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Altitudinal
distributionand
damage
intensity
of
Cypress
aphidon
Cupressuslusitanicaof different age classes was investigated at SUA Training
Forest. Abundance of natural enemies of Cypress aphidat different age classes
(young 1-10years, middle 11-25 and old >25years) and altitudinal ranges (lower
1700-1930 m.a.s.l, middle 1931-2125 m.a.s.l and upper 2126-2300 m.a.s.l) was also
determined. Systematic sampling was used, whereby every 5 th tree along the row of
the study plot/block was considered as a candidate. Five shoots in lower, middle and
upper crown part of selected tree were randomly cut and put in labeled zipped
plastic bags for laboratory assessment of the aphids and natural enemies. Results
from this study indicated that Cypress aphid was un-equally distributed throughout
the altitudinal ranges and age classes. The abundance of Cypress aphid per twig was
19.6, 24.9 and 33.7 individuals for lower, middle and higher altitude respectively
and was significantlydifferent (p<0.05 and f=6.57). Also the abundance of Cypress
aphid was 33.7, 16.6 and 18.8 per twig for young, middle and old age classes,
respectively although the abundance was not significantlydifferent (p<0.05 and
f=10.82). Mean damage intensity was 37.62%, 22.02% and 27.03% for young,
middle and old trees respectively and the differences was significant (p<0.05 and
f=7.04). Younger treesat higher altitude were more attacked by Cypress aphid. Three
natural enemies namely Pauesiajuniperunum, Hoverfly larvae and Spider miteswere
detected on the affected twigs but they were verylow in numbers. Therefore, in order
to reduce the damage and spread of Cypress aphid in Olmotonyi, it is recommended
that mature trees must be harvested and release Pauesiajuniperunum bio-control
agent which has given positive results in Kenya and Malawi.
Key words: Cinaracupressivora, Cupressuslusitanica,altitude, age classes and
damage intensity. |
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