Stage Specific Life Table of Rice Leaffolder, Cnaphalocrocis medinalis (Guen.) at Different Temperature Regimes

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.

Population Dynamics of the Rice Leaf Folder <i>Cnaphalocrocis medinalis</i> Guenee: A Lifetable Study

“…Earlier a high rate of egg mortality had been reported as a common trait (Cuthbertson et al, 2013) and among Lepidopteran insects' mortality during the early larval stages is typically significant (Soufbaf et al, 2010). Similar to the present study, Park et al (2014) reported high egg mortality (43%); and Jian et al (2012) and Manikandan et al (2023) reported high early larval mortality and pupal survival while rearing C. medinalis at 27± 1°C on rice leaves. The results observed by Ankit et al (2016) are also in line with the present study in terms of egg hatching (63.45%), while higher pupation (56.66%) was reported, which might be due to the varietal difference or variation in the temperature and humidity conditions of rearing.…”