Trichogramma Japonicum: A biological control against rice stem borer

Rice is a major food crop for more than 60% of India’s population, particularly; it is staple food for every Naga population. It is cultivated throughout the state under both upland and lowland conditions. Amongst various pests affecting the crop, stem borer is a major insect pest in district attacking almost 90% of the area under paddy. Common symptom of stem borer infestation are a)  larvae bore into the basal stem above the water level causing death of flag leaf b) infested tiller produce white ear heads/empty panicles. Hence, to overcome this infestation, a biological control method has been popularized by KVK, Phek in nearby villages. As an organic approach for pest control, trichocards containing trichogramma eggs parasitoids have been proven most effective against several lepidopteran pests. It is very tiny parasitic wasp belonging to Trichogrammatidae family. It is 0.4 to 0.7 mm in length and 0.15 to 0.25 mm in width. Under laboratory conditions three main species are produced of which light coloured Trichogramma chilonis, medium coloured T. brasiliensis and dark coloured T. japonicum are important. Adult can fly upto 18-20 meters. After 12 hrs of emergence Trichogramma adult starts laying eggs in the eggs of Corcyra.

Application method: Each card contains 10,000-20,000 eggs. Cards are cut into pieces depending upon the area. These cut pieces are pasted on 2 ft bamboo stick or stapled at the lower surface of leaf in the field at a distance of 10 m after 30 days of paddy transplanting. The eggs should be released 6 times at weekly interval. On an average 50,000 Trichogramma eggs parasitoid are required per hectare. Observations recorded showed that yield increased by 20-30% compared to the untreated plots.

Liza Barua Bharali
SMS, Plant Protection
KVK, Phek