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Osmia caerulescens is a generalist solitary bee well‐adapted to altered anthropogenic environments, and the kleptoparasitic wasp Sapyga quinquepunctata has been cited among its natural enemies. We analysed offspring characteristics of O. caerulescens and S. quinquepunctata, at population and individual levels, and compared these characteristics between sunny and shady aspects and between two zones within the valley that differed in landscape complexity (simple and complex zones). The offspring production of O. caerulescens was higher in sunny aspect at population and individual levels while S. quinquepunctata was positively associated with the zone with a lower proportion of agricultural land (complex zone). We did not detect a relationship between number of brood cells parasitised and number of brood cells established by host. Despite the parasitism being higher in the area with favourable characteristics for both species, the reproductive success of O. caerulescens did not show signs of reduction. At the individual level, nests with fewer brood cells were more likely to be parasitised. Studying the relationship of environmental factors and landscape features at population and individual levels provides a better understanding of how these characteristics could be driving the offspring production of the solitary bee and their ecological interactions.

de Paz, Víctor, Baños-Picón, Laura, Rosas-Ramos, Natalia, Tobajas, Estefanía, Tormos, José, Asís, Josep D. (2021): The role of artificial ponds in maintaining dragonfly populations in an intensified farmland landscape. A case of study in Zamora, Spain. Journal of Natural History 54 (37-38): 2439-2454, DOI: 10.1080/00222933.2020.1850901, URL: http://dx.doi.org/10.1080/00222933.2020.1850901

The development of reliable evaluation schemes is essential to assess the status of biodiversity, particularly under the current scenario of biodiversity loss across agroecosystems. In these areas, ecological infrastructures contribute heavily to enhance biodiversity and underlying services, and their contribution depends on their ecological quality. Based on the questionnaire by Boller et al. (2004) for temperate areas, we propose a reliable tool for evaluating the ecological quality of woodland patches, hedges and grass strips associated with Mediterranean agroecosystems (simplified questionnaire). Since management practices and organism composition vary across geographical regions, the implementation of evaluation tools adapted to other geographical regions is deemed necessary. The development of the simplified questionnaire followed a five-steps' approach: (i) application of the Boller's questionnaire in the field; (ii) Boller's questionnaire adaptation; (iii) development of the simplified questionnaire through the assessment and simplification of Boller's questionnaire; (iv) evaluation of the simplified questionnaire effectiveness; (v) proposal of plant indicator species associated to the different quality levels obtained from applying the simplified questionnaire as an additional tool for quality assessment that complements such questionnaire. A total of 482 ecological infrastructures were evaluated in La Rioja (Spain) using the Boller's questionnaire, and their vegetation assessed by inventorying their floristic composition. We analyzed the relationship between plant species richness, as a proxy of the overall biodiversity, and the different items included in the Boller's questionnaire. According to these results, a new questionnaire was proposed, in which only variables significantly related to plant species richness were included. Our results showed that the quality groups established when applying our simplified questionnaire were more consistent than those obtained when using the Boller's questionnaire. Overall, 35 plant species resulted as significant indicators for the four levels of quality obtained from applying the simplified questionnaire. We point out that the assessment tool based on simplified questionnaire is straightforward and easy to apply by both experts and non-experts. We also propose the simplified questionnaire development procedure as a guide to create evaluation questionnaires adapted to other ecological infrastructure types.

In several groups of insects, body structures related to feeding and oviposition are known to have a hardened cuticle by incorporation of transition metals. However, a functional link between metal enrichment and ecological pressures (i.e., adaptation) has been only rarely shown, opening the possibility that in some lineages, the evolutionary history may account for most of the observed variation (i.e., phylogenetic constraint). Here, we addressed this question in the hyper-diverse Hymenoptera (bees, wasps, ants, and sawflies), in which Zn and/or Mn have been found enriching the mandibles of a number of species. Across 87 species spanning most of the extant superfamilies, we found Zn enrichment to be widespread (57 species). Although lacking in the most primitive “Symphyta”, our ancestral state reconstruction was not conclusive in determining whether Zn enrichment was a derived state for the complete order, but it was clearly the ancestral state for the Apocrita, where it was lost in few lineages, notably in Aculeata (where it was then reacquired at least three times). Mn, on the other hand, occurred very rarely in mandibles (10 species). Our comparative analysis revealed a strong phylogenetic effect explaining most Zn % and Mn % variation in mandibles. Additionally, species with herbivorous larvae were less prone to have Zn (but not Mn) than those with carnivorous larvae, although a causal effect of diet on this trait was unlikely. Furthermore, species emerging from concealed vs. unconcealed development sites have similar likelihood to have metal-enriched mandibles. Evolutionary history seems to constrain metal enrichment in hymenopteran mandibles, yet the few observed losses and regains of this trait during evolution claim for deeper investigations on the role of alternative, here untested, ecological pressures., The study was funded by a SECTI post-doctoral contract from the Universidad de Castilla-La Mancha (to CP), by a SYNTHESYS grant from the European Union (ES-TAF 5333) (to CP),and by the following funded projects from Ministerio de Economía, Industria y Competitividad (España): CGL2017-83046-P (to CP and CO) and CGL2010-16730 (to JT and JDA).

Within agricultural landscapes, ecological infrastructures like hedges, grass strips or wildflower strips, can be essential for the provision of ecosystem services, and their role in maintaining and promoting functional biodiversity has been widely demonstrated in temperate zones. However, although the Mediterranean basin is considered to be a biodiversity hotspot, there is a lack of information about the role played there by these elements in biodiversity conservation. Spiders are generalist predators that are considered important components of biodiversity in vineyard ecosystems, where they can play a prominent role in the natural control of pest populations. Nevertheless, the influence that ecological infrastructures have on driving spider assemblages in Mediterranean vineyard agroecosystems is practically unknown. In a study conducted in an area exclusively devoted to traditional vineyard crops (La Rioja, northern Spain), we analyzed spider assemblages across four types of linear ecological infrastructures differing in their structural diversity: woodland hedges, rosaceous hedges, grass strips and flower strips. Spider assemblages were examined across three levels of organization (taxon, guild and body-size group). Taxonomic composition was different among infrastructures, as was guild composition and the distribution of body sizes. Abundance and richness of spiders were higher in more structurally diverse infrastructures. The response to habitat type differed among guilds but, overall, higher densities of spiders from different guilds were found in hedges. Body-size groups had a more balanced distribution in strips and hedges with higher levels of structural diversity. Our results suggest that it is crucial to preserve varied typologies of ecological infrastructures, with an optimal level of complexity and heterogeneity, to maintain diversified assemblages of these important biocontrol agents within Mediterranean vineyard agroecosystems.

