Spatial Distribution Pattern oiAscotisselenaria (Lepidoptera: Geometridae)larvae in a Small-Scale of Citrus Orchard

摘要

This study was conducted to understand the settlement process of Ascotis selenaria larvae into citrus orchards with respectto oviposition site and analysis of the spatial distribution pattern of the larvae. A. selenaria eggs were not found on citrus trees in field and green house, but not on citrus trees in the field. A. selenaria larvae showed a significant clump distribution in the greenhouse. In the open citrus field, the index of dispersion was around1.0 in most cases, with a weak clumping degree. However, the ^-statistic was between -1.96 and1.96, indicating a statistically significant random distribution. In addition,the Green's index (a clumping index) was very low in all cases, even though the clump distribution was accepted, for most samples, the probability distribution of larval frequency in the field satisfied the probability distribution functions of Poisson(random pattern) and the negative binomial (clump pattern) distribution. In addition, the temporal distribution of the larvae in the open field showed a pattern which was formed by colonizers from outside oviposition sites. Further, the difference in larval spatial distribution between field and greenhouse orchards was discussed.