Annual Fluctuation and Seasonal Falling Pattern of Mature Acorns of the Beech Family and a Survey of Their Acorn- Infesting Insect Fauna on Subtropical Okinawa Island

TROPICS Vol. 18 (4) Issued April 30, 2010

Annual fluctuation and seasonal falling pattern of mature acorns of the beech family and a survey of their acorn- infesting insect fauna on subtropical Okinawa Island

1 2 3 4 5 Kenta TERUYA , Takakazu SHINZATO , Kazuhiko KINJO , Takeshi SASAKI and Toshio NAKAO

1The United Graduate School of Agricultural Sciences, Kagoshima University, Faculty of Agriculture, University of the Ryukyus, 903－0213 Okinawa, Japan. 2Subtorpical Field Science Center, Faculty of Agriculture, University of the Ryukyus, 903-0213 Okinawa, Japan 3Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukyus, 903-0213 Okinawa, Japan 4University Museum, University of the Ryukyus, 903-0213 Okinawa, Japan 5Department of Biological Production and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, 889－2192 Miyazaki, Japan. *Corresponding author, Tel & Fax: 098-946-1259, E-mail: [email protected]

ABSTRACT A survey of the number of fallen cardamomi, P. graniceps, P. variabilis , and N. acorns from trees of three species in the beech biceratala on Okinawa Island. Additionally, there family (Fagaceae; Lithocarpus edulis, Castanopsis are more species in the post-dispersal acorn- sieboldii, Quercus miyagii) and the insects that eat feeding guild (PAF guild) than in the mature acorn- these acorns was conducted on subtropical feeding guild (MAF guild), and it is inferred that Okinawa Island between 2000 and 2005. The this guild difference represents a difference largest number of L. edulis acorns fell in 2001, between subtropical Okinawa Island and the whereas only a few acorns fell in 2005, and there temperate zone. was little annual variation in the other years. The acorn production of C. sieboldii was repeatedly Key words: Acorn-infested insect fauna, synchronized and abundant, with large numbers of Castanopsis , Fagaceae, Lithocarpus , Quercus , fallen acorns in 2000 and 2003. Although Q. Seasonal falling pattern, Subtropical Okinawa miyagii produced large numbers of fallen acorns in Island 2000 and 2005, none were collected in 2002 and 2004. The years of maximum production of mature fallen acorns did not coincide among the three INTRODUCTION species during the 6-year study period. Eleven Beech trees, which are dominant in cool temperate species of acorn-infesting insects were confirmed: regions, have been well studied (Kamitani, 1986; Yasaka five coleopterans, three lepidopterans, two et al. 2001). Many temperate Japanese species of the hymenopterans, and one dipteran. Curculio beech family (Fagaceae) exhibit masting behavior hilgendorfi, Poecilips cardamomi, P. graniceps, and (Hashizume and Yamamoto, 1974; Kanazawa, 1975, 1982; P. variabilis damaged acorns of all three tree Saito et al. 1988; Ohkubo et al. 1989; Imada et al. 1990; species, whereas P. advena damaged only C . Mizui, 1991; Takeda, 1992; Yamashita, 1994; Terazawa et sieboldii and Q . miyagii acorns. Neoblastobasis al. 1995; Sone et al. 1996, 2002; Ubukata et al. 2000; Maeto biceratala damaged C. sieboldii and Q. miyagii and Ozaki, 2003). Acorns of the beech family are acorns, but Camptomastyx sp. and Tortricidae damaged by coleopteran and lepidopteran larvae (e.g., (Olethreutinae) sp. damaged only those of C. Kanazawa and Nishikata, 1976; Miguchi and Maruyama, sieboldii. Cynipidae sp. 1 damaged L. edulis and 1984; Miguchi, 1996; Igarashi and Kamata, 1997) and are Cynipidae sp. 2 damaged Q. miyagii , whereas important as a food resource in forest ecosystems. Tipulidae sp. damaged L. edulis and Q. miyagii. According to Terazawa and Koyama (2008), 35 insect This study is the first to document the presence of P. species damage acorns and are found in large number in 232 Kenta TERUYA, Takakazu SHINZATO, Kazuhiko KINJO, Takeshi SASAKI and Toshio NAKAO

