감귤 귤응애(Panonychus citri) 생명표 통계량 및 개체군 변동 행렬모형

Abstract

The citrus red mite, Panonychus citri (Acari: Tetranychidae), is a serious pest in citrus orchards in Jeju, Korea. This pest feeds chlorophyll in the cells of leaves and fruits resulting in the inhibition of photosynthesis and early leaf drop. Eight to 13 generations are completed a year in Jeju area. Various computer simulation models that have been developed to analyse the population dynamics of Tetranychid mites require complex biological parameters with a lots of experimental data. In this studies, life table parameters of P. citri were estimated by using the age-specific survival and age-specific fecundity data on 6 species of citrus leaves. Also, temperature-related parameters were estimated by using previously reported development data, and a temperature-dependent matrix model for P. citri was constructed based on the parameters. The obtained results were as followings. 1. The egg incubation times were shorter on Shiranui, Kiyomi and Lemon as 7.7, 7.8, 7.5 d, respectively than other species of citrus. The development time of deutonymph was shortest on Kiyomi as 1.7 d. Total immature development time was shortest on Kiyomi as 13.3 d, while it was longest on Miyagawa as 15.4 d. In the experiments for the fecundity on different species of citrus, a higher fecundity was observed on Shiranui and Lemonon as 39.6 and 29.7 eggs, respectively, while a lower fecundity was obtained on Kiyomi and Setoka as 21.6 and 21.1 eggs, respectively. 2. The obtained development and fecundity data were subjected to estimate the life table parameters of P. citri on different species of citrus leaves: net reproductive rate, generation time, intrinsic rate of natural increase, finite rate of increase and doubling time. The estimated values for intrinsic rate of natural increase which affect directly population increase in the field were high on Shiranui and Lemon as 0.1519 and 0.1395, respectively; while the values were low on Setoka and Kabusu as 0.1056 and 0.1177, respectively. 3. To analyse the effects of inorganic nutrient contents in citrus leaves on the development time and fecundity of P. citri, Pearson correlation coefficients were estimated between the paired variables. The results showed no statistical significantly between differences contents and development or fecundity, although there were a higher positive correlation in P, K, and Na contents. 4. Temperature-related biological parameters of P. citri were estimated by using previously reported development data. In the estimated development modes of eggs, larvae, pronymphs, and deutonymphs, development rates increased with increasing temperature to a maximum, and then decreased in a high temperature region showing a typical development curve in arthropod species. Also, temperature-dependent total fecundity model, age-specific oviposition rate model, and age-specific survival rate model were developed to construct an oviposition model for P. citri. 5. A stage-structured matrix model was developed to project the population dynamics of P. citri, which composed of five age classed: eggs, larvae, protonymphs, deutonymphs and adults. The development models of each stage and fecundity curve of P. citri were successfully incorporated into the projection matrix. 6. To evaluate the predictability of the matrix model developed in this study, model outputs were compared with actual field data in a cool early season and hot mid to late season, 2004. The outputs of matrix model showed a typical exponential form of population growth. In the comparison of egg and adult populations, the model outputs pursued closely the actual field patterns till 30 d after model running in the both of early and mid to late seasons. Consequently, the developed matrix model could be used to estimate the population density of P. citri for a short period of 30 d in citrus orchards.