Ants, squirrels, aliens, plastic

One of the best known tactics in war is to destroy bridges to slow down an advancing enemy or to cut the enemy's supply lines. Apparently the same tactic works for one species of weakling ants in Africa, which loses 60 to 80 percent of its battles with other ant species. To protect themselves, this army prunes the leaves on its favorite tree species so the leaves don't touch other trees. In effect, pruning destroys the bridges. Pruning also destroys the flowers so trees fail to reproduce by seed. How the trees manage to reproduce is still a good question. (Oct. 9, 1999)

Rattlesnakes may strike fear in the hearts of most people and may drive horses to bolt, but they don't scare California ground squirrels. According to an article by Susan Milius in Science News, when ground squirrels spot a rattler it's like a bull seeing a red cape. They get "attitude." They get mad. They charge the snake, kick dirt at it, throw pebbles at it and even try to bury the snake under all the dirt and stone. If a snake strikes at a squirrel, these aggressive little fighters jump quickly out of the way, even applying a sideways flip. When a snake manages to land a punch, the squirrel just rubs the strike spot and charges in to do battle again. Luckily for the squirrel, it has proteins in its blood that render harmless the venom that would be enough to kill a human.(Oct. 9, 1999)

Despite Customs and the Border Patrol, illegal aliens have entered the United States in record numbers and are taking over. No, not people; 6,500 species of insects and arachnids, molluscs, plant pathogens and other undesirables. Like most invaders, this influx has wiped out some native species and pushed others to the brink, according to a two-volume study, "Status and Trends of the Nation's Biological Resources," by the U.S. Geological Survey issued in mid September. It isn't only aliens that are having an impact on U.S. ecological resources. Water use has a major impact on ecological resources, writer Susan Milius reports the study as saying. A land-use chapter points a finger at suburban sprawl. But it isn't only what is known that is worrisome. What isn't known is just as scary.

As tomato plants being to wither with the onset of the first frosts of fall, consider the black plastic mulch beneath them. Beltsville (Md.) Researcher Cathleen J. Hapeman has discovered that in 1998 an average of 63 liters of water ran off each square meter of plastic-mulched soil. This was four times what ran off from a field mulched with plant material. In addition, the plastic-covered field lost 15 times as much dirt per hectare as the plant-mulched field and 19 times as much insecticide and fungicide ran off from the plastic mulched field. When this chemical-laden runoff was caught in test containers holding aquatic organisms, the water was found to be much more toxic than water from the plant-mulched field. Hapeman questions whether the impacts of soil loss and chemical run off justify the use of plastic just to harvest a crop 3 or 4 weeks earlier.

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