Recent data on the biology and population dynamics of Oulema hoffmannseggii (Coleoptera: Chrysomelidae) and its associated parasitoids

Oulema melanopus and Oulema hoffmannseggii have been mistaken for a single species. However, their differentiation has been definitively established through the examination of male genitalia. The analysis revealed that the aedeagus size of O. hoffmannseggii was smaller (1.125 ± 0.007 mm) than to O. melanopus (1.375 ± 0.008 mm). Over a 4-year period, the study of species abundance highlights a significant prevalence of O. hoffmannseggii (77%). Both species were observed to have one generation per year, with the highest emergence of new adults occurring in May; however, no egg-laying was observed until adults declined in June. Notably, the peak number of O. hoffmannseggii pupae was recorded at the end of April. Subsequently, from 86% of collected pupae parasitoids successfully emerged within an average of 10.8 ± 0.8 days, with 93% originating from pupae collected on spikes and 79% from those collected on leaves. Molecular analysis of these parasitoids identified them as belonging to the Ichneumonidae family. Among them, six specimens were classified under the Pimplinae subfamily, closely related to Itoplectis maculator, while five specimens grouped within Cryptininae subfamily, and two specimens were linked to representatives of the Pteromalidae family.