Sex ratios in field populations of Epidinocarsis lopezi, an exotic parasitoid of the cassava mealybug, in Africa
1. In cassava fields in Africa, population sex ratios of Epidinocarsis fopezi vaned from 0.44 (males to total parasitoids) at low host densities to highly male-biased ratios of 0.70 at high host densities. 2. This variability is caused by the difference in allocation of sons and daughters to hosts o...
| Autores principales: | , , , |
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| Formato: | Journal Article |
| Lenguaje: | Inglés |
| Publicado: |
1991
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| Materias: | |
| Acceso en línea: | https://hdl.handle.net/10568/101697 |
| _version_ | 1855532936267300864 |
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| author | Dijken, M.J. van Neuenschwander, Peter Alphen, J.J.M. van Hammond, W.N.O. |
| author_browse | Alphen, J.J.M. van Dijken, M.J. van Hammond, W.N.O. Neuenschwander, Peter |
| author_facet | Dijken, M.J. van Neuenschwander, Peter Alphen, J.J.M. van Hammond, W.N.O. |
| author_sort | Dijken, M.J. van |
| collection | Repository of Agricultural Research Outputs (CGSpace) |
| description | 1. In cassava fields in Africa, population sex ratios of Epidinocarsis fopezi vaned from 0.44 (males to total parasitoids) at low host densities to highly male-biased ratios of 0.70 at high host densities. 2. This variability is caused by the difference in allocation of sons and daughters to hosts of different sizes, through the following mechanisms: (a) small, i.e. second instar, hosts are mainly used for the production of male offspring, whereas in large, i.e. third instar, hosts a variable, female-biased sex ratio is produced; (b) E.fopezi does not selectively oviposit into large hosts but always accepts both small and large hosts for oviposition upon encountering; (c) in the field, this parasitoid is time-limited, and not egg-limited. On the basis of an optimal diet model, such general host acceptance is shown to be the best strategy. 3. Thus, sex ratio increases with host density for three reasons: the proportion of small hosts encountered in the field increases with increasing host density, small hosts are used for male production, and hosts are always accepted when encountered. |
| format | Journal Article |
| id | CGSpace101697 |
| institution | CGIAR Consortium |
| language | Inglés |
| publishDate | 1991 |
| publishDateRange | 1991 |
| publishDateSort | 1991 |
| record_format | dspace |
| spelling | CGSpace1016972024-01-17T12:58:34Z Sex ratios in field populations of Epidinocarsis lopezi, an exotic parasitoid of the cassava mealybug, in Africa Dijken, M.J. van Neuenschwander, Peter Alphen, J.J.M. van Hammond, W.N.O. cassava fields production 1. In cassava fields in Africa, population sex ratios of Epidinocarsis fopezi vaned from 0.44 (males to total parasitoids) at low host densities to highly male-biased ratios of 0.70 at high host densities. 2. This variability is caused by the difference in allocation of sons and daughters to hosts of different sizes, through the following mechanisms: (a) small, i.e. second instar, hosts are mainly used for the production of male offspring, whereas in large, i.e. third instar, hosts a variable, female-biased sex ratio is produced; (b) E.fopezi does not selectively oviposit into large hosts but always accepts both small and large hosts for oviposition upon encountering; (c) in the field, this parasitoid is time-limited, and not egg-limited. On the basis of an optimal diet model, such general host acceptance is shown to be the best strategy. 3. Thus, sex ratio increases with host density for three reasons: the proportion of small hosts encountered in the field increases with increasing host density, small hosts are used for male production, and hosts are always accepted when encountered. 1991 2019-06-25T17:08:59Z 2019-06-25T17:08:59Z Journal Article https://hdl.handle.net/10568/101697 en Limited Access Van Dijken, M.J., Neuenschwander, P., Van Alphen, J.J.M. & Hammond, W.N.O. (1991). Sex ratios in field populations of Epidinocarsis lopezi, an exotic parasitoid of the cassava mealybug, in Africa. Ecological Entomology, 16, 233-240. |
| spellingShingle | cassava fields production Dijken, M.J. van Neuenschwander, Peter Alphen, J.J.M. van Hammond, W.N.O. Sex ratios in field populations of Epidinocarsis lopezi, an exotic parasitoid of the cassava mealybug, in Africa |
| title | Sex ratios in field populations of Epidinocarsis lopezi, an exotic parasitoid of the cassava mealybug, in Africa |
| title_full | Sex ratios in field populations of Epidinocarsis lopezi, an exotic parasitoid of the cassava mealybug, in Africa |
| title_fullStr | Sex ratios in field populations of Epidinocarsis lopezi, an exotic parasitoid of the cassava mealybug, in Africa |
| title_full_unstemmed | Sex ratios in field populations of Epidinocarsis lopezi, an exotic parasitoid of the cassava mealybug, in Africa |
| title_short | Sex ratios in field populations of Epidinocarsis lopezi, an exotic parasitoid of the cassava mealybug, in Africa |
| title_sort | sex ratios in field populations of epidinocarsis lopezi an exotic parasitoid of the cassava mealybug in africa |
| topic | cassava fields production |
| url | https://hdl.handle.net/10568/101697 |
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