Biological Control

Ongoing Research Projects

BioPro Biological control of below-ground pests using combinations of insecticidal Pseudomonas bacteria, fungi and nematodes
(BLW research project with Giselher Grabenweger, Agroscope)

Biological control is an environmentally friendly way of protecting plants against pests and diseases. Under optimal conditions, soil-borne microbes are an effective method for controlling root pests. However, there are few products on the market because registration is expensive and the requirements for risk analysis are unclear. In addition, the effect can vary greatly between years and locations. To improve efficacy and consistency, different biocontrol organisms can be combined.

Previously, three promising biocontrol agents were evaluated and combined against the cabbage maggot Delia radicum. Insecticidal pseudomonads and their combination with insecticidal nematodes and fungi were particularly effective in greenhouse experiments and a field trial. For the development of a Pseudomonas product and a combined application, efficacy and consistency as well as interactions between the biocontrol organisms must be investigated and a risk analysis carried out.

We will conduct several field trials to test the efficacy and consistency of the consortium against the cabbage maggot. In pot experiments, we want to track if the three biocontrol agents co-infect the same insect. To build effective consortia, we will test if other species and strains of insecticidal pseudomonads, nematodes and fungi can also be combined without adverse effects. As risk assessment, we will mainly explore non-target effects (i.e. assays with non-target organisms like bumblebees) and monitor the persistence of the biocontrol agents in the field over time.

This project could lead to the development of a new biocontrol agent and a new biocontrol method based on combinations. Additionally, we will develop a risk assessment strategy, which can serve as guideline for companies applying for registration.

Collaborations: Wolfgang Vogt, agrobiota, Germany; Marco Rey, Gemüse Rey, Switzerland; Raquel Campos Herrera, ICVV, Spain; Jürg Enkerli, Agroscope, Switzerland; Jana Collatz, Agroscope, Switzerland.

Molecular determinants contributing to insect and plant associated lifestyles of beneficial pseudomonads
(Joint SNF project with Christoph Keel, University of Lausanne)

Root-associated fluorescent pseudomonads are of agricultural importance because they can improve the health and performance of crop plants due to their manifold plant-beneficial activities, including pathogen control. We discovered that a particular subgroup of these pseudomonads, Pseudomonas protegens and P. chlororaphis, exhibits activity against plant pathogens and pest insects. The bacteria colonize pest insects (in particular Lepidoptera) with ease and exert strong oral and systemic toxicity. In the insect host, production of a potent insect toxin (Fit) is specifically switched on and contributes to insecticidal activity of these bacteria, yet additional virulence factors remain to be unravelled. It is not known which genomic equipment enables the pseudomonads to colonize and kill insects following oral infection and how they switch their lifestyle from a plant to an insect environment. Our project aims at identifying additional/novel factors contributing to insect and plant interactions of P. protegens and P. chlororaphis using an integrated, whole genome-based approach which combines comparative genomics with comparative transcriptomics and targeted and high-density random mutational analyses. We hope to provide pioneering knowledge on the nature of insecticidal activity of plant-beneficial pseudomonads and on host-adapted expression of genes allowing these bacteria to switch from plant to insect hosts.