Novel approaches for monitoring and controlling gyspy moth, Lymantria dispar (L.) (Lepidoptera Erebidae), in Mediterranean cork oak forests

The gypsy moth, Lymantria dispar (L.), is the major threat to cork oak forest in Mediterranean area. In Sardinia (Italy), the management of gypsy moth population outbreaks have usually been conducted through the aerial applications of Bacillus thuringiensis kurstaki-based formulations, whereby more than 100.000 hectares of forests have been protected from pest defoliation. Nonetheless, continuous research aimed to develop new sampling approaches to identify infested areas and to improve the effectiveness of control strategies is needed. In line with this, the present three-year PhD work was conceived to advance available methods for monitoring and controlling the gypsy moth in Mediterranean area. Firstly, the spatial distribution of L. dispar egg masses among cork oak trees was studied during the different pest population development phases and sequential sampling plans based on the count of egg masses on trees were developed. Secondly, the effectiveness of different Btk strains sprayed at large scale was evaluated at different application doses. Our results showed the possibility of alternating different Btk strains for resistance management purposes and of applying lower doses than labeled. Finally, the efficacy of a Lymantria dispar multicapsid nucleopolyhedrovirus (LdMNPV) formulation against larval infestations was tested in field conditions. Our results highlighted the potential use of LdMNPV as an alternative to Btk-based formulations for protecting Mediterranean cork oak forests.