Abundance of cypress aphid, Cinara cupressi, and tree damage in cultivated Cupressus lusitanica in Gambo, Arsi Negelle.
Exotic invasive pests cause immense economic damage worldwide. Cypress aphid, an exotic forest pest, Cinara cupressi, has caused enormous Cupressus and Juniperus loss in Ethiopia. In the efforts to manage the pest, Pauesia juniperunum, a biological control agent was released. However, the pest is still a bottleneck and damages are being reported in different areas. Thus to minimize damage and tackle future outbreaks it is important to monitor the pest status. Therefore the present study assessed the abundance of cypress aphid and infestation level and extent of damage the insect caused in mono-cultivated C. lusitanica in Gambo, Arsi Negelle, Ethiopia. Aphid abundance and tree browning were assessed for 10 months, every other month, by taking three 60 m*60 m areas and splitting them into 4 quadrants of 20 m*20 m. Aphid abundance data was collected by walking diagonally in each quadrant and sampling three branches from the top, middle, and bottom parts of each tree. Tree damage was assessed based on a 1-5 measuring scale. The results showed that adult and nymph cypress aphid abundance significantly varies between sampling periods where the first sampling period having significantly higher cypress aphid count per twig than the last two sampling periods of the year, 4th and 5th. Tree infestation also varies between sampling periods and had a positive correlation with aphid count. With an increase in the aphid count tree infestation also increased. The result further showed variation in the distribution of aphids on different positions of the crown (bottom, middle, and top whorl). Twigs on the bottom and middle whorls had a higher aphid count than top whorl. The results also showed that during all the sampling periods in each quadrant all the trees were found to be infested by cypress aphid. In conclusion, cypress aphid is abundant in the area and the abundance showed a varying trend through the year. All the trees sampled showed infestation symptoms, therefore; timely surveillance is important to manage possible future damage.