IndianJ. Nen/a/ol. 27 (2).222-232
(19<17)
. STUDIES ON BIOTIC POTENTIAL AND PREDATION EFFICIENCY OF
IOTONCHUS MONHYSTERA (MONONCHIDA: NEMATODA)
MUJIB I. AZMI
Plant Protection Division, Indian Grassland and Fodder Research Institute, Jhansi- 284 003.
Abstract: Mononchid nematode, lu/unchus monlryslera was cultured in I% soil-beef extract
agar. Estimate of biotic potential i.e. intrinsic rate of natural increase was calculated from the data
generated on generation time and rate of egg production by individual female. Equation !()r these
variables in the laboratory cultures within the temperature range of 5 to 33°C were derived. Predation
efficiency of I.monhyslera was studied in agar as well as in soil. Percentage of predator causing 50%
predation of Meloidogyne incognita and Pratylenchus zeae within five days in soil was calculated
by profit-log dose analysis.
Key words: Biotic potential, predator, prey, Iolonchus monhyslera, pest management.
Predation efficiency and agricultural
importance of mononchid nematodes have
been attracting most of the researchers (Cohn
& Mardechai, 1974; Nelmes, 1974; Small,
1979; Small & Grootaert, 1983). Cassidy
(1931) concluded, that under suitable
conditions /otonchus brachylaimus might
partially control pest nematode populations.
In the present paper an attempt has been
made to study the biotic potential i.e. intrinsic
rate of natural increase through life cycle data
of mononchid nematode, I.monhystera (Cobb,
1917) Jairajpuri, 1970 in laboratory cultures.
Preliminary assessment of its predation
efficiency in reducing the populations of plant
parasitic nematodes, Meloidogyne incognita
and Pratylenchus zeae has also been
evaluated.
MATERIALS AND METHODS
Culture of Organisms
Predator: I. monhystera was cultured in
I % soil extract agar (Springett, 1964)
supplemented with 1% beef- extract. Beef
extract was prepared by boiling Ig beef in 100
ml water for 15 min in properly closed Petridishes and kept at constant temperature of
25°C. After one month the cultures were
subcultured in separate Petri-dishes poured
with fresh media. Predators were regularly
supplied with either Aphelenchus avenae or
Acrobeles sp. as prey.
Alternate prey: Fungalfeeder nematode,
A. avenae and bacterial feeder nematode,
Acrobeles sp. were cultured in com meal agar
media at 25°C (Tarjan, 1955). These cultures
were also maintained in properly closed Petridishes and kept at constant temperature of
25°C in an incubator. Every month these
cultures were subcultured in Petri-dishes
poured with fresh media.
Target Prey: Plant-parasitic nematodes,
M incognita and P. zeae were cultured in pots
filled with steam sterilized sieved field soil,
Cowpea (Vigna unguiculata) and maize (Zea
mays) plants Were used as hosts, respectively.
I
BIOTIC POTENTIAL AND PREDATION OF IOTONCHUS MONHYSTERA
Observation
out at different temperatures.
on biotic potential
Reproduction
and
223
development
of
Predation
efficiency tests
I.monhystera were observed in embryo dishes
containing I % soil-beef extract agar mediwn.
In this study predators
were supplied with
only A. avenae as prey. The time taken in
embryonic
development,
duration
in each
Direct
observation
observations
test:
on the frequency
prey encounters
Direct
of predator-
were made in Petri-dishes
containing I % water agar under stereoscopic
juvenile stages (J l' J 2' J 3 and J J and the time
when adult female started egg production
microscope. ~Individual prey nematodes were
were recorded. Per day egg production by
single female were estimated by taking
The prey nematodes tested were juveniles of
hundred days cumulative·data
of each female
separately.
All these observations
were
recorded at seven different temperatures viz.,
15, 18,21,24,27,30
and 33°C. Ifneeded, a
little distilled water was added to the medium
to prevent dehydration in embryo dishes. Each
set of observations was started with ten last
sta~e juveniles
from the stock cultures
maintained at 25°C. Since no male was found
placed in the path of the predator (female).
