Status of pine woolly aphid (Pineus boerneri) in Sao-Hill forest plantation, Tanzania

Abstract

The status of Pine Woolly Aphid (Pineus boerneri) was studied at Sao-Hill forest plantation, Southern Highlands of Tanzania. The major objectives of the study were to determine distribution and abundance of Pine Woolly Aphid (PWA) affecting main plantation species (Pinus patula and P. elliottii) and to assess intensity of damage between different age classes. Other objectives were to determine the parts of the tree crown mostly damaged and the extent of damage and to find out relationship between aphid abundance and damage. The main findings of the study were; the population densities of adult PWA did not differ significantly (p>0.05) for both P. patula and P. elliottii among the three blocks (Divisions) studied. However, Division one was more affected by aphids than other Divisions with the mean total adult population number of 17.4, 16.5 and 13.6 for P. patula and 6.7, 6.3 and 6.1 for P. elliottii for Divisions I, II and III, respectively. The mean total adult aphid population was found to be 10.1, 20.2 and 17.3 for P. patula for young, middle and old age classes respectively. In P. elliottii stands where only old class was observed, the mean total adult aphid was 19.1. Similarly, this age class was more affected than P. patula. On the other hand, the middle part of the tree crown was more damaged than other crown parts. There was a strong relationship between aphid abundance and damage between Divisions and age classes with coefficient of determination (R2) of 99.7 and 99.9%, respectively. The overall low intensity of aphid population recorded was probably due to the effect caused by predators like Tetraphleps raoi and some native natural enemies. Silvicutural operations, regular insect survey and monitoring programmes should be intensified in order to reduce the intensity of attack and spread of the pest. © 2011 Academic Journals Inc.