PREVALENCE AND DISTRIBUTION OF DIFFERENT NATURAL ENEMIES IN THE HARLEQUIN LADYBIRD HARMONIA AXYRIDIS (COLEOPTERA COCCINELLIDAE)

Abstract

The harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae) is one of the most common invasive alien species in the world, which has a global impact on biodiversity and agriculture, and causes economic loss and harm to humans. This insect can be infected by different natural enemies, but their interactions remain understudied. In the present study, 581 adult Ha. axyridis specimens were collected from 21 localities in Hungary with the help of citizen scientists and examined for natural enemies. The parasitic nematode Parasitylenchus bifurcatus (Nematoda: Allantonematidae) is reported in Hungary on the harlequin ladybird for the first time. The ladybirds were also infected by the ectoparasitic fungus Hesperomyces virescens (Ascomycota: Laboulbeniales) and parasitoid Dinocampus coccinellae (Hymenoptera: Braconidae). The nematode parasite was present in all localities where Hesperomyces-infected ladybirds appeared. The prevalence of recorded natural enemies varied by locality: for P. bifurcatus it ranged from 1% to 8%; for He. virescens from 2% to 36%; and for the parasitoid it was 4%. Besides, a statistically significant positive correlation was shown between the nematode and the fungus co-infection using Spearman’s correlation. A study on the multiparasitism of harlequin ladybirds was not yet performed in Hungary. The study area is located between two distant areas in Europe where co-infections had already been observed, indicating that this is probably not a sporadic phenomenon, but that parasitism of the harlequin ladybird by multiple natural enemies might be prevalent throughout the area.