Electrophysiological responses of carrot psyllids (Trioza apicalis), in different phases of their life cycle, to volatile carrot and conifer compounds

Carrot psyllids (Trioza apicalis) pose a constant threat to carrot production in parts of Europe, and treatments with chemical insecticides are common. To be able to develop alternative control tactics, more knowledge about the psyllid's host-finding behaviour and underlying physiology is needed. Using single-sensillum recordings from overwintered and non-overwintered males and females, we found essentially identical responses for the two groups and for both sexes. Using six compounds emanating from carrots or conifers, the psyllids' overwintering plants, and extracts of carrot leaves, five different olfactory sensory neuron classes could be distinguished from our high-quality recordings, viz. #1 responding strongly and exclusively to terpinene-4-ol, #2 responding strongly and most often exclusively to nonanal, #3 responding moderately strongly to terpinolene, #4 responding strongly to (Z)-3-hexenal and most often weaker to terpinolene, #5 responding exclusively to carrot extract.