3. Results
The experiments began on 23 June 2009. At the outset of the
trials, the cowpea used contained an average of 50.75 23.26 living
adults of C. maculatus per 500 g of sample. There were 30.80 2.80
holes per 100 seeds and 27.4 7.00% of the seeds carried eggs.
Living within the seed were 2.40 2.12 adults and 20.95 16.56
larvae per 100 seeds.
Monthly observations of the following parameters were made
on the 23rd of each month from July through November (Table 1).
The highest mean was recorded in B. senegalensis and control
treatments during the first two months and thereafter declined
(Table 1). By the fifth month, the number of C. maculatus adults
was similar in all treatments. The most heavily infested seeds
with eggs were in the control and B. senegalensis treatments. At
the first, second and fourth observations, phostoxin-treated and
solar-disinfested grain exhibited the lowest proportion of grains
carrying eggs of C. maculatus. After two months of storage, the
population of larvae was highest in the control followed by the
B. senegalensis treatment. Three months later, the proportion of
seed containing C. maculatus larvae was greatest in the control,
while the other treatments had significantly lower numbers. By the
end of the fourth and fifth months, recorded numbers of larvae
were low in all the treatments.
Adults were most abundant in B. senegalensis and control
treatments during the first two observation periods. By the third
month, the number of adults of C. maculatus per 100 grains was
higher in the treatment with B. senegalensis. By the end of the sixth
month the number of adults had fallen and all treatments had
comparable numbers.
For all observations, the proportion of holed grain was greatest
in the control and B. senegalensis treatments. After 5 months of
storage all seeds in the control and B. senegalensis treatments had
one or more holes. The lowest average holes (31.33e33.44%) were
seen after phostoxin treatment and solar disinfestation. Hermetic
bagging and treatments with ash and sand exhibited holing rates
higher than seen with phostoxin, respectively 44.78%, 46.61% and
44.11%.
The phostoxin and solar disinfestation treatments exhibited
the lowest mean number of holes. The control and B. senegalensis
treatments showed 8e9 times more holes compared to phostoxin
and solar disinfestation. The ash and sand treatments recorded
a mean number of emergence holes lower than the control but
more than double the phostoxin treatment. Hermetic bagging
and solar disinfestation did not differ significantly from the
phostoxin treatment. Weight losses of 51.58% and 60.94% were
observed respectively in the control and B. senegalensis treatments.
Weight losses were much less in all other treatments
(Table 2).