Abstract:Species invasion is becoming a major ecological event affecting economic development and public health in the world. In order to explore the ecological squeeze effect of the malignant aquatic invasive species Pomacea canaliculata to the native near-niche species, the Bellamya purificata was selected as the test animals. Two sets of experiments were conducted. In the direct ecological competition experiment, P. canaliculata directly competed with B. purificata for the survival resources, while in the indirect endocrine interference experiment, the effects of secretions of the two kinds of snails on each other were observed. In order to simulate the competition of different water bodies in the field, two densities of the two kinds of snails were set, namely, 6 snails in each group (low density group) and 12 snails in each group (high density group). Different proportion of individual combinations of the two kinds of snails were set under two densities. In the low density group, the ratio of the number of P. canaliculata to B. purificata is 2︰4, 3︰3, 4︰2, while in the high density group, the ratio of the number of P. canaliculata to B. purificata is 4︰8, 6︰6, 8︰4. The data was analyzed using Excel and Spss17.0, and the significance test was analyzed using T-test. The results showed that no matter which group of experiments, the relative change rate of weight and the survival rate of P. canaliculata were better than those of B. purificata (Fig. 2, Fig. 5). In the direct competition experiment, the relative change rate of weight of P. canaliculata was significantly better than that of B. purificata (P < 0.05), but there was no significant difference in the survival rate (Fig. 3). In the low-density group, there was no significant difference in the relative change rate of weight and survival rate of the two kinds of snails; while in the high-density group, the relative change rate of weight of B. purificata was significantly worse than that of P. canaliculata (P < 0.05) when the number of B. purificata was extremely large (8), but the relative change rate of weight of B. purificata was not significantly different from that of P. canaliculata, but the survival rate of B. purificata would be significantly lower than that of P. canaliculata (P < 0.05) when the number of B. purificata was small (4) (Fig. 3). In the indirect secretion interference experiment, the relative change rate of weight of P. canaliculata was significantly better than that of B. purificata (P < 0.01), and its survival rate was higher than that of B. purificata (Fig. 4). In the low-density group, the survival rate of P. canaliculata of the high number (4) was significantly higher than that of B. purificata of the high number (4) (P < 0.05); while in the high-density group, B. purificata of the high number (8) all died within 28 days. Since the survival rate of B. purificata was high even in the high-density in the control group, which indicated that this effect was not caused by B. purificata itself, but caused by the indirect secretion stress of P. canaliculata. This life strategy of P. canaliculata caused a large number of deaths of B. purificata (Fig. 5). The above results fully indicated that the indirect secretion interference effect of P. canaliculata had a more serious ecological threat than the direct ecological squeeze effect, and the regulation ability of intraspecific competition of P. canaliculata was better than that of B. purificata, which may be an effective life history strategy for P. canaliculata as an invasive species.