4-Methyl-5-Nonanol (Ferrugineol) as an aggregation pheromone of the coconut pest, Rhynchophorus ferrugineus F. (Coleoptera: Curculionidae)^osynthesis and use in a preliminary field assay

Abstract

4-Methyl-5-nonanol (ferrugineol), the more attractive component of the aggregation pheromone of Rhynchophorus ferrugineus F. (Coleoptera: Curculionidae) was synthesized by a Grianard reaction with-butylmagnesiumbromide and 2-methyl-1-pentanal. Oxidation of 2-methyl-l-pentanol in pyridinium chlorochromate wasused toobtain 2-methyl-1-pentanal. The overall-yield of the synthesis from 2-methyl-1-pentanol was 6i%. At a release rate of 0.38 f 0.08 mg synthetic ferrugineol per day from capillaries suspended in bucket traps filled with soap water, significantly more weevils were caught compared to a control trap (0.23 + 0.04 weevils/trap/day vs 0.00 weevils/trap/day respectively) in the field. Significant differences were not observed between male and female trap catches using ferrugineol as a bait (0.12 * 0.02Itraplday and 0.11 f O.Ol/trap/day respectively). Ferrugineol remained attractive to weevils for a t least 60 d. The weevil response to the bait was observed only between 1800-2000 and 0600-0800 h. In a comparative field assay of synthetic ferrugineol with the coconut bark steam distillate, a known attractant for the red weevil, ferrugineol attracted signiticantly more weevils than the latter (0.25 k 0.12 weevils/trap/day vs 0.06 k 0.04 weevils/trap/day, p<0.05).