No abstract

The change in air temperature will influence the insect behavior, physiology and population dynamics of insects as they are poikilothermic. Global temperature has increased by 1.09°C during 2001-2020 when compared to 1850-1900. It is projected that the temperature will further increase by 5.7°C under high emission scenario, if mitigation strategies are not adopted. Increase in temperature would affect the physiology and population dynamics of the insects. A study was undertaken to understand the effect of different temperature regimes on rice leaffolder. Survival fraction decreased with increasing temperatures as more successful development was at lower temperature regimes. Apparent mortality increased towards the higher temperature regimes as the insects cannot tolerate high temperature stress. The Mortality Survivor Ratio (MSR) revealed that the population increase would be more at higher temperature regimes as the MSR remained higher at higher temperature regimes. The Indispensable Mortality was lesser under higher temperature regimes as the number of adults emerged in the high temperature regime was less. Generally, K - values increased with increasing temperature. It indicates that the insects which happened to live under higher temperature regimes were reproduction oriented as most of the energy was spent in reproduction rather than for living longer time.

The yellow stem borer (YSB) Scirpophaga incertulas (Walker) (Pyralidae: Lepidoptera) is one of the major pests in rice producing areas and accounts for 27 to 34 per cent loss in the crop yield. Climate change especially temperature increase will affect the insect physiology, behavior and development. An investigation was undertaken to study the effect of temperature on Scirpophaga incertulas (Walker) by constructing the stage specific life table to understand its behaviour in the future climate. Experiments were carried out at four different temperature regimes viz., 28.0°C, 30.0°C, 32.0°C and 34.0°C. The results revealed that the survival fraction of a particular stage reduced with increasing temperatures. The calculated apparent mortality indicated that the percentage of insect died, increased with increasing temperatures. The results showed that the Mortality Survival Ratio (MSR) was observed to be increasing with increasing temperatures for all the stages. The value of IM was observed to be decreasing with increasing temperatures. The generation mortality of YSB was increasing with increase in temperatures for all the stages. The experiments revealed that the insects which happened to live under higher temperature would die faster and most of their energy is spent for reproduction rather than for living long time.