The effectiveness of natural enemies in controlling pests may be determined by many traits linked to their ability to regulate the density of their prey. In this respect, the phenomenon of pseudoparasitism, in which female parasitoids reject a host after inserting their ovipositor into it, is fairly common among hymenopteran parasitoids. However, in spite of this its effect on hosts is rarely reported in entomological and biological control literature. For this reason, in the present study, the pseudoparasitism by the parasitoid Spalangia cameroni Perkins of the Mediterranean pest Ceratitis capitata (Wiedemann) and its effect on several biological parameters of the host were studied under laboratory conditions. The results indicate that the percentage pseudoparasitism by S. cameroni of medfly in the laboratory is high, even slightly higher than host-feeding, which is commonly used to evaluate the potential of parasitoids as biological control agents. In addition, the adults that emerge from pseudoparasitized medfly pupae have a male-biased sex ratio, low levels of survival and are frequently damaged, which results in small adults and an inability to mate successfully. In conclusion, our results indicate that pseudoparasitism is common and enhances the effectiveness of S. cameroni attacking medfly, which highlights the importance of this phenomenon when selecting parasitoids to be included in a biological control programme.

The parasitoid Spalangia cameroni Perkins is a commercially available biocontrol agent of filth flies that is also used, especially through inundative releases, for the biological control of fruit flies. Adequate host selection behaviour is essential to the reproductive performance of parasitoid females, and innate and learned host species preferences play a key role in it. Therefore, in this study, the effect of natal host species [the medfly Ceratitis capitata (Wiedemann) or the house fly Musca domestica Linnaeus], either an innate or learned host, on later S. cameroni female host preference was assessed. In both innate and learned host preference experiments, most examined variables (realized fecundity, total progeny, induced mortality and sex ratio) did not differ significantly for the parasitoid line (parasitoids reared on medfly or house fly), but they did differ for the two attacked hosts, with the variables being higher in the house fly. In the learned host preference experiment, these variables did not differ significantly with experience (i.e., the host species on which parasitoids had performed previous parasitic activity). Superparasitism (the number of pupae with supernumerary eggs) differed significantly for the two attacked hosts and with experience, being higher in the house fly and in females experienced with medfly, respectively, but it did not influence the total progeny. The lower realized fecundity and induced mortality shown by experienced S. cameroni females compared to inexperienced females may be due to the fact that experienced females could be less likely to accept novel host types than naive females. These results indicate that rearing S. cameroni on medfly or house fly pupae seems to have little influence on the later performance of this parasitoid in its subsequent use against populations of both fly pests.

Stefanescu, C., Aguado, L.O., Asis, J.D., Banos-Picon, L., Cerda, X., Marcos Garcia, M.A., Mico, E., Ricarte, A., Tormos, J. 2018. Diversity of insect pollinators in the Iberian Peninsula. Ecosistemas 27(2): 9-22. Doi.: 10.7818/ECOS.1391 Numerous observations and studies that have been carried out in recent decades show that, in addition to bees ((Hymenoptera; Anthophila), other groups of insects play a major role in entomophilous pollination. This article reviews the information and literature available on the contribution of the main groups of pollinators that traditionally have been considered as "secondary": beetles, butterflies and moths, dipterans, wasps and ants. For each of these groups a common outline is followed, with a brief introduction, a summary of the basic characteristics - both morphological and behavioral - in relation to pollination, their effectiveness as pollinators and their conservation status in the Iberian Peninsula. This review highlights the importance of all these groups in entomophilous pollination and the need to include them in comprehensive studies on this phenomenon. Although data are generally very limited, there is clear evidence of a general decline in most of these groups which calls for a pressing need to improve knowledge about their population trends.

Biological parameters of parasitoid wasps have a decisive effect on their effective performance as biological control agents. The mode of reproduction, several mating-dependent biological parameters (such as longevity, fertility, percentage parasitism, induced mortality and population reduction) as well as superparasitism of the parasitoid Aganaspis daci (Weld) infesting larvae of the medfly Ceratitis capitata (Wiedemann) were assessed under laboratory conditions. The results indicated an arrhenotokous haplodiploid mode of reproduction, with unmated females producing only males and mated females producing a female-biased offspring (♀♀/(♀♀+♂♂) = 0.73) ratio from the first day of life. Additionally, positive mating status showed a significant negative effect on longevity (14–22 days), but no significant differences on fertility, percentage parasitism, induced mortality or population reduction between mated and unmated females. A strong effect of the age of females on fertility and percentage of parasitism was also found, with both decreasing with increasing female age and a similar oviposition pattern for mated and unmated females. Our findings showed the occurrence of superparasitism in this species, with a significant negative effect of host abundance and a significant positive effect of parasitoid (conspecific females) abundance on superparasitism rate. The existence of self-superparasitism was confirmed for females acting alone, whilst female aggregation led to a higher intensity (up to eight eggs/host pupa) and percentage of, presumably, conspecific superparasitism. The information reported here on several biological aspects of A. daci infesting C. capitata supports the use of this parasitoid in biological control programmes against medfly and highlights the importance of several factors, such as the sex ratio or the parasitoid/host ratio under rearing and field conditions, when planning mass production and field releases of this parasitoid.

