[Repellency of volatiles from bracts of banana flower bud to Frankliniella occidentalis].

Abstract

Frankliniella occidentalis infested a wide range of crops. However, no F. occidentalis was found on banana flower bud. To investigate the effect of volatile of banana bud on the behavior of F. occidentalis, we utilized Y-tube olfactometer to assess the behavioral responses of F. occidentalis 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 F. occidentalis 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 F. occidentalis, 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 F. occidentalis. 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 F. occidentalis. 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 F. occidentalis, with α-pinene, β-pinene, D-limonene, DL-limonene, and β-caryophyllene as the core compounds.