Peanut
Jewel Beetle
Sphenoptera indica
Insect
In a Nutshell
- Feeding damage in root and stem.
- Wilting and drying of plant.
- Hollowed stems.
Can also be found in
Peanut
Symptoms
The grub burrows into the stem close to the soil surface and feeds on the internal tissues of the stem and main roots. The damage hinders the transport of water and nutrients to the aerial parts of the plant, that eventually wilt and die. Due to the feeding activity of the grub and its distribution pattern in the soil, infested fields usually show patches of dead and wilting plants. When plant are pulled out of the soil, in the hollowed stems grubs can be observed.
Recommendations
Organic Control
Braconids and trichogrammatids parasitoid wasps parasitize on the eggs and grubs. Dragon flies are predators of the jewel beetle. Bio-insecticides based on Nuclear Polyhedrosis Virus (NPV) or green muscardine fungus have also been used successfully against this pest.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatment if available. The application of insecticide granules in the planting row can be effective to reduce population of beetles. Chlorpyriphos used at later stages of plant growth can avoid severe damage.
What caused it?
The adult beetle is dark with a jewel-like shiny body that is about 10 mm long and 3 mm wide. Females lay eggs singly at the base of the main stem. Depending on the growth stage, the larvae may differ in size and color. Usually their color ranges somewhere between brown and yellow. Apparently legless, they can grow to a length of more than 20 mm. They are characterized by an elongated, dorso-ventrally flattened body and a globular head and thorax. It attacks groundnut during the later stages of crop growth, around 50 days after sowing. The grub burrows into roots or stems and feeds on internal tissues , hindering the transport of water and nutrients.
Preventive Measures
- Grow tolerant varieties.
- Monitor the field and destroy infested plants.
- Cover the soil with well decomposed organic manure.
- Keep a eye on the biodiversity in the field and its surroundings.
- Plow deep after harvest to expose the pest to its natural predators.
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