]pn. ]pn. ]. Environ. Entoillo l. Zoo l. 19 (2) : 59 - 67 (2008) 環動昆第19 巻第2号: 59 - 67 (2008) 。riginal Article Comparisons of cocoon density and survival processes of the blue 幽 striped nettle grub moth Parasa lepida (Cramer) between deciduous and evergreen trees Hiroichi Hiroichi Sawada 1) ，Y oshihisa Masumoto 1)， Takashi Matsumoto 2) and Takayoshi Nishida 3) 1) 1) School of Environmental Science ，The University of Shiga Prefecture ，日 ikone ， Shiga 522-8533 ， Japan 2) 2) Graduate School of Human and Environmental Studies ，Kyoto University ，Kyoto 606-850 1. Japan 3) 3) Laboratory of Insect Ecology ， Graduate School of Agriculture ，Kyoto University ，Kyoto 606-8502 ， Japan (Received (Received March 17 ， 2008 ; Accepted May 1， 2008) Abstract We studied population dynamics of the blue-striped nettle grub moth Parasa lepida (Cramer) ， in terms of cocoon density density over four years from 2004 to 2007 at the campus of The University of Shiga Prefecture ，Hikone ， western Japan Japan on a wide range of host trees including both deciduous trees (36 spp. of 282 individual trees) and evergreen trees trees (15 spp. of 122 individual trees). Detailed survival processes were examined by tracking developmental stages both both on the deciduous Chinese tallow tree Triadica seb 俳ra (1.) Small (Euphorbiaceae) and an evergreen oak Quercus myrsinaefolia myrsinaefolia Blume (Fagaceae) to identify factors responsible for the population dynamics and the host utilization patterns. patterns. The density of cocoons was significantly higher in deciduous hosts than in evergreen hosts in the first generation ， but this tendency disappeared in the second generation. Life table analyses revealed there was a higher cocoon cocoon density in deciduous T. sebifera than in evergreen Q. myrsinaefolia in the first generation but detected the opposite opposite tendency in the second generation. These generation specific trends were attributable to the greater egg density density and thεhigher survival rate during the larval stage in the first generation ，and to density-dependent occurrence occurrence of larval death due to nuclear polyhedrosis virus (NPV) in the second generation on T. seb( メera. Key words : Parasa lepida (Cramer) ，Population dynamics ，Life table ， Host plan t， Deciduous tree ，Evergreen trεE Introduction Introduction Hattori ， 1981). Moreover ， larvae of P. lepida ， armoured with sharp spines ， are annoying. The blue-striped nettle grub moth Pa 印刷 lepida P. lepida is highly polyphagous. For instance (Cramer) (Cramer) (Lepidoptera: Limacodidae) is an invasive Robinson et al. (2001) listed 78 species belonging to 35 pest pest originally distributed widely in the tropics and families ， such as Leguminosae ， Arecaceae ， and subtropics ， such as southern China ， south-east Asia ， Euphorbiaceae. as the host plants in India and India ，and central-south Africa (Hirashima ， 1989; Southeast Asia. Moreover ， P. lepid α1S， a notonous pest Zhang ，1994). Invasion of P. lepida was first recorded in of fruit trees ，damaging coconuts ，coffee ，mango and Kagoshima in 1921 but it was rare until the 1960s cacao in Indonesia (Kalshoven ，198 1) and mango (Miyata 1981). Ever since the end of the 1970s particularly in India (Kapoor et al. ，1985; Jeyabalan and outbreaks outbreaks have occurred frequently in western Japan Murugan ， 1996). Extreme polyphagy was also (Miyata ， 1981) together with rapid northward documented in Japan. Yamazaki et al. (1 994) revealed expansion expansion of the distribution range ，now reaching to the presence of cocoons on 194 trees of 85 species northern northern Kanto (Nakano ， 2003). During the 1980s P. belonging to 34 families among a total of 463 trees of lepida lepida established a pest status ，seriously defoliating 166 species belonging to 48 families growing in the cherry cherry trees ，persimmons and various trees on the Botanical Garden of Kyoto University ，Kyoto ， western streets streets and city gardens in urban areas (Oda and Japan. By tracking cocoon density of P 目 lepia αfor 51 Corresponding Corresponding author : [email protected] -59 Sa 、，y ada et α/ tree tree species over three years in Hikone. western the start to the end of cocoon spinning ，from late July J apan. Nishida et al. (2006) reported the host to early September in the first generation and from utilization utilization as follows: 1) The cocoon was observed on middle September to early November in the second 26 26 tree species (66.7 %) among 39 common tree generation. On the grounds that P. lepida pupates species ， 2) The cocoon density was relatively high in exclusively in the lower parts of tree trunks ，we the the Japanese red maple Acer pycnanthum ， the Japanese counted the number of cocoons on tree trunks less maple A. palmatum var. matsumurae (Aceraceae) ，an than 2.5 m in height for each census tree. Cocoons evergreen evergreen oak Quercus