title: Fitness costs of intrinsic competition in two egg parasitoids of a true bug.
abstract: Intrinsic competition in insect parasitoids occurs when supernumerary larvae develop in the same host as consequence of multiple ovipositions by females of the same species (intra-specific competition) or by females of different species (inter-specific competition). Studies on intrinsic competition have mainly focused on understanding the factors that play a role in the outcome of competition, while fitness-related effects for the parasitoid surviving the competition have been poorly investigated, especially in egg parasitoids. Interestingly, even the winning parasitoid can experience fitness costs due to larval development in a host in which multiple factors have been injected by the ovipositing females or released by their larvae. In this paper we studied fitness-related traits associated with intra- and inter-specific competition between Trissolcus basalis (Wollaston) and Ooencyrtus telenomicida (Vassiliev), the main egg parasitoids associated with the southern green stink bug Nezara viridula (L.) in Italy. We investigated the impact of intrinsic competition for the surviving parasitoid in terms of body size, developmental time, number and size of oocytes. Our results indicated that T. basalis adults did not experience fitness-related costs when surviving intra-specific competition; however, adults were smaller, took longer to develop and females produced fewer oocytes after surviving inter-specific competition. A different outcome was found for O. telenomicida where the emerging females were smaller, produced fewer and smaller oocytes when suffering intra-specific competition whereas no fitness costs were found when adults survived inter-specific competition. These results support the hypothesis that the impact of intrinsic competition in egg parasitoids depends on the severity of the competitive interaction, as fitness costs were more pronounced when the surviving parasitoid interacted with the most detrimental competitor.
authors.affiliation: Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Viale delle Scienze edificio 5, 90128 Palermo, Italy. Electronic address: cusumanoantonino@unipa.it.
authors.forename: Antonino
authors.initials: A
authors.lastname: Cusumano
authors.affiliation: Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Viale delle Scienze edificio 5, 90128 Palermo, Italy.
authors.forename: Ezio
authors.initials: E
authors.lastname: Peri
authors.affiliation: Horticultural Research and Development Centre, Agriculture and Agri-Food Canada, 430 Boul. Gouin, St-Jean-sur-Richelieu, Quebec J3B 3E6, Canada.
authors.forename: Guy
authors.initials: G
authors.lastname: Boivin
authors.affiliation: Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Viale delle Scienze edificio 5, 90128 Palermo, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Colazza
mesh_terms: D000818:Animals; D049628:Body Size; D003163:Competitive Behavior; D005260:Female; D020062:Heteroptera / Q000469:parasitology*; D006790:Host-Parasite Interactions; D007558:Italy; D008297:Male; D010058:Oviposition; D010063:Ovum / Q000469:parasitology; D014863:Wasps / Q000254:growth & development / Q000502:physiology*
keywords: Developmental time; Host quality; Nezara viridula; Oocyte; Ooencyrtus telenomicida; Size; Trissolcus basalis