Jesús Selfa

Phylogeny of the parasitic wasp subfamily Charipinae (Hymenoptera, Cynipoidea, Figitidae)

The Charipinae are a major group of hyperparasitoids of Hemiptera. Here, we present the first cladistic analysis of this subfamilys internal relationships, based on 96 morphological characters of adults. The data matrix was analysed using uniformly weighted parsimony. The effects of using alternative weighting schemes were explored by performing additional searches employing implied weights criteria. One of the caveats of implied weights analysis is that it lacks an objective criterion for selecting the value of the concavity function. In the present study, differential weighting was used to explore the sensitivity of our results to the alternative assumptions made in the analysis and to select one of the most parsimonious trees under equal weights, which we regard as being the hypothesis that minimizes the amount of ad hoc assumptions. The validity of the two existing tribes and the monophyly of all the genera of Charipinae were tested, in particular the cosmopolitan and highly species‐rich Alloxysta and Phaenoglyphis, which appear repeatedly in ecological and biochemical studies of host–parasitoid associations. The evolution of several major characters and the relationships between genera are discussed. On the basis of the phylogenetic results, we discuss a number of taxonomic issues. A new classification of the subfamily is proposed in which no tribes are maintained, Carvercharips is synonymyzed with Alloxysta, and the creation of a new genus from Nepal is justified. Our analysis points to the need for a world revision of the basal genus Phaenoglyphis, which is shown as paraphyletic.

Female-female attraction influences nest establishment in the digger wasp Stizus continuus (Hymenoptera: Crabronidae)

Although digger wasps are good models for the study of nest site selection, the behaviour of females in relation to time of nest establishment has rarely been considered despite this being the key to discrimination between substrate availability-based and a female attraction-based selection. We carried out a study on nest establishment by the digger wasp Stizus continuus (Klug), giving to all nests dug by the wasps both spatial (nearest neighbour distance to nests, proximity of vegetation, soil hardness) and temporal (day of excavation) attributes. Stizus continuus females dug more nests under bush edges, where the soil was much softer. There was no tendency for females to maximize distance between nests at the moment of establishment. On the contrary, as shown by different nearest neighbour statistics, females preferentially tend to dig close to conspecific nests (if one considers both the whole study area and two subareas free of vegetation and at different times of the nesting season). Moreover, those nests that were active (still provisioned) attracted more females than the inactive nests at the moment of nest establishment. We conclude that female S. continuus are attracted by conspecifics at the moment of nest establishment and that clumped patterns of nests are a result of such social attraction rather than a result of limited available substrate; moreover, such attraction could be better detected when comparative analyses are employed and best at a multiple-scale view.

Winter feeding leads to a shifted phenology in the browntail moth Euproctis chrysorrhoea on the evergreen strawberry tree Arbutus unedo.

1 The browntail moth Euproctis chrysorrhoea is a highly polyphagous univoltine forest pest. Although its young larvae usually overwinter in diapause from early autumn to the beginning of spring, winter larval feeding has been reported when this species feeds on the evergreen woody shrub strawberry tree Arbutus unedo. 2 The present study investigated life‐history traits of four populations of E. chrysorrhoea feeding on A. unedo, including phenology of the different life stages, larval feeding activity and diapause incidence. By modelling the relationship between larval size and host plant leaf persistence, elevation and mean annual temperature, we also studied larval development in ten populations of this species sampled from a range of geographical locations in Spain, from both A. unedo and deciduous hosts. 3 The results obtained revealed that on A. unedo, E. chrysorrhoea phenology has shifted: from October to March, A. unedo larvae doubled their size, whereas, on deciduous Ulmus minor and Quercus faginea, larval size did not change. General linear models demonstrated that such differences were not related to environmental variables. We also found that on A. unedo larval feeding was arrested for 2 months, with this period representing a true diapause. 4 The results obtained in the present study suggest that E. chrysorrhoea populations are phenologically adapted to their local host plants, and that the presence of foliage is a key element in the phenological shift reported on A. unedo. These results may have implications with respect to the formation of E. chrysorrhoea host races.

Temporal asynchrony and spatial co-occurrence with the host: the foraging patterns of Nemka viduata, a parasitoid of digger wasps (Hymenoptera: Mutillidae and Crabronidae).

