Possible role for Melothria pendula (creeping cucumber) in the epidemiology of whitefly-transmitted Squash vein yellowing virus

Florida ranks first in the production of watermelon (Citrullus lanatus) in the United States. Since 2004-2005, growers have periodically suffered large losses from a disease caused by Squash vein yellowing virus (SqVYV). This virus will also infect the cucurbit weed Melothria pendula, (creeping cucumber). Creeping cucumber is found throughout Florida and has previously been shown to be important in the spread of aphid-transmitted cucurbit viruses.  SqVYV is transmitted semi-persistently by the sweetpotato whitefly, Bemisia tabaci, biotype B.  The objectives of this study were to compare the transmission of SqVYV to and from creeping cucumber and watermelon, and to compare the behaviors of alighting, settling, and ovipositing between infected and non-infected creeping cucumber leaves. The transmission experiment showed that there were no differences between whitefly transmission to and from creeping cucumber and watermelon. There was no difference in oviposition preference for non-infected or SqVYV-infected leaves 3 days after the release. Results from the whitefly preference experiment showed that, during the first few hours, whiteflies preferred to settle on infected creeping cucumber leaves rather than on non-infected leaves. By the third day, however, whitefly preference shifted to non-infected leaves. Creeping cucumber could be important as an alternate host of the virus and a source of virus for watermelon crops. Because whiteflies can acquire SqVYV from an infected plant in a few hours, their alighting and settling behavior of first preferring infected leaves and then moving to non-infected leaves could lead to an increase in the spread of SqVYV.