Abstract:
The objective of this study was to investigate the susceptibility
of four date cultivars to the attack of the saw toothed grain beetle
Oryzaephilus surinamensis (L) which is a very important store pest in
Sudan. The four dates cultivars were, Barakawi, Gondeila,
Bentamoda, and Gaw. The latter cultivar is locally propagated from
seeds. The date fruits of these four cultivars were harvested and
brought from Tangasi horticultural gardens in the Northern state in
season 2003. The study was conducted during the period early
December 2003, to mid January 2004. a total period of 6 weeks. The
study was carried out in a date store at Omdurman date market. The
larvae and adults of the pest inflict variable degrees of damage which
may reach a heavy a stage when the pest feeds on fruit content and
changes it to a powder made-up mostly of faeces. Even a minor
damage reduces the quality and marketability of the dates due to the
presence of adults, pupae, larvae and insect faeces mixed with dates .
The degree of damage is evaluated weekly in a well designed
experiment. The results showed that Barakawi was the most resistant
cultivar against the beetle where the infestation reached only a mean
of 18.4%, Gaw showed 27.9%, Bentamada 35.6% and the least
resistant cultivar was Gondeila where the recorded infestation reached
40%.
The effect of the presence of the fruit cap (perianth) on the
degree of the infestation of the fruits was studied. The result showed
clearly that the higher the percentage of the fruit retaining their caps,
the lower the percentage of the infestation and vice versa. The mean
percentage of infestation among the fruits that lost their caps was
47.3% while the infestation percentage among the dates that retained
their caps was 15.4%. This indicates that the damage of this pest could
be significantly reduced by careful harvesting and handling of the
dates.
