BIOLOGICAL CONTROL-PARASITOIDS AND PREDATORS
Local and Landscape Drivers of Ant Parasitism in a Coffee
ALDO DE LA MORA,1 GABRIELA PE´REZ-LACHAUD,2 JEAN-PAUL LACHAUD,2,3 AND
STACY M. PHILPOTT4
Environ. Entomol. 1–12 (2015); DOI: 10.1093/ee/nvv071
ABSTRACT Parasitism of ants that nest in rotting wood by eucharitid wasps was studied in order to examine whether habitat and season influence ant parasitism, vegetation complexity and agrochemical use correlate with ant parasitism, and whether specific local and landscape features of agricultural landscapes correlate with changes in ant parasitism. In a coffee landscape, 30 coffee and 10 forest sites were selected in which local management (e.g., vegetation, agrochemical use) and landscape features (e.g., distance to forest, percent of rustic coffee nearby) were characterized. Rotten logs were sampled and ant cocoons were collected from logs and cocoons were monitored for parasitoid emergence. Sixteen ant morphospecies in three ant subfamilies (Ectatomminae, Ponerinae, and Formicinae) were found. Seven ant species parasitized by two genera of Eucharitidae parasitoids (Kapala and Obeza) were reported and some ant–eucharitid associations were new. According to evaluated metrics, parasitism did not differ with habitat (forest, high-shade coffee, low-shade coffee), but did increase in the dry season for Gnamptogenys ants. Parasitism increased with vegetation complexity for Gnamptogenys and Pachycondyla and was high in sites with both high and low agrochemical use. Two landscape variables and two local factors positively correlated with parasitism for some ant genera and species. Thus, differences in vegetation complexity at the local and landscape scale and agrochemical use in coffee landscapes alter ecological interactions between parasitoids and their ant hosts.
KEY WORDS coffee, eucharitidae, formicidae, vegetation complexity
Deforestation and intensification of agroecosystems contribute to global loss of diversity and to alterations in species interactions and ecosystem services provided.
Ecosystem services are “the conditions and processes through which natural ecosystems, and the species that make them up, sustain and fulfill human life” (Daily 1997). In agroecosystems, richness and abundance of some organisms decrease due to habitat simplification and landscape modification (Dauber et al. 2005, Garcı´a
Estrada et al. 2006). Some implications of biodiversity loss are the disruption of ecological processes and alteration of interaction networks that support mutualisms and ecosystem services (Naeem 2002, Fischer et al. 2006). Species interactions are modified by landscape changes including fragmentation (Tscharntke et al. 2002), changes to matrix quality (Vandermeer and Carvajal 2001, Steffan-Dewenter et al. 2002), modifications to forest shape, edge, or area (Tscharntke et al. 2002), and habitat loss or degradation (Fischer and
Lindenmayer 2007). In any habitat where interaction networks are simplified, there may be reductions in ecosystem functioning (Dobson et al. 2006, Jonsson et al. 2012) and hence in the provisioning of services.
Habitat loss and landscape simplification drive biodiversity loss that in turn drives declines in ecosystem processes and functionality (Clergue et al. 2005,
Tscharntke et al. 2005, Fischer and Lindenmayer 2007,
Philpott et al. 2009).
In contrast, some agroecosystems harbor high levels of biodiversity and may act as refuges for biological diversity that can provide ecosystem services such as biological pest control and pollination (Perfecto et al. 1996, Moguel and Toledo 1999, Tscharntke et al. 2005,
Jose 2009, Power 2010, Vandermeer et al. 2010). Different taxa vary in response to increases in tree diversity, canopy shade, and decreased agrochemical use (Moguel and Toledo 1999, Mas and Dietsch 2003, Garcı´a Estrada et al. 2006, Gagic et al. 2012); thus, some taxa may be more sensitive to agricultural landscape changes and act as indicators of habitat simplification (e.g. Pocock and Jennings 2008, De la Mora and Philpott 2010). There are now numerous examples of increases in ecosystem services provided in less intensive agricultural systems, such as shaded coffee, compared with more intensive farms (e.g. Jha et al. 2014). Thus, we must focus on understanding how to promote less intensive agricultural production in order to prevent the increase of insect pests, reduced pollination, and 1 El Colegio de la Frontera Sur, Ecologı´a de Artro´podos y Manejo de Plagas, Carretera Antiguo Aeropuerto Km 2.5 Tapachula 30700,
Chiapas, Me´xico. 2 El Colegio de la Frontera Sur, Conservacio´n de la Biodiversidad,
Avenida Centenario km 5.5, Chetumal 77014, Quintana Roo, Me´xico. 3 Centre de Recherches sur la Cognition Animale, CNRS-UMR 5169, Universite´ de Toulouse UPS, 118 route de Narbonne, 31062
Toulouse Cedex 09, France. 4 Environmental Studies Department, University of California,
Santa Cruz, 1156 High St., Santa Cruz, CA 95064. Corresponding author, e-mail: email@example.com.
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Environmental Entomology Advance Access published May 6, 2015 loss of other ecological services (Kruess and Tscharntke 1994, Steffan-Dewenter 2002, Jha and Vandermeer 2010). Agricultural intensification and habitat complexity may strongly affect host–parasitoid interactions (Wilkinson and Feener 2007, 2012; Visser et al. 2009;
Jonsson et al. 2012). Natural enemies, especially the parasitic Hymenoptera, play an important role in pest regulation (Rodrı´guez and Hawkins 2000, Varone and
Briano 2009), and parasitoids and parasitism are affected by local habitat changes and changes at the landscape level (Klein et al. 2002, Fischer and
Lindenmayer 2007). In addition, hymenopteran parasitoids are sensitive to agrochemical use and thus examining different host–parasitoid interactions where agrochemical use varies is necessary.