Temperature Thresholds and Thermal Requirements for the Development of the Rice Leaf Folder,Cnaphalocrocis medinalis

Abstract

The rice leaf folder, Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae) is a predominant foliage feeder in all the rice ecosystems. The objective of this study was to examine the development of leaf folder at 7 constant temperatures (18, 20, 25, 30, 32, 34, 35° C) and to estimate temperature thresholds and thermal constants for the forecasting models based on heat accumulation units, which could be developed for use in forecasting. The developmental periods of different stages of rice leaf folder were reduced with increases in temperature from 18 to 34° C. The lower threshold temperatures of 11.0, 10.4, 12.8, and 11.1° C, and thermal constants of 69, 270, 106, and 455 degree days, were estimated by linear regression analysis for egg, larva, pupa, and total development, respectively. Based on the thermodynamic non-linear optimSSI model, intrinsic optimum temperatures for the development of egg, larva, and pupa were estimated at 28.9, 25.1 and 23.7° C, respectively. The upper and lower threshold temperatures were estimated as 36.4° C and 11.2° C for total development, indicating that the enzyme was half active and half inactive at these temperatures. These estimated thermal thresholds and degree days could be used to predict the leaf folder activity in the field for their effective management.

Increased temperature induces leaffolder outbreak in rice field

“…However, in this study we only considered climatic factors. Although leaffolder colonizes and causes damage during the rice-growing season, ripening and reproductive stages show the highest infestations and generate higher-amount losses in rice production (Padmavathi, Katti, Sailaja, et al, 2013;Wada et al, 1980). Though our analysis shows that recent outbreaks of leaffolder in rice can arise due to ongoing climate change, as supported by other recent laboratory reports (Liao et al, 2014;, other factors might also have a vital role for this problem.…”

“…However, in this study we only considered climatic factors. Although leaffolder colonizes and causes damage during the rice‐growing season, ripening and reproductive stages show the highest infestations and generate higher‐amount losses in rice production (Padmavathi, Katti, Sailaja, et al, ; Wada et al, ).…”

“…After an adult moth lays its eggs on a leaf, and following the incubation period, first instar larvae then emerge and feed on the leaf (Fraenkel & Fallil, ). This feeding reduces chlorophyll, leaf water content and photosystem II activity, while severely infested leaves quickly desiccate (Padmavathi, Katti, Sailaja, et al, ). Resultant rice losses can be severe (Bautista, Henirichs, & Rejesus, ; Liu et al, ; Padmavathi, Katti, Padmakumari, Voleti, & Subba Rao, ).…”

Development and reproductive potential of predatory pirate bug, Blaptostethus pallescens (Poppius) at different temperatures

“…According to Chhagan and Stevens (2007) 419.8 degree days, above lower threshold temperature of 10.1°C, were required to complete development of green house thrips (Heliothrips haemorrhoidalis Bouché) from egg to adult on lemon fruit and they proposed the information valuable in determining the optimum time for initiating greenhouse thrips monitoring programme or for applying control measures against thrips. Padmavathi et al, (2013) estimated 11.1°C lower threshold temperature and thermal constant of 455 degree days for rice leaf folder, Cnaphalocrocis medinalis Guenée and suggested the involvement of enzymatic activity above lower threshold temperature to complete development process. *Calculated on the basis of developmental threshold temperature using Wilson and Barnett (1983) formulae…”

Computational modeling to describe the dynamics of fall armyworm <em>Spodoptera frugiperda</em> (J.E. Smith) (Lepidoptera: Noctuidae) in <em>Bt</em> crop areas

“…Therefore, an insect should be able to accumulate a determined amount of energy (degree-days) to molt to another stage. This amount of energy is called the thermal constant (GALLO et al, 2002;PADMAVATHI et al, 2013). The thermal constant can be defined as the number of degree-days required for a development change to occur.…”