Spatial analysis of mass trapping: How close is close enough?

Abstract

BACKGROUND: The identification of new attractants can present opportunities for developing mass trapping, but standard screening methods are needed to expedite this. We have developed a simple approach based on quantifying trap interference in 4 × 4 trap arrays with different spacings. We discuss results from sex pheromones in Lepidoptera (lightbrown apple moth, Epiphyas postvittana), Diptera (apple leafcurling midge, Dasineura mali), and Homoptera (citrophilous mealybug, Pseudococcus calceolariae), compared with a kairomone for New Zealand flower thrips (Thrips obscuratus). RESULTS: The 25:1 ratio of catch in corner to centre traps observed at 750 D. mali traps/ha was still evident as ~5:1 at 16 traps/ha, suggesting trap interference even at such low trap densities. Trap competition for sex pheromone lures at close spacing (<5 m) was evident in 16 trap arrays of the Pseudococcus calceolariae, but less so for Epiphyas postvittana. No trap competition was observed at 4 m spacings with the kairomone for T. obscuratus. CONCLUSIONS: The ratio of catch in traps in the corner : centre of a 16 trap array at different spacings offers a rapid preliminary assessment method for determining potential for mass trapping. Additional knowledge of vital rates and dispersal is needed for predicting population suppression. Our approach should have value in mass trapping development.