Effect of Daytime and Tree Canopy Height on Sampling of , a ' Phytoplasma mali' Vector.

The psyllids and reproduce on apple () and transmit the bacterium ' Phytoplasma mali', the causative agent of apple proliferation. Adult psyllids were collected by the beating-tray method from lower and upper parts of the apple tree canopy in the morning and in the afternoon. There was a trend of catching more emigrant adults of in the morning and in the lower part of the canopy. For remigrants, no differences were observed. The findings regarding the distribution of adults were reflected by the number of nymphs collected by wash-down sampling. The density of was too low for a statistical analysis. The vector monitoring and how it is commonly performed, is suitable for estimating densities of . Nevertheless, above a certain temperature threshold, prediction of density might be skewed. No evidence was found that other relatively abundant psyllid species in the orchard, viz. , , , and , were involved in ' Phytoplasma mali' transmission. The results of our study contribute to an advanced understanding of insect vector behavior and thus have a practical impact for an improved field monitoring.