The larval–pupal endoparasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae) is currently the most commonly employed biological control agent against Tephritid fruit flies in the Americas. However, this parasitoid remains largely ignored and is not used in many regions, including the Mediterranean Basin. In this study, the potential of D. longicaudata as a biocontrol agent against the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae) was addressed in an area of eastern Spain (the Valencian community). The parasitic activity of parasitoids and the effects of climatic conditions were evaluated throughout a 1-year period in field-cage experiments in which parasitoids were confined with apples artificially infested with medfly larvae. The following parameters were calculated and related statistically to several environmental conditions: the parasitism rate, the induced mortality and progeny sex ratio. The results show that D. longicaudata is able to parasitize medfly larvae throughout the year under semi-natural conditions. Important fluctuations in the parasitism rate (from almost zero to 42%) and the induced mortality (from 6% to 80%) were partially influenced by climatic conditions. The parasitism rate increased with mean temperature and decreased with mean relative humidity, while the induced mortality decreased with minimum relative humidity. The optimal climatic conditions for the activity of the parasitoid were a mean temperature of 16–24°C combined with a relative humidity of 45%–60%. Overall, these results suggest that reduction in the medfly population due to D. longicaudata activity is feasible and provide information about the optimal time period for parasitoid release in the field. In conclusion, D. longicaudata has a significant potential to control C. capitata in the Mediterranean region.

The effect of environmental factors is essential to the success of parasitoids as biological control agents, as it determines their foraging activity, development, and survival. The larval-pupal parasitoid wasp Aganaspis daci (Weld) (Hymenoptera: Figitidae) is known to have a very low fertility (i.e., off-spring production) in the field in certain Mediterranean areas, probably due to its inability to efficiently oviposit under such climatic conditions. In this study, the percentage of parasitism and induced mortality (mortality of host pupae attributed to parasitoids, from which adults do not emerge) caused by this wasp to the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), was assessed under field conditions across 1 year, using medfly-infested apples and parasitoid-confined release in a lemon orchard of southeastern Spain. As A. daci is known to have very few emergences in the field, fertility was assessed in the laboratory from parasitized pupae recovered from the field. We found average parasitism rates of 27% and high induced mortality rates of 66% under field conditions. Consequently, medfly population reduction (total mortality of C. capitata caused by A. daci, i.e., induced mortality + % parasitism) was, on average, 87%. Parasitism and induced mortality varied throughout the year, depending on the average temperature and relative humidity. The interaction of these factors resulted in the highest parasitism rates at low mean temperature and humidity values; likewise, the highest percentages of induced mortality were obtained with a combination of high mean temperature and low mean humidity values. In conclusion, A. daci may exert a strong impact on medfly populations, being a good candidate for inundative field releases for the management of C. capitata in the Mediterranean Basin.

The percentage parasitism, fertility and induced mortality (mortality of host pupae attributed to parasitoids, from which adults do not emerge) of the parasitoid Aganaspis daci (Weld) infesting larvae of Ceratitis capitata (Wiedemann) were studied under laboratory and greenhouse conditions for temperature, host location (larvae provided in artificial diet or inside fruit) and host density. For larvae in artificial diet in the laboratory, our findings revealed that 23–25 °C is the most suitable temperature range, leading to high rates of parasitism, fertility, induced mortality, population reduction (total mortality of C. capitata caused by the parasitoid, i.e., induced mortality + percentage parasitism), and female-biased sex ratio (♀♀/♀♀ + ♂♂ = 0.55). Regarding host density, parasitism and fertility corresponded to a Type III functional response with a female-biased sex ratio (0.54–0.61), while induced mortality decreased with an increase in host density, and population reduction presented the same type of response as parasitism and fertility. Regarding the larvae inside fruits in the laboratory, the analysis showed that parasitism and fertility, depending on host density, also showed a Type III functional response and female-biased sex ratio (0.51–0.62). For larvae provided inside fruits in the greenhouse, our results showed no significant differences regarding fruit position or host density on the percentage parasitism, induced mortality or population reduction, although there was a female-biased sex ratio (fruit position: 0.64–0.72; density: 0.66–0.76). Regarding host density, parasitism and fertility corresponded to a Type II functional response. The induced mortality decreased with increasing density and host population reduction had the same type of response as parasitism and fertility. The information reported here on the key demographic parameters and functional response of A. daci infesting C. capitata under various environments and situations, will assist to evaluate the potential use of this parasitoid as a biological control agent against this pest. Our results show A. daci displays an excellent ability to locate, capture, parasitise, or simply kill C. capitata, under laboratory and field conditions.

The most harmful hymenopteran pests of Pinus sylvestris L. are conifer sawflies from the family Diprionidae, including the widespread Diprion pini (L.). Natural enemies of this pest are still poorly known in many European areas where attacks occur. We studied the egg parasitoids of D. pini at four sites in two mountainous areas of Spain: the Sierra de Francia (western Spain) and the Sierra de Albarracin (eastern Spain). At all sites, the dominant egg parasitoid was Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae), whereas other three chalcidoid species were rare. All these species were previously recorded in association with D. pini, but we report here their first record in Spain. Neochrysocharis formosa attacked up to 32.3% of egg clusters of D. pini in the Sierra de Albarracin and 18.5% in the Sierra de Francia. In the attacked egg clusters, this species parasitized up to 35% of eggs in the Sierra de Albarracin and 23.7% in the Sierra de Francia, with a marked female-biased sex ratio. Contrary to the clustered pattern of parasitism observed for N. formosa while attacking other gregarious diprionids, the oviposition in egg clusters of D. pini followed a random pattern, probably due to the froth roof (spumous coating) that covers its eggs and interferes with the egg-searching behavior of females. Indeed, other parasitoid species of D. pini have been reported to behave similarly.

