Abstract
Although numbers were low in winter, males of Unionicola intermedia were found throughout the year. A mean of 2.5 (±0.26 SE) males per mussel was found with a range of 0 to 20. Females had a mean of 13.07 (±0.87 SE) per mussel and a range from 0 to 57, with the highest mean in August. The incidence of males was much lower than that of females. Nymphs and females were highly aggregated and males showed aggregation at a lower level of significance for nine months of the year. Although the primary sex ratio is unknown, the tertiary sex ratio is 86% female and on a monthly basis ranged from 68.9% to 96.7% female. It is speculated that reproduction is arrhenotokous. The sex ratio and the significant seasonal variations of the active stages may be influenced by the dispersal pattern of this species and by the biology of its host.
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Baker, R.A., Hick, P.E. & Hill, V. Seasonal changes in the population of the mite Unionicola intermedia (Hydrachnellae, Acari) from the freshwater mussel Anodonta anatina (Unionidae). Hydrobiologia 242, 63–68 (1992). https://doi.org/10.1007/BF00017644
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DOI: https://doi.org/10.1007/BF00017644