M incognita and P. zeae, A. avenae and
Acrobeles sp. If predators were disturbed
observations were discontinued.
Frequencies
of predator-prey encounters were recorded in
three categories i.e., encounter with attack,
with wounding, and wounding with feeding.
For each observations
five days starved
predators
we~e used. Predators
were
introduced in agar two hours before the tests
in any culture, therefore, the sex ratio was
were initiated. Wounded and unfed prey were
removed fromt the track. Data were analysed
invariably
with chi-square test fixed ratio, homogenity
considered
one. Reproduction,
development, egg production and prey density
were checked daily. Every week adult worms
were transferred to a fresh culture medium
of ratio and independence.
Agar
inoculum
test:
This test was
conducted in small cavity blocks filled with
regularly.
1% water agar. Five predators (female) and
Intrinsic rate of natural increase (rm)
were calculated by the formula (Small, 1982).
rm=
In (PXE)
GT
Where P is the sex ratio; E is the mean per
day egg production of single female; GT is the
.fifty prey were inoculated simultaneously in
each 'cavity block. Predators were inoculated
at four different starvation stages i.e., freshly
isolated, 5, 10 and 15 days starved. Each prey
species, M incognita (juveniles) P. zeae, A.
avenae and Acrobeles sp. were inoculated
separately. There were four treatments for
each species of prey viz., 5 freshly isolated
generation time i.e. time taken for development
predators
from egg to onset of egg production; In is the
predators
natural log transformed value. Equations and
predators
curve fittings of GT, E and rm were worked
predators
+ 50 prey; 5 five days starved
+ 50 prey; 5 ten days starved
+ 50 prey; 5
+ 50 prey.
fifteen days starved
This
experiment,
224
MUJIB I. AZMI
replicated five times, was run for 24 h. The
data were recorded on the number of
nematodes predated i.e., killed or killed and
eaten. Per cent nematode predated were
analysed for significance. The Arc percentage
transformed values were used for the analysis
of variance in completely randomized design.
Soil inoculum test: This test was
conducted in 400 ml steam-sterilized sieved
field soil (75% clay, 25% sand and 25%
moisture) filled in 500 ml plastic pots.
Predators were obtained from 1% soil-beaf
extract agar culture maintained using
Acrobe/es sp as prey. Approximately 50:50
mixed population of 1 monhystera and
Acrobe/es spwere used for predator inoculum.
Juveniles of M incognita were obtained by
placing egg masses collected from the roots
of tomato (from the pot culture) on tissue
paper supported by galvanised wire mesh. P.
zeae were collected from the soil and roots
(from the pot culture) by modified Baerman
technique. Nematodes were inoculated in one
ml water into a groove near host plants.
Surface sterilized (with 0.1%/ mercuric
chloride solution) seeds of cowpea var. NP-3
were sown in seven pots 5 days before the
inoculation of nematodes. Five hundred
juveniles of M incognita were inoculated in
each pots. Simultaneously, predators were
inocula~t
seven levels viz., 0, 20,30, 40,
50 60 and 80 (obviously equal numbers of
Acrobe/es sp. also came with the predator into
the sQil).In this way this experiment consisted
of seven treatments. After keeping them for 4
days nematodes wete extracted from the soil
by modified Baermann technique in 24 h.
Number of nematodes in the roots were
counted by fixation and staining in methyl
blue lactophenol and clearing in lactophenol
(Franklin & Goodey, 1949). The same test
was also conducted for P. zeae using maize
var African Tall as host plant. Both these
experiments were replicated five times.
Number of surviving nematodes in each pOt
were estimated. Data were analysed
statistically using completely randomized
design. Analysis of variance were computed
by log (n+ 1)transformed values of nematodes.
Per cent predation were estimated. Corrected
per cent predation were calculated by the
Abbott formula' (Busvine, 1971).
