Abstract:
Effective integrated pest management (IPM) of the melon fly Zeugodacus cucurbitae
(Coquillett),
a
devastating
pest
threatening
horticultural
production
in
Africa,
is
urgently
needed.
In
this
study,
a
caged
field
experiment
was
implemented
in
Thika,
Kenya
to test the efficacy of Metarhizium anisopliae (Mechnikov) Sorokin ICIPE 69
for Z. cucurbitae control in courgette Cucurbita pepo L. Treatments included: (1) dry
conidia of M. anisopliae ICIPE 69 applied in an autodissemination device (fungus); (2)
dry conidia of M. anisopliae ICIPE 69 in an autodissemination device combined with
cuelure, a male attractant (fungus + cuelure); (3) a commercial insecticide (profenofos + cypermethrin)
(insecticide); and (4) an untreated control (control). Each treatment
was replicated thrice and the experiment was conducted twice during two
seasons. Flies (300/tunnel) and treatments were introduced at flowering. One day
later, 25 flies/tunnel were randomly collected from each cage to assess conidial acquisition
(for
fungus
and
fungus + cuelure
treatments
only)
and
mortality
during
a
10-
day
interval
in
the
laboratory.
Flies
in
the
fungus + cuelure
treatment
acquired
more
conidia
(18.02 ± 0.48 conidia/fly) than those in the fungus treatment (11.93 ± 0.40
conidia/fly). Flies in the fungus + cuelure treatment experienced the highest mortality
(95.31% ± 1.69%),
while
those
in
the
insecticide
treatment
experienced
the
lowest
(38.70% ± 4.32%).
Dry
conidia
were
collected
from
the
autodissemination
devices
(in
the fungus and fungus + cuelure treatment) daily for 7 days after flowering to
check for compatibility through germination tests. Percentage germination reduced
over time from 86.45% ± 1.77% and 87.72% ± 1.71% on day 1 to 16.39% ± 2.11% and
42.76% ± 1.74% on day 7 (seasons 1 and 2, respectively). The yield was significantly
different among treatments and was, across seasons, highest in the fungus + cuelure
(6961 ± 550 kg/ha) and insecticide (7267 ± 352 kg/ha) treatments and lowest in the
control treatment (2089 ± 155 kg/ha).
