Evening star., 1948-10-25
Stars, Men and Atoms
Radioactive Mosquitoes.
Used in Fever Research
Insects Can Be Traced in Study
OF How Disease Spreads
By Thomas X. Henry

By Thomas r. Henry
Radioactive mosquitoes are being used BY
the Rockefeller Foundation In its fight against
yellow fever
1t was found at the Foundations laboratory
at Lagos. Nigeria. that when the insects in.
the larval stage Of their development were
exposed to weak solutions of radioactive
phosphorus the adults which developed from
these immature forms remained themselves
radioactive throughout life. When released
they could be identified whenever recaptured.
The method Is being used to discover the
rate and direction Of spread Of q mosquito
colony and the average length Of life. It ID
necessarily quite laborious, ITS man-hours
being required for the recapture of Is RADIO
active insects out Of a colony Of 5000 which
had been treated with the phosphorus bath.
Bombarding the yellow fever virus within
the cells OF a mosquito was attempted in
another experiment. Insects made radioactive
In the larval stage were infected with virulent
yellow fever virus. They showed, however.
no alteration in degree of infection or in.
ability to transmit the virus to baby mice
when compared with nonradioactive controls
similarly infected. The virus itself seemed
to lose none Of its potency. The rate Of
mortality among the mice was about the
same In both cases.
In other experiments underway at the Lagos.
laboratory efforts are made to find the effects
Of changes in single elements of the environ
ment, such as increases in temperature, on the
biting habits Of the insects Such observations
preclude the presence Of an observer who not
only modides the climate by the heat of his
own body but introduces a series of stimuli
affecting mosquito behavior
A way has been devised Of observing the In.
sects entirely by sound with the climatic varia.
tions manipulated by remote control With the
insects in sound-proof chamber and q sensi-
tive microphone leading to high gain ampli.
fer. the mean sound-energy level under con.
slant conditions is a function OF the number
OF mosquitoes in f1ight-a necessary prelude
to biting. BY means of q recording system It
Is possible to measure continuously this sound
energy which can be translated into the per.
centage Of insects flying at any instant. :
- 4
First successful gratis between unrelated
species Of plants have just been reported 10
the American Association for the Advancement
Of Science.
Sweet clover has been grated on both sun.
flowers and tobacco, COW peas on tomatoes,
clover on geraniums and tomatoes on Rera-
NUNS
Ihe work Is reported by DR.. Louis q. Nickel
OF Yale University The results are considered
far more than natural curiosities since they
challenge basic concepts of plant physiology.
In a successful graft the veins" of the
two components must be united into common
system. Hitherto this has been possible only
with very closely related plants Of the same
species-as between two varieties Of roses or
apples. Desirable varieties with weak roots
are grated on close relatives with strong root
systems, thereby bringing about a more vizor.
Gus growth This has represented one Of the
most significant developments In agricultural
science.
That the graft could be made between two
unrelated species hitherto has been considered
on the edge Of impossibility, since the vascular,
systems are so different. The accomplishment
was largely the result Of extreme care and pa
tience. 49, 81.
The grated plants appear to be growing viz.
orously, the Yale botanist reports, and there
is every reason to believe that they will con.
tlnue to thrive. Some have been growing for
more than five months
The practical applications have not vet been
considered. Obviously there is no advantage
on growing sweet clover on sunfiowers but
throughout nature there may be many exam.
pies which will be of economic value.