Identification, symptoms and nature of damage of Whorl Maggot, Leaf folder and Hispa

1. Identification, symptoms and nature of damage of Whorl Maggot, Leaf folder and Hispa End Previous Next

2. Introduction Rice is the world’s most important food crop and is the staple food for more than half of the population. In India, rice is grown on about an area of 45.0 million hectares with a production of 89.0 million tonnes. However, rice productivity of 3.01 t/ha in India is inferior to 6.26 t/ha in China and 3.51 t/ha in Sri Lanka. Spiderlings on rice crop End Previous Next

3. Rice crop being monitored for pests Pest-induced yield loss is one of the major factors responsible for poor rice yield in the country. Whorl maggot, leaf folder and hispa are important pests of rice inflicting up to 10% yield loss. Whorl maggot and hispa are important during vegetative crop phase while leaf folder damages crop throughout the crop season. Heavy fertilization and irrigation increase damage due to these pests End Previous Next

4. 1. Whorl Maggot (Hydrellia philippina) Identification • Whorl maggot adult is black fly resembling housefly but smaller in size while maggots (larvae) are greenish yellow, similar to leaf colour. Whorl maggot adult Courtesy: knowledgebank.irri.org • Fly lays eggs on leaf surface and after hatching maggot reaches centre of the leaf whorl. Whorl maggot Courtesy: knowledgebank.irri.org End Previous Next

5. Nature of Damage The pest damages the crop from seedling to maximum tillering stage and does not harm the crop after flowering. Characteristic damage is damaged tissue along the margins of emerging leaf. On leaf expansion, yellow damaged areas are conspicuously evident. Tillering gets reduced and maturity may be delayed. Economic thrershold level: 20% damaged hills up to 30 days after transplanting. End Previous Next

6. 2. Leaf Folder (Cnaphalocrosis medunalis • Leaf folder has become important pest of rice during post green revolution years and can inflict up to 20% yield loss on an average. Heavy nitrogen and irrigation are especially stimulating to this pest. • Identification • Moths are orange brown with many wavy lines and dark band on the margin of the wing while young larvae are greenish white and full grown ones greenish yellow. Leaf folder adult End Previous Next

7. Nature of Damage • Female lays eggs singly on leaves and after hatching larvae fold the leaves by stitching together leaf margins at several points. Under heavy infestation crop presents a white look from distance. Leaf folder larva • Larva feeds inside the fold eating away the green matter, leaving only white thin membranous epidermis. Leaf folder damage End Previous Next (Cont.....)

8. One larva can damage more than one leaf. Larvae may be found inside the fresh folds. Predators such as rove beetles and lady bird beetles are important predators of this pest. Avoidance of excess use of nitrogenous fertilizers helps to lower incidence of this pest. Rove beetle- predator Economic threshold level (ETL) 3-4 % freshly damaged leaves or 2 freshly damaged leaves/hill. Lady bird beetle-predator End Previous Next

9. 3. Hispa (Dicladispa armigera) Identification The rice hispa is now a regular and major pest of rice in north eastern, eastern and central India particularly under lowland conditions where sporadic outbreaks have been reported frequently causing extensive yield loss. Adult beetle is shiny blue, black in colour with spines on their wings while grubs (larvae) are minute yellowish in colour. Hispa adults End Previous Next

10. Hispa damage in rice Courtesy: www.ikisan.com Nature of Damage Both adults and grubs feed on leaves mainly during vegetative crop growth phase. Eggs are laid singly near the tip of the leaf blade generally on ventral surface. The hatching grubs mine in to the leaf blade and feed on chlorophyll and these can be seen under the dirty white affected leaf part. End Previous Next

11. Adults scrape chlorophyll between the leaf veins and the lamina, producing characteristic white parallel ladder like streaks on the streaks on leaves. In severe epidemics, the leaves dry up and present a scorching appearance. High humidity after rains and intermittent bright sunshine appears to favour the development of this pest. Economic threshold level (ETL) 2 adults or 2 damaged leaves/hill Hispa grub & its damage End Previous Next

12. Let Us sum up • Whorl maggot damages the crop from seedling to maximum tillering • stage and does not harm the crop after flowering. Characteristic • damage is damaged tissue along the margins of emerging leaf. • Whorl maggot damage reduces tillering and maturity may be delayed. • Leaf folder larvae fold the leaves by stitching together leaf margins • at several points. Under heavy infestation crop presents a white look • from distance. End Previous Next (cont.....)

13. Heavy nitrogen and irrigation stimulate leaf folder incidence • resulting in heavy yield losses. Hence, avoidance of excess use of • nitrogenous fertilizers helps to lower incidence of this pest. • Rice hispa is now a regular and major pest of rice in north eastern, • eastern and central India particularly under lowland conditions. • Both adults and grubs of hispa feed on leaves mainly during vegetative crop growth phase. • High humidity after rains and intermittent bright sunshine appears • to favour the development of hispa.