It’s a trap How sticky fluids help carnivorous plants catch insect prey

January 3 – Febuary 28, 2021

Meeting Abstract

S8-9  Wed Jan 6 16:30 – 17:00  It’s a trap! How sticky fluids help carnivorous plants catch insect prey Kang, V*; Federle, W; Department of Zoology, University of Cambridge, UK; Department of Zoology, University of Cambridge, UK

Many plants secrete sticky fluids that fulfil important biological functions. Climbing plants, such as the English ivy, use adhesive secretions to cling to vertical surfaces, while orchid flowers courier their pollen to other flowers by gluing their pollinaria to bees. One of the most striking and specialised uses of sticky secretions can be found in carnivorous plants. These plants live in nutrient-poor soils and supplement their nutrition by catching and digesting insects. Many carnivorous plants, including sundew (Drosera) and several pitcher plant species (Nepenthes), secrete sticky fluids to aid in prey capture and retention. Despite the important biological function of these adhesive secretions, we have a limited understanding of the chemical and physical properties. In addition, we lack insight into the forces experienced by insects trying to escape from the sticky secretion. In this study, we use the sticky pitcher fluid from N. rafflesiana to investigate the underlying mechanisms of their effective prey capture. We show that a greater proportion of ants sink in pitcher fluid than in water, likely based on the combined effect of reduced surface tension and delayed dewetting of the fluid from insect cuticle. We also demonstrate that retracting insects from sticky pitcher fluid required significantly more work than retracting them from water, which can further impede their escape. Detailed chemical characterisation of the fluid revealed that it is made up of a large acidic polysaccharide. This polysaccharide is also the principal component of the sticky capture fluid of sundew plants, a distant relative to Nepenthes pitcher plants, raising interesting questions about the evolutionary origins of this shared trait.

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