Submitted to: Frontiers in Ecology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2025
Publication Date: 9/18/2025
Citation: Quicke, D.L., Brown, A., Hajibabaei, M., Naik, S., Ratnasingham, S., Sones, J., Smith, M.A., Zamora, N., Brown, J.W., Matson, T., Miller, S., Burns, J., Goldstein, P.Z., Metz, M., Robbins, R., Solis, M.A., Chacon, I., Espinoza, B., Phillips-Rodriguez, E., Hebert, P.N., Janzen, D.H., Hallwachs, W., Butcher, B.A. 2025. Caterpillar diet breadth in a large and diverse Neotropical wildland, Area de Conservación Guanacaste (ACG) northwestern Costa Rica: toxins, silica, aluminium and sclerophylly. Frontiers in Ecology and Evolution. 13:1647436. https://doi.org/10.3389/fevo.2025.1647436.
DOI: https://doi.org/10.3389/fevo.2025.1647436

Interpretive Summary: United States growers spend billions of dollars a year trying to control moth caterpillar pests that feed on food systems, such as crops and stored products. Some species feed on a single plant species, others feed on a myriad of plant species from dozens of distantly related plant families, and the host plants of many species, especially exotic, invasive species, are unknown. This research explores, describes, and models the feeding patterns of caterpillars collected, reared, and identified over a 30-year period at a 147,000 hectare site in Costa Rica. It is the largest data set ever produced with over 29,000 unique caterpillar-plant species relationships comprising over 7,210 species of moths in 56 families and 2,490 species of plants in 174 families. We demonstrate patterns of plant-feeding specialization and generalization among the species of moth families and can therefore predict the feeding habits of moth caterpillars with unknown biology by their relatedness to species for which we do know their biology. The feeding patterns we discovered will be used by taxonomists, evolutionary biologists, ecologists, and pest managers to inform research and planning, and contribute to identification tools delivered directly to growers, producers, and quarantine personnel.

Technical Abstract: The Lepidoptera-food plant association collected over approximately 38 years in Area de Conservacion Guanacaste (ACG) in northwestern Costa Rica are described and analyzed. The data set analysed comprises 431,212 individual rearing records, 197,366 of which are unique rearings, i.e., the specific caterpillar-plant-associations were collected on separate dates and from different plants of the same species. Within the dataset, 29,187 different caterpillar food plant trophic associations were revealed. Identifications of Lepidoptera are based on barcode data from reared adults combined with morphological and ecological information. We examine the diet generalist-specialist spectrum in relation to the primary ecosystem (dry forest, rain forest and cloud forest, which do, however, overlap), food plant taxonomy, known distribution anti-herbivory chemical defences and Lepidoptera taxonomy. We also evaluate changes in the Lepidoptera fauna over a 30-year period (1990 to 2020). In general, members of the most species-rich Lepidoptera families at ACG showed little food plant specialisation; however, there were a few notable deviations from this pattern. For example, Sphingidae showed a conspicuous preference for Rubiaceae, and Hesperiinae for monocotyledon species and non-Hesperiinae for Fabaceae and no monocots. Among plant families for which there are over 1000 independent caterpillar rearings Acanthaceae, Apocynaceae, Arecaceae, Costaceae, Melastomataceae, Moraceae, Piperaceae, Poaceae, Rubiaceae, Rutaceae and Solanaceae hosted the most specialised herbivore species. However, plant families with the fewest rearings, e.g. Aristolochiaceae and Zamiaceae also hosted food species-specific caterpillars. We discuss plant characteristics that are associated with the highest levels of specialisation as well as the characteristics of the Lepidoptera families. We speculate that plant antiherbivory defences play a large role in determining the dietary breadth of the herbivores feeding on many plant families, and these defences include not only obvious entomotoxic secondary plant metabolites but also silica and probably aluminium accumulation.