Transcript Insect-Pest Dynamics and Arthropod Diversity in SRI and Conventional Methods of Rice Cultivation Ch.

Insect-Pest Dynamics and
Arthropod Diversity in SRI
and Conventional Methods
of Rice Cultivation
Ch. Padmavathi, R. Mahender Kumar,
K. Surekha, P.C. Latha, L.V. Subba Rao,
M. S. Prasad, V. Ravindra Babu, J.S. Prasad,
O.P. Rupela1, Vinod Goud2, I.C.Pasalu
and B.C.Viraktamath
Directorate of Rice Research, Rajendranagar, Hyderabad
1ICRISAT, Patancheru, 502324, Andhra Pradesh
2WWF – ICRISAT campus, Patancheru, 502324, Andhra Pradesh
Introduction
o In India, rapid increase in area under HYV of rice
accompanied by high use of fertilizers has led to
increased incidences of pests and diseases.
o Number of insect pest species in paddy increased
during 1965-95 from 3 to >13 (Krishnaiah et al., 1999).
o Paddy receives 20% of total pesticides. Use is high
in AP, KN, MH, Gujarat & Punjab (Shetty, 2004).
o Earlier reports indicated that rice plants in SRI are
more resistant to insect-pests and diseases due to
their healthy growth.
Methodology
Field Experiments – DRR Ramachandrapuram farm,
ICRISAT campus
Soil - sandy clay loam
Seasons - rabi and kharif in 2006
Design - split-plot design
Main plots - MTU 1010, Shanti & DRRH2 in rabi
BPT 5204, Swarna & DRRH2 in kharif
Sub-plots - methods of crop husbandry
(SRI, Eco-SRI and conventional)
Replications - four
SRI and conventional method - same inputs applied
Eco-SRI - total nutrients through organic source only
Pest dynamics
o Pest incidence and damage recorded on ten marked
hills at three stages of crop growth period viz., at
maximum tillering, booting and harvest stages.
o Damage symptoms recorded by counting number of
damaged leaves by each pest species, total tillers &
dead hearts at vegetative stage, and panicle-bearing
tillers and white ear heads at reproductive stage.
Arthropod diversity - Insects were collected using
standard sweep net. Each plot was swept thrice, and
insects collected were sorted separately. For plots with
conventional method (flooded soil), water samples
were collected for aquatic insects.
Results
Pest dynamics
Five insect pests, viz., whorl maggot, hispa, yellow
stem borer, leaf folder and green leaf hoppers, were
observed at different stages of crop growth period.
Among these pests, incidence of yellow stem borer
was high in various treatments followed by leaf folder.
Others pests occurred at low level.
In Rabi 2006, the mean per cent of dead hearts was
significantly different at maximum tillering stage for
the alternative methods of rice cultivation and also
among the varieties.
Hispa damage
Stem borer damage
Leaf folder damage
Yellow stem borer damage during rabi
Mean % dead hearts at
maximum tillering stage
MTU
1010
Shanti DRRH2
Mean
Mean % white ear heads at
harvesting stage
MTU
1010
Shanti
DRRH2
Mean
ECO- 0.98
2.03
0.69
SRI
(1.18) (1.51) (0.98)
1.24
1.49 13.83
(1.23) (1.29) (3.51)
3.40
(1.97)
6.24
(2.26)
SRI
3.59
6.99
2.71
(1.92) (2.73) (1.61)
4.43
3.62 28.34
(2.08) (1.92) (5.14)
5.62
(2.34)
12.53
(3.13)
CON
8.31
11.36 8.26
(2.94) (3.42) (2.88)
9.31
3.33 21.17
(3.07) (1.83) (4.18)
2.25
(1.56)
8.92
(2.52)
Mean 4.29
6.79
3.89
(2.01) (2.55) (1.82)
2.82 21.11
(1.68) (4.27)
3.76
(1.96)
CD
CD
Methods (M)
Varieties (V)
Interaction
= 0.62
= 0.54
= NS
Methods (M)
Varieties (V)
Interaction
Figures in parentheses are square root transformations (√ X+0.5)
=
=
=
0.54
0.78
NS
Stem borer damage at flowering stage in Kharif
4
Eco-SRI
3.5
SRI
Per cent whiteheads
3
Conv
2.5
2
1.5
1
0.5
0
BPT 5204
DRRH2
Swarna
Defoliators damage in Kharif
3
Eco-SRI
2.5
SRI
Per cent damaged leaves
Conv
2
1.5
1
0.5
0
BPT 5204
DRRH2
Swarna
Leaf mite damage in SRI method of rice cultivation
S.No Variety
1
2
MTU 1010
Swarna
Loss of green
colouration
< 10 %
31 – 50 %
3
BPT 5204
< 10%
Diversity indices
Total abundance
Number of species
Shannon’s index (H)
Evenness (E)
Simpson’s index
Berger Parker index
Menhinick index
Margalef index
SRI
263.34 ± 32.19
Conventional
210.67 ± 27.90
20.34 ± 0.67
1.92 ± 0.05
0.33 ± 0.02
18.67 ± 2.03
1.91 ± 0.04
0.37 ± 0.04
0.76 ± 0.02
0.38 ± 0.04
0.78 ± 0.005
0.35 ± 0.02
1.27 ± 0.10
3.48 ± 0.16
1.28 ± 0.05
3.29 ± 0.29
Stem borer damage in various varieties/hybrids
25
Per cent white ears
SRI 10 day old seedlings
SRI 25 day old seedlings
20
15
10
5
0
DRRH1
KRH2
PHB 71
KH
Rasi
Varieties / Hybrids
Tulasi
Jaya
PB1
Effect of age of seedlings on stem borer incidence
8 day
9
18day
8
7
28day
6
5
4
3
2
1
0
SRI
Normal
Influence of spacing on stem borer incidence
10
9
25x25 cm
20x10 cm
8
7
6
5
4
3
2
1
0
SRI
Normal
Conclusions
o Among various pests, stem borer damage was high. Dead hearts
were low in SRI as compared to conventional method. White ear
heads were high in SRI.
o Among the cultivars, Shanti recorded more damage in rabi and
DRRH2 in kharif seasons.
o Damage was more in plots of 8-day old seedlings at 20 x 10 cm
compared to 25 x 25 cm spacing.
o Total abundance and species richness was higher in SRI as
compared to conventional method.
Future line of work
o Need for systematic assessment of damage & losses
o Factors responsible for the increased incidence
o Pest management options