Las relaciones secretas entre cactus, sírfidos y bacterias contribuyen al mantenimiento del ecosistema semiárido mexicano

Abstract

We commented on the diversity of a cactus-syrphid- bacteria community focusing on the exploitation of decaying cacti resources by flies. The Copestylum (Diptera: Syrphidae) larvae feed on necrosed tissues and they are critical in the processes of vegetal decomposition of cacti in semi-arid scrublands from Mexico. Though a field experiment, the cactus decomposition rate was significantly faster when insects were present, and more amounts of nitrogen were recuperated by larvae action. Additionally, we described the gut bacterial diversity inhabiting two saprophagous syrphids (Copestylum limbipenne and Copestylum latum) and their breeding substrate in the columnar cactus Isolatocereus dumortieri using molecular techniques. The main findings are: 1) larvae of the studied species are dominated by several Gammaproteobacteria, Enterobacteriaceae, including nitrogen-fixing genera and pectinolitic species; 2) decayed tissues have a dominant lactic acid bacterial community. Obtained results indicate that Copestylum larvae play an important role in maintaining this cactus forest ecosystem and suggest how significant, but as yet under studied the role of insects is in maintaining ecosystem processes of arid habitats.