Studies which quantitatively analyse how aculeate parasitoids exploit their window of opportunity to find and attack a host are scarce, despite the recognized importance of parasitic pressure as a driving force that promotes aggregate nesting in their hosts. We have studied the activity and behaviour of the velvet ant Nemka viduata, an ectoparasitoid of immature stages of the digger wasp Stizus continuus. Due to the resource exploited by the parasitoid (mature larvae and prepupae), and in general agreement with basic optimal foraging theory, we expected a major activity at late stages of the host seasonal provisioning period, an independence from the host daily provisioning patterns and a spatial positive association with host nest density. In accordance with these predictions, during the season, the parasitoid resulted was more active at the end of the host provisioning period, and across the day, it showed an inverse quadratic pattern of activity, in contrast to the positive one shown by the host. Thus, at both temporal scales, N. viduata activity was highly asynchronous with that of the host. At a spatial scale, however, the activity of the velvet ants was correlated with host nest density, although there is weak evidence suggesting that areas of high host density suffered from a higher rate of parasitism. Multivariate analyses confirmed a number of relevant factors associated with velvet ants’ activity, including nest density (positive), air temperature and the hour of the day (both negative). In addition, the activity of both male S. continuus and male N. viduata entered in the models in association with female parasitoid’s activity, probably because of their mating strategy.

Phaenoglyphis villosa (Hartig 1841) (Hymenoptera: Figitidae: Charipinae): a complex of species or a single but very variable species?

Abstract The status of Phaenoglyphis villosa (Hartig 1841), the only species in this genus with the radial cell partially open along the wing margin, is discussed. A complete synonymy list, redescription, morphological variability and some biological peculiarities of P. villosa are given. After studying numerous specimens from different countries from all continents, we concluded that this species is either very variable or might be a complex of sibling species. Auloxysta tarsata Belizin 1973, is a new synonym of P. villosa and P. dolichocera (Cameron 1889) was re-established as a valid species.

Age and size thresholds for pupation and developmental polymorphism in the browntail moth, Euproctis chrysorrhoea (Lepidoptera: Lymantriidae), under conditions that either emulate diapause or prevent it

Size and age thresholds for pupation are important life history traits of insects. They are the ultimate consequences of the underlying physiological mechanism that optimize resource allocation. Such thresholds may have a plastic response under time-varying environmental conditions, developmental polymorphism (i.e., plasticity in the number of instars before pupation) being a common strategy adopted by insects to overcome this challenging situation. In this study, we systematically explore the variables related with both age and size thresholds for pupation and developmental polymorphism in the browntail moth, Euproctis chrysorrhoea (Lepidoptera: Lymantriidae), by rearing a group of caterpillars under conditions that either emulate larval diapause or prevent it. As an innovative approach, we evaluated the importance of predictor variables by means of generalized linear modeling in a multi-model inference framework. Our results show that (i) rearing conditions affect fitness, (ii) rearing conditions, size of hatchlings, size and age at maturity and sex are related to the number of instars before pupation, and (iii) there are both age and size thresholds for pupation which differ between sexes and between larvae reared under different conditions. Results are discussed in the context of lepidopteran plasticity in life history traits and its relationship with optimal molting strategies.

Emergence and dispersal relative to natal nest in the digger wasp Stizus continuus (Hymenoptera: Crabronidae)

The position of the emerging point has rarely been investigated as a factor possibly affecting the future nest settlement behaviour in Hymenoptera, in particular within nest aggregations. We studied the emergence and dispersion patterns of the digger wasp Stizus continuus. Individuals emerged daily in clumped patterns, possibly revealing a certain synchrony of emergence from the same nests, and protandry appeared both at seasonal and daily level. Differences between the number of females that nested relatively close or far from their emergence holes (EH) were either significant or not, depending on the year, and observed dispersal distances from the natal nests did not differ from those obtained by random simulations. By contrast, females nested close to the nearest conspecific nest. Size did not affect the dispersion patterns. EH are thus not important cues for nest establishment, and conspecific nests are probably the key cue for nest-founding females. In addition, males did not prefer to establish territories close to their natal nest.

First Host Record for Acanthaegilips (Hymenoptera: Figitidae: Anacharitinae) and Description of a New Species From Venezuela

Abstract A new Acanthaegilips species from Venezuela is described, i.e., Acanthaegilips notiobiellus sp. nov. Diagnostic characters of the new species and data about its biology, distribution and morphological variability are presented. We report here the first known host of Acanthaegilips as Notiobiella cixiiformis (Gerstaecker, 1888) (Neuroptera: Hemerobiidae).