Fig. 1. Location of the study stands on Okinawa Island.

temperate regions. Among them are insects specializing regeneration. They confirmed the presence of eight on Fagaceae, including seven lepidopterans and two species of acorn-infesting insects on Quercus serrata, Q. dipterans. Generalists include 25 lepidopterans and one glauca, Q. myrsinifolia, and Lithocarpus edulis, which all hymenopteran. Families of acorn-infesting insects north live in the same zone. The acorn-infesting insect Kobuzo of the temperate regions of Japan include Attelabidae, rectirostris damaged acorns of all four tree species. Curculionidae, Scolytidae, Cynipidae, Tortricidae, Fukumoto (2000) maintained that damage by acorn- Noctuidae, and Tipulidae (Maeto, 1993a, 1995; Ueda et al. infesting insects is a major cause of mature acorn 1992, 1993; Ueda, 1996, 2000a, b, c; Ueda and Osumi, mortality, and Maeto (1993b) reported a relationship 2003; Fukumoto, 2000; Fukumoto and Kajimura, 2000a, b, between the quantity of acorn production and rate of 2001). Damage to the genus Quercus from acorn-infesting insect damage. Thus, annual fluctuations in acorn insects occurs worldwide, with Attelabidae, Curculionidae, production appear to be closely related to the rate of Tortricidae, and Cynipidae found in both the tropics and damage by acorn-infesting insects and the number of the Mediterranean region, which is climatically similar to sound acorns remaining. the subtropics (Branco et al. 2002; Leiva and Fernández- The Ryukyu Islands, which lie within the subtropical Alés 2005; Bonal et al. 2007; Espelta et al. 2008; Muñoz forest zone, are home to six species of Fagaceae. Of and Bonal, 2008). Few studies have investigated damage these, Castanopsis sieboldii and L. edulis are at the to Fagaceae acorns from acorn-infesting insects in the southernmost limit of their natural distributions, and Q. subtropics, tropics, or Mediterranean regions. The annual miyagii is endemic. Curculio hilgendorfi, a dominant fluctuation and seasonal falling pattern of mature insect in the northern forests of Okinawa Island, eats C. Fagaceae acorns in subtropical zones, as well as sieboldii acorns (Morimoto, 1981), but other insects that fluctuations in the populations of the insects that eat damage these acorns are not known, and no insects that them, are thus important areas of research. damage L. edulis or Q. miyagii have been identified. Ueda et al. (1992) stressed the importance of In this study, we investigated the acorn-infesting investigating the relationship between seeds and their insect fauna, annual acorn production, rate of damage, predatory insect fauna in studies of natural tree and number of surviving sound acorns in the subtropical Mature Fagaceae acorns and acorn-infested insects of Okinawa Island 233 forests of the Ryukyu Islands by examining annual is mountain valleys. fluctuations in the acorn production of C. sieboldii, L. edulis, and Q. miyagii and the insects that eat these Numbers of fallen acorns acorns. Two circular seed traps, 1 m2 each, were placed beneath the canopy of each surveyed tree (total number of traps: L. edulis, 10; C. sieboldii, 12; Q. miyagii, 10) to collect fallen STUDY AREA AND METHODS flower spikes and acorns. The survey was conducted at the following three sites The survey was conducted between 2000 and 2005. beginning in April 2000: a mountain site on Nishime-dake In 2000, two surveys were conducted each month, at the (site A: 26°48’N, 128°16’E, 351 m above sea level (asl); middle and the end of the month, to investigate the acorn a pedestrian path 1.5 m in width traverses this site); and production period. Based on the results of the 2000 Yona Field, a study site of the Faculty of Agriculture of survey, the 2001-2005 surveys were conducted twice the University of the Ryukyus (76 Hayashi group, sites B monthly at the middle and end of each month from and C: 26°44’N, 128°14’E, 318 m asl, and 26°44’N, September