Harnessing host plant resistance: A promising approach to tackle whiteflies and viral diseases in squash

Squash (Cucurbita sp.) is an important cash crop for Georgia, contributing significantly to its economy. However, the sustainable production of squash is threatened by whiteflies (Bemisia tabaci (Hemiptera: Aleyrodidae)) and whitefly-transmitted viruses, such as cucurbit leaf crumple virus (CuLCrV), cucurbit yellow stunting disorder virus (CYSDV), cucurbit chlorotic yellows virus (CCYV), and squash vein yellowing virus (SqVYV). Insecticides and reflective mulches are commonly used to manage whitefly populations, but their efficacy is diminishing due to the emergence of resistance among whiteflies. Therefore, the development of squash varieties resistant to whiteflies and associated viruses is crucial for sustainable production. This study evaluated 16 experimental squash germplasm lines for resistance to mixed infections of CuLCrV, CYSDV, and CCYV. Cucurbita moschata, Bridgelines, and wild species C. Ecuadorensis and C. Okeechobeensis showed lower virus accumulation, indicating resistance. In contrast, C. Pepo lines were more susceptible to the viruses. These results suggest that resistance can be introgressed from resistant species into susceptible C. Pepo lines. This study provides valuable information for breeding programs aimed at developing squash cultivars resistant to at least one of these whitefly-transmitted viruses, thereby improving the sustainability of squash production in Georgia.