Mucus production and microbial activity in the gut of two species of Amynthas (Megascoledicae) from cold and warm tropical climates
1992
Barois, I.
Amynthas gracilis inhabits warm lowlands and A. corticis tropical highlands; both are epigeic and their nutrition is largely based on soil. These species were used to test whether "the hypothesis of mutualism" is less intense in epigeic worms and to demonstrate the importance of temperature in this process. The mucus production of the anterior part of the gut contents of A. gracilis and A. corticis was 18 and 15% (of dry mass of gut content), respectively, which was the same as for Pontoscolex corethrurus. The water content in the gut of Amynthas was more than twice the field capacity of the control soil. The microbial activity (oxygen consumption) of the hindgut, measured at 28 degrees C, was slightly higher for A. gracilis than for A. corticis (38 and 32 nl mg-1 dry soil h-1 respectively). The microbial activity decreased more than 3-fold, and more than 8-fold at 21 and 15 degrees C respectively. When these oxygen consumptions are compared with those of the endogeic P. corethrurus (62 n] mg-1 dry soil h-1) it is noticed that the epigeic species have a lower microbial activity in their gut, and therefore a less intense relationship with the soil microflora than endogeic species. However, Amynthas spp tended to present a facultative mutualism because they have high content of mucus and water in their gut but the temperature should be above 21 degrees C.
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