Attractiveness of some host plant and conspecific male semiochemicals to the banana weevil, Cosmopolites sordidus (Germar, 1824)

Abstract

The attractiveness of some chemicals derived from host plant and conspecific male sources in olfactometer bioassays was studied. The attractiveness of the chemicals was examined at two concentrations and, in some cases, in combination with banana rhizome. Pieces of banana rhizome on which male weevils (Cosmopolites sordidus) had fed were also compared with similar pieces of fresh rhizome. The attractiveness of the chemicals to the weevil varied with concentration. At 10 µl, 3-methyl-butyraldehyde, 2-methyl-butyraldehyde and isobutyraldehyde proved to be very attractive to the weevil. At the same concentration, 4-mercaptophenol, valeraldehyde and methachrolein were also moderately attractive. At both 1 and 10 µl, 2-methylbutyraldehyde was attractive. Ethyl acetate and 3-carene were attractive to the weevil at the lower concentration of 1 µl. A combination of 4-mercaptophenol, 2-n-butylfuran, 3-methylbutyraldehyde and valeraldehyde with the banana rhizome were attractive, while 2-methylbutryaldehyde caused the rhizome to be repellent to the weevil. Rhizomes eaten by male weevils were more attractive than uneaten ones. The attractiveness of the combination of some of the chemicals with the rhizome and the additive or synergistic action of the rhizome for otherwise unattractive chemicals suggests that these chemicals can be used to improve on the trapping efficiency of split pseudostem and rhizome traps in the field.

Ghana Journal of Agricultural Science Vol. 37 2004: 75-84