The development and fitness of insects depend on the temperature to which they are exposed. The thermal windows are defined as the temperature range between the minimum and maximum rate of development for individual species. The intrinsic optimal temperature for development proposed by Ikemoto is one of important factors that determine the fitness of optimum life history. The temperature requirements for development of 65 species from five orders of insects was obtained from several journals. The minimum and maximum rate of development was estimated using empirical models. The temperature tolerance range of enzyme activation was estimated using Shape-Schoolfield-Ikemoto (SSI) model. The mean and range of intrinsic optimal temperature were 20.89°C and 15.7~27.7°C. The mean intrinsic optimal temperatures of Hemiptera and Endopterygota (Coleoptera, Diptera, Hymenoptera and Lepidoptera) were 20.97°C and 20.71°C. The mean and range of thermal windows were 25.59°C and 16.69~36.13°C. The mean thermal windows of Hemiptera and Endopterygota were 25.53°C and 25.62°C. also not much different. Each species of insects had a limited temperature range for development. It is needed further studies for understanding the ecological, physiological and evolutionary response of insects to their thermal environments.

The growth, differentiation, development and fecundity of insects are influenced by temperature. The relationship between the development rate of insect and temperature has been studied since 1978 in Korea. The relationship between temperature and insect development was published in the Korean Journal of Applied Entomology (71 papers). The contents about Hemiptera, Lepidoptera, Coleoptera, Diptera, Hymenoptera, Acarina and Neuroptera were published in 27, 16, 7, 6, 4, 5, and 2 papers of the journal. Approximately 33 functions from many international journals were published to figure out the relationship between temperature and development rate of insects. The functions have been developed based on two principal ways – simplified analytic method and biophysiological approach. The empirical models are based on the law of total effective temperature and heat summation. The biophysiological models are based on the equations of Arrhenius and Eying. The thermal constant and lower temperature threshold are estimated using linear functions. The minimal and maximal development rate are presented by nonlinear equations. The Sharpe-Schoolfield-Ikemoto (SSI) model showed the intrinsic optimal temperature. Cumulative proportion of development completion for each life stage of insects was analyzed using Weibull and sigmoid functions. We discussed the application and implication of linear and non-linear temperature dependent development models.

Chrysanthemum stunt viroid (CSVd) is a serious pathogen affecting chrysanthemum that has caused significant economic losses to Chrysanthemum flower production worldwide. Control of CSVd disease is difficult due to its contagious nature and long latent period in the field. As chrysanthemum is most often produced by implanting seedlings, it is necessary to diagnose CSVd infection before cultivation. In this study, we screened CSVd infection in seedlings from 30 varieties including 5 domestic, 6 Japanese, and 19 European varieties. Molecular diagnosis of the combination of RT-PCR and nested PCR showed that CSVd was not detected by the first RT-PCR but detected by the second nested PCR analysis in 10 varieties, including 1 domestic, 2 Japanese, and 7 European varieties. Further comparison of 10 identified CSVd nucleotide sequences showed that those are highly conserved (99-100%) and the most similar to an isolate (AB006737) identified in Hokkaido, Japan. Our study suggests that the combination of RT-PCR and nested PCR analysis is successful for the CSVd diagnosis of seedlings and the molecular diagnosis is necessary to prevent the introduction and propagation of viroid disease into the fields.