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Bioscience Methods 2014, Vol.5, No.3, 1-11
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under irrigated and rainfed conditions. During the
major dry season (December-March), persimmons and
syncomore figs dominated the wild fruit flora with
infestation peak reaching 200 flies per kg fruit. During
the early dry season (April-June), the host flora was
succeeded by both cultivated and wild species
dominated by mango, icacina, albarillo, marula plum,
tropical almond and sheanut. The peak infestation of
these species occured in alternation over the months
with each fruit species recording not less than 100
flies per kg fruit at the peak fruiting period. The
mango season stretched from mid March to early July
with peak infestation in April and June for the early
and late season mangoes, respectively. These fruit
species were widely distributed in the ecology,
providing fertile breeding grounds for the resurgence
of both
B. invadens
and
C. cosyra
. Moreover, the
occurrence of other wild fruits such as syncomore figs
and sour sops generally overlaped the early rainy
season, serving as important survival niches especially
through the prolonged spells in parts of May and June.
The mid season period, which stretched from July to
September, was dominated by tropical almonds,
peaches and sour sops, with some patches of late
mangoes, sheanut and albarillos. Tropical almonds
and peaches appeared to be the major reservoir hosts
for the flies during this period. The major peach
season began in August and extends through the end
of the year. This species proved to be the most
abundant, persistent and widely distributed hosts in
the ecology accounting for the highest populations of
B. invadens
and
C. cosyra
during September and
October. Wild jujube also becomes available as
alternative reserviours for the flies from September
until the end of December during which time
syncomore figs and persimmons begin their
re-apperance as suitable hosts for the flies through the
drier periods of the new year.
The results obtained relating to the emergence of the
fruit fly species from the main hosts compared as a
function of the study regions and seasons are shown in
Figure 2. It was observed that fruit fly infestation was
generally highest in the Northern region and lowest in
the Upper East Region while the Upper West Region
experienced moderate infestation. In all regions,
emergence of both fruit fly species was at the lowest
level at the beginning of the year, but this assumed a
sharp increase after February, reaching a peak around
August. Thereafter, tephritid emergence dropped
steadily to very low level by December. During the
first four months, rate of emergence of
C. cosyra
was
found to be higher than that of
B. invadens
, but the
reverse occurred from April until August when
C. cosyra
becomes dominant again for the rest of the season.
Figure 2 Emergence dynamics of
B. invadens
and
C. cosyra
from the 12 main hosts (pooled data) in relation to the study regions