How to induce ant–plant interactions: Seed baiting to enhance its dispersal as a tool for restoration

Abstract

In degraded drylands, direct sowing is one of the most widespread revegetation practices, but its efficiency is low and usually seed enhancement techniques are needed to increase its success. We evaluated how to induce seed dispersal by ants (myrmecochory), as this interaction could improve the chances of seed germination and seedling establishment, via seed transport to ants' nests where seeds are protected and the soils enriched. Our objective was to develop seeds with the addition of baits attractive to ants without affecting seed germination. First, we tested the attractiveness of baits of different sizes and ingredients by performing cafeteria experiments in nests of the omnivorous ant Dorymyrmex tener, the most abundant and effective seed disperser ant in the Patagonian steppe. Then, we attached the most preferred baits (small baits containing pate, sugar and clay) to seeds of two native plants species (Acaena splendens and Oenothera odorata) with relevant characteristics for restoration purposes and tested their attractiveness to ants. We used different strategies to attach the bait to the seeds (e.g. encrusted, agglomerate and seeds on the surface) looking for the most attractive and simplest one. We found that only baited seeds were removed and the interaction was induced regardless of the way the bait was attached. Also, germination of seeds with bait was similar to that of seeds without bait in O. odorata, but reduced in A. splendens. We showed that it is possible to encourage ants to transport previously non-attractive seeds through the design of baits, potentially improving direct sowing efficiency.