Segona cita a la península Ibèrica d'Elasmus nudus (Nees, 1834) (Hymenoptera: Eulophidae), aspectes morfològics i biològics d'aquesta espècie

Es descriu i s'il·lustren els caràcters més importants d'Elasmus nudus (Nees, 1834) amb la finalitat de millorar les descripcions antigues i incompletes d'aquesta espècie. Aquesta troballa representa la primera cita per a la província de València i la segona per a la península Ibèrica. Es destaquen diferents aspectes biològics; així E. nudus ha estat obtingut com a parasitoide secundari de E. chrysorrhoea L., 1758 (Lepidoptera: Lymantriidae) atacant Apanteles lacteicolor (Viereck, 1911) (Hymenoptera: Braconidae), un parasitoide primari del lepidòpter esmentat. Pediobius pyrgo (Walker, 1839) (Hymenoptera: Eulophidae) ataca les pupes de E. nudus, que és un parasitoide terciari del lepidòpter. Aquests resultats qüestionen el parasitisme directe de E. nudus en E. chrysorrhoeaFemale and male of Elasmus nudus (Nees, 1834) are redescribed and illustrated in order to improve old and imprecise descriptions. This record represents the first record for Valencia and the second for the Iberian Peninsula. Biological aspects od this species are commented; E. nudus was found to be a secondary parasitoid of Euproctis chrysorrhoea L., 1758 (Lepidoptera: Lymantriidae) through Apanteles lacteicolor (Viereck, 1911) (Hymenoptera: Braconidae), a primary parasitoid of the browntail moth. Pediobius pyrgo (Walker, 1839) (Hymenoptera: Eulophidae) develops itself at the expense of E. nudus pupae as tertiary parasitoid. Our results question the direct parasitism of E. nudus on E. chrysorrhoe

Contrasting effects of heat pulses on different trophic levels, an experiment with a herbivore-parasitoid model system

Under predicted global climate change, species will be gradually exposed to warmer temperatures, and to a more variable climate including more intense and more frequent heatwaves. Increased climatic variability is expected to have different effects on species and ecosystems than gradual warming. A key challenge to predict the impact of climate change is to understand how temperature changes will affect species interactions. Herbivorous insects and their natural enemies belong to some of the largest groups of terrestrial animals, and thus they have a great impact on the functioning of ecosystems and on the services these ecosystems provide. Here we studied the life history traits of the plant-feeding insect Plutella xylostella and its specialist endoparasitoid Diadegma semiclausum, when exposed to a daily heat pulse of 5 or 10°C temperature increase during their entire immature phase. Growth and developmental responses differed with the amplitude of the heat pulse and they were different between host and parasitoid, indicating different thermal sensitivity of the two trophic levels. With a +5°C heat pulse, the adult parasitoids were larger which may result in a higher fitness, whereas a +10°C heat pulse retarded parasitoid development. These results show that the parasitoid is more sensitive than its host to brief intervals of temperature change, and this results in either positive or negative effects on life history traits, depending on the amplitude of the heat pulse. These findings suggest that more extreme fluctuations may disrupt host-parasitoid synchrony, whereas moderate fluctuations may improve parasitoid fitness. (Résumé d'auteur

Biogeographic evaluation of the dragonflies and damselflies in the Eastern Iberian Peninsula

Insects are one of the most diverse groups of animals in terrestrial ecosystems, and are thus a good model system to study macrogeographic patterns in species' distributions. Here we perform a biogeographical analysis of the dragonflies and damselflies in the Valencian Country (Eastern Iberian Peninsula). We also compare the species present in this territory with those in the adjacent territories of Catalonia and Aragon, and with those present in the whole Iberian Peninsula. Furthermore, we update the list of species of dragonflies and damselflies in the Valencian territory (65 species), and discuss the current status of two of them: Macromia splendens and Lindenia tetraphylla. Our results highlight that the Valencian Country has a higher proportion of Ethiopian elements but a lower proportion of Eurosiberian elements than Catalonia and Aragon. We also emphasize the importance of volunteer work in providing new knowledge on this group of iconic insects, and the relevance of museum collections in preserving them. The role of climate change in the distribution of Odonata is also discussed

Experimental removal of dominant plants alters the diversity of a network of flower-visiting insects

Plants form the base of complex communities on terrestrial ecosystems, and are the basic resource for insect herbivores and their associated natural enemies. Most plants contain flowers, and important interactions occur in these organs. Many insects are flower visitors and are known to be affected by habitat loss, fragmentation, and changes in landscape structure, but few studies have experimentally tested how habitat loss alters the structure of flower-visiting insect communities.In this study we focused on thrips (Insecta: Thysanoptera) as a model system. Previous studies in Reunion have revealed that flowers of the following exotic plants species host highly diverse communities of flower-visiting thrips : Solanum mauritianum, Lantana camara, Ipomea indica. Here, we tested the hypothesis that elimination of S. mauritianum flowers (as an important habitat for adult thrips) will trigger changes in thrips communities in the other two plants.We established replicated communities involving the three plants, and in a paired design, S. mauritanicum flowers were eliminated or not. The effect of this treatment on thrips was assessed during one month, by estimating their abundance, richness (i.e. the number of species) and diversity (shanon and simpson indexes). A community of eleven native and exotic thrips species was found. The treatment did not have any effect on insect abundance or diversity, but it had an effect on richness: elimination of S. mauritianum flowers had a negative effect on the richness of the number of species found on L. camara, but not on I. indica. At the landscape level, we observed that both the proportion of sugarcane and habitat fragmentation correlated with thrips richness. These correlations, however, were only observed when S. mauritianum flowers were eliminated, and not in our controls. Although our study was performed on exotic plant species, we provide evidence that at a fine spatial scale, the loss of a plant species that hosts a large diversity of flower-visiting insects can have consequences that cascade to the community of insects inhabiting other plants. Future studies are needed to unveil whether similar effects occur in communities of non-exotic plants, and to explore the consequences of habitat loss at a larger scale

