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- Title
La Fecondité de Baetis rhodani Pictet.
- Authors
Benech, V.
- Abstract
The fecundity of Baetis rhodani throughout a seasonal cycle is measured and the production by the spring generation is calculated from the figures obtained. Females of B. rhodani cannot be identified with certainty and therefore they were not caught wild but bred from mature nymphs in the laboratory. Various measurements were made (Fig. 1). Eggs range in number from 4500 in February and March to 200 per female in July. This decrease coincides with a diminution in size and a rise in temperature (Fig. 2). In summer there are about 200 fewer ovarioles per female and production per ovariole is about half what it is early in the year. Smaller females produce not only fewer eggs but also smaller eggs (Fig. 3). The relation between certain dimensions and number of eggs is found to remain close (Table 4), and it is therefore possible to predict how many eggs will be laid per square metre from a quantitative sample of full-grown nymphs that have been measured (Table 6). Continuous sampling and measuring therefore make it possible to calculate the number of eggs at the beginning of a given generation and the number of adults that ultimately emerge. Calculation of production is based on the assumption that mortality follows the Allen curve (Fig. 10). It is shown that the very small nymphs, ignored in many other calculations of production could contribute up to 18% to the total production of the spring generation.
- Subjects
BAETIS; FERTILITY; BAETIDAE; MAYFLIES; FLIES; NYMPHS (Insects); INSECT larvae
- Publication
Freshwater Biology, 1972, Vol 2, Issue 4, p337
- ISSN
0046-5070
- Publication type
Article
- DOI
10.1111/j.1365-2427.1972.tb00375.x