EUROPEAN JOURNAL OF ENTOMOLOGY

Eur. J. Entomol. 102 (4): 675-681, 2005

Diet composition and body size in insect herbivores: Why do small species prefer young leaves?

Lukáš ČÍŽEK

Institute of Entomology, Czech Academy of Sciences, Branišovská 31, 370 05 České Budějovice, Czech Republic;

The hypothesis that small body size is correlated with preference for young leaves was tested in a community of leaf-chewing insect herbivores feeding on Ficus wassa in a humid tropical forest in Papua New Guinea. Feeding experiments on 48 species of herbivorous insects revealed a negative correlation between body size and a preference for feeding on young leaves. While small species preferred young leaves, large species showed no preferences, or preferred young leaves only slightly. This relationship was found for the entire leaf-chewing community, as well as for many of the constituent taxa on several taxonomic levels, from orders to genera. Taxonomic position of a species played little role in determining its preferences. It is proposed that higher toughness and lower nutrient content may act as complementary defences, which prevent small insects from feeding on mature foliage. While the low nutrient content of mature leaves may affect smaller herbivores due to their relatively higher metabolic rate and lower digestion efficiency, their toughness complicates feeding mechanically and may prevent the compensatory feeding necessary to offset the low nutritive value of mature leaves.

Keywords: Body size, constraint, diet composition, herbivory, insect, leaf toughness, Papua New Guinea, phenology, specificity, plant defence, young leaves

Received: January 10, 2005; Revised: April 11, 2005; Accepted: April 21, 2005; Published: November 3, 2005  Show citation