Biology and control of maize stem-borer (Chilo partellus Swinhoe) in Peshawar

Khan, M.R.; Khan, B.M.

Science and Industry 6(1/2): 124-130

1968


Accession: 000030202

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Abstract
Chilo partellus (Swinh.) is a pest of maize and sorghum that is widespread in Pakistan and causes serious losses in the Peshawar region. Its life-history on maize was studied in the laboratory and in the field there. The eggs are laid in clusters on the lower surface of the leaves, and the number laid by a single female ranged from 269 to 361. Hatching took place after 3-5 days. There were five larval instars, and the larval period lasted 19-24 days, or 220-222 days in the case of overwintering larvae, and the respective pupal periods were 6-8 and 9-11 days. The life-cycle of non-hibernating generations was completed in 32-41 days, and there were five overlapping generations a year. Full-grown larvae bored down the maize stems and overwintered in the stubble. In a test repeated annually for three years (1964-66), nine insecticides were evaluated for the control of the Pyralid on maize. Each was applied three times at 15-day intervals, the first application being made on the tenth day after germination, and the percentage of plants, and later of the stubble, that had been infested was determined. Granules containing 2.5% trichlorphon (Dipterex) applied by hand at 35 lb/acre were superior to spray treatments with eight other compounds. In a comparative test of three granular insecticides in 1966, application at 40 lb/acre of one containing 5% carbaryl (Sevin) afforded the best control. In the treated plot, 6.81% of the plants and 10% of the stubble were found to be infested, as compared with over 14 and 30.5% in untreated plots. In a further test, microbial control was compared with chemical control, and it was found that 1.5% endrin granules at 25 lb/acre were more effective than three other compounds and than Bacillus thuringiensis (as Thuricide 90% F) at 2 lb/100 gal. Infestation levels of 4.35% of the crop and 3.49% of the stubble were recorded after treatment with endrin, as compared with 8.62 and 44.75%, respectively, in untreated plots. The effect of time of sowing on infestation was investigated by sowing maize at 15-day intervals from 15th January to 30th October. The infestation levels were found to be low in maize that had been sown up to the beginning of May and highest in maize that had been sown in mid-May and especially mid-June, in which 71.24% of the plants became infested. In another test, six leading maize varieties were evaluated for resistance to the Pyralid. No measures for the control of pests were applied, and the infestation levels were determined at 15-day intervals from 10 days after germination. The varieties differed significantly in their susceptibility to attack, the least susceptible being a synthetic hybrid.