The life cycle of butterflies is closely related to the growth of food plants and, through a prolonged coevolutionary process, has undergone an ecological adaptation. So, it is important that control the egg-laying number and place to secure enough food plant by female adult to guarantee the survival of the larvae. To study whether oviposition control of the Luehdorfia puziloi takes into greater consideration food plant leaf biomass or leaf abundance, correlation among the egg cluster size, the leaf size, and the number of leaves around egg clusters was investigated. According to the results, the egg clusters size exhibited positive correlation with the leaf size of food plants on which eggs had been laid but did not do so with the number of surrounding leaves. In addition, the number of egg clusters laid exhibited positive correlation with the number of surrounding food plant leaves but not with the leaf size on which eggs had been laid. Consequently, for the Luehdorfia puziloi, the females’ recognition of the leaf size seems to be the most important factor in the egg cluster size, and the number of egg clusters had positive correlation with food plant density per unit area.
In herbivorous insects, food plant’s growth and larval growth are known to have synchronized through a prolonged co-evolutionary process and it mainly achieved by oviposition behavior of adult (Ehrlich and Raven 1964). Most butterfly larvae feed mainly on certain plants and long-distance travel is difficult in their early larval stage, so, selection of egg-laying location and egg production number considerably affects food securement for larvae and survival during larval period (Rausher and Papaj 1983, Banno 1984, Ohsaki and Sato 1994, Hunter and Mcneil 1997, Benrey and Denno 1997). Consequently, in the oviposition process, butterflies select egg-laying locations according to the types and the degree of growth of food plants (Porter 1992, Watanabe et al. 1986, Thomas 1983), and some species prefer locations with a high density of food plants while others prefer those with a low density (Hirose et al. 1976, Rausher 1983, Root and Kareiva 1984). In addition, some select egg-laying locations in consideration of the avoidance of parasitoids or natural enemies (Fox and Eisenbach 1992), and others select open or sunny spaces according to the scenery (Warren 1987).
Egg-laying behavior of butterflies can be classified two categories. First, laying one egg at a time and second, laying many at one time as egg cluster. The latter case, egg production number control is required more importantly than in the former case (Stamp 1980). Butterflies have been reported to be capable of recognizing food plant leaf size and growth (Alonso and Herrera 1996), and in an experiment related to butterflies egg cluster size, the larvae of groups with large egg cluster sizes exhibit relatively high survival rates and low predation ratios (Lawrence 1990). The egg cluster size can be affected by several factors. For example, it can be changed according to the food plant species, and large egg clusters appear with certain food plants (Kagata and Ohgushi 2001) and it exhibits positive correlation with food plant growth rate (Reed 2003) as well as the number of leaves (Vasconcellos-Neto and Monteiro 1993). It also can be affected according to food plant density (Tsubali 1995) and the ages of the female usually smaller for an aged (Begon and Parker 1986).
Butterflies in the genus
The
In the present study, through the examination and analysis of the size of leaves on which the
Matsumura(1919) reported this species as
The butterfly is univoltine with adult emergence in early spring, and the females lay eggs in clutches on leaves of the larval host-plant, which is any available species of the genus
The area studied was on Mt. Noseong (350-400 m above the sea level) in Hwabuk-myun, Boeun-gun, Chungcheongbuk-do,
South Korea. On Mt. Noseong, afforested areas and trees such as pine trees, chinese cork oak trees (
Butterflies were studied during the entire 1999 field season (late April-early May). To study the correlation between the egg cluster size of the
As for statistical analysis, SAS (StatView 5.0.1) was used to conduct regression (simple and multiple) analysis and an x2 test of goodness of fit and a variance-mean ratio test were conducted for an analysis of the spatial distribution of egg clusters (Blackman 1942). To calculate food plant leaf area which is difficult directly to calculate, the long axis length was measured then regression equations for the leaf size and the long axis length were calculated in the laboratory using a Computer-Coordinating Area Curve meter. According to the results, the leaf size and the long axis length exhibited correlation, and it was demonstrated that estimating the leaf size according to the long axis length could be an appropriate means to calculate leaf area (Fig. 3).
>
The Size of Food Plant Leaves and the Luehdorfia puziloi
The egg clusters of the
>
The Size and Number of Food Plant Leaves and the L. puziloi
To understand whether the size of the egg clusters was controlled by the size and number of food plant leaves, major axis length of food plant where egg were laid, number of leaves, and egg cluster size were subjected to regression analysis. The result showed a positive correlation (F = 48.54, p < 0.0001, df = 202) between the leaf size and the egg cluster size, however, the size of the egg clusters and the number of surrounding (within a radius of 3 m) food plants did not (F = 0.318, p < 0.812. df = 53). In addition, the results of regression analysis conducted with the number of food plants around the egg clusters divided
per radii of 1~3 m also did not exhibit correlation (Fig. 5A and B). Consequently, the females of the
>
The Number of Food Plant Leaves and the Laying Frequency of the L. puziloi
The number of food plant leaves and the laying frequency of the
[Table 1.] ANOVA table between the number of clutches and the number of host-plants
ANOVA table between the number of clutches and the number of host-plants
find significance when they were subjected to simple regression analysis per radii of radius 1 m, 2 m, and 3 m and the correlation coefficients were very low (Fig. 5B). Consequently, the number of egg clusters of the
In this study, we suggested that the size of the egg clusters of the
of the
In this study, the average egg production number of the
the average egg production number in the size of the egg clusters collected for the present study was 40%, lower than 66~70% for Japan. Such differences seem to be because the size distribution of the egg clusters of Korean
The egg production number of the
In the present investigation, a case where many egg clusters had been laid on one food plant leaf was observed, but whether a single butterfly had laid these egg clusters could not be directly confirmed. Judging from changes in the colors of the eggs, the oviposition periods seemed to be disparate. There were 25 cases (12.3% of the total) which found two egg clusters or more on one leaf, 9 cases for two egg clusters, 1 case for three egg clusters, and 1 case for 4 egg clusters (Fig. 7A). The correlation analysis between the size of egg clusters and the leaf size also exhibited positive correlation and there was no preference regarding the leaf size in selecting the leaf for oviposition, identical to the results for the total egg clusters (Fig. 7B). However, even though it was not determined whether such ovipositional habits were due to preference regarding considerations of the locations of food plants, they do not seem to be efficient for larvae’s food distribution.
Through the present study, it was possible to obtain advanced knowledge of the factors for female butterflies’ recognition of food plants for control the egg production number of the