Estadísticos vitales de Steatoda retorta González, 1987, y anílisis comparativo con los de Latrodectus mirabilis (Holmberg), Latrodectus antheratus (Badcock), Latrodectus corallinus Abalos, Latrodectus diaguita Carcavallo y Tidarren sisyphoides (Walckenaer) (Araneae, Theridiidae)∗

Contribución No. 185 del Centro de Estudios Parasitológicos y de Vectores (CEPAVE).

Abstract

This paper completes the study of the life cycle of Steatoda retorta, which was published before (González, 1987). The dates given in this paper were obtained from specimens reared in laboratory. Variations of mortality, survivorship and mean life expectation were studied. The survivorship curve indicates that the experimental population was affected by mortality since age 4 to 9 being this a critical period because the nymphs moult from I to II and from II to III instars. The curve shows another critical period when the population moults to adult stage. The mean life time of the cohort was 37.09 weeks. These results were compared with the data recorded for L. mirabilis, L. antheratus, L. corallinus, L. diaguita and Tidarren sisyphiodes. This analysis showed differences as: a) The survivorship curve of Steatoda retorta is more convex than the others because there is no differential mortality between males and females, b) The higher value of the mean life expectation in Steatoda retorta occurs when the first critical period finished (II, III instars). In the species of Latrodectus and Tidarren sisyphoides this occurs when the populations are at adult stage, c) The value of the mean life time of the cohort and the life cycle is higher in Steatoda retorta than in the other species.

Notes

Contribución No. 185 del Centro de Estudios Parasitológicos y de Vectores (CEPAVE).