Preference for Oviposition by Sweetpotato Whitefly, Bemisia tabaci (Gennadius)1, in Two Soybean Genotypes, and Volatile Release

Abstract

Soybean, Glycine max (L.), in the field is very susceptible to infestation by sweetpotato whitefly, Bemisia tabaci (Gennadius). Preference for oviposition by whitefly in two soybean genotypes was evaluated, and a profile of volatile compounds in healthy plants was obtained. The average number of eggs per square centimeter was 4.1 to 13.7 in ‘Nainari’ variety and 15.1 to 28.4 in an experimental line. Trichome averaged 6.5 per square centimeter in Nainari and 6.8 in the experimental line. The average length of trichomes of Nainari was 311 microns and in the experimental line was 342. Solid-phase microextraction and gas chromatography-mass spectrometry were used to obtain the profile of volatile compounds in two Nainari soybean genotypes and one experimental line: cis-3-hexenyl acetate; cis-3-methyl-1,3-pentadiene; 4-methyl-1,3-pentadiene; cis-3-hexenyl valerate; cis-2-hexen-1-ol; 9-ethyl-9-heptyloctadecane; tetradecane; tridecane; and 2,6-bis(1,1-dimethylethyl)-4-(1-oxopropyl) phenol. In plants infested with whitefly eggs and nymphs, eight compounds were identified in Nainari and seven in the experimental line: M-xylene; 1-octen-3-ol; d-limonene; cedrene; propanoic acid, 2-methyl-, 2-methyl propyl ester; 3-methylnonane; longifolene; caryophyllene; 2,5-cyclohexadiene-1,4-dione, 2,6-bis (1,1-dimethylethyl)-; alpha-farnesene; pentanoic acid, 2,2,4-trimethyl-3-carboxyisopropyl, isobutyl ester, and 2,6-bis(1,1-dimethylethyl)-4-(1-oxopropyl) phenol. Differences in the profile of volatile compounds in healthy Nainari plants might explain oviposition repellency.