VARIABILITY OF SEX-RATIO, MATING PROBABILITY AND EGG-PRODUCTION IN ANINTESTINAL NEMATODE IN ITS FLUCTUATING HOST POPULATION

Citation
V. Haukisalmi et al., VARIABILITY OF SEX-RATIO, MATING PROBABILITY AND EGG-PRODUCTION IN ANINTESTINAL NEMATODE IN ITS FLUCTUATING HOST POPULATION, International journal for parasitology, 26(7), 1996, pp. 755-763
Citations number
20
Categorie Soggetti
Parasitiology
ISSN journal
00207519
Volume
26
Issue
7
Year of publication
1996
Pages
755 - 763
Database
ISI
SICI code
0020-7519(1996)26:7<755:VOSMPA>2.0.ZU;2-5
Abstract
Haukisalmi V., Henttonen H. & Vikman P. 1996. Variability of sex ratio , mating probability and egg production in an intestinal nematode in i ts fluctuating host population, International Journal for Parasitology 26: 755-764, In dioecious parasites, the chances of co-occurring with the opposite sex depend on the sex ratio, abundance and distribution pattern of parasites within the host population. Theory suggests that if the abundance and degree of aggregation are very low, mating probab ility may decrease so much that the parasite population is vulnerable to extinction, Our aim is to determine the factors affecting the matin g probability and egg production in Heligmosomum mixtum (Heligmosomida e), an intestinal nematode of the bank vole, Clethrionomys glareolus, at Pallasjarvi, Finnish Lapland. We also search for factors responsibl e for the persistence of H. mixtum in its fluctuating host population. The results showed that during high parasite abundance practically al l nematode females co-occurred with males, but during a phase of very low abundance only 15% of females had a chance to mate, Comparison of observed mating probabilities and those predicted by a theoretical mod el (May & Woolhouse, 1993) showed that deviation from the assumption o f complete aggregation between males and females results in underestim ation of the mating probability. Sex ratio and the degree of aggregati on showed a minor effect on mating probability, The sex ratio (proport ion of females) of H. mixtum, which was female-biased (0.58), showed a negative correlation with the mean intensity of infection in the mont hly samples (decreasing female-bias at high mean intensity), but no si gnificant relation to the intensity of infection (number of worms in a host individual). The long-term persistence of H. mixtum in its stron gly varying host population seems to be due to the high transmission e fficiency and long life-span of the parasite. Copyright (C) 1995 Austr alian Society for Parasitology.