PRESENCE-ABSENCE SAMPLING OF 2-SPOTTED SPIDER-MITE (ACARI, TETRANYCHIDAE) IN PEAR ORCHARDS

A sampling plan was developed for rapidly assesing densities of Tetranychus urticae in pear Pyrus communis orchards. To estimate the mean number of mites per leaf on a 4-ha block of pears, a sample of leaves taken from the inner-base area of each of 10 randomly chosen trees was checked for the presence-absence of twospotted spider mite on each leaf. The mean number of mites per leaf (Y) can be estimated from the proportion of leaves infested (X) according to the equation log(Y + 1) = -0.0015 + 1.0859X. -from Authors