Abstract
Psyllids are small (2.5–4 mm), phytophagous, plant sap-feeding insects. Several species, in the genus Cacopsylla , are known as pests of fruit trees in Europe and adjacent countries. Interestingly, some species are multivoltine, such as the pear psyllids Cacopsylla pyri and C. pyricola , while closely related psyllid species of pear, plum, and apple ( C. pyrisuga , C. pruni , and C. picta, resp.) are univoltine and migrate between Rosaceae fruit tree species and evergreen conifers in higher regions. Therefore, the latter species have to cover great distances between their two diverging habitats. To uncover adaptations of the flight behavior and ability to the different life-history strategies, the flight of migrating ( C. pruni ) and non-migrating ( C. pyri and C. pyricola ) psyllids is investigated with a flight mill, showing that the seasonal migration of C. pruni correlates with the motivation to initiate long straight distance flights, indeed. Interestingly, C. pyri and C. pyricola showed great differences in their flight motivation and performance, indicating a greater dispersal propensity of C. pyri than C. pyricola . In addition, the determination of the protein, soluble carbohydrate, and glycogen content of pear psyllids revealed the consumption of carbohydrates during the psyllids’ flight. The content of the energetic resources is discussed in relation to their flight propensity.