Measuring insecticide resistance in a vacuum: Exploring next steps to link resistance data with mosquito control efficacy

Insecticide resistance is a great challenge facing mosquito operational control agencies across the United States, where few active ingredients with unique modes of action are available for use, increasing resistance pressure and further hampering resistance management strategies. Emergence and expansion of insecticide resistance in mosquitoes can be detected by resistance monitoring programs; however, there are gaps in our knowledge regarding the link between resistance bioassay results and operational control outcomes. We conducted a literature review to assess both public health and agricultural studies on pesticide resistance bioassays and control outcomes. In total, we screened 576 articles, 32 (6%) articles met our inclusion criteria and were reviewed for insecticide resistance and control efficacy data. Most studies were conducted primarily in North America (44%) and Africa (28%). Most papers focused on resistance profiles for agricultural pest species (n = 18). This was followed by mosquitoes (n = 12); 8 of the studies reported results on Anopheles spp. Pyrethroids (69%) were the most frequently tested class for insecticide resistance, followed by organophosphates (28%). The WHO tube test (25%) was the most commonly used bioassay method, followed by the CDC bottle bioassay/modified CDC bottle bioassay (16%). We note several knowledge gaps regarding the interpretation and measurement of insecticide resistance. These gaps are grouped into four topical areas: 1) resistance bioassays, 2) population resistance dynamics, 3) reference strains, and 4) spatial and temporal factors.