Molecular Food Web of Lepidopteran Hosts and Their Parasitoids in a Tropical Secondary Forest in Thailand

A semi-quantitative molecular food web was constructed for caterpillars (Lepidoptera) and juvenile insect parasitoids dissected from them, using the barcoding region of the mitochondrial cytochrome oxidase c subunit 1 gene. Sample collection was carried out in a secondary forest in Saraburi province of Thailand. A total of 5,673 caterpillars were collected between November 2015 and November 2016. Overall, 6%. of these were found to be parasitised. DNA barcoding revealed 118 provisional host species and 119 species of parasitoids. The most abundant caterpillar hosts were Haritalodes derogate (Lepidoptera, Crambidae) and the most abundant parasitoid was a tachinid fly, Peribaea sp. (Diptera, Tachinidae). Apparently, specialist parasitoids constituted 80% of the species, however, this seems likely to be an overestimate because of the large number of singletons. Compared with a number of other comparable food web studies the connectedness of our web was extremely low whereas generality, vulnerability and linkage density were very high. This might reflect the heterogeneous nature of the recently disturbed study area. Understanding the relationship and the unique attributes of secondary forests is essential for enhancing biodiversity and maintaining ecosystem stability in these fragile environments.