Pr=
Po - Pc X 100
lOO-pc
Where Pr is the corrected per cent
predation, Pois the observed per cent predation
and Pc is the per cent of death in the control
pots. Percentage inoculum of the predator
caused 50% predation (PD50) of M incognita
and P. zeae was computed by the method of
Reed-Muench (Woolf, 1968) and their
standard errors (SE) were calculated by the
method of Pizzi (1950). Probit of predation
and log (I ++) percentage predator graphs
were plotted for M incognita and P. zeae
separately.
RESULTS AND DISCUSSION
Culture and biotic potential
The species of predacious mononchid
nematode, 1 monhystera was observed to
reproduce without male in all cultures.
Mechanism of egg laying was on the same
BIOTIC POTENTIAL AND PREDATION OF IOTONCHUS MONHYSTERA
225
pattern as observed in Acrobeloides sp.
(Jairajpuri&Azmi, 1977). Feeding is essential
statistically
for egg production. Nelmes (1974) observed
(1982) in his observation
that many mononchs feed most voraciously
vulvapapillatum. Mean egg production per
during
day per female increased with the increase of
the
cannibalism
period
of egg
was
laying.
observed.
No
Embryonic
it was presumed
that the mean would be
normal as concluded
by Small
with Lahronema
temperature from 15 to 33°C. The curve which
fits true to this trend is given in fig. 2 equation
development took 16 and 7 days at 15 and
33°C temperatures. At the temperature less
that describes the· mean egg production
than 15°C development
single female per day is as follows
was very slow and
by
undetectable, whereas at the temperature more
than 33°C it failed in this culture which might
be due to rotting by bacterial contaminations.
Therefore, all these studies were carried out
within the temperature range of 15 to 33°C. It
E
= 3.1
X
10-3
t
2.19
Where E is the mean number of eggs
produced by single female per day, t is the
temperature within the range of 15 to 33°C.
was also noticed that only 50% of the juveniles
reached the adult stage in all cultures.
With the data like generation time (GT)
and mean number of eggs produced by single
Table 1 showed the time taken for the
development of predator in the culture medium
at different temperatures.
their development
The time taken for
was gradually
with the increase of temperature.
decreased
Generation
time (GT) i.e. from egg to onset of egg
production stage varies from 57.9 day to 25.9
day at the increasing temperature range (15 to
33°C). The curve (Fig. 1) fits for this pattern
8.897
t
X
102
different
temperatures.
the
very low at 15°C but later on increased with
the increase of temperature (r = 0.99). The
regression equation which holds good is
rm
= 4.31 x
1O-3t
- 6.75 x
10-2
_
3.4235
increase, t is the temperature within the range
of 15 to 33°C.
Understanding
Where GT is the generation time and t
stands for temperature within the limits of 15
to 33°C
Per day mean egg production
female were estimated
Fig. 3 shows
relationship between temperature and the
intrinsic rate of natural increase rm. It wa:i
Where rm is the intrinsic rate of natural
is described by the equation.
Gt=
female per day (E), the intrinsic rate of natural
increase was· calculated for each female at
of each
by pooling hundred
days egg production of each female separately.
No data were taken after hundred days because
(intrinsic
rate
of biotic
of natural
potential
increase)
of
mononchid predators is necessary for making
a reasonable judgement of their potential for
biological control.
Predation efficiency
Direct observation test:
The direct observation
tests on predator
MUJIB I. AZMI
226
60
20
15
Fig.l Relationship
of generation
25
20
30
t'e
time (GT) and temperature
(OC) of
l.mo"hyslera
(P<:O.OI)
.
•
6
ill
'3
o
15
20
25
30
tOe
Fig. 2 Relationship
of mean per day egg production
per lemale (E) and temperature
(0C) of
l.monlryslera (p< 0.01)
BIOTIC POTENTIAL AND PREDATION OF IOTONCHUS MONHYSTERA
0.08
227
•
o
15
20
25
30
Pc
Fig. 3 Relationship of intrinsic rate of natural increase (rm) and temperature
90
.' /'./"
I' /0/ //0/,//4
PREDATOR
./1016
8
12
00,,0--6
6
(OC)
of l.monhystera (p< 0.0 I)
"
>-
~50
0..
