Spatial distribution of the cottony camellia scale, Pulvinaria floccifera (Westwood) (Hemiptera: Coccidae) in the tea orchards

摘要

In the north of Iran, near the Caspian Sea, about 35,627 ha is cultivated with tea plant, Camellia sinensis (L.) Kuntze on both plain and hilly land. The cottony camellia scale, Pulvinaria floccifera (Westwood) (Hemiptera: Coccidae) is one of the mostimportant pests of tea orchards in the north of Iran. Spatial distribution is an important item in entomoecology and needs to be studied for many pest management programs. So, weekly sampling of P. floccifera population was carried out throughout the 2008-2010 season, in the tea gardens of the Tonekabon region of the Mazandaran province of Iran. Each cut branch of tea was determined as a sample unit and after primary sampling, sample size was calculated using the equation: N = (ts/dm)2, (d = 0.15, sample size = 50). The data acquired were used to describe the spatial distribution pattern of P. floccifera by Tylor's power law, Iwao's mean crowding regression, Index of Dispersion (ID), and Index of Clumping (/DM). Tylor's power law (R2 > 0.84) and Iwao's mean crowding regression (R2 > 0.82) indicated that spatial distribution of 1st and 2nd nymphal instars is aggregated, but the distribution of 3rd instars, adults, and egg ovisacs is uniform. A result of ID and JDM showed that distribution of 1 St, 2nd, and 3rd instars, adults, and egg ovisacs were aggregative each time the sampling was done.