Mealy Bug on Rice
Mealybugs remove plant sap by sucking and weaken the plant, causing a myriad of symptoms. The most visible ones are the presence of white waxy fluff on leaf sheaths, the curling and wilting of leaves, and more generally plant stunting. Heavily infested plants do not bear panicles and they do not fully exert from the boot. To confirm the cause of damage, check for presence of waxy yellowish to pinkish egg deposits, unwinged pink female adults living in colonies inside the leaf sheath, and winged pale yellow males removing plant sap from stem or leaves.
The population buildup of the rice mealybug is favored by dry periods, well-drained soils and the presence of grassy weeds that harbor the insect. It then occurs in great number during the rainy season.Regular irrigation of the field during the growing period resulted in lower intensity of infestation.Irrigation schemes may influence the abundance of the pest. High level of fertilization with nitrogen and potassium and low levels of calcium favor the development of the disease. Application of raw coir pith, raw sugarcane trash and farmyard manure reduced the infestation.
Biological control agents such as small encyrtid wasps, spiders, chloropid fly, drosophilid, and lady beetles are effective against the mealybug.The following have been identified as effective natural enemies: Oxyopes javanus, Domomyza perspicax, Leucopis luteicornis, Scymnus sp., Adelencyrtus sp., Doliphoceras sp., Parasyrphophagus sp., Xanthoencyrtus sp., and Gyranusa sp.
Always consider an integrated approach with preventive measures together with biological treatments if available. The mealybug has a protective waxy covering over its entire body and a secure position in between the stalks and leaf-sheath, so that it is very difficult for any insecticide to reach it. Some solutions of buprofezin, thiomethoxum and dimethoate along with azardiractin have been proved effective against mealybugs.