Susceptibility of snap bean cultivars to the sweetpotato whitefly, Bemisia tabaci, in the southern United States

Abstract

The sweetpotato whitefly, Bemisia tabaci Gennadius Middle East-Asia Minor 1 (MEAM1), is a major insect pest on vegetables worldwide. Enormous economic losses result from whitefly damage. The application of chemical insecticides is commonly used by vegetable growers to control MEAM1. However, this pest has developed considerable resistance to most insecticides. Therefore, alternative plant protection strategies are required, such as using host plant resistance. In this study, 24 local and commercially available cultivars of snap bean (Phaseolus vulgaris L.) in the southern United States were determined for their susceptibility to MEAM1 during three seasons (2020 fall, 2021 spring, and 2021 fall). In each season, the number of MEAM1 adults, eggs, and nymphs was assessed weekly for 6 weeks, and snap bean yield was evaluated at the end. During the 2020 fall, the number of adults per leaf was highest on Week 1 (22 adults/leaf) but was not significantly different among the cultivars. The least number of eggs/leaf disk was observed on the ‘Jade’ cultivar. Cultivars ‘Gold Mine’, ‘Golden Rod’, ‘Long Tendergreen’, and ‘Royal Burgundy’ supported a significantly lower number of nymphs/leaf disk. Overall, the number of eggs and nymphs was highest on Week 2 and Week 4, respectively. Snap bean yield was significantly higher on cultivars ‘Affirmed’, ‘Momentum’, ‘PV-857’, ‘Sybaris’, and ‘Tema’. In the spring and fall of 2021, temperature and relative humidity were positively correlated with whitefly infestations. These results provided valuable information for whitefly management on snap beans based on host plant resistance and yield.