Alma Mater Studiorum – Università di Bologna DOTTORATO DI RICERCA IN Entomologia Agraria Ciclo XXV° Settore Concorsuale di afferenza: 07/D1 Settore Scientifico disciplinare: AGR/11 TITOLO TESI New associations between native parasitoids and exotic insects introduced in Italy and in Europe (Nuove associazioni tra parassitoidi indigeni e insetti esotici neointrodotti in Italia ed in Europa) Presentata da: Dr. Francati Santolo Coordinatore Dottorato Relatore Dr.ssa Maria Luisa Dindo Dr.ssa Maria Luisa Dindo Esame finale anno 2013 Table of contents Introduction ................................................................................................................................... 3 Cacyreus marshalli Butler ............................................................................................................. 5 Introduction ............................................................................................................................... 5 Aims of research .................................................................................................................... 8 Materials and Methods ............................................................................................................. 8 Insect rearing ......................................................................................................................... 8 Acceptance and suitability of Cacyreus marshalli and Galleria mellonella by Exorista larvarum .................................................................................................................................. 9 Acceptance and suitability of Cacyreus marshalli and Galleria mellonella by Brachymeria tibialis ............................................................................................................. 10 Statistical analysis ............................................................................................................... 11 Results ...................................................................................................................................... 11 Acceptance and suitability of Cacyreus marshalli and Galleria mellonella by Exorista larvarum ................................................................................................................................ 11 Acceptance and suitability of Cacyreus marshalli and Galleria mellonella by Brachymeria tibialis ............................................................................................................. 13 Discussion ................................................................................................................................. 14 Dryocosmus kuriphilus Yasumatsu ............................................................................................ 16 Introduction ............................................................................................................................. 16 Aims of research .................................................................................................................. 21 Materials and Methods ........................................................................................................... 21 Statistical analysis ............................................................................................................... 23 Results ...................................................................................................................................... 24 Parasitoids found ................................................................................................................. 24 Parasitoids emerged (quantitative and qualitative data) ................................................. 26 Flight time (time from gall collection to insect emergence) ............................................. 27 Percentage of parasitism ..................................................................................................... 28 Discussion ................................................................................................................................. 29 Harmonia axyridis (Pallas) .......................................................................................................... 31 Introduction ............................................................................................................................. 31 Aims of research .................................................................................................................. 39 Part one: searching parasitoids in the field .......................................................................... 39 Materials and Methods ........................................................................................................... 39 Statistical analysis ............................................................................................................... 40 Results ...................................................................................................................................... 41 Part two: Dinocampus coccinellae (Schrank) ....................................................................... 46 Introduction ............................................................................................................................. 46 Biology .................................................................................................................................. 46 1 Aims of research .................................................................................................................. 50 Materials and Methods ........................................................................................................... 50 Breeding of insects ............................................................................................................... 50 Host acceptance, suitability and development time of Dinocampus coccinellae in Harmonia axyridis ................................................................................................................ 51 Fecundity and longevity of Harmonia axyridis parasitized by Dinocampus coccinellae ............................................................................................................................................... 52 Development of Dinocampus coccinellae on Harmonia axyridis reared with artificial diet ........................................................................................................................................ 53 Statistical analysis ............................................................................................................... 54 Results ...................................................................................................................................... 55 Host acceptance, suitability and development time of Dinocampus coccinellae in Harmonia axyridis ................................................................................................................ 55 Fecundity and longevity of Harmonia axyridis females parasitized by Dinocampus coccinellae ............................................................................................................................ 56 Development of Dinocampus coccinellae in Harmonia axyridis reared with artificial diet ........................................................................................................................................ 58 Discussion ................................................................................................................................. 60 General conclusions ..................................................................................................................... 64 References cited ....................................................................................................................... 66 Photographs were made by myself 2 Introduction The introduction of exotic insect species is one of the most important threats to biodiversity (Colombo and Juker, 2004). This phenomenon may cause both economic and environmental damage, like production losses, increases of pesticide treatments, and modification of native flora and fauna. To prevent these invasions, besides international regulations, there are institutions like the European and Mediterranean Plant Protection Organization (EPPO), with the aim to control imported goods or determine and study and harmful pests. Nevertheless, the introduction of exotic pests is an increasing issue, difficult to control. Classic insect biological control, based on importation of natural enemies from the country of origin of the exotic pest (Caltagirone, 1981), has been successfully used for over 120 years, and use of more than 2000 species of natural enemies has resulted in the control of at least 165 pest species worldwide (van Lenteren et al, 2006). This strategy has provided good results, even in recent time, in the world (Mineo et al, 1999; Hanks et al, 2000; Viggianiet al, 2000; Lambkin, 2004; Quacchia et al, 2008); but has also raised some criticism (Michaud, 2002), as well as concern about the potential negative effects induced by exotic natural enemies on indigenous and, in general, on non-target insects (Howarth, 1997; van Lenteren et al, 2003). The introduction of non- native natural enemies to new landscapes creates novel interactions with native communities; these interactions can adversely affect the demographics of native species, which may in turn prevent non-native species from establishing