Natural control of Achatina fulica (Mollusca, Gastropoda) by Ocypode quadrata (Crustacea, Decapoda) in anthropogenic littoral vegetation at Ilhéus, State of Bahia, Brazil

Abstract

The aim of this study was to evaluate the predation
of the introduced African snail Achatina fulica by the native crab Ocypode quadrata, both of them are common organisms
in the anthropogenic sea shore vegetation of the northern littoral at Ilhéus, State of Bahia, Brazil. A preliminary laboratory
test was carried out aiming to verify if the mollusk was caught alive by O. quadrata. After sampling the A. fulica
population in a human settlement on the littoral, 30 burrows of O. quadrata were individually marked, and all empty
shells of A. fulica were collected in a 50 cm radius around them, each 15 days, over a period of a little more than six months.
The empty shells were successively examined and measured. Ocypode quadrata shows a strong preference for individuals
of A. fulica with less than 4 cm (75% of captured mollusks), probably because the prey is more easily handled and
extracted from the shell. The preservation of O. quadrata habitat, even in partially anthropogenic places, is especially
important when focusing on the natural biological control of the invading mollusk A. fulica.
Additional key words: exotic species, littoral, Neotropical region, predation, sea shore vegetation