Insects incidence and woody species composition of Yegof Forest, South Wollo, Ethiopia

Abstract

Yegof is a neglected state forest with limited attention has challenged with biotic and abiotic stresses. Insect pests are among the biotic stresses in reducing the economic value of the forest. This study aimed to assess the incidence and severity of insects on woody species. The systematic sampling technique was deployed to take a total of 40 sample plots (20 m × 20 m) from four directions along the transect lines that radiated from the peak of Yegof mountain to bottom of the forest. In each plot's diameter at breast height, height, density of woody species, damage incidence and severity of different insect species were collected and specimens were taken to laboratory for identification. A total of thirty-nine wood species were identified. The result revealed that cypress aphid caused damage of 90% and 45% on Cupressus lucitanica and Juniperus procera, respectively. In this study, the insect Ophelimus eucalypti caused high Eucalyptus camaldulensis leaf damage (80%) with severity of 75% (8 scales). Olea europaea subsp cuspidata was highly damaged (63%) with high significant severity (51-75%) by olive lace bug, Plerochila australis. It was observed that olive lace bug secreted a honeydew and sooty mold developed on the lower part of the leaf. This could cause the photosynthesis process halted due to stomata closing and leaf area reduction. The researchers and users should give attention on reducing the damage of pests. Further study on climate change, insect pest and woody species interactions are vital.