Thursday, August 18, 1994

Bugs - I go to an entomologists' conference

GUELPH, AUG 18, 1994 - The Bug People have come to town to tell how they help solve crimes, cure life-threatening diseases and reconstruct the genetic code of long extinct animals.

Bug People, as people who study insects informally call themselves, are taking part in a Congress on Dipterology, the study of winged insects such as flies, mosquitoes and midges being held at theUniversity of Guelph this week. Scientists from Universities and Museums around the world are roaming the halls of Guelph, proudly introducing themselves as a "Mosquito woman" or a "Blackfly man" depending on the insect that they specialize in. But one participant, Guelph student Ian Smith says "I really hate that." understandably, as his interest is in a group of insects called dung flies.

"Flies are the most common and diverse group of animals in Canada" says Dr Terry Wheeler, a post-doctoral fellow at Guelph, who says little is known about the habits of the estimated 20,000 species of flies that make Canada their home. Wheeler says he studies flies. "Because they're everywhere, they're easy to find." He extracts some glass vials from a bag with a huge logo of a fly on it. "I could spend the rest of my career studying these" as he shows the tiny insects preserved in fluid in the vials. "I found these in my garden." He explains they are an unknown species of biting midges which kill and eat mosquitoes. Like tiny hawks, the midges wait on leaves, then swoop down on the unsuspecting mosquitoes. He said the six specimens, which have yet to be given a name as a species, are the only ones collected to date.
Wheeler's specimens
 People weren't always so friendly to insects. Adrian Pont, of the University Museum of Oxford told the Congress that flies and other bugs had been persucuted by the Church and State in Medieval Europe "It was quite common - insects could be tried in civil or ecclesiatic court, and could bebanished or executed. Once the Bishop of Lausanne in Switzerland formally excommunicated a swarm of June bugs."

Scientists at the Congress say that precise understanding of the life cycle of flies give them suggestions on how to deal with them. Flies affect humanity in harmful and beneficial ways. Tom Scott, a professor at the University of Maryland, says that half of the population of the tropics are susceptible to diseases spread by mosquitoes and other insects. "You've got malaria, filariasis, yellow fever, dengue fever... there are about 100 million cases of malaria a year, and one million of those are fatal."

Insect also cure diseases. Dr John Stoffolano, of the University of Massachusetts, says that doctors at hospitals in the US have been requesting him to send them the maggots, the immature larvae, of the blowfly, an insect that eats dead and decaying animals and people. Stoffolano says "that for centuries,the blowfly has been used to treat serious infections - soldiers wounded in battle noticed that wounds that became infected with maggots after the blowfly laid their eggs in them actually healed better than wounds without the maggots - they only eat decaying flesh - they don't damage nerves or other living tissue - and the saliva of the maggots contain a bacteria that releases an antibiotic that prevent other bacteria from invading the wound." He says that in one case, he was asked for the maggots by doctors treating a 300 pound woman who had developed a "hospital infection" in surgical incisions after receiving liposuction. Hospital infections are caused by bacteria found in hospitals that have become resistant to antibiotics. "None of the antibiotics could fight it." he says, but the woman became better after the maggots were deliberately put in the infected incisions. "First they put the maggots in the wound, then they cover it with a gauze bandage and leave it for a few days. Then they remove the maggots with tweezers."

Blowflies also play a role in solving crimes. Steven Marshall, a professor at Guelph and the Chair of the Congress, which features a panel on Forensic Dipterology, the study of flies in criminal investigation, says the blowfly and other carrion eating insects start laying their eggs in a body in a very specific order after death, which allows investigators to determine when a murder victim died and when the body was left outside. "I examined the clothes of Christina Jessop for insect eggs to determine how long the body had been it the field" where it was found. "It was very sad - it was this cute little jacket with a 'Penny-Farthing' design on it."

Hiromu Kurahashi, a scientist from Japan says his work with blowflies helps pinpoint the exact date a body was left outside, and if the body had been moved, where it had been before it was discovered."The forest supplies the results to the forensic scientist". He says that certain insects only lay their eggs during a few days in the year, and others only in a certain area. "We can determine the time a body was exposed to within three days."
Hiromu Kurahashi

Some scientists at the Congress study insects that have been extinct for 125 million years. In the film Jurassic Park, scientists recreated dinosaurs from DNA taken from blood found mosquitoes trapped millions of years ago in amber. David Grimaldi, of the American Museum of Natural History in New York, has extracted fragments of DNA from insects in amber which are between 25 and 125 million yeas old but says "It's a huge leap from that and reconstructing the DNA genome (the complete genetic code of a living creature) - the day you can use fragments of DNA to reconstruct dinosaurs is the day people become immortal! - you could just go to the graveyard and make clones of people from their DNA."! Grimaldi says insects became trapped in amber after they got stuck in resin in ancient forests. After millions of years, the resin hardened into amber, which is used in jewelry.

One of the most unusual flies described at the conference is the Ant-decapitating fly, studied by former Guelph student Brian Brown, now at the Los Angeles County Museum. He says the tiny flies"chase after the ants, lay their eggs in their bodies, and the larvae eats the contents of the head after they hatch." He said sometimes the head drops off the ant while it is still alive. "They first started studying these flies after this guy noticed these ants walking around with no head." He said ants had evolved defenses against the fly. "Some of them just run away" but leaf cutter ants in South America"have smaller ants running around on the leafs they carry to chase them (the flies) away".

Bug People are experts in one important field: What is the best insect repellent? Richard Merrit, a biting insect expert from Michigan State University, says the best repellant is "OFF or Skintastic -anything with DEET works best." He dispels the myth that Skin-So-Soft works any better. "It works for about 20 minutes" and says some gimmicks to control mosquitoes don't work. He says transmitters that broadcast an ultrasound signal that is supposed to repel mosquitoes "is geared to the wrong gender - the males responded to the frequency, but it's the females that bite! Traps are absolutely worthless - only three percent of what they trap is biting insects."


Copyright 1994, 1996, 2015

No comments:

Post a Comment