Operational Methyl Bromide Fumigation Trials and Residue Assessment in Sukkur and Khairpur Date Godowns: Efficacy Against Saw-toothed Grain Beetle (Oryzaephilus surinamensis), Non-Target Effects, and Worker Safety

Le résumé fourni par la source

Date palm (Phoenix dactylifera) is one of the most important horticultural crop in Sindh, Pakistan, contributing significantly to local livelihoods and national export earnings. However, substantial post-harvest losses occur due to pest infestations that continue to damage stored products. The Oryzaephilus Surinamensis which is commonly known as the saw-toothed grain beetle, is a major pest that adversely affects the quality, marketability, and phytosanitary standards of dried dates. This study presents the operational fumigation trials conducted during 2022-2023 at commercial storage facilities in Sukkur and Khairpur to evaluate the efficacy of methyl bromide (MeBr) against O. surinamensis , as well as the persistence of the residues, environmental impacts, and worker exposure. The experiments were carried out under field-based standardised procedures using calibrated doses of MeBr and controlled exposure time. A series chemical analysis were also performed, against pest mortality, and MeBr residues in the treated dates were quantified using gas chromatography-mass spectrometry (GC-MS). The results showed more than 95% mortality within 48 hours, indicating the rapid effect of MeBr. However, the residue levels were exceeded international maximum residue limits (MRLs), posing challenges for export compliance. Ecological assessments further indicated unintended non-target mortality, including impacts on benificial species, while worker exposure surveys revealed considerable inhalation risks and inconsistent use of personal protective equipment (PPE). Overall the findings provide useful information for regional pest management programs and highlight the need for stricter safety protocols, improved residue monitoring, and a gradual transition toward less hazardous and more sustainable fumigation practices in Pakistan’s date industry.

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