IPM in Rice Systems in Indonesia

IPM in Rice Systems in Indonesia

EESC 3310 Agroecology

Tara Pisani Gareau

Learning Objectives

  • The primary aim is to explain key approaches and ecological mechanisms behind the findings of a pivotal study:

    • Reference: Settle et al. 1996. "Managing Tropical Pests through Conservation of Generalist Natural Enemies and Alternative Prey." Ecology, 77(7):1975-1988.

Justification for the Research

  • Context of Research:

    • Indonesia has faced significant pest problems in rice systems due to increased rice acreage and continuous production, particularly the emergence of two key pests:

    • Yellow Stemborer (Scirpophaga incertulas):

      • A prevalent pest impacting rice since the late 1960s.

      • The government supported large-scale aerial insecticide applications to control this pest.

    • Brown Planthopper (Nilaparvatta lugens):

      • Emerged as a significant pest by 1974, prompting further concern.

      • Yearly subsidies for insecticides increased to manage the pest situation.

      • Economic Impact: By late 1970s, Indonesia incurred losses amounting to approximately $1 billion in rice from this pest, excluding the cost of insecticides.

  • Shift in Pest Control Strategy:

    • In the 1980s, there was a new emphasis on Integrated Pest Management (IPM).

Study Regions in Indonesia

  1. Northwest Java (Karawang District):

    • Practices:

      • Rice-rice production throughout the year.

      • Long dry fallow periods (1-3 months) with dry stubble burning.

      • Irrigation controlled by the government.

      • Synchronous planting across large irrigation blocks (ranging from 500 to 3,000 acres).

      • Surrounding forest fragments.

  2. Central Java (Bantul District):

    • Practices:

      • Rice-rice-vegetable rotation per year.

      • Short dry fallow periods (1 month).

      • Water managed at the village level, ensuring year-round availability.

      • Traditional non-synchronous planting.

      • Integration of native vegetation into rice landscapes.

    • Visual Reference: Photos by Barker and Stonehouse.

Research Methods

  • Details on specific methodologies used in the study were not provided in transcript text. Further research may be needed to elaborate on methodological approaches employed in the study.

Effect of Organic Matter Inputs

  • Referencing Settle et al. (1996), the study presented data on the number of detritivores and plankton feeders in the rice fields of Indonesia, correlating these populations to different levels of organic matter (OM).

Effect of Pesticides

  • Comparative analysis of untreated vs. treated fields:

    • Populations measured include:

    • Detritivores

    • Plankton Feeders

    • Arthropod predators

    • Herbivores

  • Populations varied significantly based on pesticide application, impacting overall ecosystem dynamics in rice fields.

  • Data visualizations indicated how populations of herbivores, predators, and other functional groups were affected over time post-transplanting. Specific numbers and days post-transplanting needs to be elaborated from graphical data.

Abundance of Arthropod Functional Groups

  1. Northwest Java:

    • Herbivore populations reached over 300/m² by day 58 post-planting.

    • Predator populations peaked around day 80 post-planting.

  2. Central Java:

    • Herbivore populations remained below 300/m² until day 78.

    • Predator populations appeared early in the cropping season and increased gradually.

  • Data reflects variances in pest and predator dynamics influenced by environmental factors.

Findings of Settle et al. (1996)

Conclusions

  • The optimal strategy for controlling the rice planthopper involves:

    1. Conserving Diversity of Natural Enemies:

    • Preserving existing populations of natural pest controllers.

    1. Reducing Pesticide Use:

    • Minimizing chemical interventions to support ecosystem health.

    1. Shortening Dry Fallow Periods:

    • Emphasizing the role of water availability for supporting detritivores, which are critical in the predator food web.

    1. Maintaining Heterogeneity in Rice Landscapes:

    • Promoting diverse agricultural practices that enhance ecosystem resilience and pest management efficacy.