Effect of Elevated Temperature on Life-History Parameters of Rice Yellow Stem Borer ( Scirpophaga incertulas Walker)

A study was undertaken to understand the effect of increasing temperature on population dynamics of yellow stem borer (YSB), Scirpophaga incertulas. Experiments were carried out in a temperature control chamber with five different constant temperatures (28 degrees C, 30 degrees C, 32 degrees C, 34 degrees C and 36 degrees C). The data on age-specific life table at varying temperature regimes revealed that the total lifespan of YSB extended to a maximum of 52 days at 28 degrees C followed by 49 days at 30 degrees C and 46 days at 32 degrees C. In general, survival of the YSB decreased with increasing temperature. Preoviposition period for YSB also decreased with increasing temperature. However, the total number of eggs laid by YSB increased with increasing temperature. Also, 50% fecundity in YSB was recorded on 49.7 days after incubation at 28 degrees C, whereas it was observed as early as 34.4 days at 36 degrees C. All the growth parameters were observed to decrease at 36 degrees C, which reveals that temperature increase above 34 degrees C is detrimental to the development of YSB. The above results reveal that, if the global warming continues at the present phase, it will negatively influence YSB and the population growth will be severely affected in the near future.