Harmonia axyridis (Boyer de Fonscolombe) (Hemiptera: Coccoidea) as a potential biological control agent of the invasive soft scale, Sphaerolecanium prunastri (Boyer de Fonscolombe) (Hemiptera: Coccoidea) in native wild apricot forests

Abstract

Abstract Background The globose scale (GS), Sphaerolecanium prunastri (Boyer de Fonscolombe) (Hemiptera: Coccoidea), has invaded wild apricot forests in their native range in Central Eurasia threatening the ancestral germplasm resource. Biological control efficacy of the harlequin ladybird, Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) against the globose scale was assessed in laboratory and field experiments. Results In the laboratory, Harmonia axyridis has a high feeding capacity on GS with numbers consumed daily increasing with temperature (15, 20, 25, 30, 35 °C), reaching an upper asymptote of 160–200 scales per day. In field cage experiments, efficacy of biological control (EBC) against first instar (49–99%) and second instar nymphs (20–80%) increased with GS density. When ants were present, control efficiency was reduced by 10–15%. In open-field experiments without cages, EBC was comparatively lower regardless of duration and how H. axyridis were released whether as adults, eggs cards or a mixture of adults and eggs cards. Conclusions In the long term, biological control with this ladybird predator could be considered as part of an IPM program package that includes banning or delaying mowing grass and understory plants in the forests that offer pollen and nectar for natural enemies.

Keywords

• Soft scale
• Sphaerolecanium prunastri
• Harmonia axyridis
• Ant attendance
• Biological control
• Efficacy