Functional trophic guilds in a subtropical arid agroecosystem: Which is the most beneficial?

Developing a habitat management program to promote the conservation and augmentation of biological control services requires a deep knowledge of the taxonomy and functional diversity of arthropods in a specific agroecosystem. We studied the impacts of the landscape structure on the arthropod community (taxonomic composition, abundance, functional groups and diversity) in potato agroecosystems at the central coast of Peru. Potato (Solanum tuberosum L.) was cultivated without insecticide application in a complex and simple landscape of the Cañete valley. During the potato cropping season arthropod samples were taken from above plant canopy using Malaise traps and from the soil strata using pitfall traps. A total of 58148 specimens were collected and classified in 379 morphospecies from 119 families, 19 orders and five classes. The highest abundance of arthropod trophic groups corresponded to indifferent species (35.1%, 153 species), followed by predators (32.5%, 74 species), herbivores (16.5%, 86 species) and parasitoids (15.9%, 61 species). Entomophagous species with the highest contributions for dissimilarity between landscapes were the hymenopteran parasitoids Dolichogenidea gelechiidivoris (Marsh) (Braconidae), Halticoptera arduine Walker (Pteromalidae), Diglyphus websteri Crawford (Eulophidae) and Ganaspidium sp. (Fitigidae)  as well asthe predators Blennidus sp. (Carabidae) and Condylostylus similis (Aldrich) (Dolichopodidae). Twenty phytophagous species associated to potato were identified with Liriomyza huidobrensis (Blanchard) (Agromyzidae) and Prodiplosis longifila Gagne (Cecidomyiidae) as the most important pests. The complex landscape had a higher taxonomic and functional diversity than the simple landscape. Biological control services of entomophagous (predators and parasitoids) species showed a higher richness compared to potato pests in complex than simple landscape. However, ecosystem services due to the entomophagous abundance were superior in simple landscape. The potato agroecosystem shelters a diverse and abundant entomophagous guild that can be improved with adequate management strategies and consequently may increase ecosystem resilience to pest outbreaks.