[Repellency of volatiles from bracts of banana flower bud to <i>Frankliniella occidentalis</i>].

<i>Frankliniella occidentalis</i> infested a wide range of crops. However, no <i>F. occidentalis</i> was found on banana flower bud. To investigate the effect of volatile of banana bud on the behavior of <i>F. occidentalis</i>, we utilized Y-tube olfactometer to assess the behavioral responses of <i>F. occidentalis</i> to different tissues of banana flower buds. We further analyzed the volatile of bracts of flower bud by gas chromatography-mass spectrometry (GC-MS), to select and test the relatively high abundant compound. We determined their behavioral effect on <i>F. occidentalis</i> by conducting an activity experiment in rose garden. The results showed that flower stamen and pistil, as well as young fruit had an attractive effect on <i>F. occidentalis</i>, with relative selection rates of 37.3% and 35.8% respectively. The bracts exhibited a strong repellent effect, with a relative selection rate of -68.6%. Among the 35 volatile compounds detected from the bracts, eight compounds had a relative content more than 1%, accounting for 61.6% of the total. They were α-pinene (16.8%), β-pinene (14.6%), D-limonene (7.9%), DL-limonene (7.9%), ocimene (6.4%), β-caryophyllene (4.8%), 1,8-cineole (4.1%), and γ-terpinene (1.0%). The α-pinene, D-limonene, and β-caryophyllene had significantly repellent effect on <i>F. occidentalis</i>. The relative selection rates were -52.0% and -35.8% at 10.0 μg·mL^-1 and 1.0 μg·mL^-1 for α-pinene, were -43.4% at 1.0 μg·mL^-1 for β-pinene, were -34.6% at 10.0 μg·mL^-1 for D-limonene, were -56.9% at 1.0 μg·mL^-1 and -28.3% at 0.1 μg·mL^-1 for DL-limonene, were -32.1% at 10.0 μg·mL^-1 and -33.3% at 1.0 μg·mL^-1 for β-caryophyllene, respectively. Results of the outdoor trial showed that the five tested compounds exhibited significantly repellent effects on <i>F. occidentalis</i>. The relative selection rates were -51.6% for α-pinene at 10.0 μg·mL^-1 and the lowest were -22.8% for β-caryophyllene at 1.0 μg·mL^-1. In conclusion, the bracts of banana flower buds were the key important tissue to repellent <i>F. occidentalis</i>, with α-pinene, β-pinene, D-limonene, DL-limonene, and β-caryophyllene as the core compounds.