Wedelia glauca (Ortega) O. Hoffmann ex Hicken i Oenothera biennis L., dues noves espècies al·lòctones per a la província de Castelló

Wedelia glauca és una asteràcia d'origen neotropical, rizomatosa i perennifòlia, amb tiges herbàcies rectes i simples (rarament superiors a un metre) que culminen en un únic capítol de 2-2,5 cm de diàmetre

Symbionts protect aphids from parasitic wasps by attenuating herbivore-induced plant volatiles

Plants respond to insect attack by releasing blends of volatile chemicals that attract their herbivores' specific natural enemies, while insect herbivores may carry endosymbiotic microorganisms that directly improve herbivore survival after natural enemy attack. Here we demonstrate that the two phenomena can be linked. Plants fed upon by pea aphids release volatiles that attract parasitic wasps, and the pea aphid can carry facultative endosymbiotic bacteria that prevent the development of the parasitic wasp larva and thus markedly improve aphid survival after wasp attack. We show that these endosymbionts also attenuate the systemic release of volatiles by plants after aphid attack, reducing parasitic wasp recruitment and increasing aphid fitness. Our results reveal a novel mechanism through which symbionts can benefit their hosts and emphasise the importance of considering the microbiome in understanding insect ecological interactions. (Résumé d'auteur

Defensive insect symbiont leads to cascading extinctions and community collapse

Animals often engage in mutualistic associations with microorganisms that protect them from predation, parasitism or pathogen infection. Studies of these interactions in insects have mostly focussed on the direct effects of symbiont infection on natural enemies without studying community-wide effects. Here, we explore the effect of a defensive symbiont on population dynamics and species extinctions in an experimental community composed of three aphid species and their associated specialist parasitoids. We found that introducing a bacterial symbiont with a protective (but not a non-protective) phenotype into one aphid species led to it being able to escape from its natural enemy and increase in density. This changed the relative density of the three aphid species which resulted in the extinction of the two other parasitoid species. Our results show that defensive symbionts can cause extinction cascades in experimental communities and so may play a significant role in the stability of consumer-herbivore communities in the field. (Résumé d'auteur

Segona cita a la península Ibèrica d'Elasmus nudus (Nees, 1834) (Hymenoptera: Eulophidae), aspectes morfològics i biològics d'aquesta espècie

Es descriu i s'il·lustren els caràcters més importants d'Elasmus nudus (Nees, 1834) amb la finalitat de millorar les descripcions antigues i incompletes d'aquesta espècie. Aquesta troballa representa la primera cita per a la província de València i la segona per a la península Ibèrica. Es destaquen diferents aspectes biològics; així E. nudus ha estat obtingut com a parasitoide secundari de E. chrysorrhoea L., 1758 (Lepidoptera: Lymantriidae) atacant Apanteles lacteicolor (Viereck, 1911) (Hymenoptera: Braconidae), un parasitoide primari del lepidòpter esmentat. Pediobius pyrgo (Walker, 1839) (Hymenoptera: Eulophidae) ataca les pupes de E. nudus, que és un parasitoide terciari del lepidòpter. Aquests resultats qüestionen el parasitisme directe de E. nudus en E. chrysorrhoea. Abstract. Female and male of Elasmus nudus (Nees, 1834) are redescribed and illustrated in order to improve old and imprecise descriptions. This record represents the first record for Valencia and the second for the Iberian Peninsula. Biological aspects od this species are commented; E. nudus was found to be a secondary parasitoid of Euproctis chrysorrhoea L., 1758 (Lepidoptera: Lymantriidae) through Apanteles lacteicolor (Viereck, 1911) (Hymenoptera: Braconidae), a primary parasitoid of the browntail moth. Pediobius pyrgo (Walker, 1839) (Hymenoptera: Eulophidae) develops itself at the expense of E. nudus pupae as tertiary parasitoid. Our results question the direct parasitism of E. nudus on E. chrysorrhoea

Interactions between parasitoids and higher order natural enemies : Intraguild predation and hyperparasitoids

Parasitoids kill and live at the expense of their hosts, but they also serve as food for intraguild predators and hyperparasitoids. Natural enemy diversity can thus challenge herbivore suppression by parasitoids, but this depends on the ecological niches of the species involved and their functional diversity. The spatial context is another important layer of complexity, particularly in areas with reduced habitat complexity and increased fragmentation. Parasitoids have evolved strategies to locate their host, but this can be affected by risk of intraguild predation or hyperparasitism. To better understand these interactions we need more long-term experiments and trophic-web studies. This will provide fundamental knowledge, improve pest control, and allow ecologists to better predict the impact of human activities on species extinctions