than a chemical eradication program might. In fact, attempts at eradication may even select for a population that is resistant to currently effective insecticides (as has been shown in the past), compounding the problem and making the pest even more difficult to control with chemicals. There are well over fifty different parasites, parasitoids, and pathogens of boll weevils. By combining some of these with the currently used cultural methods, I think we could obtain adequate control more effectively and for less cost than by widespread aerial spraying with malathion. Same goes for the Med fly. After years of arerial spraying to no avail, they are finally seriously considering using biocontrol (in CAL).

FWIW, my opinion is that this program in Texas is politically motivated. There are literally over 100 insect pests of cotton, and it has (one of?) the highest rates of insecticide use of any crop in the US. There are quite a few cotton growers in Texas. If the state were to spray widely on a routine basis, the cotton growers would have a lot less to worry about and their insecticide use would be subsidized. The only real obstacle to this gravy-train is the organic cotton growers.

In closing, I'd like to point out that I am not an anti-pesticide freak. In fact, quite to the contrary, I have frequently posted to this and other related groups expounding on the virtues of products such as DDT. However, based on what we have learned about the various negative impacts of widespread, indiscriminate pesticide use, I think we need to dummy-up. Chemical control is an effective tool, but it is not the cure-all the previous generation believed it to be. The wave of the future in pest control is IPM. Lecture over.

tracy

Thank you Tracy for one of those rare, substantive posts that takes a discussion to another level. I agree with you that even a simple knowledge and acceptance of basic ecological prinicpals is inconsistent with faith in eradication, especially in a world as mobile as this one -- except in the case of complete loss of species, the one form of eradication which has been proven to be stable. I do not think the boll weevil is ready for listing under the ESA.

As I read your post, I could not help but think of the irony of senior scientists in certain agrichemical companies, and their cohorts in academe, arguing recently before the EPA's Scientific Advisory Panel that they have figured out an ingenious and essentially full proof resistance management strateggy for BT-transgenic cotton. Here is an industry urging upon the policy process "good science" arguing that resistance to BT will not emerge because they have figured out how to express the BT-producing gene at such a high level that any insect within the field will just keel over from little more than a sniff. Geez, I just can not believe that reasonable people and respected scientists would buy into such a stupid and implausible notion. I suppose there is a theoretical foundation for the argument, but how can people really accept that expression of the gene in the field, across all growing conditions and genetic variablity is going to always express the gene high enough? It will not work; there is soild scientific evidence showing why, yet government has been "convinced" by the experts that it might.

BT resistant insects, once on the loose throughout the south, will create havoc in southern fruit and vegetable industries, and create a BT-resistant gene pool that will soon (a generation or so) eliminate BT worldwide as an effective natural insecticide. Nice trick. It is a shame such a series of events appears to be ready to unfold. I wonder if farmers, denied of BT-susceptable strains of insects, can sue the gov't or chemical companies for a taking?