Submitted to: Silverleaf Whitefly: 1997 Supplement to the Five Year National Research and
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2001
Publication Date: January 25, 2002
Citation: SIMMONS, A.M., LEVI, A. WATERMELON GERMPLASM FOR RESISTANCE TO BEMISIA. SILVERLEAF WHITEFLY: 1997 SUPPLEMENT TO THE FIVE YEAR NATIONAL RESEARCH AND. 2002. Abstract p.192. Technical Abstract: Like many vegetable crops, the cultivated watermelon, Citrullus lanatus var. lanatus, is plagued by Bemisia. Citrullus contains four known diploid species. However, there have not been any reports on screening Citrullus germplasm for resistance to whiteflies. This study was conducted to identify potential germplasm sources that could be used in the improvement of watermelon for whitefly resistance. The study was conducted on 42 Citrullus genotypes. Seven watermelon cultivars, a triploid line, and 16 U.S. Plant Introduction accessions (PIs) of C. lanatus var. lanatus; 10 PIs of C. lanatus var. citroides; and 8 PIs of C. colocynthis were evaluated for resistance to B-biotype B. tabaci. Bioassays were conducted on non- preference, and on ovipositional and survival performance of the whiteflies. Adults and eggs were observed on all genotypes studied, but the abundance of the insects and the survival of the nymphs varied greatly among genotypes. Most of the watermelon cultivars and C. lanatus PIs tested were highly susceptible to whitefly infestation, while the C. colocynthis PIs exhibited whitefly resistance. Trichome density on the resistant genotypes (C. colocynthis PIs) were elevated compared with the susceptible genotypes. However, we believe that the observed resistance was primarily related to effects of plant nutrition on the whiteflies. This study identified useful sources of germplasm (such as PI 386015, PI 386018, and PI 386024, all of C. colocynthis) which can be used for the improvement of watermelon for resistance to whiteflies. Currently, F2 populations (Charleston Gray x PI 386024) are being constructed and will be used to determine the mode of inheritance of whitefly resistance in watermelon.