Use of pheromone traps to assess Lasioderma serricorne (F.) (Coleoptera : Anobiidae) infestation in a cigarette factory on the Cape Verde islands

Lasioderma serricorne (F.) (Coleoptera: Anobiidae) is the most serious insect threat to stored tobacco and cigarettes on the Cape Verde islands. A monitoring programme using sex pheromone traps for the cigarette beetle was initiated to detect sources of infestation and to assess the risk of tobacco damage. Trials were conducted to obtain estimates of the mean density of L. serricorne and to analyse its spatial pattern. The manager of the cigarette factory used the trap records to assess risk and implemented an empirical action threshold of 10 insects/week/trap. Post-fumigation data collection showed that the pest populations had been reduced by 87 %. The variability in the trap catches indicated an aggregated pattern of distribution and negative binomial distribution fitted the data more accurately than the Poisson distribution. From Iwao's Patchiness or Mean Crowding Regression, at high relative population densities, it was shown that the individuals may form colonies. Although the spatial pattern of the adult male cigarette beetles followed an aggregated distribution at high relative densities, when these relative densities were lower the spatial pattern changed and random and uniform populations occurred.