© Benaki Phytopathological Institute
Nematicidal effect of macrolides on
Meloidogyne incognita
27
der laboratory conditions, due to exposure
to the tested bioproducts after two time in-
tervals is illustrated in Fig. (1). Hatching was
inversely proportional to the concentration
of the bioproducts. After 3 and 7 days expo-
sure, the most effective compounds caus-
ing hatching reduction were ABM (96.32
and 85.41%, respectively) and EMB (88.55%
and 71.23%, respectively) at 400 mg/l. At
2000 mg/l, hatching inhibition was 73.83%
and 69.40% for SPI and 77.72% and 73.35%
for SPIT (Fig. 1). LC
50
values on hatching in-
hibition after 3 and 7 days exposure were
respectively, for ABM 24.61 mg/l and 46.89
mg/l, for EMB 47.97 mg/l and 83.09 mg/l, for
SPI 629.53 mg/l and 781.52 mg/l and for SPIT,
487.46 mg/l and 635.66 mg/l (Table 1).
J
2
mortality increased by increasing com-
pound concentration and exposure time,
whereas no mortality occurred in the con-
trols. After 24 and 48 h exposure, J
2
mor-
tality for ABM at 100 mg/l was 73.01% and
86.00%, respectively, and for EMB 51.43%
and 63.08%, respectively. SPI at 1500 mg/l
caused a 45.22%and 50.66%mortality, while
SPIT 32.86% and 42.03%, respectively. This
indicates that there is a marked increase in
J
2
mortality caused by ABM over EMB and by
SPI over SPIT (Fig. 2). Probit analysis of these
results indicates that, after 24 h exposure,
ABM was the most toxic compound against
J
2
(LC
50
= 36.64 mg/ml) followed by EMB,
SPI and SPIT. LC
50
values after 48 h expo-
sure were 22.89, 79.03, 1611.27 and 2355.52
mg/l for ABM, EMB, SPI and SPIT, respective-
ly. In general, these compounds could be ar-
ranged according to their effectiveness on J
2
mortality as follow: ABM > EMB > SPI > SPIT
(Table 1).
Effect of test compounds against M. in-
cognita at pot assay
All treatments showed differential nem-
aticidal properties when compared to the
untreated inoculated control. Gall formation
was significantly suppressed by EMB, ABM,
SPI and SPIT with reductions of 71.65, 69.46,
64.54 and 64.01%, respectively. However, no
significant differences were observed be-
tween ABM and EMB and between SPI and
SPIT (Table 2). Except for EMB, no significant
differences were observed between the
lower and the higher rates of ABM, SPI and
SPIT. The same trend was exhibited with re-
spect to egg masses/root system. EMB was
the most effective followed by ABM, SPI and
SPIT, reducing egg masses by 76.28, 74.57,
56.20 and 51.24%, respectively. No signif-
icant differences were detected between
the lower and higher rates of all treatments.
With respect to the number of eggs/egg
mass, EMB, SPI, ABM and SPIT recorded re-
ductions of 61.71, 54.08, 52.34 and 45.61%,
respectively. The application of EMB, ABM,
SPI and SPIT suppressed population density
in soil by 91.82, 89.26, 74.33 and 72.64%, re-
spectively, compared to the control. No sig-
nificant differences were observed between
the lower and the higher rates of all applied
treatments (Table 2).
The effect of ABM, EMB, SPI and SPIT as
a soil drench on the shoots and roots of the
tomato seedlings is shown in Table 3. Shoot
height increased in all the treated plants by
23.35% to 48.24%. The maximum increase
was observed in plants treated with SPIT,
followed by SPI, EMB and ABM. No signifi-
cant differences were observed between the
lower and the higher rates of all treatments.
Noticeable increases were also recorded in
the mean root length of plants treated with
SPI, SPIT and EMB, i.e. 19.85%, 8.82% and
4.41%, respectively, whereas ABM reduced
root length by 4.78%. Noticeably, the high-
er rate of SPIT exhibited a root length reduc-
tion by 5.88% (Table 3).
Regarding dry shoot weight, data indi-
cate an increase as compared to the control;
the highest dry weight was observed with
SPI (43.46%), followed by SPIT (34.11%), ABM
(16.93%) and EMB (16.54%). ABM at the low-
er rate (10 folds) decreased dry shoot weight
by 8.97%. Plants treated with ABM showed
significant differences between the low-
er and the higher rates, whereas no signif-
icant differences were found between the
lower and the higher rates of EMB, SPI and
SPIT (Table 4). All treatments recorded an in-
crease in dry root weight over the untreated
inoculated control. Such increase was min-
