Strongly Biased Sex Ratio in Cuckoo Wasp Chrysura Hirsuta (Hymenoptera: Chrysididae), a Parasitoid of the Mason Bee

Entomological Science (2011) doi:10.1111/j.1479-8298.2011.00500.x

SHORT COMMUNICATION

Strongly biased sex ratio in cuckoo wasp Chrysura hirsuta (Hymenoptera: Chrysididae), a parasitoid of the mason bee

Osmia orientalisens_497 1..3

Tomoyuki YOKOI1, Takuto HIROOKA2,5, Takeshi TERADA3,5, Shusaku SUGIMOTO4,5, Mayumi TAMARU5, Sachiko SATOH5 and Ikuo KANDORI5 1Laboratory of Insect Ecology, Graduate School of Environmental Sciences, Okayama University, Okayama, 2Entomological Laboratory, Faculty of Agriculture, Kyushu University, Fukuoka, 3Entomological Laboratory, Graduate School of Agriculture, Kagoshima University, Kagoshima, 4Graduate School of Agriculture, University of the Ryukyus, Okinawa and 5Laboratory of Entomology, Faculty of Agriculture, Kinki University, Nara, Japan

Abstract We examined the rate of parasitism and sex ratio of the cuckoo wasp Chrysura hirsuta (Gerstaecker) (Hymenoptera: Chrysididae) that emerged from nests of the mason bee Osmia orientalis Benoist (Hymenoptera: Megachilidae) in Nara, Japan. Nests of O. orientalis were found in empty shells of two snail species, Satsuma japonica (Pfeiffer) and Euhadra amaliae (Kobelt). The percentage of parasitism by cuckoo wasps per all collected cocoons tended to be high (20–50%) even though interannual variation and the average number of cocoons per nest did not differ across snail shell species within each year. Our results from three years of observation, combined with previous reports, showed that the adult sex ratio of C. hirsuta was strongly female-biased, which suggests that the species reproduces by thelytokous parthenogenesis. Key words: Megachilidae, nest, parasitism, snail shell, thelytokous parthenogenesis.

Host preference and offspring sex ratio are important species to the previously described seven species (Maeta factors for understanding the basic life cycle and behav- 1978; Maeta & Miyanaga 1999). However, C. hirsuta ior of chrysidid wasps. All known cuckoo wasps are only parasitizes Osmia orientalis Benoist (Maeta 1978, either parasitoids or cleptoparasites of a broad range of 1980). Osmia orientalis nests in empty snail shells and insects. Almost all of the species in the subfamily Chry- other Osmia bees nest in pre-existing cavities in dead sidinae are nest parasites of bees or wasps although the wood (Shibuya 1939; Maeta 1978, 1980). tribe chrysidini attacks not only megachilid bees but also Certain aspects of the basic life history and parasitic wasps of Eumenidae and even Monema ﬂavescens behavior of C. hirsuta have been reported (Shibuya Walker (Lepidoptera: Limacodidae) (Kimsey & Bohart 1939; Matsumoto 2009; Yokoi et al. 2010). Osmia ori- 1990; Terayama et al. 2010). In Chrysidini, Chrysura entalis females oviposit in cells in the empty shells of hirsuta (Gerstaecker) is a known parasitoid of mega- several snail species. Chrysura hirsuta females then chilid bees in Europe (Berland & Bernard 1938). In sneak into the nest and lay eggs in each cell while the Japan, the bee genus Osmia (Hymenoptera: Megachil- female O. orientalis is absent. The ﬁrst instar larva waits idae) comprises eight species (Ikudome 2010; Murakami for the host to pupate following its last larval instar, and & Ikudome 2011) following the addition of a new then begins sucking the host’s blood (Shibuya 1939; Matsumoto 2009). Two or more C. hirsuta females will lay eggs in one host cell although only one individual Correspondence: Tomoyuki Yokoi, Laboratory of Insect will emerge as an adult from each cocoon (Shibuya Ecology, Graduate School of Environmental Sciences, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, 1939). Thus, strong resource competition occurs among Okayama 700-8530, Japan. larvae as they use a single host. Although data regarding Email: [email protected] the parasitism rate of C. hirsuta has previously been Received 1 June 2011; accepted 25 September 2011. reported (Shibuya 1939; Iwata 1978), the adult sex ratio

