Phosphine resistance among stored product insect pests: A global meta-analysis-based perspective

Phosphine is the most common fumigant used for stored product protection, and its use intensified with the global phasing out of methyl bromide due to its ozone depletion characteristics. These use patterns led to phosphine resistance, which was subjected to a globe-wide survey in the 1970's, but without a subsequent (global) update. Thus, the present work aimed to undertake a comprehensive review of the phosphine resistance literature published since the initial survey in 1975 until 2021. Next, meta-analyses were used to synthesize and quantify the resistance observed within the main insect pest species of stored products. Forty-six papers were recognized surveying 13 species of stored product insect species, encompassing 980 populations around the world; 72.96% of these populations exhibited phosphine resistance, and 10 out of the 13 species evaluated exhibited resistance in more than 60% of the populations tested. The most widespread problems were observed with the lesser grain borer (Rhyzopertha dominica), the rice weevil (Sitophilus oryzae), and the red flour beetle (Tribolium castaneum). The frequency of resistant individuals ranged from 12 to 48% for the populations. The levels of phosphine resistance were higher for the lesser grain borer (73-fold on average), followed by the red flour beetle (32-fold), and the maize weevil (28-fold). Furthermore, a considerable variability was observed within species and among localities. Therefore, phosphine resistance remains an ongoing problem and worldwide concern, with increasing levels and prevalence among key pest species of stored products, although reports and monitoring are largely circumscribed to four countries-Australia, Brazil, Greece, and the US.