Oviposition site selection and attachment ability of Propylea quatuordecimpunctata and Harmonia axyridis from the egg to the adult stage

Surface features of plants can inuence the searching efciency and survivalof predatory insects. Surfaces act as barriers preventing attachment of both phytophagesand also their insect predators. In this regard, we focused on the oviposition site selectionand the attachment ability of all life stages (eggs, larvae, imagines) of two commonladybird species, Propylea quatuordecimpunctata and Harmonia axyridis (Coleoptera:Coccinellidae), on articial and natural substrates with different surface features andproperties (roughness, wettability). Both species preferred a hydrophilic surface as theoviposition site and this can be correlated with the better performance of both larvaeand adults on these substrates compared with hydrophobic ones. The egg glue of bothladybird species can wet hydrophobic surfaces such as those of many plant leaves andalso with prominent 3D wax coverage. The surface roughness has an important role inthe oviposition site selection in P. quatuordecimpunctata, but not in H. axyridis. Theoviposition preference for smooth surfaces in P. quatuordecimpunctata could be due tobetter performance of larvae on smooth substrates compared with rough ones. The eggglue of both species can adapt to articial and natural surfaces characterized by differentasperity sizes faithfully replicating their shape, except for very high asperity sizes or bigtrichomes. The results of the present research can shed light on the mechanical ecologyof the evolutionary successful Coccinellidae and may aid in the development of suitablesubstrates for coccinellid egg-laying, in order to improve the mass rearing technique ofspecies used in biological control