Abstract

Phosphine (PH₃) is widely used as a fumigant for the control of stored product pests. Indiscriminate use of PH₃ leads to the development of resistant strains. Thus, an experiment was conducted in a laboratory scale fumigation chamber to determine the synergistic effect of carbon dioxide (CO₂) and PH₃ on the mortality of Tribolium castaneum during fumigation of paddy. PH₃ gas generation varies depending upon grain moisture content and dosage of PH₃ used for fumigation treatment. Thus, the maximum PH₃ concentration with respect to saturation time was achieved when paddy were treated with 98% CO₂ + 3 ppmPH₃ at 17% moisture content, leading to a quick mortality of different life stages of T. castaneum with minimum LT₅₀ and LT₉₉ value. Among the different stages of T. castaneum, pupal stage was more resistant to all the treatments compared to larva and adult stages. PH₃ residues in all the treatments were below the recommended level and it can be considered as safe for consumption.

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