Phenology and Development of the Yellow Rose Aphid, Acythrosiphon porosum (Sanderson), in Northern Florida and Southern Georgia

Abstract

The yellow rose aphid, Acythrosiphon porosum (Sanderson), is a cosmopolitan pest of roses and strawberries. Acythrosiphon porosum is one of only a few arthropod pests of roses occurring in northern Florida and southern Georgia. Hybrid roses are widely planted around the city of Thomasville, GA, which is known as the Rose City. Three ‘Grandiflora’ rose cultivars ‘Queen Elizabeth’, ‘Roundelay’ and ‘Spartan’ were used to determine cultivar and location effects on A. porosum seasonal abundance and natural enemies. Developmental rate, longevity and nymph production of A. porosum were also investigated at 4 temperatures, 10.0, 15.5, 21.1, and 26.7°C, in environmental chambers using cut leaf discs of ‘Queen Elizabeth’ on agar plates. Acythrosiphon porosum occurred throughout much of the year except for the coldest winter and warmest summer months and reached highest populations during the cooler weather of spring and fall. Cultivar differences were statistically significant at all locations where ‘Queen Elizabeth’ averaged higher aphids per leaf than ‘Roundelay’, which averaged higher aphids than ‘Spartan’. Aphid numbers did not significantly differ in comparisons of leaves sampled from the bottom, middle or top third of the plant's canopy height. Developmental rate calculated as the time from nymph to nymph was most rapid (x̄ = 10.3 d) at 21.1 °C, but no aphid development was observed at 26.7°C. Total egg production was highest (x̄ = 27.5 nymphs per aphid) at 10.0°C as was longevity of 60.1 d. Highest nymph production (1.5 per d) was observed at 21.1 °C. Many generalist predators and two parasitoid species were found in low numbers attacking A. porosum: Syrphophagous aphidovorus (Mayr) (Hymenoptera: Encyrticidae) and Ephedius sp. (Hymenoptera: Aphidiidae).