[Edited_by_A._Ciancio,_C.N.R.,_Bari,_Italy_and_K.(Bookos.org)

210
M.S.T. ABBAS
The high rate of spread of this pest is due to the human intervention, by
transporting infested young date palm trees and offshoots from infested to
healthy areas and countries. For example, the insect invaded Egypt when
infested offshoots were imported from UAE in November 1992 (Cox, 1993).
Also, as reported by Ferry and Gomez (2002), there was evidence suggesting
that the first weevils were introduced into Spain from adult palms imported from
Egypt.
Leefmans (1920) published the first original investigation on the pest in
Indonesia, and gave a complete description of the pest suggesting various
control measures.
2. HABITAT, INFESTATION AND DAMAGE
The crown and trunk of the palm tree represent the natural habitats of all stages
of R. ferrugineus. In old coconut palms the infestation is restricted to the crown,
while in young trees of coconut and date palms it is present in the crown but
mainly in the trunk. More often the insect resides in the trunk where it passes
many generations, feeding into the soft tissue portions until the trunk is
completely hollowed out and the tree falls down. The early symptom of RPW
infestation is a brown and bad smelling sap exudated from the point of
infestation. However, such a symptom could be invisible, especially when
infestations occur at the base of the trunk.
The infestation by RPW varies in relation to the height and age of the date
palm trees. In a study in Saudi Arabia 50% of infestations occurred at heights
between 0 and 1 m from the trunk base, whereas 38% was within 1–2 m
(Anonymous, 2001). As for the age of palms, most of infestation was found in
palms 5–10 years old, while prevalence was lower in palms older than 15 years.
In a similar study in UAE, Khalifa et al. (2007) reported percentages of
RPW infestation in different date palm plantations as 77.8% at 0–50 cm and
20.4% at 51–100 cm (total prevalence was 98.2% within 0–1 m). No infestation
could be detected at heights higher than 3 m. Similarly, prevalence was 12.8% at
ages up to 5 years and gradually increased to 64.8% at 6–10 years of age. The
infestation was noticed to decrease gradually to reach 17.1, 3.3 and 1.3% at ages
of 11–15, 16–20 and >20 years, respectively. However, in Egypt, in old palms
some infestations were found at the heights around 6 m, so that the palms were
broken at that level (unpublished). This case was attributed to the fact that RPW
infestation occurred at the crown of palm and the larvae moved, in tunnels,
downward until the tree collapsed at that height.
2.1. Infestation Spreading
Once RPW is introduced into an area or even a country, it has great ability to
disperse and expand. For example, R. ferrugineus was introduced for the first
time in Egypt through imported offshoots transplanted in two close locations in
Sharkyia governorate, northeastern of Cairo (Cox, 1993). Since then, great