Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia / ULLeptoglossus occidentalis Heidemann (Heteroptera: Coreidae) is an invasive pest seriously damaging conifer seeds. Native from North America, the insect was first detected in Europe in 1999, and recorded in Portugal in 2010. Both nymphs and adults feed on seeds of several conifer species. Bug impact on seed production of Stone pine, Pinus pinea, is of major concern in the Mediterranean Basin countries because cone production and seed yield have decreased during the last years quite simultaneously to the records of L. occidentalis. Thus, the insect has been considered the most plausible cause of this decrease. However, there was still a substantial lack of knowledge about the effective impact of bugs and their ecological adaptations on Stone pine.
My main goal was to add valuable and pertinent knowledge to understand the interactions between seed bugs and Stone pine. At first, a careful revision of all the literature available about Leptoglossus occidentalis was carried out, together with discussions with other European researchers working on this pest, in order to define the PhD aims. The PhD plan was then divided into three main issues. I first characterized and measured the importance of bug damage on seeds of Stone pine. In a second part, I investigated the ecological interactions between invasive bugs and Stone pine cones and seeds. Bug host preference was tested between Stone pine and the other two main native pine species growing in southern Europe (P. pinaster and P. halepensis), and cues possibly underlying such preferences were suggested. I also evaluated the impact of the bug in Stone pine seed orchards under two different management strategies. In a third part, I suggested possible invasion routes of L. occidentalis in the Iberian Peninsula, using genetic data and field recordsN/