myrsinaefolia (Fagaceae). and being formed on substratum annexed to a census tree the the Chinese tallow tree Triadic αsebi 耐α(Euphorbiaceae) ， were included in the data of the census tree. To avoid 3) 3) Plant phylogeny may play a minor role in double counting ， each cocoon was marked with a felt determining determining the cocoon density ，and 4) In the first pen after being counted. generation generation the cocoon density was higher among deciduous deciduous species than among evergreen species. Life t且ble In In this study we report the host utilization of P. Life tables of P. lepida were constructed for both T. lepida lepida by comparing the cocoon density between seb すき ra (deciduous tree) and Q. myrsina 宅folia (evergreen deciduous deciduous and evergreen hosts. together with detailed tree) by pooling data of each tree species over 6 survival survival processes of all the developmental stages on generations 企om the first generation in 2005 to the second deciduous deciduous T. seb 俳ra and evergreen Q. myrsinaefolia. By generation in 2007. Both host species were selected examining examining these data we discuss factors affecting host 四 because of the relatively high cocoon densities and the related related differences in the cocoon density of P. lepida abundance of trees that can ensure large sample sizεs. The numbers of census trees were 10 in 2005 and 13 Materials Materials and Methods in 2006 and 2007 for each tree species. The height and diameter diameter of the census trees were similar for T. sebifera The study area and Q. myrsinaefolia with a tree height of 3.6-6.2 m and We performed field censuses at the c乱mpus of The 3.0-5.6m ，respectiv 巴ly ，and a tree diameter of 与20 cm D University University of Shiga Prefecture (USP) (N35 1 7' ，E and 8司 17 cm at 20 cm above the ground ，respectively 136 0 15' ). located in the southern suburbs of Hikone The census periods covered whole developmεntal city ， western Japan. The campus of USP was stages from the beginning of the adult emerg 日nce to constructed constructed in 1995. with 70 species of trees planted in the last formation of the cocoon ，from middle May to the the 30 ha area. The campus was similar to a large early September in the first generation and from scale scale city park ，with a large number of P. lepida August to early November in the second cocoons cocoons observed on the tree trunks During the census periods all thεleaves of the trees trees were checked for the number of eggs and Census of cocoon density batchεs every other E 乱ch egg batch was We chose a total of 51 tree species comprising 404 individually marked by attaching a label nearby and individual individual trees (36 species of 282 deciduous trees and thereafter mortality factors ， such as hatching failure ， 15 15 species of 122 evergreen trees) among predation ，parasitoids and so on ，were checked. If a approximately approximately 70 tree species planted in the campus. group of newly hatched larvae was found ，nearby The deciduous trees included T. seb ぴera ，Yoshino leaves were examined intensively for 時 the presence of cherry cherry Prunus X yedoensis ，and J apanese zelkova Zelkova the egg batch from which the larvae derived to count serrata serrata and the evergreen trees included Q. the egg batch size. the number of hatched larvae ，and myrsinaefolia ， Q. glauca ， and Camphor laurel the number of parasitized eggs. Y oung instars are Cinnamomum camphora. The census started from the very conspicuous because they are gregarious with first first generation in 2004 and ended at the second very noticeable feeding scars on leaves. The cocoons generation generation in 2007. over 8 generations during the four were checked using the same methods described in years. years. 1n principle we conducted the censuses on 10 the previous section. trees trees for each tree species except when the maximum number of tree species was less than 10. The censuses Comp 紅色on of life table data between the 何 '0 host plants were performed once a week during the periods from Survival processes were compared between T -60 一 Comparisons Comparisons density and survival processes o[ the 仇 rasa lepid α sebif 台ra 呂nd Q. m) 刊 tna そfolia for each generation and log C 礼一 log Cb = (log Ea -log Eb) + (log S a -log S year. year. The cocoon density of a given generation or year (E) b) + (l og S (L) a -log S (L) b) (3) was determined as follows. Equation Equation (3) means that in terms of the common C =E x Ll E x C/L =E xS (E )x S (L) (1) logarithm ，the difference in the cocoon density between the two host plants is expressed as the sum Here ，C ，E ，and L denote the density of cocoons ， of between-plant differences in the following three life eggs ，and hatched larvae ，respectively ，whereas S (E) stage components; egg density (E) ，egg survival (S and S (L) denotεthe survival rate during the egg and (E) )， and larval survival (S (L) ).