EVALUATION OF THE PLANT PESTICIDES VERTIMEC AND MATCH AGAINST BIOMPHALARIA ALEXANDRINA, THE SNAIL VECTOR OF SCHISTOSOMA MANSONI

The molluscicidal activity of seven pesticides, commonly used
as plant pesticides has been evaluated against adult Biomphalaria
alexandrina snails. The tested pesticides are Basudin, Cidal, Imidor,
Neomyl, Selecron, Match and Vertimec. The results showed that
Match and Vertimec were the most toxic ones with LC90 values of
0.46 and 0.18 ppm, respectively after 24 hrs exposure. Therefore, they
were evaluated against the hatchability of snail's eggs, snail's growth,
and snail's fecundity; moreover, against Schistosoma mansoni
miracidia and cercariae. It was noticed that the snails could not
survive more than 2 weeks of continuous exposure to LC25 of
Vertimec with a highly significant reduction in their reproductive rate
80.7% in comparison with control group. However, few snails
survived 4 weeks of continuous exposure to LC25 of Match , their Lx
was 0.3 (30% survival rate) under these conditions, the reduction in
snail's reproduction rate was significantly high, being 53.8%.The
hatchability of snail's eggs (of 1, 3 and 7 days old) was slightly
suppressed by their exposure for 24 hrs to LC of Match or90 Vertimec ,
being 88.5% and 63.5%, respectively for eggs of 7 days old.
Moreover, increasing the concentration of these pesticides to 2 LC90
caused more suppressive effect on egg's hatchability to be 55.2% and
52.5% respectively, compared to 95.4% for control eggs.
There are no obvious changes in growths of exposed snails
throughout the exposure period (4 weeks). The survival rates of snails
exposed to 0.06 ppm of Vertimec for 24 hrs / week or 72hrs / week
could not survive more than three or one week respectively .
EVALUATION OF THE PLANT PESTICIDES VERTIMEC884
Vertimec was more effective against Schistosoma mansoni
(miracidia and cercariae) than Match, as these larval stages were
killed within one hour of exposure to LC25, LC50 or LC90 of these
pesticides