Sex determination in the snake mite Ophionyssus natricis (Gervais) (Dermanyssidae)
1963 - Volume: 5 Issue: 2 pages: 180-184
evolution and genetics
1. Chromosome determinations were made on early cleavage divisions. The squash technique with aceto-orcein and aceto-carmine stain was utilized and it was established that the chromosome number is n = 9 and 2n = 18 in Ophionyssus natricis. 2. All but four of 179 eggs obtained from virgins were haploid. The four diploid eggs were laid by three females and were preceded and followed by haploid eggs. Chromosome counts were made on 226 eggs from 20 mated females and 103 were haploid and 123 were diploid. This approximates a 1: 1 ratio (1o< P<.20). 3. Our cytological data and rearing data (Camin, 1953) indicate that sex is determined in Ophionyssus natricis by the haplo-diploid mechanism.
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