Spotted pod borer (Maruca testulatis) is a major pest of legume crops, including red gram, green gram, black gram, and lab-lab. In recent years, this pest has had a significant outbreak. The outbreak can be attributed to several factors, including food availability, cultivation of medium and local varieties, weather conditions, and breeding habits close to flowering.
The spotted pod borer causes damage to the crops by feeding on the pods and leaves, leading to reduced crop yield and quality. In addition, it also feeds on the leaves of daincha, green manure, further reducing soil fertility. Management of spotted pod borer includes both cultural and chemical methods.
Cultural methods such as crop rotation, intercropping, and planting early maturing varieties can help to reduce the pest population. Additionally, timely weeding and removal of crop residues can help control the pest. Chemical methods include the use of pesticides. Integrated pest management (IPM) practices, combining cultural and chemical methods, can provide effective and sustainable management of spotted pod borer in legume crops.
Spotted Pod Borer Management in Green Gram
Identification of Spotted Pod Borer
The Spotted Pod Borer can be identified by its distinct appearance in various life stages. The eggs of this pest are oval and yellow. The larva is greenish with a brown head and short dark hairs on black warts on the body. The pupa is found in a thin silken cocoon on the pod or leaf fold and is yellow with a greenish body. The moth has white patches on the dark brown forewings and a dark border on the white hind wings.
The Life Cycle of Spotted Pod Borer
The Spotted Pod Borer’s life cycle includes four stages: egg, larva, pupa, and adult. The female moth lays eggs in small clusters of 10 to 15 on leaves, buds, and flowers. After hatching, the larva feeds on the plant’s leaves and pods, causing damage. The larva is greenish-white with a brown head and has two pairs of dark spots on the back of each segment.
The pupation stage occurs in a silken cocoon in leaf webbings or the soil. The pupa is yellow with a greenish body. After completing the pupation stage, the adult moth emerges from the cocoon. The adult moth has light brown forewings with white markings and hindwings with brown markings at the lateral edge.
Causes/Conditions Favorable for Spotted Pod Borer Spread in the Field
The Spotted Pod Borer infestation occurs during the seedling stage until podding/ seed setting, and it thrives in temperatures between 20 – 28°C. The yield losses caused by this pest are estimated to be 20 – 50%. The larvae of the Spotted Pod Borer are nocturnal. They primarily attack the stems, peduncles, flowers, and pods of various host plants, including gram, lablab, chill, peanut, tobacco, cotton, soybean, sesame, sugarcane, castor, Hibiscus, and other hosts.
Damage Symptoms of Spotted Pod Borer
- The nature of the damage caused by this pest includes the larva webbing together leaves, buds, and pods and feeding inside these webs.
- The larva also bores into the pods and eats up the ripening seeds, resulting in significant yield losses.
- Damage includes the presence of webbed masses of leaves, buds, and pods and a crown mass of excrement at the entrance into the larval burrow.
- Additionally, the pest can cause defoliation in the early stages and the presence of round holes in the pods.
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