Host plant resistance in melon to sweetpotato whitefly in California and Arizona

Abstract

Sweetpotato whitefly biotype B (MEAM1 cryptic species of Bemisia tabaci; SPWF) feeding severely impacts fall season melon (Cucumis melo L.) yield and quality in the lower deserts of California and Arizona. Melon accessions PI 313970 and TGR 1551 (PI 482420) have been reported to exhibit host plant resistance (HPR) to SPWF. Potentially higher and lower levels of HPR to SPWF were observed in ad hoc comparisons of numbers of adults per leaf on six melon accessions, PI 313970, TGR 1551, 'Impac', and 'Top Mark' in a naturally infested field test at Holtville, CA in fall 2012. Replicated field tests at Holtville in fall 2013 and spring 2014 (when SPWF populations are lower than in the fall) compared SPWF infestation of five (PI 116482, PI 123689, PI 124107, PI 124431, PI 145594) of the six accessions with PI 313970, TGR 1551, TGR 1937 (PI 482431), 'Top Mark' and 'Impac'. Statistically significant differences were found in both seasons among the entries for numbers of adults per sampled leaf, eggs, crawlers, red eyes, or nymphs cm-2 leaf area at many but not all sampling dates. Though there were significant (P<0.05) differences among the entries for number of adults per sampled leaf at seven weekly sampling dates in fall 2013, none of the accessions had consistently fewer adults than 'Impac' or 'Top Mark'. There were few differences among the entries in spring 2014 for numbers of adults per sampled leaf. PI 116482 had the most, and PI 145594, PI 313970 and TGR 1937 had the fewest adults, on average.