Ma. Ángeles Marcos-García

The reproductive ecology of Medicago citrina (Font Quer) Greuter (Leguminosae): a bee-pollinated plant in Mediterranean islands where bees are absent

The reproductive ecology of Medicagocitrina was studied in the Columbretes archipelago (Mediterranean Sea), where bees are absent. The flowers were self-compatible, homogamous, nectar producers, depended on large floral visitors for tripping and pollination. Several characteristics of the reproductive biology of M.citrina indicate an adaptation to an isolated environment characterised by scarcity of appropriate pollinators. As a result of this scarcity, fruit and seed set under natural conditions were significantly lower compared to hand-pollination treatments. The main flower visitors were mostly flies and blowflies, with Eristalis tenax (Syrphidae) and Calliphoravicina (Calliphoridae) being the most efficient pollinators. We argue that because M. citrina faces pollen limitation in the small islets of Columbretes, it presents an interesting case study of pollination related to island endemism and diversity.

Breaking down Complex Saproxylic Communities: Understanding Sub-Networks Structure and Implications to Network Robustness

Saproxylic insect communities inhabiting tree hollow microhabitats correspond with large food webs which simultaneously are constituted by multiple types of plant-animal and animal-animal interactions, according to the use of trophic resources (wood- and insect-dependent sub-networks), or to trophic habits or interaction types (xylophagous, saprophagous, xylomycetophagous, predators and commensals). We quantitatively assessed which properties of specialised networks were present in a complex networks involving different interacting types such as saproxylic community, and how they can be organised in trophic food webs. The architecture, interacting patterns and food web composition were evaluated along sub-networks, analysing their implications to network robustness from random and directed extinction simulations. A structure of large and cohesive modules with weakly connected nodes was observed throughout saproxylic sub-networks, composing the main food webs constituting this community. Insect-dependent sub-networks were more modular than wood-dependent sub-networks. Wood-dependent sub-networks presented higher species degree, connectance, links, linkage density, interaction strength, and were less specialised and more aggregated than insect-dependent sub-networks. These attributes defined high network robustness in wood-dependent sub-networks. Finally, our results emphasise the relevance of modularity, differences among interacting types and interrelations among them in modelling the structure of saproxylic communities and in determining their stability.

Seasonal Abundance of Aphidophagous Hoverflies (Diptera: Syrphidae) and Their Population Levels In and Outside Mediterranean Sweet Pepper Greenhouses

Abstract The species composition and the population dynamics of aphidophagous syrphids (Diptera: Syrphidae) in polyethylene-covered greenhouses of sweet pepper (Capsicum spp.) were studied over a 3-yr period in southeastern Spain. Modified Malaise traps were used to sample the adult flies within the greenhouses, accompanied by direct sampling of syrphid larvae on the sweet pepper plants. Over a 2-yr period, modified Malaise traps also were used to record the movement of syrphids into the greenhouses from the surrounding environment. Additionally, the effect of opening or closing the side walls of the greenhouse (ventilation management) on syrphids was assessed by census techniques. In total, nine species of aphidophagous syrphids were found as larvae, preying on aphids on sweet pepper plants. Three of these species, Eupeodes corollae (F.), Episyrphus balteatus (De Geer), and Sphaerophoria rueppellii (Wiedemann), made up 98% of the larvae collected. There was a temporal succession during the season, attributed to temperature, and variability among years related to drought. S. rueppellii seems to be the most adapted to survival in the high temperatures and dry conditions. Modified Malaise traps proved effective for monitoring adult syrphids in greenhouses, but they also captured species whose larvae are not associated with the aphid colonies in sweet pepper. This indicates that when studying aphidophagous syrphids, sampling of adults by Malaise trap should be accompanied by sampling of larvae. Larger numbers of syrphids were captured outside of the greenhouse than inside. Opening the side walls of greenhouses increased syrphid numbers within it, and this should be considered in pest management regimes.

