INFLUENCE OF FOOD FREQUENCY IN THE ONTOGENY

OF Loxosceles laeta (ARANEAE, SICARIIDAE)

Gonçalves-de-Andrade, R.M., Kupper, A.N., Marinho, P.A., Tambourgi, D.V.

Laboratório de Imunoquímica, Instituto Butantan, São Paulo, SP, Brazil

Loxosceles laeta is the specie of brown spider that produces the most toxic venom. Cases of human death after envenomation by spiders, in Santa Catarina state, Brazil are associated with this specie. Studies about the mechanisms of the venom action are being developed to create the basis of an efficient treatment since serum therapy does not work efficiently. To perform these studies it is necessary breeding and kept these spiders in laboratory and only adult spiders are used to extract the venom.

Loxosceles laeta spiders become adult generally after one year. In order to study factors affecting the time for spider development, we investigated the influence of feed frequency in the spider ontogeny. Ninety-six spiderlings hatched of the same egg sac were fed with larvae of Tenebrio mollitorand distributed in three groups: 32 animals received food every day, 32, three times per week and 32, one time per week. The inter-moults time was registered in weeks for each instar and group, and data were submitted to a two-tail t-Test (P<0.05). The results showed statistically significant differences between the inter-moults periods of the spider groups which were fed every day and three times per week, as compared with the spiders group that have been fed one time per week. The moult time was always bigger for spiders that were fed one time per week. These data indicates that the best food frequency for a faster spider development, without affecting their length and avoiding time work consume, is three times per week.

Supported by The Wellcome Trust.

CORRESPONDENCE TO:

Rute Maria Gonçalves de Andrade, Rua Marco Aurélio, 371, São Paulo, SP, CEP: 05048-000, Brasil, Email: rutemga@netscape.net