Bees are important pollinators that use resources from both cropped and natural habitats in agroecosystems, and the amount of extant resources have proven to be critical in the adoption of parental investment decisions. Thus, the mixed effects that resource distribution and the organisms’ foraging and dispersal movements have on parental decisions cannot be adequately evaluated without the use of different spatial scales. We assess the effects of the landscape context and the local habitat type on the offspring traits of Osmia caerulescens L. Bees were obtained from standardized trap-nests established in Mediterranean crops. We analyzed the effects that the percentage of semi-natural habitats, the local habitat type, and the nest hole diameter have on offspring weight, the number of emergent progeny and offspring sex ratio. Both landscape and local scale factors affected the offspring traits in significant and interactive ways, and landscape-scale effects varied depending on local factors. Considering our...

Longevity, developmental time and offspring survival of parasitoid wasps are decisive in their effective performance as biocontrol agents. Optimum temperature range determines parasitoid survival, development and reproduction. Thus, controlling this abiotic factor is a key to the success of pest management programs. Adult longevity, developmental time from egg to adult and survival of immatures of Aganaspis daci were assessed in the laboratory under different constant temperatures; adult longevity without hosts, but with the provision of water and honey, and developmental time and survival of immatures from host pupae, whose larvae had been exposed to parasitoids. Results showed that longevity depended on temperature decreasing in the range 15–20 °C (36 – 25 days), but was lower in the range 25–35 °C (10 – 7 days). Regarding developmental time from egg to adult and survival of immatures, our results showed that 20 and 25 °C are the most suitable temperatures. At 15 and 30 °C mortality of the immature stages was very high (>90%) or developmental time to adult was very slow (>3 months). Immatures did not survive at 35 °C. We found no significant differences in developmental time to adult or survival of immatures between 20 and 25 °C. The sex ratio of parasitoid progeny was female biased at 25 °C; the proportion of females increased at all cases with temperature. The to and K for total development were 8.5 °C and 500 DD, respectively. Our findings provide some guidance for future inundative or inoculative field releases of this parasitoid for the management of Ceratitis capitata in Spain.

Some of the negative effects of agricultural intensification on biodiversity can be counteracted by the implementation of practices typically associated with organic farming. The efficiency of key ecosystem services, such as natural pest control or pollination, depends on biodiversity and could determine agricultural productivity and food security. In terrestrial ecosystems, both land use and topographic features are important filters in shaping taxa distribution. It is essential to identify which factors significantly drive changes in populations in order to maximize the abundance and richness of beneficial arthropods and to support the underlying services they provide across agroecosystems. Although traditional orchards are high nature value farming systems that maintain high levels of biodiversity, there is a lack of information on how organic farming affects these systems. We examined beneficial arthropod communities to disentangle the extent to which predators, parasitoids, and pollinators are shaped by local field management (organic vs. conventional management) and topographic features (hillside aspect, i.e. the orientation of the slope). In traditional cherry orchards in western Spain, beneficial arthropod communities were assessed by using a combination of different sampling methods. Our results show that communities differed between farming systems. Overall, dominant or most representative parasitoid and pollinator taxa benefited from organic management, whereas predators showed a more heterogeneous pattern in their abundances probably due to their varying responses to habitat characteristics. Topographic features, although being a factor for some of the studied groups, did not strongly affect beneficial arthropod communities. Our results indicate that, in traditional orchards, the effects of farming system on beneficial arthropods are not easily predictable. Due to the variability in habitat preferences found among different functionally important taxa, we highlight the importance of continuing to unravel the specific responses of beneficial arthropods to local management practices.

A “space-for-time substitution” was used to analyse how the communities of Spheciformes wasps varied in different diversity parameters for a period of 15 years after a summer wildfire in a Mediterranean agroecosystem (Arribes del Duero, western Spain), employing Malaise traps and yellow pan traps to sample the communities. Both the habitat and the particular environmental conditions marking the interannual population variations in Spheciformes communities exert an important influence on the resultant assemblage, although the time after the wildfire was the most important factor in the recovery of species H′ diversity and evenness after the disturbance. Fire caused a drop of diversity and evenness values. Nevertheless, evenness recovered continuously, while H′ diversity continued to decrease until experiencing a recovery as from the fourth-fifth year post-fire. The effect of the time after the wildfire on abundance (N) or richness (S) values was not significant.

The final instar larva of Synergus filicornis (Cameron) (Hymenoptera: Cynipidae: Synergini) is described and illustrated. Morphological structures of a diagnostic value are discussed. The most remarkable character states shown by the mature larva of this species lie in the integument, which unlike the rest of described cynipoid mature larvae, presents tegumental differentiations. Additionally the antennal orbits, unlike those of other described Synergini mature larvae, did not present one seta on each antennal orbit. The immature larvae can be differentiated from the mature larva by the following characters: a) number and location of sensorial tegumental differentiations on the head, b) number of sensilla on the maxillary palpi, and c) morphology of the mandibles. The determination of the mandibles size, in this species, permits the estimation of the larval stages number.

Spalangia cameroniPerkins (Hymenoptera: Pteromalidae) is a pupal parasitoid of the Medfly,Ceratitis capitata(Wiedmann) (Diptera: Tephritidae), one of the principal pests of Spanish agriculture.Spalangia cameroniis a potential biocontrol agent for this pest if methods can be developed to mass-rear it effectively onC. capitata. Here, we report on the use of freeze-killed pupae ofC. capitatato maintain a laboratory colony ofS. cameroni, with a view to setting up a mass-rearing protocol. Realised fecundity, adult progeny, sex ratio, and superparasitism level were the principal parameters analysed. No significant differences were found in respect of these parameters between living or freeze-killed Medfly pupae used as hosts, although sex ratios showed a bias towards females in the case of freeze-killed pupae. Freeze-killed pupae were concluded to present the best option for the laboratory-rearing ofS. cameroni, on account of ease of rearing, and avoidance of the emergence of Medfly adults.

