Nearctic female <i>Agriotes pubescens</i> and Palearctic female <i>A. lineatus</i> (Coleoptera: Elateridae) produce the same sex pheromone

In central Canada, surveys for the three invasive (Palearctic) Agriotes species-A. obscurus, A. lineatus, and A. sputator-commonly collect A. pubescens, a North American native (Nearctic) click beetle (Coleoptera: Elateridae) that generally co-occurs with Nearctic A. mancus. Despite the abundance of A. pubescens on farmland, its life history and potential economic impact remain largely unknown. Here, we report the identification and field testing of the A. pubescens sex pheromone. We collected headspace volatiles from a single female beetle on Porapak Q, then extracted the female's pheromone gland, and analyzed aliquots of both Porapak extract and pheromone gland extract by gas chromatographic-electroantennographic detection (GC-EAD) and by GC-mass spectrometry. In GC-EAD recordings of gland extract, two esters-geranyl butanoate and geranyl octanoate-elicited antennal responses from A. pubescens males. In a field experiment in Quebec, traps baited with a 1:1 blend of these esters captured approximately 100× more A. pubescens males than traps baited with a single ester. This is the same trap lure used for capturing A. lineatus. In this experiment, and in a similar one run in British Columbia, heterospecific pheromone components added to conspecific pheromone lures reduced captures of A. mancus, A. sputator, A. lineatus, and A. obscurus by 29%, 96%, 44%, and 71%, respectively. These data indicate that, in North America, lures containing pheromone components of multiple Agriotes congeners may not be optimally attractive to all target species.