Alginate beads in pest control


Alginate beads as vehicles for the application of entomopathogenic nematodes and bacteria against economically important soil-dwelling pests

Entomopathogenic nematodes (EPN) and bacteria (EPB) have great potential as biological control agents against soil-dwelling insect pests. During the first phase (end March 2016) of the National Research Programme Sustainable Use of Soil as a Resource (NRP68), EPN populations were found to be extremely low in Swiss agricultural soils, independent of agricultural practices, as compared to soils from natural habitats, where EPN densities were much higher. The situation for EPB is expected to be similar. It is therefore recommended that, in crop fields with soil insect problems, an augmentative approach be used to increase the numbers of these beneficial organisms. The greatest obstacles to an effective application of these biological control agents are the high cost of current application methods and a limited shelf-life. The project of the second phase of the NRP68 granted to Ted Turlings, with Monika Maurhofer (ETHZ) and Christoph Keel (UniL) as co-applicants, aims at overcoming these obstacles by utilizing the knowledge obtained during the first phase in combination with a technique that was developed in a parallel SNF-sponsored economic stimulus project. It concerns a novel application method that is based on encapsulation of EPN and EPB in alginate beads, which are to be improved by supplementing them with useful plant-derived substances. Certain substances will put the EPN in a state of quiescence, which keeps them in good shape while they are embedded in the beads. Others will be used to attract and encourage the pests to feed on the beads. Both of these effects have already been demonstrated to work under laboratory conditions for certain target pests.