Influence of constitutive and induced volatiles from mature green coffee berries on the foraging behaviour of female coffee berry borers, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae)

The coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), is currently a major threat to coffee crops around the world. Although some studies have identified host-derived volatile organic compounds as attractant semiochemicals for H. hampei, the chemical composition reported in the literature is quite variable and different individual compounds have been proposed to be attractive. Despite this variability, it seems likely that H. hampei utilizes complex volatile blends to locate suitable berry hosts for oviposition. Therefore, the aim of this work was to evaluate the influence of constitutive and H. hampei-infested volatiles, emitted by mature green berries of a Brazilian variety of coffee, Coffea arabica (IBC-Palma), on the foraging behaviour of H. hampei females. Chemical analysis of volatiles from mature green coffee berries showed a similar chemical profile compared to previous studies. The major compounds were limonene, (E)-ocimene, conophthorin, (E)- and (Z)-linalool oxide, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene, methyl salicylate, geranylacetone, beta-acoradiene, alpha-acoradiene, (E,E)-alpha-farnesene, (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene and alpha-pinene. The compounds (E,E)-alpha-farnesene, (E)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, (E)-ocimene, alpha-copaene and conophthorin were produced in higher amounts in infested berries compared to non-infested berries. Four-arm olfactometer bioassays showed that H. hampei did not distinguish between volatiles emitted from mature green, mid-ripe and ripe coffee berries. In addition, Y-tube olfactometer bioassays showed that females responded to volatiles from non-infested and infested mature green berries, preferring constitutive over herbivore-induced volatiles. Furthermore, (E,E)-alpha-farnesene, (E)-4,8-dimethyl-1,3,7-nonatriene and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene changed the foraging behaviour of H. hampei, by reducing the attractiveness of volatiles from non-infested berries.