The Use of Mass Trapping to Suppress Population Numbers ofProstephanus truncatus(Horn) (Coleoptera: Bostrichidae) in Small-Scale Farmer Granaries in Mozambique

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This study evaluated the potential of mass trapping to reduce Prostephanus truncatus population numbers in granaries and hence its possible utilisation as pest management tool. Universal moth traps (Uni-traps) were used to trap the pest and its predator, Teretrius nigrescens Lewis (Coleoptera: Histeridae), in granaries of small-scale farmers in three villages of the Gaza Province of Mozambique during the maize storage period of August 2013 to January 2014. Five granaries were selected in each village. Two baited pheromone traps were set up adjacent to each of three of these granaries. The other two granaries were used as controls, without traps. Numbers of both the pest and its predator were monitored in these traps as well as in stored maize ears inside the granaries for a 6-month period. Mean numbers and densities of P. truncatus, the percentage damaged maize kernels and maize kernel weight loss in granaries with and without traps were compared by means of t-tests. The Cohen's standard of effect size was applied to measure the magnitude of differences between studied variables. An average of 1272 individuals of P. truncatus was caught per trap. Mean densities of P. truncatus recorded per maize ear in granaries with traps were lower (27 individuals/ear) than of those without traps (129 individuals/ear). Mean numbers of T. nigrescens per trap followed similar patterns between granaries with and without traps. The percentage of damaged maize kernels was higher (62 %) in granaries without traps than in those with traps (22 %). Highly significant negative correlations were found between mean numbers of P. truncatus caught in traps and mean infestation in maize ears inside granaries. These findings indicate that mass trapping holds potential for control of P. truncatus in granaries of small-scale farmers.