Host plant resistance against aphids in Capsicum

Aphids are a major problem in pepper cultivation. Not only do they cause direct damage by feeding, which results in wilting, defoliation and fruit loss, they also cause damage indirectly by the viruses they transmit. Chemical control is widely used. However, due to environmental concerns, there are more and more restrictions on the use of these compounds (especially Neonicotinoids) and alternatives are needed. One such alternative is host plant resistance.

Several aphids can cause problems in pepper cultivation. Off these the green peach aphid (Myzus persicae) and the foxglove aphid (Aulacorthum solani) are the most important in paprika cultivation in the Netherlands and are the focus of this proposal.

Over the past years WUR has identified a good source of resistance against the green peach aphid in Capsicum baccatum and characterized its mode of action. One major resistance QTL, containing receptor like kinase genes (RLKs), was identified in a C. baccatum cross. However, very recently we found out that introduction of this QTL in Capsicum annuum, did not result in a resistant phenotype. Most likely this means that an additional factor from C. baccatum is needed to get the resistance to work in C. annuum. In this project we want to identify this factor(s).

In addition we want to identity resistance against the foxglove aphid and make it available for use in breeding. We already have some indications that variation for resistance against this aphid is present in Capsicum species crossable with C. annuum.

So, this project aims to make our pepper growers less dependent on chemical insecticides by creating the scientific basis for the development of aphid resistant varieties. The project is expected to result in novel resistances against both aphid species that will function in C. annuum. From a scientific point of view the project is highly interesting as it is expected to elucidate which factor, in combination with the already identified RLKs is needed to get the M. persicae resistance to work in C. annuum. The project will also result in the identification of resistance QTLs against A. solani, the other major insect pest in pepper, and insight in its mode of action. Both may provide leads for insect resistance breeding in other crop species as well.