Distribution of Immatures and Monitoring of Adult Sweetpotato Whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), in Peanut, Arachis hypogaea

Abstract

The sweetpotato whitefly, Bemisia tabaci (Gennadius), attacking peanut, Arachis hypogaea L., in Georgia was identified as Strain B. Based on the Brooks-Dyar rule for geometric growth, four nymphal instars occurred on peanut. Average length and width (μm), respectively, for the instars were (mean ± SE): first, 207.8 ± 5.4, 120.9 ± 4.4; second, 314.9 ± 8.8, 194.0 ± 6.4; third, 442.6 ± 11.2,289.1 ± 8.0; and fourth, 619.3 ± 9.2, 428.7 ± 4.4. Few immatures were found on the terminal and second leaf of a lateral branch. They were most abundant on leaves 3, 4, and 5, and then numbers declined with an increase in leaf age. Immatures occurred on both upper and lower leaf surfaces. Immatures were equally distributed among the tetrafoliates of a peanut leaf, but their location on upper versus lower leaf surface varied over time. Yellow sticky traps placed in a horizontal position at ground level or at canopy level and with the sticky surface upward were most effective in capture of adult sweetpotato whiteflies. The number of immatures on peanut leaves was only weakly related to the number of adults captured in sticky traps 1 wk earlier.