白蚁菌圃上小白球菌和炭角菌的生态关系初报

Ecological Relation Between Termitosphaeria Duthiei and Xylaria Nigripes on the Termite Combs

通过人工调节pH、CO_2分压、温湿度以及有机氮等条件,探讨了白蚁巢内两种优势真菌的生态关系.结果表明:小白球菌和炭角菌除对温湿度要求相似外,不同之处在于小白球菌适应于高浓度CO_2、低pH值(3.8-4.2),低浓度有机氮,以及对酵母浸膏也有一定的要求.而炭角菌要求低浓度CO_2、高pH值(5.0-6.3),又需要高浓度有机氮.根据这些实验,我们初步认为白蚁的存在产生了丰富的有机酸和高浓度CO_2,可能给小白球菌造成了特定的pH环境,成为蚁巢菌圃上优势真菌的主要选择因子,在“废巢”菌圃上,有机酸和CO_2浓度的降低,炭角菌分泌的代谢物质引起菌圃pH值的上升,可能是炭角菌成为优势种的原因.

The ecological relation between two dominant species of fungi in the termite nest was studied by means of a controlled environmental condition of CO2, pH, temperature, humidity, organic nitrogen, etc. The results indicated that Termitosphaeria duthiei and Xylaria required similar humidity and temperature, but Termitosphaeria duthiei required higher CO2, lower pH(3.8-4.2), low concentration of organic nitrogen and certain Yeast extract, while Xylaria required lower concentration of CO2, high pH value (5-6.3) and higher concentration of organic nitrogen. According to the results, it was considered that the aboundant organic acids and high concentration of CO2 caused by Termites gave Termi tosphaeria duthiei a certain pH environment by controlling comb pH value, which may be the principal selective factor making T. duthiei dominant in the nest. In the abandoned nest the decrease of the amount of organic acids and CO2 concentration, the ascension of pH value caused by Xylaria secretion, higher concentration of organic nitrogen caused by T. duthiei and high humidity are the reasons why Xylaria becomes the dominant species of fungi.