Dietary preferences of Hawaiian tree snails to inform culture for conservation

One strategy to safeguard endangered species against extinction is raising subpopulations in ex situ facilities. Feeding animals ex situ is difficult when their diet is cryptic. We present a combined molecular and behavioral approach to assess the diet of Achatinella, a critically endangered genus of tree snail, to determine how diet of captive snails differs from wild snails. Cultured snails are currently fed biofilms growing on leaf surfaces, as well as a Cladosporium fungus isolated from this same habitat Amplicon sequencing of DNA extracted from feces of wild and cultured snails confirms that this Cladosporium is abundant in the wild (-15% of sequences), but it dominates the ex situ snails' diet (-38%) and the diet of captive snails is still significantly less diverse than wild snails. To test the hypothesis that snails have diet preferences, we conducted feeding trials. These used a surrogate snail species, Auriculella diaphana, which is a confamilial Oahu endemic, though non-federally listed. Contrary to our expectations we found that snails do have feeding preferences. Furthermore, our feeding preference trials show that over all other feeding options snails most preferred the no-microbe control, which consisted only of potato dextrose agar (PDA). PDA is rich in simple carbohydrates, in contrast to the oligotrophic environment of wild tree-snails. These results suggest further research should focus on calorie budgets of snails, devising new approaches to supplementing their ex situ diet and determining whether a wild diet is an optimum diet (C) 2016 Published by Elsevier Ltd.