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Chemical components stimulating oviposition bySitophilus zeamais in rice grain were isolated from rice bran and were found to be a mixture of ferulates, diglycerides, and free sterols. Oviposition preference of the species can be induced by synergistic action of these compounds.
A heterogeneous life cycle of individuals in a population was examined on its adaptive significance to an unstable environmental condition. The trend of population growth was simulated by a simple mathematical model in which a part of population in a certain generation was carried over to the next generation without participating in the reproduction. With(More)
1. A computational model accounting for motion detection in the fly was examined by comparing responses in motion-sensitive horizontal system (HS) and centrifugal horizontal (CH) cells in the fly's lobula plate with a computer simulation implemented on a motion detector of the correlation type, the Reichardt detector. First-order (linear) and second-order(More)
The regulation mechanism of insect population is considered in this paper using a very simplified model of the reproduction curve which has two equilibrium points. In many insects each generation does not overlap in a population and appears periodically, and it seems more convenient to deal with the population fluctuation in the unit of generation. In this(More)
1. The functional response to, and preference for, the host density in a parasite were examined experimentally using an icheumon wasp,Exidechthis canescens, and its hostCadra cautella under controlled conditions. 2. Wasps were more active in host-searching at higher than lower host densities. Percent parasitism increased rapidly with initial increments in(More)
Field-grownPinus densiflora seedlings were inoculated withBursaphelenchus xylophilus and the incidence of pine wilt disease was analyzed with respect to the spatial relationships between pine seedlings and adjacent seedlings of other tree species in a pure pine stand and three stands mixed withAlnus sieboldiana, Sarothamus scoparius or naturally associated(More)
To evaluate the effect of adjacent tree species on the susceptibility of Japanese black pine (Pinus thunbergii) to pine wilt disease, an inoculation experiment was conducted usingP. thunbergii seedlings potted with seedlings of six tree species,i. e. Alnus sieboldiana, Eurya japonica, Lespedeza bicolor formacutifolia, Pinus thumbergii, Robinia pseudo-acacia(More)
The experimental population of insect has been studied with an assumption that the maximum rate of population increase which would be realized at the opt imum condition with no harmful effect of population density takes constant value f rom generat ion to generation. T h a t is, for instance, the innate capaci ty for increase or intrinsic rate of natural(More)