InsectPest Dynamics and Arthropod Diversity in SRI

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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
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• 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 1965-95 from 3 to gt13 (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.

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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
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• 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.

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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.
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Leaf folder damage
Hispa damage
Stem borer damage
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Yellow stem borer damage during rabi
Figures in parentheses are square root
transformations (v X0.5)
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Stem borer damage at flowering stage in Kharif
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Defoliators damage in Kharif
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Leaf mite damage in SRI method of rice cultivation
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Diversity indices
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Stem borer damage in various varieties/hybrids
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Effect of age of seedlings on stem borer incidence
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Influence of spacing on stem borer incidence
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• Conclusions
• 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

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