INFESTATION OF MAIZE BY PROSTEPHANUS-TRUNCATUS INITIATED BY MALE-PRODUCED PHEROMONE

Delta traps baited with maize cobs, which were infested each with one male Prostephanus truncatus (Horn) (Col.: Bostrichidae), were distribu ted in southern Benin and collected after one, two, three and four wee ks. The numbers of P. truncatus caught during the different trapping p eriods were not significantly different. Sixty-four percent of the tra pped P. truncatus were females. Females attracted during the one-week trapping period produced a mean of 6.9 progeny during the seven days. The sex ratio of the progeny was 1:1. Trap catches with the infested c obs were on average 13 times lower than catches with 2 mg of the artif icial pheromone. Estimation of P. truncatus densities in a maize store at the beginning of the storage period (based on laboratory data) rev ealed that small initial numbers of P. truncatus, possibly attracted b y a single male, sufficed to initiate high infestation rates later in the storage season.