Contribution of symbiotic mycangial fungi to larval nutrition of a leaf-rolling weevil

Some phytophagous insects have been known to inoculate certain fungi on plant substrates. In many cases of such insect–fungi relationships it has been considered that fungi contribute to insects by decomposing lignin or polysaccharides, and that the insects feed on the decomposition products or fungi themselves. Females of the leaf-rolling weevil in the genus Euops (Attelabidae) store spores of symbiotic fungi in the mycangia and inoculate them on leaf rolls. To determine the effect of mycangial fungi on larval nutrition in E. lespedezae, the nutritional value was compared between leaves with and without mycangial fungi. Two Penicillium species were isolated from the mycangia. These mycangial fungi showed little effect on the decomposition of lignin and polysaccharides, and showed little effect on enhancement of soluble sugars within leaves. Thus, the mutualism between Euops and its mycangial fungi contrasts with the mainly nutritional mutualisms between wood-infesting insects (termites, bark/ambrosia beetles, and wood wasps) and lignin/polysaccharide-decomposing fungi.