Biology and Seasonal Incidence of Shoot borer, Chilo infuscatellus Snellen in Sugarcane.
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Date
2015
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Rajendra Agricultural University, Pusa (Samastipur)
Abstract
The study on biology and seasonal incidence of shoot borer, Chilo infuscatellus Snell. experiments were conducted during 2014-15. The study on biology of Chilo infuscatellus was conducted in laboratory at Department of Entomology, whereas a field experiment was laid out at Research Farm of S. R. I., Pusa to assess the seasonal incidence of Chilo infuscatellus.
The study on biology of sugarcane shoot borer under laboratory conditions revealed that the eggs were oval in shape, dorsoventrally flattened, looked like a scale of fish and were laid in masses on the under surface near to midrib of the leaf. Freshly laid eggs were creamy white in colour, which gradually changed to yellowish. The incubation period varied from 4.35 to 4.45 days (4.4±0.02). The larvae passed through five larval instars to complete the larval period. The total larval period varied from 16.66 to 17.23 days (16.94±0.12). The pupa was obtect type, brownish in colour and its period varied from 6.92 to 7.5 days (7.21±0.13). The male and adult period varied from 3.62 to 3.80 and 4.31 to 4.45 days, respectively. The per cent hatching of Chilo infuscatellus ranges from 78.3 to 92.4 per cent (85.35±3.15). Total life cycle C. infuscatellus from egg to adult emergence varied from 31.95 to 32.82 days (32.28±0.20).
The absolute population of shoot borer (larvae) was noticed in the field from 1st fortnight of March, 2014 to 2nd fortnight of August. The peak population was recorded in the 1st fortnight of May. The relationship between population of insect and weather parameters showed significant positive correlation with maximum temperature i.e., as the temperature increased the corresponding population of insect also increased.
The mean per cent incidence of shoot borer was recorded from March to (month), harvest of the crop. The maximum (9.32 %) incidence was recorded in the first fortnight of May, 2014 and lowest (1.2 %) incidence recorded in the second fortnight of August, 2014. The maximum temperature showed significant positive correlation with incidence whereas, relative humidity and rainfall were showed negative role.
Extent of parasitization on shoot borer eggs by Trichogramma chilonis Ishii. was recorded the peak parasitization in the month of May which ranged from 12.3 to 15.6 per cent. The correlation analysis between parasitization and weather parameters, revealed that maximum temperature showed significant positive correlation whereas, relative humidity at 07 00 hrs and rainfall showed significant negative correlation.
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