Javed, Habib Iqbal (2005) STUDIES ON THE RESISTANCE RESISTANCE IN MAIZE AGAINST STEM BORER, CHILO PARTELLUS (SWINHOE), PYRALIDAE, LEPIDOPTERA. PhD thesis, University of Arid Agriculture, Rawalpindi.
Maize stem borer, chilo partellus (Swindhoe) is the most notorious pest of maize crop which damages the crop considerably and reduces the yield by 10-20% but sometimes the losses may be upto 80%. It is one of the major contributing factors responsible for low yield in Pakistan. Maize ( Zea mays L.) is one of the major Kharif (Summer growing season) crops in Pakistan. It is the leading world cereal in total production and its also has the highest yield among the cereals. In Pakistan, there is no maize cultivar resistant to borer. Generally, it is controlled by insecticides which not only cause environmental pollution and hazards to human beings and animals, but also increases the cost of production. Resistant maize can be effective and safe solution for minimizing the pesticide use, improving natural balance and enhancing the activity of bio-control agents, it can also reduce the cost of production. Keeping these factors in mind, current studies on resistance in maize against C. partellus were conducted at the National Agricultural Research Centre (NARC), Islamabad, Pakistan. A resistant source against C. partellus was identified through screening and evaluation under natural and artificial conditions. Initially, about 400 different exotic and indigenous maize germplasm accessions were screened for resistance to C. partellus under natural conditions during spring 2000. Ninety-five accessions survived. During Kharif 2000, out of the ninety-five accessions, plant survived in 10 accessions under artificial and in 50accessions under natural conditions. For artificial infestation, 15 newly hatched larvae were released at 4-5 leaf stage of the crop by camel hair brush near the whorls. The progenies were reproduced from their survived plants by self pollination. During spring 2001, the ears maintained were used for further screening and testing. During Kharif 2001, stem borer larvae were released twice at 4-5 leaf stage of the crop and then 10 days after first release for final selection. The materials were combined through bulk pollination and made three resistant genotypes: BR-1, BR-2 and BR-3. Differences for these traits between resistant and susceptible germplasm. Intensity of damages on leaves, and number and total length of tunnels per plant showed very clear differences among the genotype of resistant and susceptible germplasms. Compared to leaf and stem, the damage to tassels and ears was less severe but the damage was significantly higher in susceptible genotypes. In resistant genotypes, none of the ear was infested. Free-choice and No-choice tests were used to observe the preference of borer for oviposition, egg hatching and survival/presence of larvae on both types of germplasms. These were statistically significant differences for all three characters among the resistant and susceptible genotypes. The growth and development of the borer was observed on different genotypes and on artificial media having dry leaf powder of different genotypes under laboratory conditions. The larval survival and pupation on resistant genotypes were significantly lower than on susceptible genotypes. In some jars of resistant genotypes, none of the larvae survived. The weights and lengths of the larvae and pupation on resistant genotypes were significantly lower than on susceptible genotypes. In some jars of resistant genotypes, none of the larvae survived. The weights and lengths of the larvae and pupae on resistant on genotypes were lower than on susceptible ones. AdultÃÂÃÂ¢ÃÂÃÂÃÂÃÂs emergence was also lower on resistant germplasm. In susceptible germplasms, male and female were almost equal but in resistant germplasm there were significantly more males than females. Fecundity and hatching were also affected g the resistance in resistant genotypes. The feeding stage of the development (larva) on resistant genotypes took significantly more time than on the susceptible ones. All other developmental stages took non-significantly longer period on resistant genotypes than on susceptible genotypes. All these studies explicitly demonstrated the existence of resistant against maize stem borer in the 3 sources (cultivars) that were selected through the initial screenings and evaluations. Grain yield plant height and stem diameter were significantly reduced in susceptible germplasms than in resistant germplasms due to stem borer damage. Leaf length and width were statistically non-significant in all genotypes indicating that these traits may have no role in resistant. In short, stem borer resistant germplasms(genotypes/ cultivars) have been identified and their resistance has been confirmed/ demonstrated by several laboratory and field tests under natural and artificial conditions. These cultivars can be further utilized through breeding selection procedures either directly environmentally friendly maize production in Pakistan and elsewhere in the world.
|Item Type:||Thesis (PhD)|
|Uncontrolled Keywords:||maize, stem borer, chilo partellus (swinhoe), pyralidae, lepidoptera, germplasm, c. partellus|
|Subjects:||Biological & Medical Sciences (c) > Biological Sciences(c1) > Zoological sciences(c1.11)|
|Deposited By:||Mr. Muhammad Asif|
|Deposited On:||09 Sep 2006|
|Last Modified:||04 Oct 2007 21:01|
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