Release dynamics and comparative toxicity of phosphine and formaldehyde against two stored-product insects | ||
| Journal of Pest Control and Environmental Sciences | ||
| Volume 23, Issue 1, 2023, Pages 16-34 PDF (501.92 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jpces.2023.467034 | ||
| Authors | ||
| Ahmed F. El-Aswad* 1; Gehad Z. Mohamed1; Neama A. Gouda2 | ||
| 1Pesticide Chemistry and Technology Dept., Faculty of Agriculture, Alexandria University, Egypt. | ||
| 2Pesticide Chemistry Department, Faculty of Desert and Environmental Agriculture, Matrouh University, Egypt. | ||
| Abstract | ||
| The release kinetics of phosphine and formaldehyde were examined, revealing that phosphine evolved rapidly under acidic conditions, whereas formaldehyde generation depended on optimizing the reactant ratios to ensure stable gas release. The optimized mixture ratio of 1:1:2 (KMnO₄: formalin: sand) produced the highest steady-state formaldehyde concentration while minimizing heat generation and maintaining reaction stability. The efficacy of both fumigants was evaluated against two major stored-product pests, Sitophilus oryzae and Tribolium confusum, across life stages. Phosphine exhibited strong, time- and concentration-dependent toxicity, with LC50 values markedly lower than those of formaldehyde, indicating more than an order of magnitude higher potency. Larvae were generally more sensitive than adults to both fumigants. Formaldehyde required higher concentrations or longer exposure to achieve comparable mortality, reflecting its slower, cumulative action. These results underscore phosphine as a highly effective fumigant for stored-product pest control, though careful application is essential to prevent resistance development. Formaldehyde may serve as a secondary option in controlled scenarios. Optimizing fumigant release, exposure duration, and species-specific strategies is critical for safe, effective, and sustainable pest management. | ||
| Keywords | ||
| Fumigation; phosphine; formaldehyde; release kinetics; insecticidal activity; stored-product insects; Sitophilus oryzae; Tribolium confusum | ||
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