Abstract: This paper researched the cause for multiplication of Chironomidae in Yan′he watershed by analysis of the interspecific association between the major insect species in patchiness wetlands of Yan′an based on the use of 2×2 contingency table, a series of parameters including variance ratio analysis, χ2-test, association coefficient(AC), Person′s correlation(PCC)，and matching coefficient between pairs of species. The result showed that the variance ratio analysis of major insect species in autumn was significantly negatively correlated(VR=0.552＜1), χ2-test results showed no extremly significant correlation, 3 pairs were significantly correlated, interspecific association tended to independent and random distribution overall. In the 210 species pair, there were 87 species pairs with |AC|＞0.6, 61 species with |PCC|≥0.3, 27 species with PC≥0.3, 72 species with DI≥0.3, and 75 species with OI≥0.3. There was significantly interspecific association for 2 species pairs, among 89 species pairs which were related to Chironomidae, AC index and PCC index showed that the interconnection between species was weak, PC, and DI and OI indexes were concentrated in district(0≤PC＜0.3). The result showed that there was no significant or strong interspecific associations observed between Chironomidae and other species in same period.

Key words: insects in autumn, patchiness wetlands, interspecific association