Escaping the evolutionary trap: Can size-related contest advantage compensate for juvenile mortality disadvantage when parasitoids develop in unnatural invasive hosts?

The quality of hosts for a parasitoid wasp may be influenced by attributes such as host size or species, with high quality for successful development usually coincident with high quality for larger offspring. This is not always the case: for the Scelionid wasp Trissolcus basalis, oviposition in eggs of the Brown Marmorated Stink Bug, Halyomorpha halys, rather than of the normal host, the Southern Green Stink Bug, Nezara viridula, leads to lower offspring survival, but survivors can be unusually large. Adult female T. basalis engage in contests for host access. As larger contestants are typically favoured in contests between parasitoids, the larger size of surviving offspring may compensate for the mortality of others. We construct a general game-theoretic model to explore whether size advantage can sustain a maternal preference to utilize a more deadly host species. We find that size advantage alone is unlikely to sustain a shift in host preference, yet such an outcome is possible when size asymmetries act simultaneously with advantages in host possession (ownership effect). Halyomorpha halys is an invasive pest of major agro-economic importance in Europe and the Americas, and use of its eggs as hosts by native parasitoids such as T. basalis has been seen as an evolutionary trap due to their high developmental mortality. Our model suggests that the recently discovered effect of host choice on offspring size may provide an escape from the trap via effects on contest biology of T. basalis which could foster a more stable association with H. halys. An evolutionary shift in the reproductive value of H. halys could increase the efficiency of T. basalis as a biological control agent of this invasive stink bug pest

Microbial symbionts of parasitoids

Parasitoids depend on other insects for the development of their offspring. Their eggs are laid in or on a host insect that is consumed during juvenile development. Parasitoids harbor a diversity of microbial symbionts including viruses, bacteria, and fungi. In contrast to symbionts of herbivorous and hematophagous insects, parasitoid symbionts do not provide nutrients. Instead, they are involved in parasitoid reproduction, suppression of host immune responses, and manipulation of the behavior of herbivorous hosts. Moreover, recent research has shown that parasitoid symbionts such as polydnaviruses may also influence plant-mediated interactions among members of plant-associated communities at different trophic levels, such as herbivores, parasitoids, and hyperparasitoids. This implies that these symbionts have a much more extended phenotype than previously thought. This review focuses on the effects of parasitoid symbionts on direct and indirect species interactions and the consequences for community ecology

Responsabilità e merito nel mondo antico. Retorica, Giustizia, Società. Atti del Convegno di Palermo, 10-11 febbraio 2016

"Merit and Responsability. A Study in Greek Values" è il titolo di un volume pubblicato ormai cinquant’anni or sono da W.H. Adkins. L’autore metteva in evidenza il mancato sviluppo, nel mondo greco, del concetto di responsabilità morale a vantaggio della nozione di arete, postulando la distanza irriducibile tra l’etica greca e quella contemporanea. Quelle di responsabilità e merito sono in effetti categorie su cui la cultura contemporanea si è notevolmente esercitata e continua a interrogarsi, soprattutto in questi anni caratterizzati da un sentimento di incertezza in tutti gli aspetti della nostra esistenza e in particolare nell’agire quotidiano e nelle relazioni sociali. E tuttavia si tratta di un insieme di riflessioni su cui il pensiero antico molto ha ancora da dirci, spesso con una complessità e una sensibilità sorprendenti

Responsabilit\ue0 e merito nel mondo antico. Retorica, Giustizia, Societ\ue0. Atti del Convegno di Palermo, 10-11 febbraio 2016

"Merit and Responsability. A Study in Greek Values" \ue8 il titolo di un volume pubblicato ormai cinquant\u2019anni or sono da W.H. Adkins. L\u2019autore metteva in evidenza il mancato sviluppo, nel mondo greco, del concetto di responsabilit\ue0 morale a vantaggio della nozione di arete, postulando la distanza irriducibile tra l\u2019etica greca e quella contemporanea. Quelle di responsabilit\ue0 e merito sono in effetti categorie su cui la cultura contemporanea si \ue8 notevolmente esercitata e continua a interrogarsi, soprattutto in questi anni caratterizzati da un sentimento di incertezza in tutti gli aspetti della nostra esistenza e in particolare nell\u2019agire quotidiano e nelle relazioni sociali. E tuttavia si tratta di un insieme di riflessioni su cui il pensiero antico molto ha ancora da dirci, spesso con una complessit\ue0 e una sensibilit\ue0 sorprendenti