to January, the period when most mature 128 ° 13’E, 339 m asl, respectively) in the village of acorns fell, and once a month at the end of the month Kunigami in northern Okinawa Island (Fig. 1). Soils at from February to August. the sites were neutral to acidic Kunigami Maaji (dry red- Female flower spikes and acorns were classified as yellow soil). flower spikes when the major and minor axes were about Sample plots for the vegetation survey were 2 mm long, and as acorns when they were more than 2 established at each site (site A, 20 × 20 m; site B, 35 × mm long. Following Matsuda (1982) and Ueda et al. 35 m; site C, 15 × 25 m). We recorded tree species, (1992), acorns were further divided into immature and diameter at breast height (DBH), and heights of trees mature acorns. Because the pericarp and ovary of Q. with DBH more than 3.0 cm. The stand densities in the miyagii grow together, we classified Q. miyagii acorns as plots were 6125, 2245, and 3733 trees per hectare at sites mature if the major and minor axes were more than 2 cm A, B, and C, respectively. Canopy trees more than 10 m long and as immature if the axes were less than 2 cm tall were C. sieboldii, L. edulis, Schima wallichii ssp. long. Because immature acorns showed almost no liukiuensis, and Diospyros morrisiana at site A; C. sieboldii, damage from acorn-infesting insects in the 2000 survey, Q. miyagii, Cinnamomum pseudo-pedunculatum, Litsea we only analyzed mature acorns in the later surveys. acuminata, Neolitsea sericea, Persea thunbergii, Distylium When the trunks of two L. edulis trees and one C. sieboldii racemosum, Ilex ficoidea, Ilex integra, Meliosma tree were broken in a 2004 typhoon, we substituted other simplicifolia ssp. rigida, Meliosma lepidota ssp. squmulata, trees and continued with the survey. Elaeocarpus japonicus, Camellia japonica, S. wallichii ssp. 2. Acorn-infesting insects liukiuensis, Schefflera octophylla, Ardisia sieboldi, and D. Each mature acorn collected from the seed traps between morrisiana at site B; and C. sieboldii, Q. miyagii, Persea 2000 and 2005 was kept in a separate box. After about 2 japonica, P. thunbergii, E. japonicus, S. wallichii ssp. months, they were cracked, and acorn-infesting insects liukiuensis, and Styrax japonica at site C. The tree species were identified. Mature acorns were classified as either at each site in decreasing order of abundance were C. sound or damaged. Damages were classified as stemming sieboldii, L. edulis, and S. octophylla at site A; D. from C. hilgendorfi, Scolytidae, Lepidoptera, Cynipidae, racemosum, C. sieboldii, and C. lutchuensis at site B; and S. other insects, humification, or a mammal or bird. The japonicus, C. sieboldi, and Q. miyagii at site C (Appendices damage ratio was expressed as the number of damaged 1, 2, and 3, respectively). acorns to the number of mature acorns per month. As Five L. edulis trees at site A, six C. sieboldii trees at some acorn-infesting insects invade acorns on the forest site B, and five Q. miyagii trees, three at site B and two at floor (Ueda et al., 1993), we also randomly collected site C, were chosen for the study. The average DBH and acorns from the forest floor, and checked for and height of the trees were as follows: L. edulis, 9.8 ± 3.5 cm identified any acorn-infesting insects. DBH, 7.9 ± 1.8 m height; C. sieboldii, 39.9 ± 10.3 cm Larvae of insects found in the acorns were reared DBH, 13.6 ± 4.8 m height; and Q. miyagii, 55.6 ± 13.3 and we identified the adults, except for Scolytidae and cm DBH, 16.9 ± 1.9 m height. Generally, the habitat of L. Lepidoptera, which were identified by specialists. We edulis is mountain ridges, the habitat of C. sieboldii is collected only a few larvae of Hymenoptera and Diptera; mountainsides to mountain valleys, and that of Q. miyagii they did not reach adulthood, and were not identified. 234 Kenta TERUYA, Takakazu SHINZATO, Kazuhiko KINJO, Takeshi SASAKI and Toshio NAKAO

