Confined-leaf tests in a greenhouse showed Lagenaria siceraria (Molina) Standley plant introduction (PI) 442369 was as susceptible to sweetpotato whitefly, Bemisia tabaci Gennadius, oviposition as Cucumis melo L., Cucurbita ecuadorensis Cutler and Whitaker, and Cucurbita lundelliana Bailey, whereas L. siceraria accessions PI 419090, PI 419215, PI 432341, and PI 432342 were resistant. Resistance rankings of L. siceraria accessions based on adult counts in greenhouse and field tests were similar. Adult entrapment among trichomes was highest on adaxial leaf surfaces of L. siceraria PI 419090. Abaxial leaf trichome density was 48.7/mm on sweetpotato whitefly-resistant L. siceraria PI 432342, 42.1/mm2 on Cucurbita lundelliana PI 540895, and ranged from 51.0 to 85.5/mm2 on Cucurbita ecuadorensis PI 540896. Leaf trichome densities of selected plants of four L. siceraria accessions ranged from 33.0 to 52/mm2 on the abaxial and from 6.3 to 20.8/mm2 on the adaxial surface. Scanning electron micrographs of the abaxial leaf surface, the preferred surface for oviposition, suggest that trichome configuration (density and arrangement of different lengths) could be a factor in reduction of whitefly oviposition on L. siceraria.
Squash leaf curl (SLC) is a virus disease of squash transmitted by the sweetpotato whitefly [Bernisia tabaci (Germ.)]. 'Cucurbita maxima Duch. ex Lam., C. mixta Pang, and C. pepo L. cultivars and the wild taxon. C. texana Gray exhibited severe symptoms in response to SLC in greenhouse and field tests. Symptoms on C. moschata (Duch.) Duch. ex Poir. cultivars were much more severe in greenhouse tests than in field tests. Three wild species, C. ecuadorensis Cutler and Whitaker, C. lundelliana Bailey, and C. martinezii Bailey, were virtually immune in greenhouse tests, but were infected in field tests. Cucurbita foetidissima HBK expressed moderate symptoms in a field test. Benincasa hispida (Thunb.) Cogn., C. ficifolia Bouche, Lagenaria siceraria (Mol.) Standl., Luffa acutangula (L.) Roxb., Luffs aegyptiaca Mill., and Luffs graveolens Roxb. were resistant to SLC in greenhouse and field tests.
Cucurbita argyrosperma, formerly known as C. mixta, is a squash species native to Mexico and Central America. Cultivars of the species which have been grown in the United States include many of the cushaws and the `Silverseed Gourd. A recent biosystematic analysis-which included studies of experimental and natural hybridization, isozymatic and morphological variation, ethnobotany, and ecological and geographical distribution-has shown that the closest relative of C. argyrosperma is C. moschata. The data reveal intriguing implications for evolution of the genus as a whole, since the previous hypothesis that C. lundelliana is the progenitor of C. moschata is refuted. A wild ancestor, three cultivated varieties and a feral derivative are recognized within C. argyrosperma. Two of the three cultivated botanical varieties-vars. argyrosperma and stenosperma -have been selected in many regions almost exclusively for seed production. The relatively large seeds are marketed either with or without hulls. The other botanical variety, var. callicarpa, has been selected for both fruit and seed production. Northern cultivars of var. callicarpa arc notable for their adaptation to marginal environments, including hot climates and poor soil conditions.
; Metwally et al., 1996 ; Padley, 2008 ). Cucurbita lundelliana is native to the Yucatan peninsula and can be hybridized with C. moschata , C. maxima , C. ficifolia , C. pepo , and C. argyrosperma ( Ferriol and Picó, 2008 ; Sitterly, 1972
, resistance to the crown rot syndrome of P. capsici was identified in the wild species, C. lundelliana , and C. okeechobeenesis subsp. okeechobeenesis . This resistance, derived from the two wild Cucurbita species, was introgressed through a series of
Squash ( Cucurbita spp.) is an economically important crop of Cucurbitaceae family valued at $230 million annually in the United States ( U.S. Department of Agriculture–National Agricultural Statistics Service, 2017 ). Among the five cultivated
cultivar Danmatmaetdol ( C. maxima ) ( Lee et al., 2001 ). Resistance to P. capsici from the wild species Cucurbita lundelliana was introgressed into 19 winter squash breeding lines ( Kabelka et al., 2007 ). An inheritance study indicated that
al., 2021 ), and no sources of resistance to CYSDV or CuLCrV in summer squash have been identified to date. The germplasm diversity within Cucurbita provides an opportunity for discovery and transfer of novel disease resistance alleles into elite
with mixed success. Efforts are underway to identify sources of resistance in Cucurbita pepo ( Padley et al., 2008 ) and to introgress resistance from the wild Cucurbita species, C. lundelliana , into C. mocshata ( Padley et al., 2009 ). To our