Decade Long Upsurge In Target Site Pyrethroid Resistance In Bed Bug Populations In The United States
Abstract Over the past three decades, the bed bug Cimex lectularius has resurged as a prominent indoor pest on a global scale. Knockdown-associated insecticide resistance (kdr) involving the voltage-gated sodium channel, targeted by organochlorine and pyrethroid insecticides, was first reported in C. lectularius within a few years of the widespread use of Dichlorodiphenyltrichloroethane (DDT) and has been implicated as a significant factor contributing to the species recent resurgence. Since then, selection with pyrethroid insecticides has intensified, yet little is known regarding its short-term impacts on the frequency of kdr-associated mutations. Here, we report temporal changes in the frequencies of three kdr-associated mutations in C. lectularius populations collected across the United States from two time periods, sampled approximately a decade apart. Results reveal a significant increase in the frequencies of kdr-associated mutations over this period, and absence of the insecticide-susceptible genotype in recent collections. Furthermore, a significant transition towards infestations possessing multiple kdr-associated mutations was observed. These results suggest that the persistent use of pyrethroid insecticides over the past decade continues to impose strong selection pressure on C. lectularius populations, driving the proliferation of kdr-associated mutations. They demonstrate that, if unabated, strong anthropogenic selection can drive the rapid evolution of adaptive traits.