Jpn. J. Environ. Entomol. Zool. 28（4）：169－172 （2017） 環動昆 第 28 巻 第 4 号：169－172 （2017） Original Article

Distributional range of a dry-wood , Neotermes koshunensis (Shiraki) (Isoptera, ), and its relationship with soil type on Okinawa-Jima Island

Koji Sugio 1)* and Yasushi Miyaguni 2)

1) Graduate School of Education, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan 2) Department of Earth sciences, Faculty of Science, University of the Ryukyus, Okinawa 903-0213, Japan

（Received: June 9, 2017；Accepted: November 18 , 2017）

Abstract We examined the distribution of Neotermes koshunensis Shiraki 1909 on Okinawa-Jima Island in the Ryukyu Archipelago, Japan, which represents the northern limit of its distribution. Termite nests were found at 115 of the 257 sites investigated. These data suggested that 26° 25′00″N is the northern limit for this . However, a zone lacking this species was found at the southern end of the island. Examination of the pattern of termite distribution in relation to the distribution of soil types suggested that the presence and absence of this species on the island was related to Jahgaru and Shimajiri mahji soils, respectively.

Keywords: distributional factor, northern limit, Okinawa Island, soil type

Introduction Yasuda et al. (2000) reported that N. koshunensis was found in the forests of the middle and southern regions of The distributional range of Neotermes koshunensis (Shiraki Okinawa-Jima Island, whereas it was not found in the northern 1909) includes the Ryukyu Archipelago (Okinawa, Japan), parts of the island. They also reported that this species was Formosa, China, and extending to Okinawa-Jima Island in the absent from areas further north than Okinawa city. However, north (Ikehara, 1966; Yasuda et al., 2000). The species is much of the information contained in that study is unusable, termed a ‘dry-wood’ or ‘one-piece’ termite because its colonies meaning the distribution of this species in Okinawa-Jima nest and spend their entire lives inside a single dead branch or Island, including its northern limit, remains poorly understood. tree, which provides both shelter and food (Maki and Abe, In the present study, we investigated in detail the distribution 1986; Abe, 1989). The colonies are typically small comprising of N. koshunensis in the middle–southern parts of about 1500–3000 individuals. Because collecting an entire Okinawa-Jima Island. We then compared the termite colony and maintaining it in the laboratory is easy, dry-wood distribution with the distribution of soil types. Based on this have been used experimentally in various studies, information, we discuss the northern limit and the including research into cellulose degradation (Tokuda et al., characteristics of distribution of this termite species. 2002; Sugio et al., 2006) and caste differentiation (Katoh et al., 2007; Miyaguni et al., 2013). Although N. koshunensis Materials and Methods colonies are not house-eating pests (Ikehara, 1966), they may cause damage to living street-trees through invasion, and by We investigated termite distribution at 257 sites including, building and extension of their nests. Nevertheless, there have forests, woods, public parks, burial grounds, ancient castles, been few reports of damage to living trees by termites in Japan and roadside trees in southern and middle Okinawa-Jima Island (reviewed by Iwata, 2006). from March 2007 to May 2009 (Fig. 1A). We fixed the time

*Corresponding author: [email protected]

- 169 - Sugio et al limit for searching for termite nests at 30 min at each site and N. koshunensis were distributed within the region extending terminated searching at the site if a nest was found in less than from 26°05′00″N to 26°25′00″N, located in the 30 min. GPS data for the investigated sites were recorded using middle–southern parts of Okinawa-Jima Island. This species a registering-type GPS (WGS84, Pokenavi Light; Empex was difficult to find at the northern end of the study area and Instruments Inc., Tokyo, Japan). was not found further north than 26°25′00″N (Fig. 1A). Therefore, we suggest that 26°25′00″N is the northern limit for Results and Discussion this termite, which supports the findings of Yasuda et al. (2000). However, further study is required to determine the We found nests of N. koshunensis at 115 of the 257 sites importance of temperature in explaining the distribution of this studied (Fig. 1A and Table 1). Although we could not species in this area. identify some tree species, the following species with termite At the southern end of Okinawa-Jima Island, we found few nests were identified: Cerasus campanulata, Leucaena colonies below latitude 26°07′30″N (Fig. 1A). Because N. leucocepha, Elaeocarpus sylvestris var. ellipticus, Ficus koshunensis was found on many islands south of microcarpa, Bauhinia variegata, Delonix regia, Ehretia Okinawa-Jima Island, including Ishigaki-Jima Island, acuminata, Morella rubra, Syzygium jambos, Acacia confusa, Iriomote-Jima Island, and Yonaguni-Jima Island (Ikehara, Erythrina variegata, and Cerbera manghas (Table 1). 1966; Yasuda et al., 2000), the absence of this termite from southernmost end of Okinawa-Jima Island may not be Table 1 Presence and absence of N. koshunensis at explained by temperature alone. Yasuda et al. (2000) reported different study sites that N. koshunensis was found in forest areas growing on

Classification of site N Presence Absence % of presence Ryukyu limestone and was absent from forests in areas lacking Forest 24 14 10 58.3% limestone. Therefore, to clarify understanding of the absence Woods 74 26 48 35.1% Public park 53 26 27 49.1% of this termite from the southernmost regions of Okinawa-Jima Burial ground 70 34 36 48.6% Island, we compared its distribution with the distribution of Ancient castle 10 6 4 60.0% Roadside trees 26 9 17 34.6% soil types on the island. Total 257 115142 44.7%

Fig 1. Relationship between the distribution of N. koshunensis and soil type in the middle–southern region of Okinawa-Jima Island. (A): presence (black circles) and absence (white squares) of this termite at individual sampling sites. (B): distribution of soil types (modified from Miyamaru, 2013). (C): overlying of (A) and (B). Shaded areas on (A) show military areas, which were not investigated.

