The present study deals for the first time the effect of two plant extracts on the ultrastructure of the
spermatozoa of three species of gastropod snails. These snails were the land snail Eobania vermiculata and
two freshwater ones Lymnaea caillaudi and Biomphalaria alexandrina. They were collected from gardens
and fruit trees (E. vermiculata) and Manzala Lake (L. caillaudi and B. alexandrina), Dakahlia Governorate,
Egypt. The extracts used were of the plants Euphorbia milii and Ethulia coynzoides. The first was used for
L. caillaudi and B. alexandrina and the second was used for E. vermiculata.
The snails used for this purpose were those still alive after the exposure period to the plant extracts (28
dayes for E. vermiculata and 24 h for L. caillaudi and B. alexandrina). Examination of the longitudinal and
transverse thin sections revealed that the genital cells gonadal follicles and the head and the neck region of
the sperm were the most affected ones. This indicates that these snails become nearly sterile where the
gonads become unable to produce spermatozoa or the liberated sperms become immotile having damaged
mitochondrial derivatives and loose their viability. This effect on sperms can be considered as a new way
to control the injurious snails to agriculture and can bring their population down to a low level within a
reasonably short period of time.