New data on the Merodon Meigen 1803 fauna (Diptera: Syrphidae) of Turkey including description of a new species and changes in the nomenclatural status of several taxa

Abstract The Old World syrphid genus Merodon Meigen 1803 is highly species-diverse and has a significant number of endemic species in the circum-Mediterranean area. The present study reports on taxonomic changes resulting from the examination of adult Merodon specimens collected in 15 Turkish provinces during the period 1992 to 2002, and provides new faunistic data. Merodon ilgazense n. sp. is described. Four species of Merodon new to Turkey are recorded: M. armipes Rondani 1843, M. auronites Hurkmans 1993, M. bessarabicus Paramonov 1924 and M. chalybeatus Sack 1913. Lectotypes are designated for two taxa: M. chalybeatus Sack 1913 and M. clunipes Sack 1913. Merodon italicus Rondani 1845 rev. stat. is reinstated as a valid species. Following a detailed study of the type material in different entomological collections, the status of 10 taxa is revised and five new synonymies are proposed: M. albonigrum Vuji Radenkovi & S˘imi 1996 n. syn. (=junior synonym of M. chalybeatus Sack 1913); M. alexeji Paramonov 1925 n. syn. (=junior synonym of M. serrulatus Wiedemann in Meigen 1822); M. aureotibia Hurkmans 1993 n. syn. (=junior synonym of M. vandergooti Hurkmans 1993); M. kaloceros Hurkmans 1993 n. syn. (=junior synonym of M. erivanicus Paramonov 1925); M. longicornis Sack 1913 n. syn. (=junior synonym of M. italicus Rondani 1845).

Life Cycle, Adult and Immature Stages of a New Species of Copestylum (Diptera: Syrphidae) from Mexico Reared from Cactaceae

Abstract Copestylum alberlena, sp. nov. (Diptera: Syrphidae) was reared from larvae collected in decaying platyclades of Opuntia Mill. (Cactaceae) in the state of Veracruz (México). The third-instar larva, puparium, and adult morphology are described. Preliminary data about its life cycle and breeding behavior are included. This species is close to Copestylum tamaulipanum (Townsend), also breeding in Cactaceae, whose male genitalia are also described and compared with C. alberlena. The most important morphological differences between immature stages and adults of C. alberlena and C. tamaulipanum are illustrated and analyzed in a comparative table.

Syrphid predators (Dipt.: Syrphidae) of gall forming aphids (Hom.: Aphididae) in Mediterranean areas: implications for biological control of fruit trees pests

Most syrphids feeding on gall forming aphids belong to Pipizini tribe. The biology of two species relatively abundant in Mediterranean areas of Southeastern Spain,Pipiza festiva Meigen, 1822 andHeringia heringii (Zetterstedt, 1843), is given after 3 years of detailed survey. In this paper we study the relationship of both species of syrphids with the gall-forming aphids associated with trees of the genusPistacia (Anacardiaceae). We also establish the relationship syrphid-aphid-fruit tree, the relative abundance in each crop, length of preimaginal stages, aphid-specificity and parasitism. At last we show the seasonal adaptations of these hoverflies and their role in biological control of some fruit tree aphid pests.RésuméLa plupart des syrphes se nourrissant de pucerons gallicoles appartiennent à la tribu des Pipizini. La biologie et l’écologie de deux espèces relativement abondantes dans les zones méditerranéennes du sud-est de l’Espagne,Pipiza festiva Meigen, 1822 etHeringia heringii (Zetterstedt, 1843), ont fait l’objet d’une recherche approfondie pendant trois ans. Au cours du présent travail, les relations des deux espèces de syrphides avec les pucerons gallicoles associés aux arbres du genrePistacia (Anacardiaceae) ont été étudiées. Des larves deH. heringii et dePipiza festiva ont été récoltées sur des colonies de pucerons présentes sur différents arbres fruitiers : poirier (Pyrus communis), cerisier (Prunus avium), abricotier (Prunus domestica) et pommier (Malus domestica).La relation syrphe-puceron-arbre fruitier, l’abondance relative dans chaque culture, la durée des stades pré-imaginaux, la spécificité alimentaire et le parasitisme ont également été étudiés. Les deux espèces de syrphides sont bivoltines: au printemps, elles se développent dans les colonies de pucerons sur arbres fruitiers et sur galles dePemphigus spp sur peupliers et à l’automne les larves sont trouvées à l’intérieur des galles de Fordinae surPistacia spp. et dePemphigus spirothecae surPopulus nigra.