Research into the driving forces behind spatial arrangement of wasp nests has considered abiotic environmental factors, but seldom investigated attraction or repulsion towards conspecifics or heterospecifics. Solitary female digger wasps (Hymenoptera) often nest in dense aggregations, making these insects good models to study this topic. Here, we analysed the nesting patterns in an area shared by three species of the genus Bembix, in a novel study to discover whether female wasps are attracted to or repulsed by conspecific nests, heterospecific nests or their own previously established nests when choosing nest-digging locations. Early in the season, each species showed a clumping pattern of nests, but later in the season, a random distribution of nests was more common, suggesting an early conspecific attraction. Such behaviour was confirmed by the fact that females started building their nests more frequently where other females of their species were simultaneously digging. The distances between subsequent nests dug by individual females were shorter than those obtained by random simulations. However, this pattern seemed to depend on the tendency to dig close to conspecifics rather than remain in the vicinity of previous nests, suggesting that females' experience matters to future decisions only on a large scale. Nesting patches within nest aggregations largely overlapped between species, but the nests of each species were generally not closer to heterospecific nests than expected by chance, suggesting that females are neither repulsed by, nor attracted to, congenerics within nest aggregations. A role of the spatial distribution of natural enemies on the observed nesting patterns seemed unlikely. Bembix digger wasp nest aggregations seem thus to be primarily the result of female¿female attraction during nest-settlement decisions, in accordance with the `copying¿ mechanisms suggested for nesting vertebrates., The research was supported by funding from the Junta de Castilla y León (SA094A09), by a grant from the Ministerio de Economia y Competitividad (Spanish Government) (CGL2010-16730), and from and by a post-doctoral contract to CP (Program JAE-Doc ‘Junta para la Ampliación de Estudios’ funded by the Spanish Research Council (CSIC) and the FSE).

Aganaspis daciandAganaspis pelleranoi(Hymenoptera: Figitidae) are important parasitoids of fruit flies. Here we studied, with light and scanning electron microscopy, aspects of their morphology that could help with plans to mass rear and thus contribute to improved pest control (preimaginal phases) and to shed light on parasitoid-pest relationships (sensillar equipment). The two species present a stalked egg, eucoiliform first and second-instar larvae and hymenopteriform third instar and mature larvae. The first instar presents tegumental differentiations in the mesoma and first metasomal segment inA. daci, but not inA. pelleranoi, while unlike other figitids, neither species displays setae in the mesosomal processes. Second and third instar and mature larvae present tegumental differentiations inA. daci, but not inA. pelleranoi. The moniliform (female) and filiform (male) antennae ofA. daciandA. pelleranoiharbor seven types of sensilla, four of them (sensilla campaniformia, sensilla coeloconica type II, and two types of sensilla trichoidea) described here for the first time in Cynipoidea. The largest sensilla were the multiporous placoid sensilla, which were smaller and more numerous inA. pelleranoi. Species also differed to some extent in morphology of sensilla coeloconica. Observations on the ovipositor revealed the presence of coeloconic sensilla on Valva I in both species.

Due to the mostly qualitative, scarce and scattered available data, it is still debated if stridulation patterns and morphology of stridulatory organ are species-specific traits in velvet ants (Hymenoptera: Mutillidae). Here, we test such an hypothesis, analysing the stridulation patterns and the associated morphology in females of six species spanning five genera and three subfamilies. In all the species, sound is produced by rubbing together a morphologically well-defined file composed of parallel ridges (on metasomal tergite III) and a weakly defined scraper (on tergite II). In all species, the resulting sound is made of sequences of pulse-trains organized in two subunits (disyllabic chirps) characterized by pulses with opposite phase. We found important differences among species in the morphology of the file concerning its size, the inter-ridges distance, the ridge thickness and the density of ridges. We also found some differences in distress-call patterns, mostly concerning the duration of syllables and the number of pulses/ms. Tergite III size seems to have some effects on file morphology and limited effect on sound patterns, though a larger sample size is required to confirm these results. Classification and Regression Tree analyses revealed that five morphological and five acoustical variables had, overall, a role in assigning correctly most individuals to their species. Overall, taxonomic relatedness among species seemed to weakly account for inter-specific morphological similarity and not to account for acoustical similarity, suggesting that ecological factors may have been important in shaping species-specific stridulation in velvet ants.

Landscape, in terms of crop diversity, together with spatial heterogeneity, connectivity and the proportion of natural elements all play a key role in the quality of the agricultural matrix. The abundant resources derived from the high productivity associated with cultivated lands within agricultural landscapes – formed by mosaics comprising small elements and systems of low agricultural intensity – may favour the populations and communities of certain insect species. Here, trap-nesting solitary bees have been studied to evaluate the effect of two Mediterranean crop systems: monocrops (vineyard and cereal) and polycrops (mixed vegetable crop) for two levels of farming intensity (high-intensity vs. low-intensity) on brood cells and emergent progeny of the bee population and community species richness. Polycrops proved favourable compared to monocrops, with the former proving particularly favourable for offspring production (brood cells and emergent progeny) of bees belonging to the genus Osmia. Bee populations, especially polylectic species, may benefit from the traits characterizing this polycrop, which provide plentiful and diverse resources both in space and time. Farming intensity, regardless the crop type, is also an important factor affecting bee community structure. Low farming intensity maintains essential semi-natural habitats providing shelter for species-rich communities. Crop richness, together with low farming intensity would provide heterogeneous landscapes with a variety of natural and cultivated resources, benefitting trap-nesting bee populations.

Females of most aculeate Hymenoptera mate only once and males are therefore under a strong competitive pressure which is expected to favour the evolution of rapid detection of virgin females. In several bee species, the cuticular hydrocarbon (CHC) profile exhibited by virgin females elicits male copulation attempts. However, it is still unknown how widespread this type of sexual communication is within Aculeata. Here, we investigated the use of CHCs as mating cues in the digger wasp Stizus continuus, which belongs to the family (Crabronidae) from within bees arose. In field experiments, unmanipulated, recently emerged virgin female dummies promptly elicit male copulation attempts, whereas 1-4days old mated females dummies were still attractive but to a much lesser extent. In contrast, old (10-15days) mated female dummies did not attract males at all. After hexane-washing, attractiveness almost disappeared but could be achieved by adding CHC extracts from virgin females even on hexane-washed old mated females. Thus, the chemical base of recognition of females as appropriate mating partner by males is coded in their CHC profile. Accordingly, differences in CHC profiles can be detected between sexes, with males having larger amounts of alkenes and exclusive long-chain alkanes, and within females specially according to their mating status. Shortly after mating, almost all of the major hydrocarbons found on the cuticle of females undergo significant changes in their abundance, with a clear shift from short-chain to long-chain linear and methyl-branched alkanes. The timely detection of virgin females by males in S. continuus could be advantageous within the narrow period of female emergence, when male-male competition is strongest.

