Evaluation of visual and olfactory cues for sampling three thrips species (Thysanoptera: Thripidae) in deciduous forests of the northern United States

The introduced basswood thrips, Thrips calcaratus Uzel pear thrips, Taeniothrips inconsequens (Uzel), and native basswood thrips, Neohydatothrips tiliae (Hood), form a thrips complex that attacks buds and foliage of basswood, Tilia americana L., trees in the northern United States. We assessed the potential for exploiting visual and olfactory cues to monitor these forest thrips. We tested blue, green, red, white, and yellow for thrips' response to visual stimuli, and anisaldehyde, ethyl nicotinate, and polar and nonpolar extracts of basswood buds or leaves for thrips' response to olfactory stimuli over a 2-yr period. Generally, yellow traps tended to elicit the greatest visual response from all three species. None of the species showed significant attraction to the test volatiles compared with controls. The introduced basswood thrips, which is closely associated with expanding buds, was the most abundant species, and occurred earlier in the spring than the two flower- or foliage-associated species. The implications of these behaviors are discussed with respect to a forest pest monitoring program.