Differences in responses to a fluctuating temperature/humidity environment between two related species of rice leaffolders based on a comparison in a constant environment

Abstract

Cnaphalocrocis medinalis (Guenée) and Cnaphalocrocis exigua (Butler), two related species of rice leaffolders in paddy fields, have similar morphological and damage properties but distinctions in distribution and migration. They grow in a rhythmically changing environment with temperature/humidity variations daily. Here, the demography and population parameters of two rice leaffolders under fluctuating (20–32 °C, RH 70–85 %) and constant (26 °C, RH 80 %) environments were explored through age-stage and two-sex life tables. The results suggested that the two rice leaffolders have different life-history parameters in both controlled environments. Under a constant environment, C. medinalis had lower egg developmental duration, adult longevities, survival, oviposition days, fecundity, increase (r), finite rate of increase (λ), and net reproduction rate (R0), and larger larval, pupal, and preadult developmental durations and adult and total preoviposition periods than C. exigua. Nevertheless, under a fluctuating environment, C. medinalis parameters, including egg and pupal developmental durations, adult longevities, male and female lifespans, oviposition days, fecundity, r, λ, R0, and mean generation times (T), were shorter than those of C. exigua. Furthermore, under comparison in a constant environment, C. medinalis had more changed parameters (shortened egg, larval, pupal, and preadult developmental durations, male and female lifespans, and T) in fluctuating environments than C. exigua parameters (shortened egg developmental durations, extended larval developmental durations, and decreased survival). These findings revealed that fluctuating environments could influence the growth and development of the two rice leaffolders, and C. medinalis was more easily responsive to fluctuating environments than C. exigua.