Citrullus crop wild relatives with resistance to whitefly transmitted viruses

Sweetpotato whiteflies (Bemisia tabaci) and the viruses they transmit can cause significant yield losses in cucurbit crops in the Southeastern U.S. Application of insecticides is the primary method of control for whiteflies in cucurbit crops, however, it is  ineffective at controlling whitefly transmitted viruses (WTVs).  In an effort to identify host resistance in watermelon (Citrullus lanatus), 21 Citrullus genotypes, representing 4 different species and crop wild relatives (CWRs), were evaluated in Tifton, GA in fall. Three C. mucosospermus (PI 560023, PI 595203, and PI 494528) and one C. ecirrhosus (Grif 16444) genotypes had reduced visual disease? symptoms (AUDPC) and Cucurbit leaf crumple virus (CuLCrV) load compared to the Charleston Grey and Estrella cultivar controls. Grif 16444 had lower adult whiteflies per leaf area than Charleston Grey, confirming previously reported antixenosis of C. ecirrhosus. Cucurbit yellow stunting disorder virus (CYSDV) and Cucurbit chlorotic yellows virus (CCYV) viral loads were not significantly lower in any of the CWRs than the cultivar controls. The resistance identified in PI 560023, PI 595203, PI 494528 and Grif 16444 can serve as sources of resistance in watermelon breeding programs.