ATHENS, Ga. -- Humans and insects have always had a kind of war going on. One can easily imagine "Lucy," the proposed ancient ancestor of humans swatting at mosquitoes on a hot day in East Africa several million years ago. Since then, it's gotten worse, if anything. Fleas carried the bubonic plague across Europe, and millions died. Mosquitoes have caused outbreaks of disease across the globe.
The greatest challenge in the man-insect wars in the new millennium, at least in the United States, may be a swarming little nuisance called the Formosan termite, a transplant from Asia that has been gnawing its way north from the Louisiana-Texas coast for the past 35 years.
The assessment of the top continuing and emerging entomological problems of the new millennium, according to Mark Hunter, an ecologist at the University of Georgia who studies insects, was published today in the Bulletin of the Royal Entomological Society in London. Hunter is also a co-author of Ecology of Insects, recently published by Oxford University Press.
While the Formosan termite is a problem that will likely get only worse, Hunter selected two other top issues that entomologists will face. First is the impact of genetically modified crops on target and non-target insects. A recent study demonstrated, for instance, that pollen from genetically modified corn plants reduced the survival, consumption rate, growth rate and pupal mass of monarch butterflies. The other problem relates to emerging and re-emerging diseases.
"Some of these, such as dengue hemorrhagic fever, have considerable public health importance, and their incidence and geographic spread are increasing," said Hunter. "Malaria, leishmaniasis, dengue and plague have come back, in some cases where they were thought to be under effective control."
Public health officials have been concerned about a recent outbreak of malaria in New Jersey that was not related to foreign travel. And in Thailand, the Chikungunya virus, which is transmitted by mosquitoes, had not been seen for nearly a decade before its recent re-emergence.
Still, no problem facing entomologists, at least in the U.S., may approach that presented by the Formosan termite, Coptotermes formosanus. It apparently arrived in the country in the mid-1960s aboard ships from southeast Asia. While most species of termites native to America feast largely on wood used in buildings or on dead timber, Formosan termites make no such distinction, cutting through live trees like chain saws.
In New Orleans, for instance, 30 percent of the city's majestic live oaks, which add much to the city's ambiance, are now infested. Hunter said one cost estimate for control of the pest was $100,000 per city block per year.
"This species gets my vote for the most important structural pest of the new millennium," Hunter said." Judging from recent news stories, the Formosan termite appears determined to consume the historic French Quarter of New Orleans. These termites destroy creosote-treated utility poles and wharves, the switch boxes of underground traffic lights, underground telephone cable, live trees and shrubs and the seals on high pressure water lines."
Costs of control in the entire country are now approaching $1 billion a year and the insect is still largely confined to the Gulf Coast. Hunter says that even if the Formosan termites stayed in that area it would be bad enough. However new studies indicate the bugs may quickly migrate as far north as Washington State to the west and Massachusetts to the east. Formosan termites, native to China, were discovered in Atlanta in 1992 and have been found in Japan, Guam, Sri Lanka, Hawaii and South Africa.
While entomologists ponder the problems associated with the Formosan termite, concerns about how genetically-altered crops interact with insects are growing. Half of the North American summer monarch butterfly population is concentrated within the U.S. corn belt states, and Hunter calls the potential impact of genetically modified corn on monarchs "profound."
"Resistance development by target pests has, of course, been an issue of concern to agricultural technologists for some years," said Hunter. "Resistance management techniques will probably grow in concert with the use of genetically modified crops. But more subtle effects are harder to predict."
The spread of emerging and resurgent insect-borne diseases has a number of causes. In some cases, the spread can be associated with ecological changes that have favored increasing insect populations. These, said Hunter, include dam construction, development projects and deforestation. Increasing human travel also appears to be playing a role.
Hunter's report, called "Some Challenges Facing Entomology in the Next Millennium," points out that the scientific world has made remarkable strides in studying and understanding insects in the past half century. Better techniques of microscopy and advances in genetics have taken the discipline into a new era. Studied in their own habitats, insects remain some of the most fascinating creatures on the planet, and since they pre-date humans by millions of years, their ability to survive remains of primary interest to scientists.
In terms of control, however, researchers discovered to their regret that the early use of broad-spectrum insecticides have set off a chain of unexpected consequences, including some target pests developing an immunity to specific chemicals. Indeed, Hunter argues, entomology as a separate branch of study faces hard times as studies move toward the molecular level.
"Let's face it, the glory days of the `ologies' are a thing of the past," said Hunter. "While we still try to instill the importance of this kind of study in our students, this kind of biology has become the luxury of zoological parks and dedicated naturalists. Entomology is really now an inadequate descriptor of what we do."
Whatever it's called, the study of insects may be as far from solving some real-world problems as ever, even though major successes have saved millions of lives. Just what emerges from the multiple problems as the number-one issue remains to be seen.
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