Biorational CO2 fumigation of sunflower and common bean: insecticidal potential and effect on seed vitality and quality

Abstract: Store product pests often cause high qualitative and quantitative losses to seeds of
agricultural plants during storage. Damages inflicted to a high category seed result in reduced
germination that practically affects agricultural production. Therefore, it is important to control insect pests and mitigate losses in storages, but at the same time to preserve the germination potential of the seeds as well as their vitality and quality. Fumigation with CO2 is a biorational method used for controlling store product pests in a variety of commodities. Its insecticidal potential is well documented, however the information about the effect on seeds is lacking. In this work, we assessed the efficacy of CO2 fumigation and its effect on vitality (germination energy and germination) and quality (fatty acid composition) of sunflower and common bean seeds. CO2, (62, 93 and 96 %), was applied to sunflower seeds artificially infested with Plodia interpunctella larvae and common bean infested with Acanthoscelides obtectus adults, in gastight bags. The lowest concentration (62 %) caused total mortality (100 %) of P. interpunctella larvae after 7 days of exposure. The two highest CO2 concentrations caused relatively high mortality after two hours of exposure (81 and 86 %), while total mortality (100 %) was achieved after 24 h. The lowest concentration caused only 62.0 % mortality of A. obtectus after 24 h of exposure. In treatments with 93 and 96 % of CO2 mortality was 88 and 93 % after 24 h exposure, respectively. Fumigation with CO2, irrespective of concentrations, showed no adverse effect on seed germination of sunflower (97.0 to 99.5 % in all treatments) or common bean (91.3-95.3 %), or on the percentage of detectable fatty acids in sunflower seeds. However, varietal differences should be considered.