The relative influence of agricultural abandonment and semi-natural habitats on parasitoid diversity and community composition.

Wild biodiversity is usually larger in semi-natural habitats than in croplands, but this pattern is not ubiquitous because it varies among taxa and geographic regions. Knowing how the diversity of natural enemies is structured at the landscape level is important to better understand when semi-natural habitats promote the conservation of natural enemies and ultimately enhance biocontrol. We explore the relative influence of agricultural abandonment and the proportion of semi-natural habitats at the landscape level on the diversity and abundance of parasitoid wasps in the Ichneumonidae family. We studied changes in parasitoid diversity both at local and regional scales (i.e. alpha vs beta diversity), and both at the taxonomic and functional level (i.e. species vs guild identities). We extracted landscape features in circular buffers of varying radii to perform a multi-scale analysis, and to assess at which scale landscape-level effects influenced parasitoid assemblages. We found that parasitoid alpha and beta diversity decreased with an increasing proportion of semi-natural habitats. The multi-scale analysis revealed that for this group of natural enemies, landscape-level effects occur at mid to low distances (i.e. less than 500m). Our results provide insights into the origin of pest natural enemies, their spillover to croplands, and may help to understand under which circumstances semi-natural habitats fail at promoting biocontrol services.

Do Refuge Plants Favour Natural Pest Control in Maize Crops?

The use of non-crop plants to provide the resources that herbivorous crop pests' natural enemies need is being increasingly incorporated into integrated pest management programs. We evaluated insect functional groups found on three refuges consisting of five different plant species each, planted next to a maize crop in Lima, Peru, to investigate which refuge favoured natural control of herbivores considered as pests of maize in Peru, and which refuge plant traits were more attractive to those desirable enemies. Insects occurring in all the plants, including the maize crop itself, were sampled weekly during the crop growing cycle, from February to June 2011. All individuals collected were identified and classified into three functional groups: herbivores, parasitoids, and predators. Refuges were compared based on their effectiveness in enhancing the populations of predator and parasitoid insects of the crop enemies. Refuges A and B were the most effective, showing the highest richness and abundance of both predators and parasitoids, including several insect species that are reported to attack the main insect pests of maize (Spodoptera frugiperda and Rhopalosiphum maidis), as well as other species that serve as alternative hosts of these natural enemies.

Ten new species of Triclistus Förster, 1869 (Hymenoptera, Ichneumonidae) from Peru, with a key to Neotropical species.

Triclistus Förster, 1869 is a widely distributed genus of the family Ichneumonidae, rich in the Old World but poorly represented in the Neotropical region. Ten new species are described: Triclistus ashaninka sp. n., Triclistus bicolor sp. n., Triclistus castilloai sp. n., Triclistus cholo sp. n., Triclistus muqui sp. n., Triclistus inti sp. n., Triclistus matsiguenga, sp. n., Triclistus megantoniensis sp. n., Triclistus warmi sp. n. and Triclistus yungas sp. n. A key to Neotropical species is also presented, and four species group are suggested, based in the head and propodeum structure.