September 26, 1975
Page 30461
THE SPRUCE BUDWORM AND ITS CONTROL
Mr. MUSKIE. Mr. President, one of our chief concerns should be the effect of man's activities on the environment. At the same time, we need to achieve control of certain pest populations which threaten our economic, social, and physical well-being. While the entire question of using pest control agents and simultaneously protecting the environment is highly complex, I would like to draw to your attention a situation in Maine where these issues are being successfully resolved.
The spruce budworm, as its name suggests, feeds on the needles of spruce and fir trees, eventually defoliating the entire tree. In Maine this year 3,500,000 acres were infested, posing a serious threat to the woods themselves and the thousands of jobs dependent on them. However, prompt work and cooperation between the Maine Forest Service and the Environmental Protection Agency resulted in early registration of pesticide, Sumithion, to combat the spruce budworm in the most severely affected areas and expanded experimental use of a biological control agent, Bacillus thuringiensis. Without EPA's approval of this pesticide there would have been little or no opportunity to combat this pest.
Recently the Smithsonian published an article highlighting the problem of the spruce budworm and the actions taken to effectively control it while still preserving the quality of our environment. So that all Senators can be aware of the successful cooperation possible between States and EPA, I ask unanimous consent, Mr. President, that this article, "Maine, Canada test a magic bullet on the budworm," be printed in the RECORD.
There being no objection, the article was ordered to be printed in the RECORD, as follows :
MAINE, CANADA TEST A MAGIC BULLET ON THE BUDWORM
(By John P. Wiley, Jr.)
Every 40 years or so, a smallish caterpillar makes a serious attempt at eating every needle off every spruce and balsam fir tree on millions of acres in Maine and Canada. It has been doing this for thousands of years; for the last few hundred, men have been recording its efforts as they record the economic losses to themselves. This crocodile of caterpillars is the spruce budworm; as the name suggests, the emerging larvae feed first on the new needles inside the buds of spruce and fir trees. They then move on, however, to the old needles as well, lowering themselves on silken threads to another branch when they have denuded the one above. A tree can survive one such experience, but after two or three years of defoliation, the tree dies.
The spruce budworm is no imported menace like the gypsy moth that is eating its way out of the Northeast; it is native to North America. In most years the budworm population is too small to cause catastrophic damage. But when the spring is warm and dry, three or four years in a row, the population explodes, particularly in stands of trees 30 to 40 years old. After the larvae wipe out the stand where they started, they molt into clouds of moths that may stretch for miles and be carried by the wind into virgin areas. With the right weather, the effect snowballs each year until thousands of square miles are threatened, as they were this year. In the woods of Maine and Quebec, the spruce budworm has eaten and bred itself into a disaster.
It may be that before man began to manage the forests, periodic explosions of budworms served some ecological purpose such as, we are now learning, forest fires do. But today the woods are owned and managed, and thousands of jobs depend on them. The question in Maine and Canada is not whether to fight the budworms, but how best to do it.
In Maine, the controversy centered in part on who would benefit and who should pay. The use of public money to protect private assets was questioned. Some went further and said it was possible that logging practices such as clear-cutting may abet budworm population explosion by insuring that all the trees in a stand reach the optimal state, from a budworm's point of view, at exactly the same time. Thus, to use tax money for spraying was in effect to subsidize bad management.
The paper companies argued that the trees are a living trust and that their continued good health is essential to the state's two largest industries — wood and its products and tourism. They also pointed out that if millions of trees are allowed to die, then millions of cords of wood will glut the market and dry it up for the farmer and small landowner.
The controversy also involved the issue of how best to fight the budworms. In years past, the solution was simple: Load up the old bombers and spray the hell out of the woods with DDT. Now that's forbidden and, even in the present emergency, few have suggested that an exception be made. So in 1975 the state used more expensive insecticides, and even so could not obtain enough to spray all the acres it wanted to. Marine officials had wanted to spray 3,500,000; they had to settle for 2,333,000.
At the same time, however, Maine expanded its experiments with bacteriological warfare, using a short-lived bacillus that is death on caterpillars and a relatively few other insects, but harmless to everything else. This year the bacillus was sprayed on about 11,000 acres west of Presque Isle. (The Quebec government tried the same magic bullet on 275,000 acres out of a total seven million sprayed.)
The weapon is Bacillus thuringensis, known universally as B.t. Like a singer who worked professionally for years before being "discovered," B.t. has been around a long time, not only in the laboratories but as a commercial product. It may now be coming into its own, however, because B.t. itself has been steadily improved, and because of the increasing pressure for rifle rather than shotgun approaches to pest control. (Most of the B.t. used in Maine was Dipel, a formulation made by Abbott Laboratories. Other manufacturers market it under the names Thuricide and Biotrol.)
A full-grown B.t. bacterium contains two elements that make it a superb enemy of defoliators. The first is a diamond-shaped crystal of a toxic protein. When eaten by a caterpillar, the toxin attacks the gut wall, making the victim too sick to eat much and unable to digest what it does eat, so it starves to death. The toxin is specific to caterpillars: Only they have the enzymes and the properly alkaline digestive system to break the crystal down. The second feature is the reproductive spore which slips through the weakened gut wall into the insect's blood stream, a perfect growth medium for it, where it multiplies until it consumes the insect from the inside, also causing death.
Application is complicated. The bacterium is alive, and itself subject to death from a variety of causes, including the ultraviolet component of sunlight. So commercial preparations include added ingredients designed to protect the bacterium.
Does the stuff really work? Yes, with qualifications. It was found to kill silkworm larvae as early as 1901. Fifty years later serious commercial development began, and B.t. was found an excellent weapon against cabbage loopers, imported cabbage worms and other caterpillars that attack certain row crops. Later it was found effective against some tree defoliators, including the tent caterpillar, cankerworm, bagworm and spanworm. B.t. also works, but not as well, against the Douglas fir tussock moth currently ravaging the Pacific Northwest. The gypsy moth and the spruce budworm are also susceptible to B.t., but both are more difficult to control. The addition of the enzyme chitinase may increase gut permeability in the budworm. So far ground application has worked very well, while, until now, aerial spraying has produced erratic results.
DAMAGE ASSESSMENT TAKES TIME
Because millions of acres are involved, the results of this year's experiments will not be known for another month or two. In Maine, Robley Nash, the state entomologist, said they would have a handle on the situation by mid-October. In Quebec, Gerald Paquet, director of entomological services for the province's department of lands and forests, said they hoped to have some results by the end of August.
In both areas budworm egg cases will be counted while the damage is assessed, and the insecticides rated on the foliage protection they provided. The number of egg cases is crucial to forecasting the severity of next year's infestation, which could be still worse.
The end of the current outbreak may be in sight, however. Epidemics move generally from west to east, as the moths are carried by the prevailing winds. Paquet said in July that the epidemic appeared to be slackening in the western part of the province. But the movement of the moths is slow. New Brunswick is still fighting the tail end of an outbreak that began in 1952.
Budworm outbreaks are not new. The use of microbial insecticides on a massive scale is new. Many people are hoping that, when the results are in, they will show that a rifle works better than a shotgun.