Standardization and criticism of sampling procedures using sticky card traps: monitoring sap-sucking insect pests and Anagrus atomus inhabiting European vineyards

Coloured sticky card traps are widely used for sampling and control of sap-sucking insect pests. In European vineyards they are used for monitoring leafhoppers [i.e., Empoasca vitis (Gothe), Zygina rhamni Ferrari, Scaphoideus titanus Ball], the vine thrips Drepanothrips reuteri Uzel and the leafhopper egg parasitoid Anagrus atomus (L.). A study was conducted to establish the trap factors that influence captures of these insects (i.e., size, inclination, exposure days, colour, position within canopy and side orientation). The total captures of grapevine leafhoppers increased as trap size increased, without a significant decline in captures relative to unit area. All leafhopper species were more attracted by vertical traps than horizontal traps, and in the latter case, E. vitis and Z. rhamni were mainly captured on the underside of the trap, while S. titanus on the upper side. For all leafhoppers and D. reuteri, efficiency decreased with the number of days the traps remained in the field. Yellow was a colour preferred by all insects, with Z. rhamni showing a strong preference for lighter yellows. S. titanus was also captured by red traps and A. atomus by colourless ones. Z. rhamni and S. titanus showed a preference for traps placed in shady positions, whereas E. vitis and D. reuteri preferred traps in sunny positions. E. vitis and D. reuteri preferred trap sides exposed to sunlight in the late afternoon and early morning, respectively. Our results were compared with the literature and discussed in relation to the feeding preference and behaviour of the different species.