Table 1 Percentage of parasitism and the sex ratio of Chrysura hirsuta collected from snail shells occupied by Osmia orientalis on the Nara campus March 2008 December 2008 December 2009 Land snail species S. japonica E. amaliae S. japonica E. amaliae S. japonica E. amaliae Number of shells collected from 9 46 69 133 214 352 the ﬁeld Number of shells nested by 0 12 5 37 2 42 O. orientalis Percentage of parasitism by – 100% (12/12) 20% (1/5) 18.9% (7/37) 50% (1/2) 16.7% (7/42) C. hirsuta per nested shells Average number (Ϯ SE) of – 3.08 Ϯ 0.47 3† 3.14 Ϯ 0.91 1† 1.57 Ϯ 0.30 C. hirsuta cocoons per nest Percentage of parasitism by – 46.3% (37/80) 50.0% (3/6) 43.1% (22/51) 20.0% (1/5) 26.2% (11/42) C. hirsuta per all collected cocoon Female sex ratio of C. hirsuta – 1.00 (37/37) 1.00 (3/3) 1.00 (22/22) 1.00 (1/1) 1.00 (11/11) †SE not applicable, as only one shell was conﬁrmed to be parasitized. –, not applicable.

of C. hirsuta individuals that emerge from each shell is single C. hirsuta adult was present in each O. orientalis unknown. In this study, we conducted field research to cell. The percentage of parasitism by C. hirsuta per investigate the adult sex ratio of C. hirsuta and the rate nested shells varied across years. However, the average of parasitism on O. orientalis. number of C. hirsuta cocoons did not differ between We conducted field work on the Nara campus of shell species within each year. The percentage of para- Kinki University, Nakamachi, Nara, Japan (34°40′N, sitism by cuckoo wasp per all collected cocoons was 135°43′E). On the campus, many insect pollinators visit lower in 2009 than in 2008. The cuckoo wasp sex ratio native and introduced plant species throughout the year was strongly female-biased in every year (Table 1).We (Yokoi et al. 2008). We collected empty snail shells at did not find any males in nested shells, nor could we three locations on the campus in March 2008. After confirm the species within cells because of death or identifying the snail species, we checked them for empty developmental failure. Other samples of C. hirsuta that cocoons or adults of O. orientalis and C. hirsuta.We were collected in other districts in Japan also included found empty shells of three land snail species: Satsuma only females (Table 2). japonica (Pfeiffer), Euhadra amaliae (Kobelt) and Our investigation revealed that parasitism by C. hir- Acusta despecta sieboldiana (Pfeiffer). suta was consistently high at this study site. Iwata We conducted a field experiment by placing empty (1978) also briefly reported on parasitism by C. hirsuta; snail shells on the campus from April to May, 2008 and the percentage of parasitized shells was 31.3% (5/16) 2009. To provide nesting opportunities for O. orientalis, and 13.2% (14/106) of the O. orientalis cocoons col- we used empty shells from two snail species, S. japonica lected were parasitized. We suggest that host-specific and E. amaliae, which we had previously collected on parasitism causes a high rate of parasitism by C. hirsuta. the campus in March and washed. We re-collected the Very little is known about sex ratios in Chrysura popu- experimental snail shells in June and kept them at a lations or any other chrysidid species. In North America, constant temperature until December. We then checked the sex ratio of Chrysura kyrae Krombein, a parasitoid the number of O. orientalis and C. hirsuta cocoons in of Osmia lignaria lignaria Say, is female-biased (Krom- each shell. Detailed sampling methods can be found in bein 1963; Maeta 1988). However, the presence of Kandori et al. (2010). Sex discrimination of C. hirsuta C. kyrae males was confirmed but C. hirsuta males were was conducted by examining the shape of the tip of the not found. We hypothesize that C. hirsuta reproduces by abdomen and assessing the presence of an ovipositor. thelytokous parthenogenesis in Japan, caused by either a Except for March 2008, we found cocoons of both genetic mechanism or through host manipulation by O. orientalis and C. hirsuta in nested shells of the two symbiotic bacteria. Although the species also lives in land snail species (Table 1). The nesting rate of O. ori- Europe, there are, to our knowledge, no studies regard- entalis was higher in the larger shells of E. amaliae than ing sex ratio. Genetic analysis is needed to investigate in the smaller shells of S. japonica. We confirmed that a the mechanisms creating the strong female bias.

Table 2 Distribution and sex records for Chrysura hirsuta in Japan Number and sex of individuals collected District Collection site References 1 female Tohoku Tamugimata-Touge, Yamagata Pref. Itami (1981) 1 female Tachikawa-cho, Yamagata Pref. 2 females Kanto Nikko, Tochigi Pref. Fukuda (1968) 1 female Utsunomiya, Tochigi Pref. 1 female Toba, Tochigi Pref. 1 female Chubu Takagi-cho, Aichi Pref. Yamada (1971) 1 female Shikoku Hiragi, Kagawa Pref. Iwata (1978) 1 female Chugoku Niimi city, Okayama Pref. Matsumoto (2009) 1 female Mirasaka-cho, Hiroshima Pref. Nakamura & Haneda (1997) 1 female Kuchiwa-cho, Hiroshima Pref.

