Control of Stored Agro-Commodity Pests Sitophilus granarius and Callosobruchus chinensis by Nitrogen Hypoxic Atmospheres: Laboratory and Field Validations

Abstract

Given the complexity of the practical usage of controlled atmospheres for the protection of agro-commodities, several researchers have pointed out that there is not enough robust scientific documentation regarding the usage of inert gases for their widespread practical application. Therefore, this work evaluated various regimes of hypoxic and anoxic nitrogen atmospheres for the control of two key stored-product pests, in laboratory and under field conditions in silos. Sitophilus granarius and Callosobruchus chinensis were selected as the tested species since they are important pests of grain/rice or legumes in Europe and Asia. Under laboratory conditions, we tested nitrogen (N2) concentrations (from 95 to 100%) and exposure times (1–20 days) on the developmental stages of both pest species. In most developmental stages of S. granarius and C. chinensis, the shortest effective exposure was found for nitrogen concentration of 99%. Based on our laboratory tests, validation studies were subsequently carried out in semi-hermetic steel silos (25t) using continuous nitrogen saturation by on-site built swing pressure generators. It was found that a full control of all stages of S. granarius and C. chinensis was achieved in 11 days of nitrogen exposure, using concentrations ranging above 99% and below 100%. Our work shows that hypoxic nitrogen treatment can be effectively achieved in small steel silos under proper technological and environmental conditions.