Breeding of insect tolerant varieties at SESVanderHave.

Various insect tolerances are becoming increasingly important for trait stacking in modern sugar beet varieties, as more and more chemical solutions are being banned, either as field or seed treatments. SESVanderHave has dedicated breeding efforts on insect tolerances and on the diseases vectored by insects such as SBR, aphid resistances, virus yellows, beet moth, curly top, and root maggots, amongst others.This presentation will focus on breeding efforts done for the virus yellow complex, as these viruses are spread by aphids. It is a complex of viruses including the Beet Yellows Virus (BYV), the beet mild yellowing virus (BMYV) and the beet Chlorosis Virus (BChV). In the 20^th century these viruses were considered as one of the worst threats to sugar beet cultivation in north-west Europe. After the restrictions on neonicotinoid-based insecticide and milder winters and springs because of climate change, these viruses made a dramatic come-back in 2020, resulting in yield losses of between 0-40% across Western Europe. SESVanderHave identified “Virus Yellows” as a top priority in its research and development program as early as 2010. Since then, we have increased our investment in disease phenotyping platforms, scientific expertise, molecular diagnostics tools and used our diverse germplasm collection to enable large-scale testing for a genetic solution to BYV, BMYV and BChV. These investments in resources and time have enabled us to exploit the genetic diversity to identify VY-tolerant germplasm to create the first generation of VY-tolerant varieties. In addition, relations to other insect tolerance breeding programs, such as root maggot tolerance, will be elaborated on.