descending order of acorn production per individual was RESULTS C. sieboldii, L. edulis, and Q. miyagii, which corresponded Figure 2 shows the annual fluctuation in the number of to the descending order of acorn size. mature acorns of L. edulis that fell into the seed traps; 360 Monthly fluctuations in the numbers of fallen mature were collected in 2001 and approximately 10 in 2005. In acorns of the three species from 2000 to 2005 are shown the other years, the number of collected acorns ranged in Figure 6. The earliest fall of mature acorns came from L. from about 100 to 180. edulis, starting in June, peaking in September, and Figure 3 shows the annual fluctuation in the number continuing until November. Castanopsis sieboldii acorns of mature acorns of C. sieboldii collected from the seed began to fall in September, peaked in November, and traps. Approximately 800 fallen acorns were collected in continued until January of the following year. Quercus 2000 and 300 in 2003, but fewer than 25 in the other years. miyagii acorns commenced falling in September, peaked Large synchronized fluctuations in acorn production in November, and continued until December. Mature occurred among years and among individual trees. acorns of the three species fell over a 4-5-month period. Figure 4 shows the annual fluctuation in the number Lithocarpus edulis began dropping acorns 2 months of fallen mature acorns of Q. miyagii collected from the earlier and stopped 1-2 months earlier than C. sieboldii seed traps. In all, 90 acorns were collected in 2005, about and Q. miyagii, which dropped acorns at more or less the 60 in 2000, 2-5 in 2001 and 2003, and none in 2002 and same time. 2004. The number of Q. miyagii acorns, which were Five coleopterans, three lepidopterans, two larger than those of the other two species, was low in all hymenopterans, and one dipteran were collected from years. As with C. sieboldii, large fluctuations were damaged acorns, as shown in Table 1. Four coleopterans observed in the number of acorns that fell both among (C. hilgendorfi, P. cardamomi, P. graniceps, and P. years and from individual trees. As seen in Figures 2, 3, variabilis), one hymenopteran (Cynipidae sp. 1), and one and 4, years with the highest number of fallen acorns did dipteran (Tipulidae sp.); no lepidopterans damaged L. not coincide among the three species during the 6-year edulis acorns. Five coleopterans (C. hilgendorfi, P. study period. cardamomi, P. graniceps, P. advena, and P. variabilis) and Figure 5 shows the mean value of total acorn three lepidopterans [N. biceratala, Camptomastyx sp., and production per individual over the six study years. The Tortricidae (Olethreutinae) sp.] damaged C. sieboldii; we

