Seasonal Fluctuations and Phenology ofProsapiaSpittlebugs (Homoptera: Cercopidae) in Upland Pastures of Costa Rica

Abstract

Seasonal fluctuations in Prosapia (Homoptera: Cercopidae) abundance were docu- mented over 4 yr in 3 upland dairy pastures of Costa Rica. P. nr bicincta (Say) completed only 1 relatively long-lived generation each year between May and September. First instars appeared in May at the start of the wet season, progressed through 5 instars and peaked in abundance in mid-June. Densities as high as 277 spittlebugs per square meter were reached. Adult populations peaked late June to early July and achieved densities up to 260 froghoppers per 50 sweeps of an insect net. Distinct peaks of adult males generally occurred 3—4 wk in advance of the maturation of 5th instars and the principal adult peaks. Males outnumbered females 5.6:1 in sweep net surveys. Nymph and adult abundance fluctuated widely among paddock-years in no clear pattern with respect to paddock or predominant forage. Phenological analyses based on cumulative insect-days did not detect differences in population initiation or development rate across paddock-years. Teneral and adult males peaked earlier than their respective females (protandry). In 5 of 8 and 4 of 9 paddock-years, adult males and females, respectively, peaked in abundance before same sex tenerals, indicating colonization of local pastures. Additional evidence for immigration was the abrupt appearance of male P. simulans (Walker) at the same time in all paddocks each year. This species did not complete its life cycle in local pastures because females and nymphs were absent from surveys. Explorations of pastures at varying elevation and distance from survey paddocks demonstrated that within 10 km P. nr bicincta populations matured 2.5 wk earlier. Adults derived from those populations may become available as colonists to local pastures. The nearest breeding populations of P. simulans to sites where males were recovered were 485 m lower in elevation and 3.4 km distant.