Presentazione

Introduzione agli atti del convegno Responsabilit\ue0 e merito nel mondo antico. Retorica, Giustizia, Societ\ue0 (Palermo, 10-11 febbraio 2016)Introduction to the proceedings of the conference "Responsibility and Merit in the Ancient World. Rhetoric, Justice, Society (Palermo, 10-11 February

Hyperparasitoids exploit herbivore-induced plant volatiles during host location to assess host quality and non-host identity

Although consumers often rely on chemical information to optimize their foraging strategies, it is poorly understood how top carnivores above the third trophic level find resources in heterogeneous environments. Hyperparasitoids are a common group of organisms in the fourth trophic level that lay their eggs in or on the body of other parasitoid hosts. Such top carnivores use herbivore-induced plant volatiles (HIPVs) to find caterpillars containing parasitoid host larvae. Hyperparasitoids forage in complex environments where hosts of different quality may be present alongside non-host parasitoid species, each of which can develop in multiple herbivore species. Because both the identity of the herbivore species and its parasitization status can affect the composition of HIPV emission, hyperparasitoids encounter considerable variation in HIPVs during host location. Here, we combined laboratory and field experiments to investigate the role of HIPVs in host selection of hyperparasitoids that search for hosts in a multi-parasitoid multi-herbivore context. In a wild Brassica oleracea-based food web, the hyperparasitoid Lysibia nana preferred HIPVs emitted in response to caterpillars parasitized by the gregarious host Cotesia glomerata over the non-host Hyposoter ebeninus. However, no plant-mediated discrimination occurred between the solitary host C. rubecula and the non-host H. ebeninus. Under both laboratory and field conditions, hyperparasitoid responses were not affected by the herbivore species (Pieris brassicae or P. rapae) in which the three primary parasitoid species developed. Our study shows that HIPVs are an important source of information within multitrophic interaction networks allowing hyperparasitoids to find their preferred hosts in heterogeneous environments

Towards the statistical construction of hybrid development methods

Hardly any software development process is used as prescribed by authors or standards. Regardless of company size or industry sector, a majority of project teams and companies use hybrid development methods (short: hybrid methods) that combine different development methods and practices. Even though such hybrid methods are highly individualized, a common understanding of how to systematically construct synergetic practices is missing. In this article, we make a first step towards a statistical construction procedure for hybrid methods. Grounded in 1467 data points from a large‐scale practitioner survey, we study the question: What are hybrid methods made of and how can they be systematically constructed? Our findings show that only eight methods and few practices build the core of modern software development. Using an 85% agreement level in the participants\u27 selections, we provide examples illustrating how hybrid methods can be characterized by the practices they are made of. Furthermore, using this characterization, we develop an initial construction procedure, which allows for defining a method frame and enriching it incrementally to devise a hybrid method using ranked sets of practice

Semiochemical exploitation of host-associated cues by seven Melittobia parasitoid species: Behavioral and phylogenetic implications

Chemical compounds (infochemicals or semiochemicals) play an important role both in intra-specific and inter-specific communication. For example, chemical cues appear to play a key role in the host selection process adopted by insect parasitoids. In recent years significant advances have been made in order to understand the chemical ecology of insect parasitoids. However, little information is available about the evolution of semiochemical use in the host location process of insect parasitoids. Here we investigated the strategy adopted by seven closely related parasitoid species in the genus Melittobia when foraging for four different suitable hosts. By using an integrated approach that combined olfactometer bioassays and phylogenetic investigations, we found that: (1) exploitation of host-derived semiochemicals is widespread in the Melittobia genus; (2) there is specificity of attraction toward the different host species tested; in particular, the early-branching species in the Melittobia genus are attracted to odors associated with leaf cutting bees (Megachile rotundata) whereas the most-diverged species are attracted to odors associated with solitary mud dauber wasps (Trypoxyilon politum). Regardless of the phylogenetic relationships, no Melittobia species exhibited attraction toward odors of factitious laboratory hosts (i.e., the flesh fly Sarcophaga bullata). Interestingly, five Melittobia species are also attracted by odors associated with honeybees hosts which indicate that these parasitoids could be potential pests of honeybees. Our study shed light on the host location within the Melittobia genus and represents a first attempt to understand semiochemical use in an evolutionary perspective in the context of parasitoids' foraging behavior