Selective foraging of Aratus pisonii (Arthropoda: Sesarmidae) on mangrove leaves in laboratory experiments

- Consumption rates of A. pisonii were higher for A. germinans green leaves and for L. racemosa in senescent leaves, and R. mangle in both conditions.
- Females of A. pisonii preferred L. racemosa as food, while the male preferred R. mangle.
- Daily feeding rates of A. pissoni was 0.01 gpsh/gphc for L. racemosa and R. mangle.
- Preference consumption is confirmed for L. racemosa and R. mangle senescent leaves.

The feeding rate and feeding preference of the crab Aratus pisonii regarding three mangrove species, red (Rhizophora mangle), white (Laguncularia racemosa) and black (Avicennia germinans), under two leaf conditions (fresh and senescent), were recorded in two laboratory experiments. Feeding rates were determined considering the dry weight of the food before feeding minus the dry weight of the remaining food after feeding, standardised on the fresh weight of each crab. A factor for the conversion of fresh weight to dry weight of each mangrove species and leaf condition was applied in order to obtain the dry weight of the food. Preferences were determined based on the consumption of one of the mangrove species when offered the three species simultaneously, under two leaf conditions. Results showed that the feeding rates of A. pisonii were high in the case of the fresh leaves of A. germinans (0.03 ± 0.06 gpsh/gphi) and R. mangle (0.02 ± 0.03 gpsh/gphi) and of the senescent leaves of L. racemosa (0.05 ± 0.04 gpsh/gphi), indicating that the crabs chose both fresh and senescent leaves of the species L. racemosa. Regarding sex, the females fed more than the males in all the experiments. Feeding rates were: with fresh leaves, A. germinans and R. mangle (0.04 ± 0.06 and 0.03 ± 0.03 gpsh/gphi, respectively) and with senescent leaves, L. racemosa and R. mangle (0.06 ± 0.05 and 0.04 ± 0.04 gpsh/gphi, respectively). Feeding preferences were: with fresh leaves, L. racemosa (0.06 ± 0.06 gpsh/gphi) and with senescent leaves, L. racemosa and R. mangle (0.05 ± 0.05 and 0.03 ± 0.03 gpsh/gphi, respectively). Under laboratory conditions, the crabs chose both fresh and senescent leaves of L. racemosa as food, and recorded greater feeding rates with fresh leaves of A. germinans and R. mangle when they had no other feeding option.