Population fluctuation of predominant sharpshooters and spittlebugs in olive orchards of Southeastern Brazil

Xylem-sap feeding leafhoppers, known as sharpshooters (Hemiptera: Cicadellidae, Cicadellinae) and spittlebugs (Hemiptera: Cercopoidea) are vectors of Xylella fastidiosa, which causes diseases in various crops. Here we studied the seasonal fluctuation of predominant species of sharpshooters and spittlebugs in olive orchards in four locations in the States of São Paulo (Cabreúva and São Bento do Sapucaí) and Minas Gerais (Maria da Fé and Wenceslau Braz), Brazil, where X. fastidiosa is associated with olive quick decline syndrome (OQDS). The insects were trapped by yellow sticky cards (10x30 cm) hanged at 0.8 m above ground in external branches of nine olive trees (spaced 30 m apart) per orchard. Traps were replaced every two weeks  from June 2015 to June 2020 and taken to the laboratory for species identification and quantification  under a dissecting microscope. Most sharpshooter and spittlebug species showed peaks in population density during months of higher mean temperature and relative humidity (September-February), except for the spittlebug Clastoptera sp.1, whose adult population peaked from February to April (late summer and early autumn). The highest population peaks (4-6 insects/trap/period) were observed for Clastoptera sp.1 and the sharpshooters Macugonalia cavifrons and Scopogonalia paula in S. Bento do Sapucaí, and for the spittlebug Sphenorhina rubra and the sharpshooter Erythrogonia phoenicia in Maria da Fé. Population peaks of S. paula and M. cavifrons were lower (2-3 insects/trap) and less frequent in Wenceslau Braz, which is located at the highest elevation (1750 m). Late summer and autumn (March-June) peaks (1-2 insects/trap) were observed for the most frequent sharpshooter (Dilobopterus costalimai) in Cabreúva, at the lowest elevation (890 m) tested; in this particular location, a single peak (2.5 insects/trap) of the spittlebug Deois flavopicta was observed in January/2017. The results suggest that spring, summer and early autumn are periods of higher risk of X. fastidiosa spread by vectors in the region.

Support: Horizon 2020 (XF Actors 727987), Fapesp (Proc. 2016/02176-7), Capes and CNPq (Proc. 310554/2016-0).