INCIDENCE AND POPULATION FLUCTUATION OF SPITTLEBUGS ON THREE PERENNIAL GRASSES: ON-FARM ASSESSMENTS

Resumen

Significant population outbreaks of spittlebugs (Hemiptera: Cercopidae) have been observed in perennial grasses (Poaceae) established in farms in South of Brazil. This situation is worrying local producers in relation to the continuous supply of forage due to the significant damage caused by this pest species complex. Thus, this study aimed to evaluated the incidence and populational fluctuation of spittlebugs (Hemiptera: Cercopidae) in three perennial grasses [Cynodon dactylon cv. Jiggs, C. dactylon cv. Tifton 85, and Axonopus catharinensis cv. SCS 315 Catarina Gigante (Poales: Poaceae)] in an experimental farm under semi-intensive milk production system. For this purpose, weekly counts of the foam produced by the spittlebugs nymphs were carried out in 10 points of 0.25 m² (0.5 x 0.5 m) each, totalizing 35 assessments from the beginning of September 2015 to the end of April 2016. The incidence of spittlebugs was significantly different among the three perennial grasses. Lower incidence of spittlebugs was observed on A. catharinensis cv. SCS 315 Catarina Gigante (4.91 nymphs foam m^-2 week^-1 in average), which is a natural species from South Brazil, followed by C. dactylon cv. Jiggs (6.51 nymphs foam m^-2 week^-1 in average) and by C. dactylon cv. Tifton 85 (7.58 nymphs foam m^-2 week^-1 in average). Moreover, three characteristic population peaks of spittlebugs was observed: the first in the end of September, the second in the middle of December, and the third in February early. However, the number of nymphs foam of spittlebugs was not significant correlated with the climatic parameters (precipitation, average temperature, and relative humidity) of periods (week) prior to the weekly sampling times. In light of these findings, A. catharinensis cv. SCS 315 Catarina Gigante constitutes an interesting option for establishing new pasture areas.