ACKNOWLEDGMENTS Maeta Y (1980) [Appendix of the nest structure of Osmia (Chalcosmia) orientalis Benoist.] Bulletin of Iwate Insect We greatly thank R. Matsumoto (Osaka Museum of Club 5, 1–4. (In Japanese.) Natural History) for advice on sex discrimination and Y. Maeta Y (1988) [Nest structure and natural enemies of Osmia Nakahara (Ryokusei Research Institute Inc.) for identi- lignaria lignaria SAY (Hymenoptera, Megachilidae)]. ﬁcation of land snails. Thanks also to members of the Chugoku Kontyu 2, 1–7. (In Japanese.) Laboratory of Entomology, Kinki University for inves- Maeta Y, Miyanaga R (1999) [Distributional records of the tigating and collecting snail shells in the ﬁeld. seven species of genus Osmia in Japan (Hymenoptera, Megachilidae)]. Bulletin of the Hoshizaki Green Founda- tion 3, 141–147. (In Japanese.) REFERENCES Matsumoto R (2009) [Osmia orientalis and Chrysura hirsuta (Gerstaecker) in Yata hill]. Hachi Kariudo 1, 1–3. (In Berland L, Bernard F (1938) Hyménoptères vespiformes. III. Japanese.) (Cleptidae, Chrysidae, Trigonalidae). Faune de France 34, Murakami K, Ikudome S (2011) [Biological notes on Osmia 1–145. (Pyrosmia) submicans recently found from Japan Fukuda N (1968) [From my insect collections]. The Life Study (Hymenoptera, Megachilidae)]. Konchu to Shizen 46, 12, 25–29. (In Japanese.) 27–29. (In Japanese.) Ikudome S (2010) Osmia (Pyrosmia) submicans Morawitz, a Nakamura S, Haneda Y (1997) [Distributional notes on wasps species new to Japan (Hymenoptera, Megachilidae). (Apocrita: Hymenoptera) from Hiroshima Prefecture]. Chugoku Konchu 24, 71–72. Miscellaneous Reports of Hiwa Museum for Natural Itami H (1981) [Three cuckoo wasps]. Hymenopterist’s Com- History 35, 31–48. (In Japanese with English summary.) munication 13, 1. (In Japanese.) Shibuya T (1939) [Habits of Osmia orientalis Benoist nesting Iwata K (1978) [Gazing at Insects for Fifty Years (II)]. Asahi in snail shells and its natural enemy, Chrysis (Holochrysis) Shimbun Publications, Tokyo. (In Japanese.) sp]. Mushi 12, 41–55. (In Japanese.) Kandori I, Tamaru M, Yokoi T (2010) [Nesting habits of a Terayama M, Suda H, Tano T, Murota T (2010) [The chrysi- pollinator: Osmia orientalis (Hymenoptera: Megachil- dine wasps of Japan: Flying jewels]. Gekkan-Mushi 472, idae)]. Japanese Journal of Applied Entomology and 2–15. (In Japanese.) Zoology 54, 77–84. (In Japanese with English summary.) Yamada H (1971) [Sphecidae and Chrysididae at Aichi prefec- Kimsey LS, Bohart RM (1990) The Chrysidid Wasps of the ture]. The Life Study 15, 34–37. (In Japanese.) World. Oxford Science Publications, New York. Yokoi T, Habe A, Kandori I, Sakuratani Y (2008) [Biodiversity Krombein KV (1963) A new Chrysura from Plummers Island, of insect pollinators in the Nara campus of Kinki Maryland (Hymenoptera, Chrysididae). Entomological University]. Memoirs of the Faculty of Agriculture of News 74, 149–152. Kinki University 41, 77–94. (In Japanese with English Maeta Y (1978) [Comparative studies on the biology of the summary.) bees of the genus Osmia of Japan, with special reference to Yokoi T, Terada T, Hirooka T (2010) [Overnight habit their management for pollination of crops (Hymenoptera: of a cuckoo wasp, Chrysura hirsuta (Gerstaecker) Megachilidae)]. Bulletin of the Tohoku National Agricul- (Hymenoptera, Chrysidae) in Nara city, Nara prefecture]. tural Experiment Station 57, 1–221. (In Japanese with Chugoku Kontyu 24, 73–74. (In Japanese with English English summary.) summary.)