Analysis of interaction between Aristolochia debilis with vigorous chemical defenses and phytophagous insects

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1. Seasonal changes and population dynamics of the papilionid butterfly, Atrophaneura alcinous and its host plant, Aristolochia debilis were investigated in a natural population. By analysing the data for the population dynamics of twelve generations of the butterly during 3 yeras, the following two results were obtained. First, when the amount of food resources (biomass of the host plant) increased extremely in any generation, the response of population density of the butterfly to the resource abundance was delayd and the population density increased in the next generation. Secondly, except the extreme increase of food resources as mentined above, there was a positive colleration between the amount of food resources and the laraval survival rates of A.alcinous. Then, we conclude that the local population of A.alcinous was regulated by the food resource abundance (bottom up). This trend may be a characteristic interactions between the host plant with vigorous chemical defense and the p … More hytophagous insect that specialized to the host plant.2. In order to evaluate the effects of herbivory and conpensatory reactions to herbivory on the productivity ofA.debilis, a series of clipping experiments in a natural population of A.debilis were conducted. We found that A.debilis had a highly conpensatory ability to herbivory. The plants which were clipped experimentally had abundant fresh leaves after clipping, by a recovery of above ground parts as conpensatory reactions. In general, the photosynthetic rate of an aged leaf is lowered than that of the fresh leaf. Therefore, it may be supported that the productivity of the plants which suffered herbivory increased by replacing from aged to newly fresh leaves on aerial parts of the plant.3. Analysing a value of leaf as a food resource for young larvae of A.alcinous by experiments of rearing on fresh and aged leaves, we found that young leaves was highly valuable for young larvae than aged ones. Therefore, considering the values of leaf for both A.debilis and A.alcinous, it may also support that the conpensatory reactions of A.debilis may play an important role in a maintenance of the system interacting between the A.debilis and A.alcinous4. In order to evaluate of a value of leaf in aspects of nutrition and chemical substance such as aristolochic acid, chemical analysis for leaves of A.debilis with reference to herbivory and seasonality is now carrying out. Furthermore, girdling behavior (the stem near the ground was girdled and the parts of phloem were removed by the larvae) by the larvae of A.alcinous was found and the significance of this behavior is now analysing by a chemical technique. Less