Biomedical subjects

A M Spickett

Publications and source records attributed to A M Spickett.

39 records · Page 3Linked to original sources

PubMed1978

Genetic incompatibility between Boophilus decoloratus (Koch, 1844) and Boophilus microplus (Canestrini, 1888) and hybrid sterility of Australian and South African Boophilus microplus (Acarina: Ixodidae).

Virgin females of both Boophilus decoloratus and Boophilus microplus, when mated with males of the other species, subsequently produced sterile eggs. Counts of spermiophore capsules in female seminal receptacles showed that the males of both species will mate with the females of both species and that B. microplus males show a slightly greater, but statistically insignificant, mating capacity than B. decoloratus males. South African B. microplus females, when mated with an Australian strain of B. microplus males, produced a 62% yield of viable hybrid progeny while the reciprocal cross produced only a 1,82% hatch of non-viable larvae. The hybrids were sterile when interbred and no hatch resulted when the Fl males were backcrossed with parent females. The reciprocal backcross of hybrid Fl females to parent males resulted in a low percentage hatch of non-viable larvae.

Animals↗

PubMed1978

Effects of 60Co irradiation on Amblyomma hebraeum Koch, 1844 (Acarina: Ixodidae).

The effects of 60Co irradiation on Amblyomma hebraeum Koch, 1844 were studied by mating normal females to males irradiated to attain dosages of 0, 2, 4, 6 and 8 kilorad. The males of all 5 groups were observed mating 7 days after being placed on the host. The higher the irradiation dosage received by the males, progressively longer were the feeding periods of the females mated with them and fewer completed their engorgement. Furthermore, the mass of the females when engorged was lower, fewer laid eggs and the number of eggs they laid decreased progressively. None of the egg batches produced by females mated with irradiated males hatched. No chromosomal abnormalities or discrepancies in spermiophore formation were found in the 2 and 4 kilorad group males, while no micro- or macroscopical growth of the 6 and 8 kilorad group male testes took place, although accessory gland development appeared normal. A. hebraeum males have a chromosome complement of 10 bivalents and a univalent sex chromosome.

Animals↗

PubMed1976

Gonad development and gametogenesis in Boophilus decoloratus (Koch, 1844) (Acarina Metastriata Ixodidae).

Phases in the growth of the reproductive organs and gametogenesis were followed in both males and females of Boophilus decoloratus (Koch, 1844). Special attention was given to the timing of meiosis, the production of mature spermiophores, mating and spermiophore relocation in the female. The main growth phase of the male testes takes place during the nymphal stage while that of the accessory gland complex takes place during the 4 days after moulting and before mating. The main growth phase of female ovaries and oviducts takes place during the post-mating period on the host and the previposition period. Meiosis in males takes place only after the attachment of the newly-moulted ticks; spematogenesis and spermiogenesis occur within a period of 4 days, after which pairing and spermatophore transfer take place. Meiosis was not observed in female ticks and it is concluded that this reduction division takes place only after spermiophore penetration of the oocytes and egg shell formation. Female ticks may be impregnated more than once, a maximum of 5 matings being deduced from counts of spermiophore capsules in the female seminal receptacle. Each spermatophore produced by male ticks yields either 1 but more commonly 2 spermiophore capsules. The reproduction of B. decoloratus is briefly discussed and compared with other Ixodoidea.

Animals↗