Palatability of mangrove leaves to invasive apple snails: the relation between feeding electivity and multiple plant characteristics

Abstract

Mangrove forests worldwide have been subjected to biological invasion. Invasive apple snails ( Pomacea canaliculata ) have established populations in some mangrove forests. The feeding behavior of P. canaliculata in mangroves has been unclear until now. The feeding electivity of P. canaliculata to mangrove leaves, including leaves from Acanthus ilicifolius, Acrostichum aureum, Kandelia candel, Aegiceras corniculatum, and Sonneratia apetala , was studied through a selective test, a non-selective test, and a T-tube test. The growth indicators, the feeding ratio, the feeding rate, the feeding amount, the electivity indicator, and the electivity frequency were determined. The weight increase ratios of P. canaliculata that consumed leaves of A. ilicifolius and A. aureum were higher than those that consumed leaves of K. candel, S. apetala , and A. corniculatum . The electivity indicator showed that P. canaliculata preferred A. ilicifolius leaves and fed little on A. corniculatum leaves. Acrostichum aureum leaves were the second most preferred food for the apple snails. The feeding electivity of P. canaliculata to leaves from five species of mangrove trees was significantly differentiated by cluster analysis, redundancy analysis, and principal component analysis. Eight feeding indicators of the apple snails were positively correlated with the leaf characteristics of nitrogen content, protein content, leaf area, moisture content, and aspect ratio and negatively correlated with the lignin, phenolic, and tannin contents. Pomacea canaliculata could discriminate mangrove leaves through physical and chemical characteristics and shift feeding electivity among mangrove leaves under intraspecific competition. Mangrove forests composed mainly of A. ilicifolius and A. aureum might be at risk of invasion by P. canaliculata . A detailed survey on benthic animals is necessary to monitor and prevent P. canaliculata invasion in mangroves.