솔수염하늘소의 개체군 모형

Abstract

The Japanese pine sawyer, Monochamus alternatus Hope (Coleoptera: Cerambycidae), is a primary vector of PWD, Bursaphelenchus xylophilus Nickle, one of the most serious threats to pine trees in Asia and Europe. To establish a sound management strategy, it is necessary to construct a phenological prediction model for M. alternatus. Therefore, the population model of the Japanese pine sawyer was constructed to understand its population ecology and predict the seasonal occurrence pattern of the developmental stages through a series of studies: (1) temperature-dependent development of egg, larvae and pupae, (2) adult reproduction, (3) post-diapause larval development. The temperature-dependent development of each stage of M. alternatus was examined in the laboratory. The relationships between development rates of egg, larvae and pupa, and temperature showed a typical temperature-dependent form with high temperature inhibition. It was well described by a nonlinear development rate model. Egg, larva, and pupa developmental rate (1/median day) were, respectively, incorporated into temperature-dependant developmental rate models, using Lactin model. The probability distribution of development time of each stage was estimated by Weibull function based on physiological age of each stage implying the summation of their daily developmental rate. An oviposition model consists of an adult aging rate model, a total fecundity model, an age-specific cumulative oviposition model and an age-specific survival model, in which physiological age was calculated from adult aging rate model. Beta distribution model was applied to the total fecundity model. A normalized cumulative oviposition rate and a survival rate with physiological age were incorporated into those age-specific models. A population model for M. alternatus was established by integrating development model of each stage, oviposition model and post-diapause development model into a system. The number of individuals shifted from a stage to the next stage was calculated by multiplying the initial number if individuals in a stage by the probabilities produced by the development distribution model of each stage. For a validation, model outputs were compared with the actual proportion of diapausing larvae and adult occurrence surveyed in three different sites, Jeju in 2016, and were successfully fitted to actual proportion of diapausing larvae and adult occurrence. The adult activity of M. alternatus monitored with a pheromone trap showed a bimodal form consisted of the first peak in mid to late June and the second peak in mid to late September in Jeju area, Korea. The two peaks were separated apparently between mid and late August, showing a valley. The pine trees without oleoresin flow were abundant during early July to early August, and declined thereafter, which did not match with the valley of adult activity curve. Thus, the hypothesis of dying pine that attracts much strongly M. alternatus adults than pheromone lures do and makes a valley may not fully explain the bimodal pattern when the diapause ecology was not considered.