Rosangela Cristina Marucci

Effects of marigold on the behavior, survival and nutrient reserves of Aphidius Platensis

Marigolds (Tagetes erecta L.) suppress nematodes and are attractive companion plants, but their role in biological control is unknown. We evaluated how exposure to marigold blooms impacts the aphid parasitoid, Aphidius platensis Brethes. Female wasps previously exposed to marigold spent more time walking and parasitizing Myzus percisae Sulzer or Schizaphis graminum Rodani aphids, and subsequently had higher parasitism rates. Meanwhile, completely starved wasps spent more time stationary and marginally more time grooming. Time spent probing, emergence rate, and sex ratio were not affected. Wasp survival was best on honey, followed by marigold, and lowest on non-blooming marigolds. Nutrient reserves of wasps given honey, aphid-infested marigold, or marigold alone were compared to newly-emerged unfed wasps. Their resulting lipid, glycogen and sugar levels were similar, suggesting that these foods helped wasps maintain reserves similar to emergence levels. These results suggest that marigold may improve biological control of aphids by A. platensis.

Life history parameters and feeding preference of the green lacewing Ceraeochrysa cubana fed with virus-free and potato leafroll virus-infected Myzus persicae

The sap-feeding aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae) causes significant damage to potato crops and is a main transmitter of potato leafroll virus (PLRV). The lacewing Ceraeochrysa cubana (Hagen.1861) (Neuroptera: Chrysopidae) is a natural predator of the aphid and an important biological control agent. The aim of this study was to determine whether the biological characteristics and feeding preferences of the predator are modified by PLRV-infected aphids. The larval and pupal stages of lacewings fed on PLRV-free M. persicae were prolonged in comparison with those of predators provided with PLRV-infected aphids or eggs of Ephestia kuehniella, although larval, pupal and adult predator survivals were not affected significantly by dietary regime. Ingestion of PLRV-infected aphids reduced the proportion of fertile female lacewings and increased their pre-oviposition period, but had no effect on fecundity or egg viability. In laboratory bioassays, the predator showed no preference for PLRV-infected or PLRV-free aphids.