Although inter-individual diet variation is common in predatory wasp populations, the factors accounting for such variation are still largely unknown. Here, we asked if paired diet dissimilarity in three species of digger wasps correlates with morphological distance and inter-nest distance, two factors previously linked to diet partitioning in vertebrates. Results sharply differed among species and generations. All sampled populations showed significant inter-individual diet variation for prey taxa, but only in half of the cases for prey size. In one generation of two species [Bembix zonata Klug and Stizus continuus (Klug)], similar-sized wasps had similar prey taxonomic spectra (and for S. continuus also similar prey size spectra), a phenomenon which probably reduces intra-specific competition. In addition, B. zonata females nesting closer to each other had more similar prey taxonomic spectra, suggesting that distant females probably hunt on different patches that harbour different prey species. For the females of a further species (Bembix merceti Parker), pairwise size difference and inter-nest distance did not affect prey dissimilarity. Both morphological distance and inter-nest distance are potentially important in shaping the overlap of individual resource use in wasps, though probably only in certain conditions such as a highly clumped distribution of nests and size-related constraints on prey selection.

Bembix is a cosmopolitan genus with more than 300 species distributed all over the world. The females of these wasps dig burrows in the ground and hunt for flies to feed their larvae. Current knowledge of the nesting behaviour of most Palaearctic species (around 50) is limited. In this study, we provide data on the nest structure, nesting activity, natural enemies and prey captured by three Bembix sand wasps present on the Iberian Peninsula: B. zonata, B. flavescens bolivari and B. merceti. We also analyze the prey spectrum of the three species, comparing our data with those available from previous studies. B. zonata exhibits the greatest selectivity index (and the narrowest niche width), capturing mainly Syrphidae to provision its nests. B. merceti shows the greatest niche width in comparison with the other two species. The inter-annual differences in the diet of B. merceti are important and are probably due to the ability of this wasp to change from one prey resource to another, depending on it...

Summary 1. Individual foraging behaviour defines the use of resources by a given population and its variation in different ways such as, for example, unpredictable interactions between taxon-biased and size-biased selection. Here we investigated how the environmental availability of prey and individual specialization, for both prey taxa and prey size, shape niche variation across generations in the grasshopper-hunting digger wasp Stizus continuus. 2. The population of S. continuus expressed selective predation, females mainly hunting species encountered on large bushes; diet changed across generations, due more to size increase in potential prey than to changes in the orthopteran community. 3. Individual females of both generations weakly overlapped the size and taxa of prey, and the niche width of the second generation increased for both prey size and taxa. 4. The greater variance in prey size in the environment accounted for the enlarged prey size niche of the second generation, but the load-lifting constraints of the wasps maintained individual prey size specialization constant. In contrast, the enlarged prey taxon niche paralleled a smaller overlap of diets between wasps in the second generation. 5. Increased niche width in the S. continuus population was thus achieved in two ways. Regarding prey size, all individuals shifted towards the use of the full set of available resources (parallel release). For prey taxa, according to the classical niche variation hypothesis, individuals diverged to minimize resource use overlap and perhaps intraspecific competition. These two mechanisms were observed for the first time simultaneously in a single predator population.

The preimaginal stages of 2 species of Liris, including the egg, 2 mature and 1 immature larvae are described. The mature larva of L. niger (Fabricius) described is very similar to the previously known immature one. The mature larva of L. festinans praetermissus (Richards) differs only in minor details from that of L. niger, with the presence in the first one of parietal bands being outstanding. To date, the last larval stage of subtribe Larrina can be defined by the following character states: (a) head no higher than wide, (b) mandible with 4 or more teeth, (c) epipharynx with a large number of slender spinules, which tend to converge toward the midline, and (d) labrum rounded apically Within the Larrina, the mature larva of Liris is characterized by the autapomorphy “epipharynx spinulose, with a bare area in the center”.

Changes of the structure of a community of Spheciformes wasps (Hymenoptera: Apoidea) along a 15 year recovery gradient after wildfires in a Mediterranean agroecosystem are reported and analysed. The species that contribute to determining the structure, change in dominance amongst the most abundant species, and variation in guild structure of the community with the passage of time since fire, as well as the environmental variables contributing to the structure of the community are also analyzed. Mediterranean Spheciformes communities are highly resistant to fire. The sampling year, representative of different climate conditions, and the time since the fire, were the main variables which affected community variation local conditions of the habitat was more important than time since fire in determining community. Local conditions; presence of trophic resources, nesting sites, and presence of prey for feeding the larvae, depended on climatological conditions and the time since fire. Variations were detected in the dominance values of the most abundant species, together with displacements among species within the same genus, as a function of the local conditions, the existing resources, and the time since the wildfire. Therefore, change in community structure cannot be attributed solely to the effect of the fire, as both climatic and environmental conditions contribute to community structure.

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.

In the present study, the mating behaviour of the velvet ant Nemka viduata (Pallas) (Mutillidae) is described both from field and laboratory observations. The whole pairing interaction, lasting around two hours, includes several behavioural phases. During pre-copula, the male seizes the female’s neck with his mandibles, and then starts to rhythmically stroke the prothorax of the female with his forelegs (this behaviour is also resumed after copulation) before curving his abdomen in order to couple the genital parts, including genital armatures (the male parameres remaining outside the female body); just prior to copulation, the female extrudes the sting, and immediately after copulation begins, she stridulates for 7–10 s, this behaviour is repeated when the pair separates. During copulation (lasting around two minutes), the male moves his antennae rhythmically, hitting the back of the female’s head with the scape. Generally, recently-mated males become aggressive towards females, but more tolerant after a few days. During the whole pairing act, females are held by the males’ mandibles, and in the field they are carried off in flight or by walking to a safe place to copulate. This would suggest that larger males, which can lift a wider range of female sizes, have a reproductive advantage, as indicated by data obtained on their load-lifting capacity with respect to the size distribution of females. A review of mating behaviour in mutillid wasps and comparisons with other lineages of aculeate and non-aculeate Hymenoptera are also given.