- 170 - Distribution characteristics of Neotermes koshunensis

In Okinawa-Jima Island, the major soil types are Kunigami Researches in Japan (in Japanese). House Household mahji (red-yellow soil; Maejima, 2016), Jahgaru (immature Pests 28: 1–27. soil; Maejima, 2016), Shimajiri mahji (dark-red and immature Katoh, H., T. Matsumoto and T. Miura (2007) Alate soils; Maejima, 2016), and alluvial soil (Fig. 1B) (Miyamaru, differentiation and compound-eye development in the 2013; National Agriculture and Food Research Organization, drywood termite Neotermes koshunensis (Isoptera, 2017). N. koshunensis was found at many sites in areas with Kalotermitidae). Insect. Soc. 54: 11–19. Jahgaru soil, which is widely distributed in the middle and Maejima, Y. (2016) Pedogenesis and classification of southern area of Okinawa-Jima Island (Fig. 1C). However, in Kunigami Mahji, Shimajiri Mahji, and Jahgaru soils the area at the southern end, it seems that the zone deficient in distributed in the subtropical islands, Japan (in Japanese). N. koshunensis was associated with the presence of Shimajiri Pedologists 60: 65–70. mahji (Fig. 1C). Because N. koshunensis does not come into Maki, K. and T. Abe (1986) Proportion of soldiers in the contact with the soil, the relationship between the soil colonies of a dry wood termite, Neotermes koshunensis characteristics and the distribution of this termite remains (Kalotermitidae: Isoptera). Physiol. Ecol. Jpn. 23: unclear. 109–117. Our study supports the northern distribution of N. Miyamaru, N. (2013) Investigation of microbial properties of koshunensis described in a previous study (Yasuda et al., 2000). soils with improvement of infertile soils in Okinawa (in However, we found a zone in the southern area of Japanese). Bul. Okinawa Pref. Agric. Res. Center 7: 1–44. Okinawa-Jima Island where this termite species was absent. Miyaguni, Y., K. Sugio and K. Tsuji (2013) The Unusual Further information on the relation between the soil type Neotenic System of the Asian Dry Wood Termite, (especially Shimajiri mahji and Jahgaru) and the life-history of Neotermes koshunensis (Isoptera: Kalotermitidae). termites is required to fully understand the characteristics of Sociobiol. 60: 65–68. distribution of this termite species. National Agriculture and Food Research Organization (2017) Japan, soil-inventory.http://soil-inventory.dc.affrc.go.jp/ Acknowledgements figure.php (accessed August 4, 2017) Sugio, K., K. Shimojo, J. Isozaki, W. Itosu, A. Tsuha, S. We thank Mr. K. Sakamoto and Mr. K. Tokumine for Kakazu and G. Tokuda (2006) Distribution of cellulase cooperation in fieldwork, and Dr. A. Yamada for comments on activity in the salivary glands and the guts of the manuscript. We thank anonymous referees for their pseudoworkers and soldiers of the drywood-feeding valuable advice. This work was supported by University of the termite Neotermes koshunensis (Shiraki) and the effect of Ryukyus Research Project Promotion Grant (Strategic defaunation (in Japanese). Jpn. J. Appl. Entomol. Zool. Research Grant) (No.17SP02103). We thank Harry Taylor, PhD, 41: 1–6. from Edanz Group (www.edanzediting.com/ac) for editing a Tokuda, G., H. Saito and H. Watanabe (2002) A digestive draft of this manuscript. β-glucosidase from the salivary glands of the termite, Neotermes koshunensis (Shiraki): distribution, Reference characterization and isolation of its precursor cDNA by 5′- and 3′-RACE amplifications with degenerate primers. Abe, T. (1989) Ecology of Termites (in Japanese). University Insect Biochem. Mol. 32: 1681–1689. of Tokyo Press, Tokyo. Yasuda, I., Y. Nakasone, K. Kinjo and S. Yaga (2000) Ikehara, S. (1966) Distribution of termites in the Ryukyu Morphology and distribution of termites in Ryukyu Archipelago. Bull. Arts & Sci. Div., Ryukyu Univ. Math. & Islands and North and South Daito Islands (in Japanese). Nat. Sci. 9: 49–178. Jpn. J. Entomol. New series 3:139–156. Iwata, R. (2006) The Most Recent Status of Termite

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亜熱帯性乾材シロアリであるコウシュンシロアリの沖縄島における分布および土壌特性との関連性

杉尾幸司 1）・宮国泰史 2）

1) 琉球大学大学院教育学研究科

2) 琉球大学理学部物質地球科学科

熱帯性乾材シロアリの一種であるコウシュンシロアリについて，分布の北限地域と思われる沖縄島中南部での詳 細な分布調査を実施した．その結果，調査した 257 地点中 115 地点で営巣を確認した．北緯 26°25′00″（うる ま市）以北では本種の生息が確認できず，同付近が本種の北限であることが明らかになった．一方で，沖縄島の南 端にも本種が分布しない地域が見られた．そこで，本種の分布域に見られる土壌の分布と比較した結果，島尻マー

ジおよびジャーガルの分布と関連があることが示唆された．

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