VAPORMATETM, a formulation of ethyl formate with CO2, for disinfestation of grain

Ethyl formate (EtF) is being evaluated as a fumigant for the rapid disinfestation of grain, including a cylinderised mixture of EtF in carbon dioxide (16.7% by weight), VAPORMATETM, formulated by BOC Ltd. Insect mortality achieved with a 3-hour dynamic (forced-flow) application versus a static application of the EtF formulation was investigated. In the dynamic application, gaseous VAPORMATETM was pumped through grain in a 65 L model silo at 6 L/min. In the static application, 2.7 L desiccators were dosed with equivalent concentrations of the EtF formulation applied to the headspace. The mortality of mixed-age cultures of the most tolerant insect species, Sitophilus oryzae (L.) and Tribolium castaneum (Herbst), were compared in the two systems over a range of EtF concentrations. The mortality of S. oryzae was also compared after a 3 or 24 h dynamic application of this EtF formulation. A high level of insect control is achievable with a 3-hour VAPORMATETM fumigation, and extending the fumigation time to 24 hours improves the level of insect control. The 3-hour dynamic application gave higher mortality than the static application. An application of EtF at a rate of 147 g/t grain by forced-flow fumigation gave very high control (>99% mortality) of a phosphine-resistant strain of Rhyzopertha dominica and the T. castaneum but lower control (82% mortality) of S. oryzae. Extending the fumigation time to 24 hours and reducing the applied amount of EtF to 100 g/t grain resulted in an improvement of the mortality of S. oryzae to 86%. 1 Corresponding author: .