In a coastal salt-marsh of Spain, the digger wasp Stizus continuus primarily hunted for grasshoppers of the genus Heteracris, revealing (at least in the period of the study and in this area) this wasp to be almost monophagous. In contrast, grasshoppers of the genus Acrotylus were ignored by the wasps in spite of their high abundance in the environment. We hypothesize that this bias occurred because Acrotylus is found more often on the soil and on grasses, while Heteracris is nearly only found on Sarcocornia bushes, which probably represent the habitat mostly exploited by the wasps for hunting. The greater variance in size of the prey collected by larger females produced weak wasp–prey size correlations. Some wasps were observed to carry in flight prey weighing close to or more than the maximum theoretically possible, suggesting that they have to descend with prey to the nest from the above-soil hunting sites.

The development and morphology of the immature phases of Pachycrepoideus vindemmiae (Rondani, 1875) (Hymenoptera, Pteromalidae) are described from a laboratory rearing culture maintained on Ceratitis capitata (Wiedemann, 1824) (Diptera, Tephritidae) using microscopic techniques, including light and scanning electron microscopy. The surface of the chorion of the egg is granulated, and the micropyle occurs at the anterior end. The labrum of the first instar larva does not have sensilla, and the second to fourth instar larvae have setae on the head. The mature larva is characterized by the position and number of the integumental differentations (sensilla and setae). On completion of larval development, an adecticous and exarate pupa is produced. As for the adult, the mandibles of the pupae are toothed. Five larval instars are recorded, based on statistical analyses of the sizes of the larval mandibles in combination with characters such as the number of exuviae and excretion of the meconium. Developmental time from egg to adult emergence was ∼18–20 days for males and ∼21–23 days for females at 21–26°C, 55–85 relative humidity, and a 16L:8D photoperiod. The results show that the eggs and different larval instars of this parasitoid can be unambiguously identified only by scanning electron microscope.

Antrusa montecristiensis, a new species of Dacnusini from Montecristo island (Italy), is described, illustrated, and compared with allied species. Specific keys of the genus Antrusa for the West Palaearctic region are provided. The preimaginal phases and the venom apparatus of A. curtitempus Fischer, Tormos, Docavo & Pardo, are described, illustrated, and compared with species of allied genera. The larva stages are similar to those of Dacnusa; the immature larvae differ in the number and distribution of the setae of the abdominal and thoracic segments, and the mature larva in the type of the tegumental differentations of the thorax and abdomen as well as in the number and size of the sensilla of the maxillary palpi. The venom apparatus of this species is very similar to that of Antrusa flavicoxa (Thomson), differing from it in length of the reservoir and the number of gland filaments.

The mature larvae of four species of Eumeninae, Allodynerus rossii (Lepeletier), Ancistrocerus auctus (Fabricius), Euodynerus dantici (Rossi) and Symmorphus murarius (Linnaeus), are described. The mature larvae of A. rossii is characterized by the number, morphology and distribution of sensilla of the labrum and epipharynx. The last instar larva of A. auctus is characterized by having an epipharynx with 14 sensilla. The most apparent differences between the mature larvae of Euodynerus lie in the number of sensilla of maxillary and labial palpi and antennae. E. dantici is characterized by presenting the antennae with four apical sensilla and maxillar and labial palpi with five sensilla on apex. S. murarius is characterized by having the opening into subatrium armed with spines and maxillary palpi with two sensilla at apex. The larval morphology of Allodynerus is described for first time.

The larvae, pupa, adults, and venom apparatus of Dacnusa cicerina sp. n., an endoparasitoid of Liriomyza cicerina (Rondani), found on Cicer arietinum Linnaeus in Spain, are described, illustrated, and compared with those of allied species. The mature larva of Eurytoma sp., possibly a hyperparasitoid of D. cicerina, also is described, illustrated, and compared with those of allied species. Keys to discriminate adults are provided and morphological structures of phylogenetic value are discussed. The adults of D. cicerina are similar to those of Dacnusa rodriguezi Docavo & Tormos (1997). The immature larvae are similar to those of Dacnusa areolaris (Nees) and Dacnusa dryas (Nixon), and the mature larva is very similar to that of D. dryas, from which it differs in having scale-like sensilla (“setae”) on the thorax and abdomen. The cast skin of the final instar, like those described for Dacnusa Haliday, has a pleurostoma with well differentiated mandible processes and a long stipital sclerite. The ven...

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.

Data are offered on the biology of five species of Bembix: B. flavescens bolivari, B. merceti, B. oculata, B. rostrata, and B. sinuata, referring to the nest structure, captured prey and natural enemies. A description is also offered of the mature larvae of B. merceti and B. rostrata, discussing some characters of interest in the differentiation of the larvae of the european species of the genus.

Spalangia cameroni Perkins (Hymenoptera: Pteromalidae) is sold commercially as a biocontrol agent of fi lth fl ies, including the house fl y, Musca domestica L. (Diptera: Muscidae). For this reason, S. cameroni is mass-reared for inundative releases to control harmful fl ies. However, the mass-rearing protocols include very little information on the infl uence of natal host on subsequent host selection by parasitoids with more than one potential host as in the genus Spalangia. Here, we report on the use of S. cameroni against M. domestica. The S. cameroni were reared using Ceratitis capitata Wiedemann (Diptera: Tephritidae) (natal host) pupae for several generations. Freeze-killed fl y pupae were used in assays to determine the fecundity, number of adult progeny and sex-ratio of this parasitoid. Realized fecundity and number of adult progeny were greater when provided with house fl y pupae than Mediterranean fruit fl y pupae. Thus S. cameroni parasitized more house fl y pupae than C. capitata pupae, even though the parasitoid was reared on Mediterranean fruit fl y for many generations. These results indicate that S. cameroni reared on C. capitata can be successfully used in inundative releases against both fruit fl ies (agriculture) and house fl ies (livestock farming).

