Sticky trap pattern size for thrips spatial vision

Colored sticky traps are used for the management of many common
agricultural insect pests. Several recent studies have shown that traps
can be improved by systematically considering properties of color vision
for the intended target species. In the current study, we extend this
approach to spatial vision, using information about the interommatidial
angle of an agriculturally important insect pest, western flower thrips
(WFT) Frankliniella occidentalis (Pergande), to predict the
spatial resolution capabilities for a yellow flower pattern across a range
of viewing distances. We tested the hypothesis that pattern sizes matching
the spatial resolution capabilities of WFT at a given viewing distance
would outperform traps with mismatched pattern sizes by measuring the
number of WFT caught on sticky traps containing differently sized flower
patterns resolvable at either 5, 10, or 20 cm, respectively. We found an
interaction between pattern size and viewing distance on WFT catch, with
significantly more WFT caught on traps when the predicted resolvable
distance of the pattern matched the distance traps were placed from a
central release point. We further tested the range over which trap
patterns are effective in more complex viewing environments using
commercial polytunnels. In polytunnel trials, we found that increasing the
distance over which patterns are resolvable increased WFT capture up to
approximately 26 cm, after which WFT capture decreased up to the maximal
visible range tested (50 cm) in the absence of additional sensory cues.
Together, these results show the utility of considering spatial vision in
improving trap performance and offer functional insights to improve pest
management in visual trap design.