Fig. 2. Annual changes in the quantity of fallen mature acorns of Lithocarpus edulis. Mature Fagaceae acorns and acorn-infested insects of Okinawa Island 235

Fig. 3. Annual changes in the quantity of fallen mature acorns of Castanopsis sieboldii.

Fig. 4. Annual changes in the quantity of fallen mature acorns of Quercus miyagii. ＊2002 and 2004 is none matue acorn 236 Kenta TERUYA, Takakazu SHINZATO, Kazuhiko KINJO, Takeshi SASAKI and Toshio NAKAO

Fig. 5. Mean value of total acorn production per tree over the six study years. * average ± S.D. (Min – Max)

Fig. 6. Mature acorn fall by month per m2 from 2000 to 2005.

did not conﬁrm damage by hymenopterans or dipterans. variabilis), one lepidopteran (N. biceratala), one Quercus miyagii was damaged by five coleopterans (C. hymenopteran (Cynipidae sp. 2), and one dipteran hilgendorfi, P. cardamomi, P. graniceps, P. advena, and P. (Tipulidae sp.). Mature Fagaceae acorns and acorn-infested insects of Okinawa Island 237

Table 1. List of the acorn-infested insect species and the Fagaceae species they affected.

Figures 7, 8, and 9 show the numbers and relative by C. hilgendorfi was a major factor in the death of mature frequency of insect-damaged mature acorns collected Q. miyagii acorns. from the seed traps. In each figure, (a) indicates the Figure 10 shows the seasonal falling patterns of number of mature acorns damaged by acorn-infesting sound acorns, insect-infested acorns, and acorns injured insects, and (b) shows annual changes in insect relative by vertebrates (mammals or birds) in 2000. The number frequency. For conﬁdence, results are excluded from (b) of L. edulis acorns damaged by C. hilgendorfi or Cynipidae for years with 30 or fewer fully mature acorns. The most sp. 1 and the number of sound acorns both peaked in abundant insect infesting L. edulis was Cynipidae sp. 1 in October, whereas mammal or bird damage peaked in 2000-2005 (Fig. 7), which had a relative frequency of July. The numbers of both C. sieboldi acorns damaged by about 90% from 2000 to 2002 and nearly 100% from 2003 to C. hilgendorfi or lepidopterans and sound acorns peaked 2004. The relative frequencies of C. hilgendorfi and in November. Mammal or bird damage was observed Scolytidae were very low, with a maximum frequency of from July to February. Both the numbers of Q. miyagii 9.6% for C. hilgendorfi in 2002 and 5.0% for Scolytidae in acorns damaged by C. hilgendorfi or Cynipidae sp 2 and 2001. Damage by Cynipidae sp. 1 was a major factor in of sound acorns peaked in November, as they did for C. the death of mature L. edulis acorns. sieboldii. Mammal or bird damage was seen in July and Curculio hilgendorfi was the most abundant insect September. infecting on C. sieboldii (Fig. 8), with a relative frequency of about 90% in 2000 and 2003, which were the years when the largest number of mature acorns were DISCUSSION produced. The relative frequencies of lepidopterans and Patterns of acorn production by L. edulis in temperate Scolytidae were low, with a maximum frequency of 6.3% zones include fruit maturation every other year or the in 2000 for Lepidoptera and 5.3% in 2003 for Scolytidae. phenomenon in which production exceeds the mean Damage by C. hilgendorfi was a major factor in the death value every 5 years (Katsuta et al. 1998), and the of mature C. sieboldii acorns. frequency of lean crops is markedly high. In the present The most abundant acorn-infesting insect in Q. survey, abundant acorn production lasting 2 to 5 years miyagii acorns was also C. hilgendorfi (Fig. 9), which had suggested the life-history strategy of L. edulis in a relative frequency of about 71% in 2000 and about 83% in subtropical zones may differ greatly from that in 2005, which were the only years when considerable temperate zones. In particular, more continuous acorn numbers of mature acorns were produced by Q. miyagii. production over years should be examined from the Similarly, the relative frequency of Cynipidae sp. 2 varied viewpoint of both the variability or stability of the from 18% to 25%, and the ﬂuctuation was large. Damage environment and productivity under the subtropical 238 Kenta TERUYA, Takakazu SHINZATO, Kazuhiko KINJO, Takeshi SASAKI and Toshio NAKAO

Fig. 7. Annual changes in the number of mature Lithocarpus edulis acorns in seed traps damaged by acorn- infested insects (a); relative frequency of acorn-infested insect species found in L. edulis acorns (b). Mature Fagaceae acorns and acorn-infested insects of Okinawa Island 239

Fig. 8. Annual changes in the number of mature Castanopsis sieboldii acorns in seed traps damaged by acorn-infested insects (a); relative frequency of acorn-infested insect species found in C. sieboldii acorns (b). 240 Kenta TERUYA, Takakazu SHINZATO, Kazuhiko KINJO, Takeshi SASAKI and Toshio NAKAO

Fig. 9. Annual changes in the number of mature Quercus miyagii acorns in seed traps damaged by acorn- infested insects (a); relative frequency of acorn-infested insect species found in Q. miyagii acorns (b) Mature Fagaceae acorns and acorn-infested insects of Okinawa Island 241 in 2000 .

Quercus miyagii

* Number of acorns per month is the total of numbers acorns collected each week.