Temporal shifts and niche overlapping in Copestylum (Diptera, Syrphidae) communities reared in cactus species in a central Mexican scrubland

Semiarid scrubland communities are highly dynamic in terms of their species composition, abundance, and functioning, given the drastic changes in climate among seasons. Spatiotemporal patterns of saprophagous Copestylum (Diptera: Syrphidae) communities in different cactus species richness have not yet been studied, although seasonal changes and plant species richness have been shown to strongly impact the diversity and distribution of many insect communities in scrublands. We analyzed the impact of seasonality and of habitat type (disturbed and undisturbed) on Copestylum communities reared from cactus species at the Barranca de Metztitlán Biosphere Reserve, in central Mexico, by comparing their community structure between seasons and habitats, and assessing the contribution of diversity components for the total diversity of this genus. We also measured patterns of temporal niche overlap among hoverfly species considering their breeding medium. Seasonal variation influenced Copestylum community composition most significantly. Species richness and abundance of Copestylum were higher in the rainy season. Additive partitioning of diversity showed that the main component for species richness is beta diversity between seasons. We detected high niche overlap during the dry season and low overlap during the rainy season. This study provides evidence of temporal shifts in xeric hoverfly communities and suggests that the Copestylum species partition resources over time.

A review of the early stages and host plants of the genera Eumerus and Merodon (Diptera: Syrphidae), with new data on four species

The genera Eumerus and Merodon (Diptera: Syrphidae) have a high taxonomic diversity (300+ species altogether), but life histories of most species are unknown. In addition, these hoverfly genera are recognised to be pests (ornamental plants and vegetable crops). In this paper, early stages of four hoverfly species are described, Eumerus hungaricus Szilády, 1940, Eumerus nudus Loew, 1848 and Merodon geniculatus Strobl, 1909, from Spain, and Eumerus strigatus Walker, 1859, from California, USA. Larvae of E. nudus were obtained from swollen roots of Asphodelus cerasiferus J. Gay. Larvae of E. hungaricus were found in bulbs of Narcissus confusus Pugsley. The host plant of the examined specimen of Eumerus strigatus is unknown. Larvae of M. geniculatus were reared from bulbs of different species of Narcissus L. Scanning electron microscope imaging was used to study and illustrate the anterior respiratory processes, pupal spiracles and posterior respiratory processes of the new early stages. A compilation of all available information on the early stages and host plants of Eumerus (21 spp.) and Merodon (15 spp) is provided, as well as an identification key to all known larvae/puparia of these genera. Eumerus elavarensis Séguy, 1961 is proposed as a new synonym of E. hungaricus and first data of this species are reported from Austria, Bulgaria, Spain and Turkey. In Eumerus, larvae are alleged to rely on the previous presence of decay organisms, but in the larvae of E. nudus the sclerotisation and size of the mandibular hooks suggest that this larva can generate decay from intact plant tissue.

Modulation of plant-mediated interactions between herbivores of different feeding guilds: Effects of parasitism and belowground interactions

Herbivory affects subsequent herbivores, mainly regulated by the phytohormones jasmonic (JA) and salicylic acid (SA). Additionally, organisms such as soil microbes belowground or parasitoids that develop inside their herbivorous hosts aboveground, can change plant responses to herbivory. However, it is not yet well known how organisms of trophic levels other than herbivores, below- and above-ground, alter the interactions between insect species sharing a host plant. Here, we investigated whether the parasitoid Aphidius colemani and different soil microbial communities (created through plant-soil feedbacks) affect the JA and SA signalling pathways in response to the aphid Myzus persicae and the thrips Frankliniella occidentalis, as well as subsequent thrips performance. Our results show that the expression of the JA-responsive gene CaPINII in sweet pepper was more suppressed by aphids than by parasitised aphids. However, parasitism did not affect the expression of CaPAL1, a biosynthetic gene of SA. Furthermore, aphid feeding enhanced thrips performance compared with uninfested plants, but this was not observed when aphids were parasitised. Soils where different plant species were previously grown, did not affect plant responses or the interaction between herbivores. Our study shows that members of the third trophic level can modify herbivore interactions by altering plant physiology.