The repellent effect of the molluscicides Niclosamide
(Bayluscide WP 70 ), Anacardium occidentale
and the latex of
Euphorbia splendens
on Biomphalaria glabrata
was observed
through the investigation of the occurrence of escape behavior
among molluscs that were exposed to dosages lower than the
LD 50.
The total number of individuals out of water among the
surviving snails in the control group provided a "Natural
Escape Index". The comparison between this total and the
total number of surviving snails in each group exposed to the
different dosages of the molluscicides after 24 hr provided
the "Molluscicide Escape Index" and the detection of a
"Repellency Range" to these snails.
The escape indexes for Niclosamide, A. occidentale and
E. splendens were 10%, 6.22% and 6.44% respectively.
Repellency occurred at the following concentration ranges:
0.01, 0.02 and 0.03 ppm Bayluscide, 0.1, 0.2 and 0.3 ppm
A. occidentale and 0.05, 0.10, 0.15 and 0.20 ppm E. splendens.
The Natural Escape Index obtained in the control group was
zero.
