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Research Project: Sustainable Approaches for Pest Management in Vegetable Crops

Location: Vegetable Research

Title: Sources of wild germplasm to improve whitefly resistance in commercial watermelon (Citrullus lanatus var. lanatus)

item Simmons, Alvin
item Levi, Amnon
item MCCUTCHEON, GLORIA - Claflin University
item Blake, Bobbie

Submitted to: International Whitefly Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2015
Publication Date: 1/15/2016
Citation: Simmons, A.M., Levi, A., Mccutcheon, G.S., Blake, B. 2016. Sources of wild germplasm to improve whitefly resistance in commercial watermelon (Citrullus lanatus var. lanatus). International Whitefly Symposium. pg 84.

Interpretive Summary: N/A

Technical Abstract: Host plant resistance is a fundamental component of crop sustainability. The Bemisia tabaci (Hemiptera: Aleyrodidae) whitefly complex is well known as a key pest of many crops around the world. It is adaptive to its environment and feeds on an impressive number of plant species (over 1,000). Yet, there is a dramatic difference in its acceptance and performance among host species. Commercial watermelon (Citrullus lanatus var. lanatus) is among the crops attacked by this pest through direct feeding and indirectly by the viruses transmitted by this whitefly. On the one hand, commercial watermelon cultivars share a narrow genetic base and they are susceptible to many pests and diseases. On the other hand, Citrullus colocynthis is a wild perennial desert melon species that has a broad genetic base and offers viable sources of resistance to insect pests and diseases of watermelon. This wild melon is indigenous to arid regions of Northern Africa, the Mediterranean, and Southwest Asia. Experiments were conducted on Citrullus genotypes from different geographic regions for their potential resistance against B. tabaci. We quickly concluded that whitefly resistance in Citrullus is based on a combination of plant tolerance, antibiosis and non-preference. Therefore, we used diverse laboratory, greenhouse, and field assays in our research. One assay was the establishment of a vertical Y-tube monitoring technique for the rapid testing of whitefly response to phytochemicals as well as for the collection of data on whitefly oviposition and survival. Using HPLC, differences among leaf chemical profiles among some Citrullus genotypes were identified; in addition, we used GS-MS to identify and compare compositions of leaf volatiles. We are using traditional and molecular approaches to improve cultivated watermelon. Wild sources of genotypes that may be useful for improving whitefly resistance in watermelon cultivars were identified, and germplasm lines are being developed and crossed with commercial watermelon cultivars.