COS 130-7 - Insects as stem engineers: Long-term interactions mediated by the twig-girdler Oncideres albomarginata chamela enhance arthropod diversity

Friday, August 12, 2011: 10:10 AM
9C, Austin Convention Center
Mauricio Quesada1, Nancy Calderon-Cortes1 and Luis H. Escalera-Vazquez2, (1)Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Morelia, Mexico, (2)Instituto de Biologia, Universidad Nacional Autónoma de México, Mexico DF, Mexico

Ecosystem engineering may influence community structure and biodiversity by controlling the availability of resources and/or habitats used by other organisms.  Insect herbivores may act as ecosystem engineers but there is still poor understanding of the role of these insects structuring arthropod communities, particularly for stem-boring insects. We evaluated the effect of ecosystem engineering by the stem-borer Oncideres albomarginata chamela on the arthropod community of a tropical dry forest for three consecutive years. Our hypothesis was that the modification of tree branches by O. albomarginata chamela plays a key role in the establishment of a new arthropod community and promotes interactions with positive effects on arthropod abundance and diversity.  To test this hypothesis, we simulated O. albomarginata chamela physical modification of S. purpurea branches, and compared the community composition, frequency of colonization, abundance and species richness of secondary arthropod colonizers between non-engineered and engineered branches (both artificially and naturally modified branches)


The results showed that ecosystem engineering by O. albomarginata chamela had strong positive effects on the colonization, abundance, species richness and composition of the associated arthropod community, and it occurred mainly through the creation of a habitat with high availability of oviposition sites for secondary colonizers. These effects cascade upward to higher trophic levels. Overall, ecosystem engineering by O. albomarginata chamela was responsible for nearly 95% of the abundance of secondary colonizers and 82% of the species richness. Our results suggest that ecosystem engineering by O. albomarginata chamela is a keystone process structuring an arthropod community composed by xylovores, predators and parasitoids. This study is the first to empirically demonstrate the effect of the ecosystem engineering by stem-boring insects on important attributes of arthropod communities

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