Lithocarpus edulis , Castanopsis sieboldii Fig. 10 . Seasonal falling patterns of insect-infested and sound acorns of 242 Kenta TERUYA, Takakazu SHINZATO, Kazuhiko KINJO, Takeshi SASAKI and Toshio NAKAO climate. Although Katsuta et al. (1998) repor ted acorn-infesting insects. Each of the three tree species we alternating patterns of bumper crops and lean harvests studied has dominant acorn-infesting insects in years ever y 15 years, the extent and patterns of such when mature acorns are produced, but the insects never fluctuations over many years in subtropical zones should damaged all of the mature acorns produced (Figs. 6, 7, be elucidated in future studies. and 8). Sound acorns undamaged by acorn-infesting Katsuta et al. (1998) and Yamashita (1994) reported insects are likely the main contributors to natural noted that C. sieboldii acorn production fluctuates notably, regeneration. with no mature acorns produced in some years, but the Fukumoto (2000) reported a clear difference species produces yields every year on subtropical between the seed-infesting insect species of Q. variabilis Okinawa Island, irrespective of the production of acorns and Q. serrata during the period when damaged acorns (Fig 3 and 8). Continuous acorn production may fell. The periods when damaged acorns fell and when important for keeping populationa size of Curculio sound acorns fell differed by approximately 1 month hilgendorf. Further study of the relationship between among the three tree species on Okinawa Island (Fig. 9). acorn production and insect pests is clearly warranted. However, on Okinawa Island, the timing of insect The genus Quercus includes annual and cyclical fruit- infestations nearly coincide, except for infestations of bearing species; fruiting may be dependent on species Cynipidae (Fig. 9). and growing conditions (Katsuta et al. 1998). Annual Compared with Curculionidae in other regions, C. fluctuations of acorn production in Q. miyagii are quite hilgendorfi on subtropical Okinawa Island has a higher large, often with no fallen acorns (Fig 4). Lack of infestation rate and infests more tree species. This may production is rare in other Quercus species (Katsuta et al. be because it is specialized to the Fagaceae in Okinawa 1998), but the reason for low production in Q. miyagii in Island; this assumption needs further investigation, as some years remains unclear. It is postulated that Q. does the phenology of acorn-infesting insect species. miyagii shows a pattern of acorn production that differs The relationships between the three main tree from that of other tree species in the temperate zone. It is species and acorn-infesting insects differed (Figs. 6, 7, therefore imperative to conduct comparative studies by and 8), Cynipidae sp. 1 was the dominant predator of L. collecting data on the high and low yields of each tree edulis acorns throughout the year, but did not damage the species. other two tree species. Likewise, C. hilgendorfi was the Takushi (1983) reported that acorns of L. edulis were dominant acorn-infesting insect to damage C. sieboldii 18-26 mm long and 12-17 mm in diameter; C. sieboldii acorns; the rate of damage to this tree by other acorn- acorns were 12-15 mm long and 9-11 mm in diameter; and infesting insects was low. Quercus miyagii suffered a high Q. miyagii acorns were 22-30 mm long and 20-28 mm in rate of damage from C. hilgendorfi and Cynipidae sp. 2, diameter. The present survey results indicated that the but Cynipidae sp. 2 did not damage the other two tree mean value of total acorn production decreased as acorn species. Based on these results, we consider Cynipidae size decreased (Fig. 5). Previous studies have pointed sp. 1 and Cynipidae sp. 2 to be specialists on L. edulis and out a trade-off relationship between size and number of Q. miyagii, respectively. Curculio hilgendorfi is a seeds (Harper et al. 1970; Stebbins, 1971; Harper, 1977). generalist on all three tree species, but inflicted the Therefore, we extrapolate that the maximum number of highest rate of damage on C. sieboldii, followed by Q. dropped acorns differs among L. edulis, C. sieboldii, and Q. miyagii and L. edulis. miyagii due to their acorn sizes. In Table 2, the acorn-infesting insect species are Poecilips cardamomi inhabits temperate to tropical classified into four guilds based on infestation stage zones; P. variabilis, tropical zones; and P. graniceps, Asia, (Fukumoto, 2000; Kamata, 2005). Insects were classified including Japan (Browne, 1961; Steven, 1992; Fukumoto into a pistillate flower-feeding guild (PFF guild), an and Kajimura, 1999). Neoblastobasis biceratala has been immature acorn-feeding guild (IAF guild), a mature recorded from Honshu, Japan, and Prim, Korea (Park, acorn-feeding guild (MAF guild), and a post-dispersal 1989; Sinev, 1999; Ueda, 2000b). However, these four acorn-feeding guild (PAF guild). The estimated PFF guild species had not previously been recorded from Okinawa consisted of Cynipidae sp. 1 and sp. 2. The estimated Island (Azuma et al. 2002). Okinawa is currently the MAF guild included C. hilgendorfi, P. cardamomi, P. southern distribution limit of N. biceratala. graniceps, P. variabilis, and Olethreutinae sp. The PAF The number of mature acorns fluctuates annually, guild consisted of P. cardamomi, P. graniceps, P. advena, P. accompanied by fluctuations in the relative frequency of variabilis, N. biceratala, Camptomastyx sp., and Tipulidae Mature Fagaceae acorns and acorn-infested insects of Okinawa Island 243

