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chromosomes taken together constitute what the geneticist calls a homol- 
ogous pair. This simply means that the two chromosomes carry paired-off 
genes for each hereditary characteristic. 
Using penetrating radiation, Rai was able to break normal chromo- 
somes. But as we have already pointed out, when the chromosomal frag- 
ments then rejoined, they sometimes linked up in abnormal arrangements. 
The abnormal chromosomes still contain all the necessary genetic in- 
formation to produce Aedes mosquitoes. There is.one important difference, 
however. When a set of normal chromosomes and a set of abnormal 
chromosomes come together in a fertilized egg, the male mosquitoes 
formed will be 70 to 90 per cent sterile. In all other respects, however, a 
normal male mosquito will be produced. This male will mature and mate 
just as any other male Aedes mosquito. But, as indicated earlier, it will 
transmit its fatal reproductive flaw to the next generation. 
Where will this work take us? It’s difficult to predict at this point, but 
one thing seems clear. If healthy, competitive, but sterile male mosquitoes 
can be produced in the laboratory, then it is probably possible to do the 
same thing with other species of insects. This achievement could, in its 
own quiet way, be the death knell for the numerous insects that threaten 
man’s well-being in one way or another. For any given insect species, all 
that is needed is to release enough of the abnormal males; since sterility 
is transmitted to the next generation, this would eventually lead to the 
virtual eradication of the insect. 
In these days of growing concern about the environment, any biologi- 
cal control of pests is preferable to chemical control—especially if the 
chemical agent used poses a long-term threat to other species. But caution 
is needed in the imposition of biological controls also. Assume, for example, 
that this pioneering work is extended to all species of mosquitoes, and that 
virtually all mosquitoes throughout the world are wiped out. What then 
happens to the food chains that claim the mosquito as one of its links? Do 
the birds, fish, and other insects that prey one the mosquito suffer starva- 
tion and a depletion in numbers, further disrupting ecological balance? 
Or is there ample food of an alternate nature available to these organisms? 
Man must satisfy himself that he has the correct answers to questions 
such as these before he indiscriminately imposes any controls on any pest 
species. This is not an argument against the use of genetic manipulation 
to control organisms dangerous to man. It is rather a plea for the judicious 
use of such controls. It may be possible to reduce mosquito populations 
to the point where the insect does not threaten man. Complete eradication, 
however, may turn out to be a wolf in sheep’s clothing. The mosquito as a 
pest and disease carrier may disappear, only to reveal an even greater 
threat to the environment. 
Man, despite any disclaimers that may be voiced, is a part of the total 
environment. He cannot place himself above it and capriciously manipulate 
the very existence of other organisms. Rather, he must weigh all such 
moves in terms of how they affect him as a participating members of the 
environment. It may indeed be ecologically wise to wipe out all mosquitoes. 
It may also open up a Pandora’s Box of totally unexpected new problems. 
—Reprinted from Narragansett Naturalist 
