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Copyright 2005, Board of Trustees, University
No. 41 August 5, 1968
Homest Lea 1 C
t^'^I -- ,.., ,--- i -.,.
Flies for the F9 generation should start emerging this week. These flies
will be located in our new quarters, thus in a safer location! Hopefully,
this will also cut down on the amount of walking--it is amazing how fre-
quently the needed item was always in the other building.
I think you will be interested in our marked fly data.
June 25 1 -1/8 mi
July 9 1 -1/8 mi
2o, 2? -1/8 mi
-1/2 mi 1i -5/8
10 -3/8 mi
1+ -3/8 mi
Thus of 40,000 flies released, we recovered 21 females and 4 males. In addition
to these, on July 23 we placed one McPhail trap at the release site and on the
30th collected one female and five males---more males than the 200 traps caught
during the entire period. During this trapping period we caught 13,395 "wild"
flies, 9696 females and 3699 males--or roughly, 2.6 females to each male. The
marked fly ratio is 5 to 1--not counting the flies captured at the release site.
Counting these, it is close to the wild population--2.4 to 1. It is also of
interest to note that 5 times as many flies have been caught in the combined
south and east quadrants as in the combined north and west. As you may know, our
prevailing winds are from the southeast. Our wild population has been remarkably
uniform--6,444 caught in the north-west quadrants and 6,951 in the south-east.
CARIBBEAN FRUIT FLY MONTHLY RESEARCH REPORT, [. .
R. M. Baranowski, Entomologist SEP 27 1 S3
Sub-Tropical Experiment Station
U~~~c~d Fl idn
1- -1/4 mi
10 -1/8 mi 1I -3/8 mi
- 2 -
I'm not sure what a lot of this means, but some of it was certainly surprising
and I'm not ready to start speculating.
Ue have a series of cages in operation now to evaluate the effect various
male-female ratios have on egg viability. The results are only from the past
month and a single series of cages so are decidedly preliminary. Our ratios
varied from 0.25 males to 1 female to 4 males to 1 female. It appears that
as you decrease the number of males below 1:1 you get a corresponding decrease
in viability. At 1:1 or 2:1 the viability is highest but then drops at 4:1
but not as low as 1:4. I think the important thing here is that our rather low
egg viability is very likely not due to a lack of mating, but rather some other
factor such as food or light.