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Several studies underline the importance of ecological barriers and differential selection in driving sympatric speciation. Host-associated differentiation (HAD) has been proposed as one of the mechanisms leading to sympatric speciation. However, it is still unclear how common HAD is or which are the factors that could promote it. In particular, not much is known about HAD in predators and parasitoids of herbivorous insects. One of the characteristics postulated to pre-dispose insects to HAD is parthenogenesis as it may favour adaptive responses to particular environments, amplifying selected gene complexes. In this study, we used amplified fragment length polymorphism (AFLP) markers to determine whether HAD is present in two parthenogenetic egg parasitoids attacking the same herbivore species – the pine processionary moth, Thaumetopoea pityocampa (Denis & Schiffermuller) (Lepidoptera: Notodontidae) – on two host Pinus species. A total of 100 loci for 59 individuals sampled in four populations of Baryscapus servadeii (Domenichini) (Hymenoptera: Eulophidae), a specialist parasitoid, and 106 loci for 117 individuals sampled in six populations of Ooencyrtus pityocampae Mercet (Hymenoptera: Encyrtidae), a generalist parasitoid, were analysed. Levels of genetic differentiation were also assessed with an outlier analysis, checking for alleles associated to host plants. No evidence of HAD was detected in any of the two parasitoid species. We hypothesize that both the lack of strict parthenogenetic reproduction and the ectophagous nature of the insect host could explain the absence of HAD. The genetic variation observed in the generalist parasitoid responded to a pattern of local adaptation, whereas no relationship with either host or geography was found in the specialist parasitoid.

Certain cryptic, palatable moths in the families Noctuidae, Notodontidae, Pyralidae, and Sphingidae exhibited responses of apparently protective value 78–100% of the time when touched on the dorsal wing surface. No interaction between the shape of the tactile stimulus and the elicited responses was found. Frequency of response to ventral wing touch was less than 40% with the 2 noctuid species tested in this manner. Aposematic, distasteful moths in the families Arctiidae, Ctenuchidae, Yponomeutidae, exhibited behaviors of potentially defensive value 10–52% of the time when touched on the dorsal wing surface. The unpalatable moths had higher thresholds for release of protective behavior. Members of both groups exhibited angled flights, straight flights, dropping with catalepsis (i.e. “playing-dead”), and no visible response, but with the frequencies of these responses significantly different. Only certain unpalatable species produced a display without flight or dropping after the tactile stimulus. Flight durations and types were very variable. The mode of the flight durations elicited in palatable moths was 0.8 sec but 0 sec in unpalatable moths. Then the palatability of each moth species was determined using local wild-caught and hand-reared birds. Common grackles (Quiscalus quiscula (L.)) seemed more likely to accept moths unpalatable to other birds. There may be broad correlations between taxonomic groupings and the total defensive ensemble present in a moth. However, convergent strategies between phylogenetically unrelated moth species were observed. RESUME Comparaison des comportements defensifs de quelques papillons; implications sur les interactions proie-predateur Certains papillons caches et appetissants, des familles Noctuidae, Notodontidae, Pyralidae et Sphingidae, presentent a 78–100% des reactions, apparemment de valeur protectrice, quand la surface dorsale de leurs ailes anterieures a ete touchee. Je n'ai pu trouver de correlation entre la force du stimulus tactile et la reponse induite. La frequence de la reponse a un contact avec la face ventrale de leurs ailes posterieures a ete inferieure a 40% chez les deux especes de Noctuelles testees de cette facon. Des papillons aposematiques et rebutants des familles Arctiidae, Ctenuchidae, Yponomeutidae, ont presente des comportement potentiellement protecteurs dans 10 a 52% des cas quand la surface dorsale de leurs ailes anterieures a ete touchee. Dans ces essais, les seuils inducteurs d'un comportement protecteur etaient plus eleves chez les especes rebutantes. Les membres des 2 groupes ont presente des vols angulaires, des vols directs, des chutes avec catalepsie, et des reponses indiscernables mais avec des frequences significativement differentes entre les 2 groupes. Seules quelques especes rebutantes ont presente une reaction sans vol ni chute apres le stimulus tactile. Les durees et les formes des vols etaient extrěmement variables. Les modes des durees des vols induits etaient de 0,8 sec chez tes papillons appetissants contre 0 sec chez les rebutants. Une fois notees les reponses comportementales induites apres les stimulus, l'appetence de chaque espece de papillon a ete determinee en utilisant des oiseaux captures localement et eleves. Quiscalus quiscula (L.) est apparu le plus capable d'accepter des papillons consideres comme rebutants par les autres oiseaux. Il peut y avoir des correlations generales entre la position taxonomique et l'ensemble du systeme defensif d'un papillon. Cependant, j'ai observe des strategies convergentes entre des especes sans relations phylogenetiques.