Multirésistance CpGV / Thèse Gingueneau

Duration: 2021-2026

Abstract:

The development of resistance in pests is a classic example of evolution in action and a major problem in agronomy. In the case of resistance to living microorganisms such as viruses used as biological control agents, understanding the adaptive mechanisms involved can help manipulate the "arms race" between the virus and its host and solve the agronomic problem posed by the resistance. Codling moth (Cydia pomonella) is the major pest of apple and pear orchards worldwide. A biological control method is used to control this lepidopteran: the granulovirus: Cydia pomonella GranuloVirus (CpGV). Each granulovirus being specific to one or a few species of insects and harmless to all other living beings, the use of these viruses is in line with the objectives of reducing the use of chemical insecticides and preserving the environment. The CpGV is one of the few effective methods available to Organic Agriculture in apple and pear orchards. After more than 20 years of large-scale use of a single viral isolate (CpGV-M), virus-resistant populations of C. pomonella have been detected, raising the question of the sustainability of this biological control method. Three previous theses have developed a new variant, CpGV-R5 capable of bypassing C. pomonella resistance to the virus in the laboratory and in the field, and studied genotypic mixtures to sustain the efficacy of this biological control (Berling, 2009; Graillot, 2015; Hinsberger, 2020). It is the component of the product Carpovirusine Evo2, commercialized by UPL A third variant also effective on resistant insects was commercialized at the same time under the name CpGV-V15 by the company Andermatt Biocontrol. In 2020, our team detected several populations with decreased susceptibility to the three isolates currently marketed in France (Siegwart et al. 2020).

Objectives:

Codling moth (Cydia pomonella), the major pest of apple and pear orchards, has been successfully controlled for more than 20 years using the Cydia pomonella GranuloVirus (CpGV), one of the few biological methods available for Organic Agriculture. However, the large-scale use of a single isolate (CpGV-M) has led to the emergence of resistant populations, threatening the sustainability of this control method. New variants (CpGV-R5 and CpGV-V15) were developed and commercialized, but since 2020 several populations with reduced susceptibility to all three available isolates have been reported.
Within a collaboration between INRAE and UPL, this project aims to: (i) unravel the genetic basis of newly evolved resistances in codling moth, (ii) develop molecular tools for high-throughput detection of resistance, and (iii) design novel viral isolates that are both durable and efficient. These objectives will combine approaches in experimental evolution (host–virus coevolution), adaptive genomics, and virology.

Virus granuose of codling moth (C. pomonella)

Credit: Isabelle Bornard (INRAE)

Partners:

Ecole nationale des mines d'Alès, Laboratoire Goëmar (NPP) de UPL.

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