Table 2. Acorn-infesting insect species of Lithocarpus edulis, Castanopsis sieboldii, Quercus miyagii on the basis of infestation stages.

sp. Note that both the MAF and PAF guilds included P. lepidopterans in this study; Mr. Akira Ueda of the cardamomi, P. graniceps, and P. variabilis. We did not ﬁnd Forestry and Forest Products Research Institute, who any species belonging to the IAF guild. identified Scolytidae and provided reference literature; Because Cynipidae that attack Q. serrata in Dr. Yoshitaka Sakamaki of Kagoshima University; and Dr. temperate zones belonged to the PFF guild, we assumed Jinbo Utsugi of Tokyo University, Faculty of Agriculture, that Cynipidae in Okinawa Island also belonged to the who provided reference literature on N. biceratala. We PFF guild. Curculionidae in temperate zones belong to also thank Dr. Tamotsu Nakandakari of University of the the MAF guild, the Curculionidae in the present study Ryukyus and Mr. Takatoshi Yukimaru, Ms. Sakura Ikadai, were considered part of the MAF guild. and other colleagues from our laboratory who helped The species in the estimated MAF guild observed with this study. commonly in L. edulis and Q. miyagii was P. cardamomi. The species in the estimated MAF guild that were seen only in C. sieboldii were P. graniceps, P. variabilis, and REFERENCES Olethreutinae sp. of Tortricidae. The species in the PAF Azuma, S., Yafuso, M., Kinjo, M., Hayashi, M., Kohama, guild that was seen only in Q. miyagii was P. cardamomi, T., Sasaki, T., Kimura, M. & Kawamura, F. 2002. whereas the PAF species observed only in C. sieboldii Check list of the insects of the Ryukyu Islands. In: was Camptomastyx sp. The species in the PAF guild Flora and Fauna of Okinawa, no. 1. 2nd ed. The observed commonly in L. edulis and Q. miyagii were P. Biological Society of Okinawa, Okinawa. 570 pp. (in graniceps, P. variabilis, and Tipulidae sp. The PAF species Japanese) seen commonly in C. sieboldii and Q. miyagii were P. Bonal, R., Muñoz, A. & Díaz, M. 2007. Satiation of advena and N. biceratala (Table 2). In the temperate predispersal seed predators: the importance of zone, C. sikkimensis and C. glandicolana infest trees at considering both plant and seed levels. Evolutionary the final stage of acorn production, whereas on Ecology, 21: 367-380. subtropical Okinawa Island, C. hilgendorfi was the only Branco, M., Branco, C., Merouani, H. & Almeida, M.H. acorn-infesting insect species in this guild, suggesting 2002. Germination success, survival and seedling that C. hilgendorfi strongly affects the acorn survivorship. vigour of Quercus suber acorns in relation to insect damage. Forest Ecology and Management, 166: ACKNOWLEDGMENTS We are grateful to Dr. Furumi 159-164. Komai of Osaka University of Arts, who identified the Browne, F.G. 1961. The biology of Malayan Scolytidae and 244 Kenta TERUYA, Takakazu SHINZATO, Kazuhiko KINJO, Takeshi SASAKI and Toshio NAKAO

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Received 16th Mar. 2009 Accepted 22nd Oct. 2009 Mature Fagaceae acorns and acorn-infested insects of Okinawa Island 247

Appendix 1. Number of individuals, DBH, and height of trees (DBH > 3.0 cm) in the vegetation plot (20 m × 20 m) of site A. 248 Kenta TERUYA, Takakazu SHINZATO, Kazuhiko KINJO, Takeshi SASAKI and Toshio NAKAO

Appendix 2. Number of individuals, DBH, and height of trees (DBH > 3.0 cm) in the vegetation plot (35 m × 35 m) of site B. Mature Fagaceae acorns and acorn-infested insects of Okinawa Island 249

Appendix 3. Number of individuals, DBH, and height of trees (DBH > 3.0 cm) in the vegetation plot (15 m × 25 m) of site C.