Jugar a extinguir ensambles: importancia de las oquedades de los árboles para la biodiversidad de insectos saproxílicos

The assessment of the relation between species diversity, species interactions and stability is a major goal for conservation strategies of saproxylic insects in Iberian Mediterranean woodlands. In these woodlands, tree hollows in standing living trees are key microhabitats for saproxylic biodiversity. We assess the variation in the tree hollow-saproxylic insect network among three woodland sites in the Cabañeros National Park (Spain), and evaluate their implications for saproxylic assemblages’ persistence, through simulations of three possible scenarios of loss of tree hollow microhabitats. The composition of tree hollows is closely related to biotic and ecological complexity of saproxylic networks, and together exhibit positive effects on network stability. By other side, different scenarios entail different reorganizations of saproxylic diversity of species and interactions, and the variation of the main interacting attributes. Woodlands providing higher proportion of large tree hollows are less sensitive to microhabitat loss. Conservation strategies for saproxylic insects in Iberian Mediterranean woodlands should consider woodland composition and configuration as key factors in the selection of priority conservation areas

Facilitation Among Saproxylic Insects Inhabiting Tree Hollows in a Mediterranean Forest: The Case of Cetonids (Coleoptera: Cetoniidae) and Syrphids (Diptera: Syrphidae)

Tree hollows offer an ideal niche for saproxylic insects in mature Mediterranean forests, where Diptera and Coleoptera are the richest groups. Co-occurrence is frequently observed among many species of both groups in these microhabitats, and some of these species have been considered to facilitate the presence of other species by acting as ecosystem engineers. One of the systems that is found in Mediterranean tree hollows is formed by cetonid (Coleoptera: Cetoniidae) and syrphid (Diptera: Syrphidae) larvae. Here, cetonid larvae feed on wood and litter and produce a substrate that is easier to decompose. To assess the possible role of these larvae as facilitating agents for the saproxylic guild, we studied whether the presence of saprophagous Syrphidae inside tree hollows is associated with the activity of cetonid larvae. Furthermore, in laboratory conditions, we tested whether cetonid larvae activity can improve the development and fitness of the saprophagous syrphid species. Our results show that “cetonid activity” was the variable that best explained the presence of saprophagous syrphid species in natural conditions. Myathropa florea (L., 1758) was one of the species most influenced by this activity. The laboratory experiment gave similar results, demonstrating that an enriched substrate with Cetonia aurataeformis Curti, 1913 larval feces improves syrphid larval growth rate and fitness of adults (measured as longer wing length) of M. florea.Financial support was provided by the Spanish Minister of Science and Innovation (CGL2008-04472, CGL2009-09656, CG L2011-23658, CGL2012-31669) and the Generalitat Valenciana (PROMETEO/2013/034 Project). I.R.S.G. was supported by Grisolia fellowships of the Generalitat Valencian

Beneficial insects associated with attractive weed plants in agroecosystems from the eastern slope of the Andes in the Colombian Orinoco basin

Se estudió la biodiversidad de insectos benéficos asociados a plantas arvenses en agroecosistemas de cacao, guanábana y arroz. Se realizaron muestreos en cinco especies de plantas arvenses asociadas a los agroecosistemas: Crotalaria striata, Indigofera hirsuta, Hyptis capitata, Melampodium divaricatum y Stachytarpheta cayennensis. Los insectos se colectaron mediante muestreos sistemáticos con red entomológica y observaciones directas a través de un transecto lineal. Se realiza por primera vez un inventario detallado de la diversidad de insectos benéficos asociada a agroecosistemas del departamento del Meta, compuesta por 66 especies/morfoespecies. Se reportan datos de interés de diez especies, entre ellos la ampliación del rango de distribución de ocho especies para la Orinoquia, así como el registro de dos nuevos géneros para Colombia: Myzinum (Hymenoptera: Tiphiidae) y Chaetogaedia (Diptera: Tachinidae). Se constata una amplia biodiversidad taxonómica y ecológica de insectos benéficos en estos ecosistemas transformados, diversidad entomológica asociada especialmente a la presencia de plantas arvenses que actúan como fuentes de alimentos suplementarios y sitios de refugio para estos insectos. Este estudio pretende aportar datos de interés para el manejo integrado de plagas, programas de restauración ecológica y conocimiento de la biología de las especies registradas.The biodiversity of beneficial insects associated with weed plants in agroecosystems of cocoa, soursop and rice was studied. Five species of weed plants associated with these agroecosystems were considered for the samplings: Crotalaria striata, Indigofera hirsuta, Hyptis capitata, Melampodium divaricatum and Stachytarpheta cayennensis. Beneficial insects were collected through systematic samplings using an entomological net, together with direct observations through a linear transect. A detailed inventory of the community of beneficial insects associated with agroecosystems in the departamento del Meta is provided for the first time, composed of 66 species/morphospecies. Eight species were recorded for the first time from the Orinoco basin, and two genera are new from Colombia: Myzinum (Hymenoptera: Tiphiidae) and Chaetogaedia (Diptera: Tachinidae). A high taxonomic and ecological biodiversity of beneficial insects was found to be associated with weed plants within these transformed agroecosystems, which provided supplementary trophic resources and refuge to the beneficial insects. This study provides interesting data for integrated pest management plans and ecological restoration programs, and contributes to the knowledge of the biology of the species reported

Control natural de plagas en cultivos mediterráneos

The spontaneous presence of natural enemies in crops represents one of the best allied to the Integrated Pest Management programs. The habitat management includes preventive measures based on close knowledge of the functioning of agroecosystems, performing actions upon pests and their enemies. These actions carried out on the habitats both in crops and in the non-cultivated areas, are aimed to conserve and enhance the populations of natural enemies. These preventive methods preserve the biodiversity of pest natural enemies in agroecosystems, using suitable management practises in agreement with ecological agriculture, and maintaining a high number of species, both predators and parasitoids

