1. 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, , Andhra Pradesh
2WWF – ICRISAT campus, Patancheru, , Andhra Pradesh

2. Introduction
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.
Number of insect pest species in paddy increased during from 3 to >13 (Krishnaiah et al., 1999).
Paddy receives 20% of total pesticides. Use is high in AP, KN, MH, Gujarat & Punjab (Shetty, 2004).
Earlier reports indicated that rice plants in SRI are more resistant to insect-pests and diseases due to their healthy growth.

3. 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

4. Pest dynamics
Pest incidence and damage recorded on ten marked hills at three stages of crop growth period viz., at maximum tillering, booting and harvest stages.
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.

5. 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.

6. Hispa damage
Leaf folder damage
Stem borer damage

7. Mean % dead hearts at maximum tillering stage
Yellow stem borer damage during rabi
Mean % dead hearts at maximum tillering stage
Mean % white ear heads at harvesting stage
MTU 1010
Shanti
DRRH2
Mean
ECO-SRI
0.98 (1.18)
2.03
(1.51)
0.69
(0.98)
1.24
(1.23)
(1.29)
13.83 (3.51)
3.40 (1.97)
6.24
(2.26)
SRI
3.59
(1.92)
6.99
(2.73)
2.71
(1.61)
4.43
(2.08)
3.62 (1.92)
28.34 (5.14)
5.62 (2.34)
12.53
(3.13)
CON
8.31
(2.94)
11.36
(3.42)
8.26
(2.88)
9.31
(3.07)
3.33 (1.83)
21.17
(4.18)
2.25 (1.56)
8.92
(2.52)
4.29
(2.01)
6.79
(2.55)
3.89
(1.82)
2.82 (1.68)
21.11 (4.27)
3.76 (1.96)
CD Methods (M) =
Varieties (V) =
Interaction = NS
CD Methods (M) =
Varieties (V) =
Interaction = NS
Figures in parentheses are square root transformations (√ X+0.5)

8. Stem borer damage at flowering stage in Kharif

9. Defoliators damage in Kharif

10. Leaf mite damage in SRI method of rice cultivation
S.No
Variety
Loss of green colouration 1
MTU 1010
< 10 % 2
Swarna
31 – 50 % 3
BPT 5204
< 10%

11. Diversity indices SRI Conventional Total abundance 263.34 ± 32.19
± 27.90
Number of species
20.34 ± 0.67
18.67 ± 2.03
Shannon’s index (H)
1.92 ± 0.05
1.91 ± 0.04
Evenness (E)
0.33 ± 0.02
0.37 ± 0.04
Simpson’s index
0.76 ± 0.02
0.78 ± 0.005
Berger Parker index
0.38 ± 0.04
0.35 ± 0.02
Menhinick index
1.27 ± 0.10
1.28 ± 0.05
Margalef index
3.48 ± 0.16
3.29 ± 0.29

12. Stem borer damage in various varieties/hybrids

13. Effect of age of seedlings on stem borer incidence

14. Influence of spacing on stem borer incidence

15. Conclusions Future line of work
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.
Among the cultivars, Shanti recorded more damage in rabi and DRRH2 in kharif seasons.
Damage was more in plots of 8-day old seedlings at 20 x 10 cm compared to 25 x 25 cm spacing.
Total abundance and species richness was higher in SRI as compared to conventional method.
Future line of work
Need for systematic assessment of damage & losses
Factors responsible for the increased incidence
Pest management options

16. Thank you