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Journal of Mosquito Research, 2013, Vol.3, No.5, 33
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Figure 8 Mean number of individual infective juveniles of
H.
bacteriophora
(=HB) and
H. indica
(=HI) emerged from a
C.
quinquefasciatus
cadaver as a function of changing initial nem-
atode density
Generally, both species were similar in their recovery
from cadavers as they were both interacting with the
same manner to increasing nematode concentration/
host with no significant difference between numbers
of their produced juveniles (P
≥
0.05).
The effect of increasing the initial nematode concen-
tration of
H. bacteriophora
on the length of the resulted
hermaphrodites (produced at the first generation within
the host) was determined. Since both species showed
similar recovery pattern, only
H. bacteriophora
was
selected in this assay. Changing concentration of nem-
atodes/host resulted in a significant change in her-
maphrodite length after 48, 72 and 96 hr of exposure.
Adult length increased with increasing initial nematode
concentration up to 150 infective juvenile/host then
declined with further increase in nematode concentr-
ation, P
≤
0.05 (Figure 9).
Figure 9 Mean adult hermaphrodite length of
H. bacteriophora
at 48, 72 and 96 hr post exposure
Initially, after 48 hr of exposure, only hermaphrodites
at low densities (below 100) were small. The effect of
high density on hermaphrodite length was delayed till
72 and 96 hr. The growth rate was nearly constant
during the 1
st
2 days and did not change by changing
initial nematode concentration, i.e. it is not affected by
crowding yet. Further increase in concentration did
not negatively affect the adult length after 2 days; i.e.
the nematodes can tolerate this level of crowding.
After 48 hr, the adult length (3.3 mm) was still greater
than those of control (2.76 mm) even at maximum
nematode density of 300. The maximum adult length
was 3.4 mm at nematode concentration of 200.
The effect of crowding was obvious after 3 to 4 days
post infection, where the adult length changed signify-
cantly upon increasing nematode concentration from 0
to 250 and decreased to a size smaller than that of con-
trol at 300 nematode/host. The maximum adult length was
4.7 mm and 5.9 mm when using 200 and 150 ij/host
after 72 and 96 hr, respectively.
After 3 days of infection, adults were significantly
shorter when concentration of nematodes infective
juveniles was raised to 250 and 300. Raising the
concentration from 50 up to 200 resulted in a gradual
increase in adult length reaching maximum length at
150~200 nematodes/host, after which adult length
decreased sharply.
After 72 and 96 hr, further increase in initial nematode
density resulted in a significant decrease in hermaphr-
odite length comparable to control levels after 72 hr
(3.7 and 3.4, respectively) and less than control after
96 hr (3.4 and 5.3, respectively) (r=
-
0.9, P
≤
0.01).
Increasing initial nematode concentration up to 300 ij/host
resulted in a decrease in the length of the emerging
juveniles of the 1
st
generation that were migrating out
of the cadaver. Maximum infective juvenile length
(651.6 µm) for
H. bacteriophora
occurred at low densities
(50 nematode/host), not at the densities producing the
maximum number of infective juveniles (Figure 10).
Infective juvenile length declined sharply upon treat-
ment until initial densities of 200 for, approximately
546.6 µm (r=
-
0.97, P
≤
0.01). The decline in length was
more gradual at higher initial densities ranging from
250 to 300 nematode/host (P
≥
0.05).