Studies on the thermal requirements for estimating the number of generations of Chilo partellus (Swinhoe) and its natural enemies in the field
2001
Jalali, S.K. | Singh, S.P. (Project Directorate of Biological Control, Bangalore (India))
Life cycle of Chilo partellus (Swinhoe and its natural enemies decreased with an increase in temperature from 18-35øC, temperature around 25-30øC was observed to be most optimal for the development and survival. C, partellus needed 588.34ø day (DD) above 17.6øC for completion of all the development stages and calculation of the accumulated degree days in the field suggested 6-7 generations of the pest in a year. Trichogramma chilonis (Ishii) needed 169.49 DD above, lower threshold temperature of 10.11øC for completion of all the developmental stages. Summation of heat units accumulated in the field in different months suggested 19-20 generations and this parasitoid will be active in the field in all months except in December when heat units accumulated, were less than required for its development. The thermal constant for development of Cotesia flavipes (Cameron) was 238.09 DD above lower threshold temperature of 14.61øC and based on the accumulation of heat units in the field, there is possibility of only one generation between December to January and one generation in each of the remaining months. Pupal parasitoid Tertrastichus howardi (Olliff) required 384.61 DD above lower threshold temperature of 8.8øC for development and this parasitoid can complete two generations between October and February and one generation in each month.
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