Lo que las oquedades esconden

What the hollows hide? Saproxylic insects comprise the largest component of the biodiversity in terrestrial ecosystems. They are the responsible for the mechanical breakdown of woody material both directly, by tunnelling and feeding in living trees that are decaying, snags (standing dead trees) and logs (fallen trees, portions of trunk and large branches), or indirectly, through symbiotic relationships with fungi and other micro-organisms that humidify wood. In this paper we open a door to reflection about the importance of the tree holes for the saproxylic biodiversity in the Mediterranean forests

Morphological, Genetic and Biological Evidences to Understand Meromacrus Rondani Diversity: New Species and Early Stages (Diptera: Syrphidae)

Meromacrus is a genus of conspicuous syrphids with saprophagous larvae, ranging from the southern United States to Argentina and Chile. However, this genus is in need of a taxonomic revision. Adults reared from larvae collected in Mexico and Peru, and other material available at different institutional collections were examined. Meromacrus cactorum sp. nov., from Peru, Meromacrus yucatense sp. nov., from Mexico, their puparia and breeding sites were described. A key to Meromacrus puparia is provided. The holotypes of Meromacrus canusium, Meromacrus gloriosus, Meromacrus laconicus and Meromacrus melmoth were also examined. The name Meromacrus draco is proposed as a junior synonym of M. gloriosus. Larvae of M. cactorum sp. nov. were found in decaying columnar cacti in Peru, while those of M. yucatense sp. nov. in a rot-hole of a Ceiba pentandra stump. Obtained results on both taxonomy and biology of these species serve as a first step towards a revision of the entire genus.AR’s position (grant number UATAL05) and GJSD’ predoctoral fellowship at the University of Alicante are funded by the ‘Vicerrectorado de Investigación y Transferencia de Conocimiento’. JQ’s postdoctoral position in the UADY was funded by the CONACyT-Mexico (grant number 128856). Funding to JHS was provided by an A-base research grant from Agriculture and Agri-Food Canada

Influence of tree hollow characteristics on the diversity of saproxylic insect guilds in Iberian Mediterranean woodlands

Saproxylic diversity assessment is a major goal for conservation strategies in woodlands and it should consider woodland composition and configuration at site and tree level as key modelling factors. However, in Mediterranean woodlands little is known about the relation with the environmental factors that structure their assemblages, especially those linked to tree hollow microhabitats. We assessed the diversity of Syrphidae (Diptera) and Coleoptera saproxylic guilds that co-occurred in tree hollows located in three different Iberian Mediterranean woodlands in the Cabañeros National Park (Spain). Furthermore, we evaluated how differences in tree hollow microenvironmental variables (understood as the physical and biotic characteristics of a hollow and tree individual) influenced saproxylic guild diversity both within and among woodland sites. We found that woodland sites that provided greater heterogeneity of trees and hollow microhabitats determined higher saproxylic guild diversity. Nevertheless, certain species or even complete guilds can be favoured in woodlands where some hollow microhabitats predominate as a consequence of historical tree management. In general, hollow volume was the main determining factor for saproxylic guild richness and abundance in woodland sites, and large hollow volume was usually related to higher diversity, which highlighted the importance of multi-habitat hollow trees. Moreover, saproxylic guilds also responded to other different microenvironmental variables, which indicated different ecological preferences among guilds. The conservation of saproxylic insects in Iberian Mediterranean areas must be addressed to protect woodland sites that provide high diversity and large numbers of tree hollow microhabitats, and practices to enhance microhabitat heterogeneity should even be encouraged.Financial support was given by the research Projects CGL2008-04472, CGL2009-09656, CGL2011-23658, CGL2012-31669 of the Spanish Government, and PROMETEO 2013/034 of the Generalitat Valenciana

Population dynamic of Aphidiinae (Braconidae, Hymenoptera) parasitoids in sweet-pepper crops in greenhouses

Se ha estudiado la composición de especies y dinámica poblacional de parasitoides de pulgón en invernaderos de pimiento (Capsicum annuum) del sureste de España durante dos años. Se utilizaron trampas Malaise modificadas para evaluar las poblaciones de afidiinos en el interior y exterior de los invernaderos, abarcando dos ciclos del cultivo de pimiento. Las principales especies dentro y fuera de los invernaderos fueron Aphidius matricariae (Haliday), Aphidius colemani Viereck, Aphidius ervi Haliday y Praon volucre (Haliday). Los afidiinos aparecen en el interior de los invernaderos a mediados de marzo y permanecen hasta mediados de junio. Las trampas Malaise modificadas representan una herramienta para estimar adecuadamente las poblaciones de afidiinos adultos en el interior de los invernaderos. La especie autóctona A. matricariae fue la especie más abundante, a pesar de las introducciones periódicas de otras especies de afidiinos. Este trabajo pone de relevancia la importancia de utilizar especies autóctonas de enemigos naturales en el control de plagas.This study shows the species composition and population dynamics of aphid parasitoids have been studied in sweet pepper (Capsicum annuum) greenhouses in Southeast Spain during two years. Modified Malaise traps were used to evaluate afidiin populations both inside and outside greenhouses, covering two cycles of sweet pepper culture. The main species inside and outside greenhouses were Aphidius matricariae (Haliday), Aphidius colemani Viereck, Aphidius ervi Haliday and Praon volucre (Haliday). Afidiins are present inside greenhouses around the middle of March to the end of June. Modified Malaise traps represent a tool to properly estimate adult afiidin populations inside greenhouses. The native Aphidius matricariae was the most abundant species, despite the periodic releases of other species. This work remarks the importance of using native natural enemies in pest management