Influência de furcraea foetida (l.) haw. sobre a sobrevivência, crescimento, reprodução e comportamento de subulina octona (brugüiére, 1789) (mollusca, subulinidae)

Abstract

Terrestrial molluscs constitute an important study group in parasitology, because some species can act as hosts for helminth parasites of domestic animals and humans. Moreover, they are agricultural plagues and can cause economic damages. Alternatively, one can use molluscicide substances to interrupt the life cycles of parasitic helminths and reduce damage to agriculture. The use of molluscicide substances of vegetal origin can represent a safe and effective method for controlling molluscs. The aim of this study was to evaluate the influence of the sap of Furcraea foetida (L.) Haw. on the biological and behavioral aspects of Subulina octona (Bruguière, 1789). To verify its effects on survival, calves eclodibility, growing and reproduction, 360 eggs, 420 fifteen days old (young) individuals and 420 adults were used. The sap was obtained by crushing the leaves and diluting with distilling water. Application was done using hand sprayers, according to two methodologies: experiments with or without substrate. The used concentrations were 0,1%, 0,25%, 0,5%, 1%, 3% and 5%. In the white control group it was sprayed distilled water, and 1% niclosamide was sprayed in the positive control. Results showed that 1%, 3% and 5% F. foetida sap acted as eggcides, on both types of experiment conducted here. For the young individuals, the substance proved to be 100% lethal in all concentrations, when tested without substrate. When using substrate, only 3% and 5% concentrations caused significant mortality. No expressive differences were observed on growth rates. When using adult individuals in substrate experiments, all concentrations proved to be lethal. However, when using no substrate, only the 3% and 5% concentrations were significative. The sap did not alter the egg production of surviving adults. To evaluate the influence of the F. foetida on behavior, 90 animals and 0,5% (T1) and 5% (T2) concentrations were used; white control group received distilled water. For the behavioral observations, the focal group and scan (15-minute intervals) sampling methods were used, in 24 hour session. T2 group showed alteration in its behavioral repertoire, while only aggregative behavior and vertical movement frequencies showed significative alterations, when compared with the control group. This probably occurred due to the repellent function of the sap in the 0,5% concentration. The results obtained in the realization of experiments demonstrated that F. foetida can be promising in terrestrial molluscs control, because, in laboratory conditions, actuated as eggcide and molluscicide for S. octona.