Insect Resistance to Fumigants in Postharvest Commodity Protection: Monitoring and Management

Abstract

As insects cause a significant proportion of postharvest losses, a range of control strategies are in practice, among which chemical treatments are at the forefront. Due to stricter regulatory requirements and consumer sensitivity toward pesticide residues, there has been a gradual decline in the use of contact insecticides, resulting in heavy reliance on fumigants to disinfest stored commodities. Among the sixteen fumigants registered for postharvest protection, the phasing out of ozone-depleter methyl bromide has left only a few fumigants meeting industry criteria. Currently, phosphine and sulfuryl fluoride are the commonly used fumigants, though the former is always the first choice, considering the range of benefits it offers. These include its universal acceptance as a residue-free treatment, excellent efficacy, inexpensiveness, versatility in use, and application in a range of storage structures. However, overreliance on phosphine has led to the development of resistance in major storage pests. In this chapter, we critically analyze the recent research advances made in resistance to phosphine, with special emphasis on monitoring and management. These include our understanding of factors responsible for resistance development, its genetic basis, various methods used for detection, the types of monitoring, and their importance and implications. We also discuss the key tactics of employing alternative treatments such as hermetic control and co-fumigation using phosphine with either sulfuryl fluoride or CO2 in an integrated system to manage pests and resistance. In conclusion, we propose some potential future directions in research toward maintaining the sustainability of phosphine as a critical disinfestant for stored commodities.