Grain cleaning as a management tool to control internal feeding pests

Abstract: Although cleaning has been proposed as a management tool to limit population growth of external feeding pests (Phillips and Throne, 2009), only one study gives detailed references on grain cleaning as a mean of disinfestation against internal feeding pests (Armitage et al., 1996). The objective of this study was to evaluate grain cleaning efficacy against Sitophilus oryzae (L.) and Rhyzopertha dominica (Fabricius). The pilot scale cleaner comprised independent and adjustable air and grain flow rates, and two inclined sieves. Twelve barrels were filled with 90 kg of soft wheat, infested with 5 adults per kg of one of the studied species, and cleaned or poured in another barrel to simulate grain turning. Adult free wheat could be obtained causing a weight loss of 1.9 ± 0.64%, with aspiration playing a major role in insect recovery. No significant difference was observed for emergence reduction rate (e.r.r) of both species between cleaning and pouring. The non-negligible e.r.r observed depended significantly on initial number of live insect per kg and specie. A significant correlation was observed between e.r.r and initial immature infestation for R. dominica but not for S. oryzae, for which mean e.r.r caused by grain disturbance was 67 ± 15%. This study, in the light of other dealing with grain disturbance, suggests that grain cleaning, applied to an early detected infestation and at adequately timed intervals could achieve very high level of mortality for internal feeding pests.