Tritrophic web structure in montane Andean forests undergoing ecological restoration

Abstract

Parasitism represents an important ecosystem service, reducing pest abundance. Since most hosts of parasitoids are herbivores, plant diversity likely shapes both herbivore and parasitoid assemblages. While restoration efforts are being adopted worldwide, mitigating habitat degradation, little is known about how tritrophic webs are organized among plant species in recovering ecosystems. Here we collected exposed herbivores (Coleoptera and Lepidoptera larvae) during four sampling months from five plant species in two restoration areas in Andean forests in southern Ecuador. Larvae were kept in the laboratory until the emergence of the adults or parasitoids. Herbivore and parasitoid diversity and parasitism rates were compared among plants. A total of 82 immature individuals (56 Lepidoptera and 26 Coleoptera—23 predatory and 3 herbivorous) were collected and 102 parasitoids emerged (all Hymenoptera except one tachinid fly). Herbivore and parasitoid assemblages showed a high species turnover between plant species. The mean parasitism rate was 35.14% and 46.67% in the two restoration sites, respectively, with no significant differences found within forests or plants. Long-term food web monitoring should be carried out to improve our understanding of how ecosystems under ecological restoration programs functionally recover.