Ecology of the egg parasitoid Aprostocetus sp., a potential biological control agent of the viburnum leaf beetle Pyrrhalta viburni

Authors: DESURMONT, GAYLORD - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); KERDELLANT, ELVEN - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL)

Submitted to: International Insects Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/5/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The viburnum leaf beetle Pyrrhalta viburni, an invasive chrysomelid native to Eurasia, poses a major threat to viburnums in North America, killing plants in natural habitats and managed landscapes as it spreads through the U.S. Although the natural enemy assemblage of this beetle in its native range is still poorly known, one egg parasitoid, an unidentified species from the genus Aprostocetus (Hymenoptera: Eulophidae) has been documented several times in Europe. Here we report the results of two years of field collections of P. viburni egg masses in 50+ sites in western and central Europe. Aprostocetus sp. was the only parasitoid recovered from P. viburni egg masses and was present in almost all sites. The mean overall parasitism rate was 10%, and parasitism varied significantly depending on the area of collection. Sites from the Mediterranean area, which is the southern limit of P. viburni’s native range, were less parasitized than the rest. Interestingly, overall egg survivorship of P. viburni was also severely reduced in sites from the Mediterranean area, suggesting that southern environmental conditions are less favorable for both the herbivore and the parasitoid. Host plant also played a role on parasitism, as egg masses from sites with the host plant Viburnum tinus tended to be less parasitized than sites with other host plants. Finally, parasitism per egg mass increased with the number of egg masses per twig, showing a cost of aggregating egg masses for P. viburni. Under laboratory conditions, mated Aprostocetus sp. females lived 53.8 days on average, the maximum longevity being 133 days. These observations increase our knowledge of this potential biological control agent, and need to be complemented by experiments clarifying its taxonomy and host specificity.