In prey-predator systems where the interacting individuals are both fliers, the flight performance of both participants heavily influences the probability of success of the predator (the prey is captured) and of the prey (the predator is avoided). While the flight morphology (an estimate of flight performance) of predatory wasps has rarely been addressed as a factor that may contribute to explain prey use, how the flight morphology of potential prey influences the output of predator-prey encounters has not been studied. Here, we hypothesized that flight morphology associated with flight ability (flight muscle mass to body mass ratio (FMR) and body mass to wing area ratio (wing loading, WL)) of Diptera affect their probability of being captured by specialized Diptera-hunting wasps (Bembix merceti and B. zonata), predicting a better manoeuvrability and acceleration capacity achieved by higher FMR and lower WL, and flight speed achieved by higher WL. In addition, wasp species with better flight morphology should be less limited by an advantageous Diptera flight morphology. Overall, the abundance of dipterans in the environment explained an important part of the observed variance in prey capture rate. However, it was not the only factor shaping prey capture. First, higher prey abundance was associated with greater capture rate for one species (B. merceti), although not for the other one. Second, the interaction observed between the environmental dipteran availability and dipteran WL for B. zonata suggests that greater dipteran WL (this probably meaning high cruising speed) decreased the probability of being captured, as long as fly abundance was high in the environment. Third, greater dipteran FMR (which likely means high manoeuvrability and acceleration capacity) helped to reduce predation by B. merceti if, again, dipterans were abundant in the environment. Wasp WL only varied with body mass but not between species, thereby hardly accounting for inter-specific differences in the wasps’ predatory patterns. However, the greater FMR of B. zonata, which implies better flight performance and greater load-lifting capacity, may explain why the capture rate in the two wasp species is affected by different factor interactions. In conclusion, although prey availability remains the primary factor shaping prey use, prey flight morphology seems to gain an additional role under conditions of abundant prey, when wasps can avoid flies with better flight ability.

In a study on the host association of the cuckoo wasp, Chrysis fulgida L., at two nesting sites in Northern Italy, it was observed emerging from nests of the mason wasp, Symmorphus crassicornis (Panzer). Although other species of eumenine wasps nested in the same area, none of them was attacked by this parasitoid. Parasitism rate per nest ranged from 0% to 66.3%, 45.8% on average. The number of parasitized cells did not decrease either with the thickness of the nest closing plug or with the length of vestibular cell. No differences in the number of cells per nest or in the length of vestibular cell were found when comparing parasitized and unparasitized nests, suggesting that the wasps probably did not abandon their parasitized nest and that the cuckoo wasp larva was not detected. A review of the host associations of the species of Chrysis of the ignita group suggests that mason wasps are the preferred hosts and that cavity-nesters are more frequently attacked than soil- or mud-nesters. The prepupa of C. fulgida is described, illustrated, and compared with the described mature larvae of Chrysididae. The postdefecating larva of this species exhibits the autapomorphy that defines the genus Chrysis: “normally developed galeae.” The most salient character shown by the mature larva of this species lies in the maxillary palpus, which has 6 sensilla at apex. This character state allows this prepupa to be differentiated from the previously described mature larvae of the genus.

In a study carried out with the trap-nesting solitary wasp Trypoxylon attenuatum (Hymenoptera: Crabronidae) in 2000, we analysed the significance of different nest characteristics, like the vestibular cell and empty intercalary cells, and its role in the reduction of mortality. Analysis of the presence of the vestibular cell suggested that it represents a nest completion structure, whose presence reduces mortality in the initial stages (M1) but does not affect that due to chrysidid parasitoids (MP). The length of such vestibular cell was found to depend mainly on the space between the last provisioned cell and the exterior, pointing to a possible role in the reduction of the remaining space that could be used by other females to establish a nest exterior to the completed one. The empty intercalary cells were smaller than the vestibular cells, did not affect M1 or MP mortality rates in the nest, and exhibited an “aggregated” pattern of occurrence. This suggests that they could be the result of “abnormal” behaviour by the female owning the nest. The total mortality rate decreased with the increase in the number of cells in the nests, also being greater in nests established at low heights above the ground. M1 was lower in the innermost cells, while MP increased towards the interior and in the nests with more cells. The distribution in the nests of cells parasitized by Trichrysis cyanea (the main natural enemy found in the wasp population studied) reflects an “aggregated” pattern, suggesting repeated attacks against certain nests.

Recently re-named as a sub-species of Mellinus arvensis, Mellinus arvensis obscurus Handlirsch 1888 was investigated ecologically and morphologically in Nepal, in order to underline the most important differences with the well known M. arvensis arvensis. Mellinus arvensis obscurus females nested in clumped aggregations on inclined plains at high altitudes, both on sunny bare soil and on a shaded grassy one. Beginning of monsoon season probably interfered with wasp activity, and females performed few provisioning flights during the day. Prey consisted of a broad range of Diptera, except for one case of a spider. Many females were observed not provisioning a nest but floating on the nesting site, and many intraspecific interactions suggested a high degree of usurpation attempts. At least one species of flies and two of ants probably acted as natural enemies of the wasp. Morphological observations on females showed that the Nepal population shares more similarities (shape of tergite I, body punctation) with the European populations than with the closer Japanese population; melanization is strong, according to west-east and altitudinal cline. The mature larva of M. arvensis obscurus Handlirsch is described, illustrated, and compared with the other mature larva of the genus. The differences between both larvae mainly lie in the presence/absence, and number or differentiation of integumental structures. We conclude that morphological traits are more important than ecological and behavioral ones in distinguishing M. arvensis obscurus from M. arvensis arvensis.