Abstract: Based on the review of definitions of niche, niche breadth and niche overlap, the advantages, disadvantages and applying conditions of 21 popular formulae measuring niche breadth and niche overlap are analysed in detail. As Hutchinson's conception of niche has three operational problems, an appropriate method for solving these problems--a multivariate statistical approach is introduced.Meanwhile, three reasons why niche overlap can't be used for measuring competition and three formulae for measuring competitive coefficierts are given.

Key words: glucosinolates, Brassicaceae, insect, relationship, regulation