title: Contrasting Patterns of Host Adaptation in Two Egg Parasitoids of the Pine Processionary Moth (Lepidoptera: Thaumetopoeidae).
abstract: Adaptation of parasitoids to their phytophagous host is often mediated by environmental conditions and by the food plant of the phytophagous host. Therefore, the host food plant can indirectly affect the survival and fitness of parasitoids that also attack quiescent host stages, such as eggs, in which the resources available to the immature parasitoid stages are limited. Our aim was to investigate how two egg parasitoid species of the pine processionary moth, Thaumetopoea pityocampa (Denis & Schiffermüller), respond to variations in egg traits at the extremes of a west-to-east geographic gradient in northern Italy. We considered one specialist [Baryscapus servadeii (Domenichini)] and one generalist [Ooencyrtus pityocampae (Mercet)] parasitoid, which reproduce mainly by thelytokous parthenogenesis and are common throughout the whole range of this pest. The size and shell structure of the pine processionary moth eggs were studied under light microscopy and tested experimentally under controlled conditions. We can conclude that 1) the pine processionary moth egg shell thickness is inversely proportional to the parasitism performance; 2) the larger eggs from the pine processionary moth eastern population produce parasitoid females of a larger size, which have greater realized fecundity; 3) the generalist parasitoid performs successfully with either the "home" or "away" (i.e., from both extremes of the geographic gradient) pine processionary moth eggs, which is not the case for the specialist parasitoid. The implications of these responses in the regulation of phytophagous populations are numerous and should be considered in population dynamics studies and pest management programs.
authors: Dipartimento di Scienze Agrarie, Alimentari ed Ambientali, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
authors: Sara
authors: S
authors: Ruschioni
authors: Dipartimento di Scienze Agrarie, Alimentari ed Ambientali, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy. p.riolo@univpm.it.
authors: Paola
authors: P
authors: Riolo
authors: Dipartimento di Scienze Agrarie, Alimentari ed Ambientali, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
authors: Nunzio
authors: N
authors: Isidoro
authors: Dipartimento di Scienze Agrarie, Alimentari, Università degli Studi di Perugia, Borgo XX Giugno, 74, 06121 Perugia, Italy.
authors: Roberto
authors: R
authors: Romani
authors: DAFNAE - Entomologia, Università degli Studi di Padova, Via dell'Università 16, 35020 Legnaro (PD), Italy.
authors: Edoardo
authors: E
authors: Petrucco-Toffolo
authors: DAFNAE - Entomologia, Università degli Studi di Padova, Via dell'Università 16, 35020 Legnaro (PD), Italy.
authors: Daniel
authors: D
authors: Zovi
authors: DAFNAE - Entomologia, Università degli Studi di Padova, Via dell'Università 16, 35020 Legnaro (PD), Italy.
authors: Andrea
authors: A
authors: Battisti
mesh_terms: D000222:Adaptation, Physiological; D000704:Analysis of Variance; D000818:Animals; D049628:Body Size; D017753:Ecosystem; D005260:Female; D005298:Fertility; D007558:Italy; D009036:Moths / Q000469:parasitology* / Q000502:physiology*; D010063:Ovum / Q000469:parasitology / Q000648:ultrastructure*; D012098:Reproduction / Q000502:physiology; D014863:Wasps / Q000502:physiology*
keywords: Baryscapus servadeii; Ooencyrtus pityocampae; Thaumetopoea pityocampae; host adaptation