The brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae), is an alien species native to East Asia and it is now invasive in Europe, where it is one of the main phytophagous pests in orchards. We hypothesized that Volatiles Organic Compounds (VOCs) may be present on Halyomorpha’s eggs and we aim at understanding their role. Using Solid Phase Microextraction, we collected VOCs from freshly laid eggs and from older eggs in order to assess VOCs variations according to the egg’s age. We identified Hexadecanoic acid and Phenethyl alcohol from new eggs and Butyrolactone from old eggs. These compounds are reported in literature as antimicrobial compounds and, for this reason, we hypothesized that the present VOCs in H. halys egg clusters may act as a protection from external infections. We carried out antifungal assays where we tested the growth of entomopathogenic fungi and fungi of plant diseases in the proximity to Halyomorpha eggs. By the measurement of fungi growth and the mortality rate of H. halys eggs we were able to show that fungi are attracted to eggs clusters (p<0.001) and that the hatching rate of nymphs was reduced in freshly laid egg clusters compared to the older (p<0.001). Our data indicate fungi’s selective virulence on H. halys eggs in respect of their age and their presumptive attraction towards the eggs by their volatiles. These results are to our knowledge the first evidence on how egg odours may influence the growth of fungi and this might lead to new control approaches in biological protection.