10
5o
Fig. 4 Log (+ I) percentage predator and probit diagram orM. incognita and P.=eae as predated by
l.monhystera.
0.008
4.2
5.2
±
1.5
±
1.9
0.011
0.13
0.14
0.12
0.15
0.049·
0.13
0.21
3.1
4.4
5.4
3.4
3.4
6.9
25.9
2.3
31.0
7.0
3.1
36.9
45.1
5.5
8.6
4.2
1.6
5.3
33
4.9
7.3
±4.9
0.075
2.1
0.022
0.036
±0.0017
0.08
±
2.7
0.09
0.10
±
±
1.7
0.062
0.13
0.09
0.07
0.08
0.09
0.13
0.19
0.0009
0.09
0.07
0.08
0.0005
0.13
0.23
0.15
0.11
0.09
0.53
0.08
7.1
5.9
3.7
5.3
8.5
5.5
7.3
10.4
8.1
27.9
29.1
2427
18
24.5
30
10.08
9.3
±
±
0.0004
0.0007
3.5
228
±
0.12
0.27
0.25
±
0.0004
6.9
12.6
8.7
7.8
16.2
±1.3
57.9
11.0
MUJIB I. AZMI
Temperature
°C
increase
ofTotal
J.monhystera
ditferent
temperatures
duration, ad: timenatural
between
last
months
and
onset atof
egg(egg to
production,
GT=
generation
time
egg), rm: intrinsic rate of natural increase.
days), number ofStage
eggs produced by single temale per day and intrinsic rate of
prey
encounter
were
conducted
with /.
monhystera female as predator and juveniles
of M incognita, P. zeae, A. avenae and
Acrobeles sp as prey. It was observed that the
predation
efficiencies
were
significantly
different in all the four prey nematode species.
Predator
attacked,
wounded and fed all of
them but their frequencies were more in case
of M. incognita
juveniles,
followed
by
Agar
inoculum
test: This experiment
was conducted to study the per cent predation
in agar medium within 24 h. The predators
used in this experiment were starved for 0, 5
10 and 15 days. The prey which were wounded
and fed or even only became motionless were
also counted as predated.
It was presumed
that even serious injury would make tl1:;m
dead. Data presented in the Table 3 showed
juveniles ofAcroheles sp. were least preferable
that the most preferable prey of this predator
was the juveniles of M incognita followed by
P. zeae andA. avenae but could be maintained
prey among the four (Table 2).
on Acritheles sp. Nehnes
juveniles of P. zeae and A. avenae, whereas
(1974) observed
BIOTIC POTENTIAL AND PREDATION OF IOTONCHUS MONHYSTERA
229
TABLE 2: Results of predation in direct observation test tor I.monhystera
Total
Prey
attack
9.67**
Encounter
50
67
93
75
98
28
58 37
60
14.95*
67
with
73
93
Attack
20.32*
with
Per
withcent encounter reactions
feeding
wounding
Wounding
encounters
M. incognita
P.zeae
A. avende
Acrobe/es sp
tor fixed ratio
hypothesis
X2
X2
for homogenity of ratio is 0.49, hence data can be pooled.
X2
tor pooled homogenity of ratio is 44.45*, hence the hypothesis of no perferencc is rejected.
X2
tor independence is 2.33, hen,ce the hypothesis of independence of prey species is rejected
* Singiticant at I%, and ** at 5% levels.
1.24
1.88
1.63
1.71
2.25
22.19
16.11
-40.0
-Perc
-79.2
-20.0
Trans.
6251.36
58.82
2.88
61.2
20.8
52.6
2.6
10.0
27.10
9.86
1.47
18.45
A.avenae
P.zeae
Perc
Trans
Trans.
Trans
15.0
12.0
1.2
22.75
246.48
0.20
73.2
39.34
24.8
60.01
29.99
9.24
75.0
Perc
26.56
6.21
75.89
94.0
25.0
TABLE 3:
Results
of
Acrobe/es
predation
Mincognila
sp.
in agar inoculum test tllr J.monhystera
Fresh
Starved
Perc: Per cent predated. Trans: the Arc sine < percentage transformed values:
LSD: Least significant difference.
that juveniles of A. av£!.nae appeared to be a
suitable prey for many mononchid nematodes.
