Evaluating the impacts of trap and lure costs and attractiveness on invasive insect trapping designs

We quantitatively examined the effects of trap and lure costs and attractiveness-which determines densities-on total insect survey costs. We modeled and compared costs for standard and reduced-density designs facilitated either by increased trap attractiveness, or by combining lures in traps. Survey costs were based on supply and replacement, and servicing distances and times. We quantified likelihoods of capture [p(Capture), survey efficacy] for each design in simulations. In a sensitivity analysis, total costs were most affected by trap density and survey area; trap-and-lure costs and durations were much less important. In a proof-of-concept example, we evaluated the impact of doubled attractiveness or tripled duration for Anastrepha ludens (Mexican fruit fly [Diptera: Tephritidae]). Increased attractiveness facilitated reducing traps by 61% and service distances by 58%, which decreased total costs by 44%. By contrast, increasing lure duration to 90 days in a 90-d survey only reduced costs by 6.5%. We then evaluated three case studies from published research. In two, though trap and lure prices at least doubled, total costs decreased by 42% or more because densities dropped by at least 59%. Moreover, p(Capture) at least doubled. In the third case study, combining three lures in traps reduced total costs by about 14% when attractiveness was unaffected, but when attractiveness declined, requiring greater densities, total costs increased 1.5 times. Incorporating traps with greater attractiveness usually reduced total costs and sometimes increased p(Capture). These examples demonstrate how to quantitatively assess trapping costs and survey efficacy to generate more optimal designs.