Charipinae fauna (Hymenoptera: Figitidae) from Asia with a description of 11 new species

BackgroundThe Charipinae from the Asian continent has been poorly studied. Previous to this study, 28 species of Charipinae had been mentioned: 19 of Alloxysta, 5 of Dilyta, 1 of Lobopterocharips, and 3 of Phaenoglyphis.ResultsThe Charipinae fauna from Asia was studied. Eleven new species are described: Alloxysta asiatica Ferrer-Suay and Pujade-Villar sp. nov., Alloxysta nepalica Ferrer-Suay and Pujade-Villar sp. nov., Alloxysta nippona Ferrer-Suay and Pujade-Villar sp. nov., Alloxysta paretasmartinezi Ferrer-Suay and Pujade-Villar sp. nov., Alloxysta pilosa Ferrer-Suay and Pujade-Villar sp. nov., Alloxysta samurai Ferrer-Suay and Pujade-Villar sp. nov., Alloxysta sharkeyi Ferrer-Suay and Pujade-Villar sp. nov., Phaenoglyphis asiatica Ferrer-Suay and Pujade-Villar sp. nov., Phaenoglyphis chinensis Ferrer-Suay and Pujade-Villar sp. nov., Phaenoglyphis indica Ferrer-Suay and Pujade-Villar sp. nov., and Phaenoglyphis japonica Ferrer-Suay and Pujade-Villar sp. nov.New records are given from the Eastern Palaearctic and Oriental regions for Alloxysta arcuata (Kieffer, 1902), Alloxysta brevis (Thomson, 1862), Alloxysta castanea (Hartig, 1841), Alloxysta consobrina (Zetterstedt, 1838), Alloxysta melanogaster (Hartig, 1840), Alloxysta obscurata (Hartig, 1840), Alloxysta pallidicornis (Curtis, 1838), Alloxysta pusilla (Kieffer, 1902), Alloxysta sawoniewiczi (Kierych, 1988), Alloxysta tscheki (Giraud, 1860), Alloxysta victrix (Westwood, 1833), Alloxysta xanthopa (Thomson, 1862), Phaenoglyphis longicornis (Hartig, 1840), Phaenoglyphis stricta (Thomson, 1877), Phaenoglyphis villosa (Hartig, 1841), and Phaenoglyphis xanthochroa Förster, 1869. Alloxysta ishizawai (Watanabe, 1950) is here synonymized with Phaenoglyphis ruficornis (Förster, 1869) and Alloxysta chinensis Fülöp & Mikó, 2013 with A. sawoniewiczi. Alloxysta simplex (Watanabe, 1950) is considered as nomen dubium and Phaenoglyphis bangalorensis Kurian, 1953 is considered to be incertae sedis. A key to the identity of all of the Charipinae from Asia is given. All new species are illustrated.ConclusionsThe knowledge about the Charipinae from Asia has been greatly improved, with many new records established and new species described. Currently, there are 43 Charipinae species: 27 of Alloxysta, 5 of Dilyta, 1 of Lobopterocharips and 10 of Phaenoglyphis.

Food load manipulation ability shapes flight morphology in females of central-place foraging Hymenoptera

BackgroundEcological constraints related to foraging are expected to affect the evolution of morphological traits relevant to food capture, manipulation and transport. Females of central-place foraging Hymenoptera vary in their food load manipulation ability. Bees and social wasps modulate the amount of food taken per foraging trip (in terms of e.g. number of pollen grains or parts of prey), while solitary wasps carry exclusively entire prey items. We hypothesized that the foraging constraints acting on females of the latter species, imposed by the upper limit to the load size they are able to transport in flight, should promote the evolution of a greater load-lifting capacity and manoeuvrability, specifically in terms of greater flight muscle to body mass ratio and lower wing loading.ResultsOur comparative study of 28 species confirms that, accounting for shared ancestry, female flight muscle ratio was significantly higher and wing loading lower in species taking entire prey compared to those that are able to modulate load size. Body mass had no effect on flight muscle ratio, though it strongly and negatively co-varied with wing loading. Across species, flight muscle ratio and wing loading were negatively correlated, suggesting coevolution of these traits.ConclusionsNatural selection has led to the coevolution of resource load manipulation ability and morphological traits affecting flying ability with additional loads in females of central-place foraging Hymenoptera. Release from load-carrying constraints related to foraging, which took place with the evolution of food load manipulation ability, has selected against the maintenance of a powerful flight apparatus. This could be the case since investment in flight muscles may have to be traded against other life-history traits, such as reproductive investment.