In this way, the four prey of this nematode
could be grouped into i.e., M incognita and
P.zeae as target prey, A. avenae andAcrobeles
sp. as alternate prey.
Soil inoculum test: Table 4 showed the
results of the experiment conducted on the
predation of M incognita juveniles in soil
within 5 days (4 days in pot and one day
during extraction). Six different inoculum
levels of predators were tested i.e., 0, 20, 30,
4050 and 60 and 80. Final recovery from the
pots which were not inoculated with predator
showed 12% reduction over extract number
230
MUJIB I. AZMI
TABLE 4: Results of predation in soil inoculum test for l.monhyslera on M. Incognila
67
137
426
00.9
64 incognila
73
53
4.7
0563
16
442
419
0169
18
89
69
90
76
3.5
343
286
36
2.8
No. of
Percent
1248
19
72
1.9
23
28
35
43
38
Correct
57
No. of nematodes recovered
2.1
32
5l.monhystera
M.
Acrobeles
sp
Acl
Abbott
formula, LSD, Least Signficant Difference.
of
M.lncognita
predation of
by
of M incognita larvae inoculated. This may
be due to natural death or extraction error.
Significant reduction in the population of M
incognita juveniles were observed in all
inoculum levels of predators. Predatory
activities were switched over from Acrobeles
sp. toM incognita. Approximately 60 to 90%
reduction in the juveniles population of M
incognita were observed when predator was
inoculated @ 50, 60 and 80 in number with
500 M incognita juveniles. Small (1979)
reported striking evidence of partial control
and predation of M incognito in tomato
through the mononchid
nematodes,
Prionchulus punctatus and Mononchus
aquatious in the pot experiments.
Table 5 showed the results of the
experiment conducted on the predation of P.
zeae at seven different inoculum levels of
predator i.e., 0, 20, 30, 40, 50, 60 and 80 with
500 P. zeae. Final recovery from the pots
whichwere notinoculatcd with predator shows
18% reduction over exact number of P. zeae
initially inoculated. This may be due to natural
death or extraction effects. Significant
reductions in the populations of P. zeae were
recorded in all trCabnents.Predatory activities
switched over from Acrobeles sp. to P. zeae.
Approximately 32 to 73% reduction in the
number of P. zeae was recorded when
lmonhystera was inoculated@ 50, 60 and 80
predator with 500 P.zeae.
Efforts were made to relate the predators
percentage inoculum with the target prey, M
incognita andP. zeae preyed. For this log
(+ 1) percentage dose of the predator, I.
BIOTIC POTENTIAL AND PREDATION OF IOTONCHUS MONHYSTERA
231
TABLE 5: Results of predation in soil inoculum test for I.monhystera on P.zeae
No. of
predator
inoculated
0
P.zeae
No. of nematodes recovered
Acrobeles sp
I.monhystera
Per cent predation
of P.zeae
Act
Correct
12.0
02.0
18
44
55.0
73.0
02.4
26
01.9
19 1.53.5
27
18
263
28
0281
360
32.0
18.0
37
48
36
46
33
57
54
72
78
400
411
337
189
76
114
2.6
2.6
Act: actual value: Correct: Corrected value calculated by
Abbott formula, LSD, Least Significant Difference.
monhystera and profit analysis were used.
The percentage dose of predator that caused
50% predation (reduction in the prey
population) of target nematodes, M incognita
and P. zeae was found to be for M incognita
as 9.2 ± 0.1 and for P. zeae as 9.3 ± 0.1 per
cent (Fig. 4).
From these studies it has become clear
that this mononchid· nematode can be
considered one of the important biological
control agent.
ACKNOWLEDGEMENT
The author thanks for Dr. S.T. Ahmad,
Head, Plant Protection Division and Dr. R.P.
Singh, Director, Indian Grassland and Fodder
Research Institute, Jhansi for encouragement
and facilities.
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Accepted for publication, June, 1997