Seasonal abundance and effect of predators (Coleoptera: Coccinellidae) and parasitoids (Hymenoptera: Braconidae: Aphidiinae) on Myzus persicae (Sulzer) (Hemiptera: Aphidoidea) densities on tobacco: a two-year study from Central Greece

Abstract

Field studies were carried out in order to evaluate the effect of predators (coccinellids) and parasitoids of Myzus persicae infesting tobacco in Greece. In an insecticide-free tobacco field in Tithorea (Fthiotis, C Greece) tobacco leave samples were taken from June until September, for two growing seasons (1996-1997). The aphidophagous coccinellids Hippodamia (Semiadalia) undecimnotata, Adalia bipunctata, Adonia variegata, Propylaea quatuordecimpunctata and Coccinella septempunctata, and the parasitoids Aphidius colemani, Aphidius ervi, Aphidius matricariae, Praon staryi and Praon volucre were recorded. Hippodamia undecimnotata was observed in higher numbers than the other coccinellids whereas Praon volucre was the dominant parasitoid during both years of the study. The hyperparasitoid spectrum was composed of Asaphes spp., Pachyneuron spp. and Syrphophagus aphidivorus with Pachyneuron spp. being the most abundant during both years. Generally, for both seasons, high M. persicae densities were recorded in July and August (mid-season) while most coccinellid individuals were found rather early in the season (June-July). On the other hand, the mummification rate showed a specific increasing trend late in the season (August-September). Furthermore, when the effect of coccinellids on mummies of M. persicae in the field was studied, it was observed that an increase in the number of destroyed mummies was accompanied by a decrease in the number of uneaten mummies.