Integrating Tephritid Trapping into Phytosanitary Programs

Abstract

Systematic deployment of attractant-baited traps has long been a mainstay of phytosanitary programs for tephritid fruit flies. Trapping arrays are used for detecting, delimiting, monitoring, and confirming eradication of tephritid populations, as well as for demonstrating minimal risk of infestation of commodities in support of trade. Designing and optimizing trapping systems to meet these various functions requires a basic understanding of the efficiency of the trapping system, including the influence of programmatic variables, such as trap density and distribution. Distance-capture functions, based on results of release-recapture tests, are discussed as one tool for assessing the sensitivity of trapping systems. As a demonstration of their use, these functions are incorporated into Monte Carlo simulations for estimating probabilities of detecting populations, including the effects of population size, time (in fly generations), and programmatic variables. Examples are provided for three key pest species: Ceratitis capitata (Wiedemann), Bactrocera dorsalis (Hendel), and B. cucurbitae (Coquillett). Results of these or comparable analyses can be used to predict potential ranges of population size at the time of detection or estimate the maximum expected size of a residual population after control measures are applied given a continued absence of captures. Optimal design of trapping systems for any given location and purpose requires consideration of a number of factors that may include, among other things, the frequency of introduction of the target pest(s), availability and feasibility of using various control methods (insecticides, sterile insect releases, etc.), potential of the pest population to spread, and/or costs of survey, eradication, and other program activities. In combination with this information, quantitative assessments of tephritid trapping systems can be used to ensure adequate and appropriate system sensitivity, identify opportunities to improve overall cost-effectiveness of phytosanitary programs, and provide scientific justification for program strategies and protocols.