Biologia comportamental comparada entre moluscos terrestres nativos e exóticos

Abstract

Objetivou-se com este estudo verificar o horário de atividade, a frequência dos atos compor­tamentais através do etograma básico e a influência da temperatura e da umidade relativa do ar sobre o comportamento de Achatina fulica Bowdich, 1822 e Megalobulimus oblongus (Müller, 1774). Ambas as espécies apresentaram atividade noturna. Os atos comportamentais mais frequentes foram “repousar”, “estar enterrado” e “alimentar” para as duas espécies. Megalobulimus oblongus foi menos ativo que a espécie exótica, porém apresentou frequência alimentar maior. O aumento da temperatura causou a redução da atividade de ambas as espécies, enquanto o aumento da umidade apenas influenciou a ati­vidade de A. fulica. Apesar de a espécie nativa ter se mostrado menos suscetível às mudanças na tem­peratura e umidade, e ter se alimentado mais que a exótica, as características biológicas e ecológicas de A. fulica, como seu grande potencial reprodutivo e a ausência de predadores naturais, fazem desta um competidor mais eficiente, capaz de colocar as populações de M. oblongus em risco de extinção.

Relative condition factor and predictive model for the presence of the invasive snail Achatina (Lissachatina) fulica in Sergipe, Northeast Brazil

“…In the metropolitan region of Aracaju, in Sergipe, Silva et al (2020) found that rainfall had a positive influence on the frequency of A. fulica, a pattern also observed in Nigeria by Onyshi et al (2018), who observed that the conditions of high humidity and rainfall were associated with an increase in the population of A. fulica. Despite this, the largest A. fulica specimens were collected during the dry season in the present study, reaching a mean of length of 5.36±1.11 cm and mass of 15.87±9.85 g. This may be accounted for by the fact that, even at high temperatures and under low rainfall, A. fulica, in particular the larger individuals, use specific behavioral strategies to cope with the relative humidity (Pilate et al 2017).…”

“…In the Brazilian state of Paraná, Fischer & Colley (2005) found that A. fulica specimens of different sizes (shell length) rested in different sites, with the larger snails tending to be more frequent on plants and other organic substrates. Pilate et al (2017) concluded that A. fulica adopts specific behavioral strategies to guarantee its survival, such as the retraction of the soft cephalopodal mass and the avoidance of unfavorable sites.…”

“…Achatina fulica uses the soil for behaviors such as resting, burrowing and estivation (Fischer 2009), which should be considered for the development of measures for the control and eradication of the species (Roda et al 2018). Climatic variables should also be considered, given that the frequencies of the different types of its defensive behavior are related directly to relative humidity and rainfall (Miranda et al 2015, Pilate et al 2017.…”

“…Fischer et al (2010) consider the ability of A. fulica to adapt to different types of habitats to be a major concern and emphasize the need to understand its ecological characteristics in order to develop the most effective strategies for the control of this invasive species. The research into the behavior of this snail will also be important for the development of more effective control strategies, as well as providing parameters for the evaluation of the risks posed by this invasive species for the native land snails of a given area (Pilate et al 2017).…”