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Breeding Maize Germplasm Tolerant to Major Insect Pests 329Cheap labour and plentyfuJ land will help in this endeavour. The insects can be held until needed forproduction of eggs/newly hatched larvae for artificial infestation under mild cold storage conditions.(ii) The capability to mass rear the SSB and produce sufficient quantities of insects at therequired time(s) for infestation must be required. Mass rearing of SSB on artificial diets based onindigenously available ingredients with simple preparation procedures are being practiced at severalinstitutes for various purposes. (Siddiqui el al., 1977; Seshu Reddy and Davis, 1979; Ochieng el al.,1985; Taneja and Nwanze, (988). The freshly emerged moths of both sexes are kept in an ovipositionchamber lined with tissue paper/creased waxed paper. The eggs may be harvested daily or after 2-3days. The papers containing eggs are cut to obtain desired number of eggs. The egg masses are keptuntil they turn black-head stage ( 3 to 4 days) and ready for use in the field. The rearing of SSB iscarried out in controlled room maintained at 27 [Ie ± 2 °c and 70-90 R.H. All precautions are neededfor the establishment and maintenance of healthy vigorous colonies of borer by the trained personnel.The insects reared continuously generation after generation on artificial diets in the laboratory or ingreen house may change genetically so that they no longer affect plants the same as do a wildpopulation. Siddiqui and Sarup, ( 1978) reported that the intensity of damage caused by the larvae ofSSB reared up to two generations on artificial diets were comparable with those obtained from naturalfood maize plants.3. Germplasm sources:Source of resistant plant material can be obtained from (i) the individual plants within apopulation or from established varieties (ii) systemic search among the lines in a variety or ingermplasm collections. As the level of insect resistance in maize are low, it requires the evaluationfor resistance in an alTay of germplasm sources. A large number of maize genotypes with resistanceto SSB have been identified in Asia and Africa (Sarup et al., 1979; Sarup et al., 1978a ,1987,Panwar and Samp, /986,1987; Ampofo el al.. 1986. Kumar,1997a ; Siddiqui and Marwaha, 1993;Van Rensberg and Van Den Berg. 1995). Some important sources of resistance to SSB are AntiguaGr.l , EBR (Entomological Borer Resistant) composite, EMR (Entomological Mass Reservior)composite, BS 7, EVA 64-mst-SO, Composite AR-76, VL-42, Local Haryana (Hosiarpur), LoponYellow-I, Local Giddarpindi (Punjab), Composite-217, Composite-214, EVA-82-4-87, MCU-508from India, Population 590 (Multiple Borer Resistant-MBR), Population 390 (Multiple InsectResistant Tropical-MIRT) and inbreds CML 67, CML 139 and CML 69 from CIM YT inbreds Mp704, Mp 705, Mp 706 and Mp 708 from Mississippi ..4. Methods of uniform artificial infestation:Techniques need to be developed for infesting test material regardless of whether insects arereared on artificial diets or host plants. Before doing infestation, such aspects as plant age to infest,number of eggs/Iarvae per application, number of application, time of day to infest, stage of insect tobe used must be considered (Gallun et al., 1975). Different ways to infest maize plants by SSB havebeen adopted (i) placing 20-25 eggs (black-head stage) directly in the plant whorls by inserting tissuepapers containing egg masses with the help of alpines (ii) placing a certain number of larvae (l0-15neonates) in the whorls of each plant using a camel's hair bmsh or an artificial inoculator. Bazooka'developed by J.Mihm (CIMMYT Review, 1977) or any of its adaptation like the Davis inoculator(Davis and Oswalt. 1979). However, in Asia Maize Entomologists have not been able to adopt"Bazooka" for infesting maize with SSB because of difficulties in getting uniform larval grits mixture.The growth stage at which resistance is best distinguished is selected for comparison amongmaize genotypes. In India, all efforts for locating resistance to SSB were directed for testing materialat early whorl stage i.e. 14-15-day old crop with 20-25 eggs (black-head stage) or 15 neonate larvae tohave desirable differences to separate the resistant and susceptible genotypes. The infestation atanthesis stage was not at all tried because the plants show inbuilt tolerance with advancement in ageof crop and even with high borer density there is no significant impact on grain yield. The insects are