Embryonic development of the fowl tick A. persicus was investigated during
cleavage stage, blastoderm formation, gastrulation and organogenesis. Cleavage
started 1 h post-oviposition (POP) and is indicated by presence of vitellophages of
different sizes. Blastoderm is formed at 48 h POP. Secondary vitellophages are
observed by 24 h POP. By 72 h POP, the germ band is formed. At 96 h POP, while
the embryonic envelops are formed, gastrulation of the germ band takes place.
Segmentation and differentiation of germ band, as well as, blastokinesis occur at 120
h POP. The stomodaeal and proctodaeal invagination started to differentiate at 120 h
POP. The anterior and posterior midgut rudiments can be observed at 144 h POP. By
168 h POP, the nervous system, as well as, rectal sac and malpighian tubules are
formed.
Histological study revealed that application of JHA (Admiral) to newly laid
eggs of A. persicus blocked the embryonic development of affected eggs at cleavage
stage and before blastoderm and pole cells formation. In 24 h-old treated eggs, few
cleavage nuclei appeared with absence of secondary vitellophages and pole cells. In
48 h-old treated eggs, the blastoderm was rudimentary and irregularly arranged. In 72
h-old treated eggs, disintegration of the rudimentary blastoderm and cracking of the
cytoplasm could be seen. Starting from 96-old eggs until hatching at 168 h, complete
destruction of the eggs was clear.