The management of sweetpotato whitefly in the southeastern US

Abstract

Sweetpotato whitefly (Bemisia tabaci) is a significant pest affecting vegetable crops in the southeastern United States, causing direct feeding damage and transmitting viruses that can lead to substantial yield losses. This dissertation investigates sustainable management strategies for whitefly control in zucchini and tomato production through two main approaches: integrated pest management (IPM) practices using insect exclusion row covers and reflective silver plastic mulching and the exploration of wild tomato (Solanum habrochaites) accessions for genetic resistance to whiteflies. Field experiments in zucchini production demonstrated that using reflective silver plastic mulching and insect exclusion row covers significantly reduced whitefly populations. Silver reflective mulching decreased whitefly densities by up to 87%, leading to a 17% increase in total yield compared to traditional white plastic mulching. Row covers reduced whitefly populations to near zero during the critical early growth stages, resulting in a 14% yield increase. These findings highlight the effectiveness of combining physical barriers and reflective mulches to manage whitefly infestations and increase crop productivity without heavy reliance on chemical insecticides. Also, the physical and chemical characterization of wild tomato accessions for resistance to whiteflies identified specific wild tomato accessions with high densities of glandular trichomes and elevated terpene production, both of which were associated with reduced whitefly infestation. These findings suggest that wild tomato accessions, particularly S. habrochaites, offer promising genetic traits for breeding whitefly-resistant cultivars. The chemical analysis revealed that terpenes such as zingiberenoids are critical in deterring whiteflies, providing a biochemical basis for resistance. This research offers a dual approach to whitefly management in the southeastern U.S. by integrating immediate, field-based IPM strategies with long-term genetic resistance through plant breeding. The findings contribute valuable insights into developing sustainable solutions to mitigate the economic impact of whiteflies on vegetable crops.