Consumption of insect and plant exudates by mouse lemurs

Abstract

While exploring Isalo National Park in southcentral Madagascar, we observed numerous nymphs and adults of the endemic flatid leaf bug (Phromnia rosea). As in many other hemipterans (including aphids, scale insects, and leafhoppers), nymphs of these leaf bugs feed on phloem and expel a liquid endearingly termed “honeydew” from their anuses. This sugary substance drops onto leaves and stems. In northwestern Madagascar, the gray mouse lemur (Microcebus murinus), golden-brown mouse lemur (Microcebus ravelobensis), Madame Berthe’s mouse lemur (Microcebus berthae, the world’s smallest primate, found only in a small area in western Madagascar), and ring-tailed lemur (Lemur catta, which are in a different family from the others) mostly consume honeydew and plant-based exudates such as gums during the dry season. Honeydew could be a critical resource during periods of food scarcity (Joly-Radko and Zimmerman 2010; doi.org/10.1007/978-1-4419-6661-2_7), and lemurs are the only mammals ever documented to eat honeydew. Precious little is known about most of the mouse lemurs, and until the late 20th century only one species was recognized – now, more than 20 are known. However, collecting field data on flatid leaf bugs and mouse lemurs is challenging. Future studies could determine whether exudates account for a substantial fraction of their calories in the dry season, and if dietary shifts are accompanied by changes in the lemurs’ gut microbiota.