橋本 佳明

The genus Utivarachna Kishida, 1940 currently comprises 23 species, with eight described from Borneo. We examined the type materials of the Bornean species, except for U. fukasawana Kishida, 1940, as well as newly collected specimens. As a result, we describe a new species, Utivarachna itiokai sp. nov., which belongs to the dusun-group. We also provide the first description of the female of Utivarachna ichneumon and redescribe the known Utivarachna species of Borneo.

Abstract Solenopsis invicta Buren (Hymenoptera: Formicidae; red imported fire ant) is an invasive species in several parts of the world. A major contributor to the spread of S. invicta is infested shipping containers. The vapor of allyl isothiocyanate (AITC), a naturally occurring organosulfur compound, is highly toxic to S. invicta; however, AITC is highly volatile. Microencapsulation of AITC in polyethylene (PE) resin slows the release of AITC, making it a potentially useful material for preventing S. invicta infestations. Here, we examined the efficacy of AITC microencapsulated in PE (mAITC) as a repellent against S. invicta infestation of cardboard boxes, a common containerized cargo. Using baited cardboard boxes, we found that the number of S. invicta individuals entering boxes containing an mAITC sheet was significantly less than that entering boxes without an mAITC sheet. When a PE cover, which is often used to protect carboard boxes during shipping, was used, vapor concentrations of AITC inside the boxes were increased and the number of S. invicta individuals entering the boxes was reduced almost to zero. These findings indicate that mAITC sheeting, especially in combination with a PE cover, is a promising material for the protection of containerized cardboard-box cargo against S. invicta infestation.

<title>Abstract</title> Accurate morphological ant mimicry by <italic>Myrmarachne</italic> jumping spiders confers strong protective benefits against predators. However, it has been hypothesized that the slender and constricted ant-like appearance imposes costs on the hunting ability because their jumping power to capture prey is obtained from hydraulic pressure in their bodies. This hypothesis remains to be sufficiently investigated. We compared the jumping and prey-capture abilities of seven <italic>Myrmarachne</italic> species and non-myrmecomorphic salticids collected from tropical forests in Malaysian Borneo and northeastern Thailand. We found that the mimics had significantly reduced abilities compared with the non-mimics. The analysis using geometric morphometric techniques revealed that the reduced abilities were strongly associated with the morphological traits for ant mimicry and relatively lower abilities were found in <italic>Myrmarachne</italic> species with a more narrowed form. These results support the hypothesis that the jumping ability to capture prey is constrained by the morphological mimicry and provide a new insight into understanding the evolutionary costs of accurate mimicry.

This study presents a species inventory of sap beetles (Coleoptera: Nitidulidae), together with descriptions of their habitat types, in lowland tropical rainforests in the middle reaches of the Baram River Basin, Borneo (Sarawak, Malaysia). Thirty-two nitidulid species belonging to 14 genera from six subfamilies were collected by banana-baited traps. There was no significant difference in species richness, abundance, diversity, or species composition between the primary and secondary forests, with 13 species being shared.

竹筒トラップを用いた管住性ハチ類の調査では、営巣ハチ類とそれらに寄生する天敵類からなる被食者_-_捕食者系を同時に把握することができるという利点がある。このような栄養段階の異なる生物群の種多様性に景観構造がどのように影響しているかを理解することは、保全をすすめていく上で重要だと思われる。ここでは、寄生者の種多様性や種構成が、さまざまな環境要素を含む景観構造とそのホストである管住性ハチ類の種多様性や個体数にどのように影響を受けているかを検討する。調査は、兵庫県武庫川流域を対象に、合計41地点の森林環境を選び、管住性ハチ類を誘引、営巣させる竹筒トラップを設置した。トラップは内径の異なる竹筒とヨシ20本からなり、1地点あたり5基ずつ2002年4-5月に設置し、同年11-12月に回収した。その結果、得られた24種の管住性ハチ類のうち11種から、ハエ目、ハチ目、コウチュウ目、ネジレバネ目に属する16種の寄生者が出現した。ホストあたりの寄生者の種数と寄生率は、それぞれ平均2.3種（レンジ0‐5）と10.9％（レンジ0‐30.0）だった。なかでも、オオフタオビドロバチは寄生者5種、寄生率14.6％、オオハキリバチは4種、23.0％と多くの寄生を受けていた。地点あたりの寄生者の種数は平均2.3種（レンジ0‐6）、寄生率は8.8％（レンジ0‐30.6）で、地域でみると種数が多く、寄生率の高い地点はおもに中流域にみられた。地点あたりの寄生者の種数は、ホストである管住性ハチ類の種数やそのセル数と有意な正の相関があった。しかし、調査地点の森林面積とは有意な相関はなかった。これらホストと寄生者が環境構造にどのように影響を受けているかについて、GISを用いた分析結果をふまえて報告する。

開発事業による生物群集への影響を評価またはモニタリングする簡便な方法を開発する目的で，軽井沢町に建設中であったゴルフ場の敷地内とその周辺の断片化された森林内に竹筒トラップを設置し，そこに営巣する管住性ハチ類とそのサンプリング効率を調べた．その結果，営巣数が多かったのは，クワヤマギングチバチ(Rhopalum kuwayamai nikkoense)，ヒメベッコウ(Auplopus sp.)，ヒゲベッコウ(Dipogon sp.)，フタスジスズバチ(Discoelius japonicus)，ヒメジガバチモドキ(Trypoxylon fronticorne japonense)，シブヤスジドロバチ(Ancistrocerus trifasciatus shibuyai)などであった．営巣率の高かった地点では営巣した種類数も多かった．またトラップの形状で，筒を円筒形に多数たばねた「バンドル式」トラップよりも少数の筒を垂直方向にすだれ状につないだ「直列式」トラップをもちいた方が，ハチの種類数・筒の利用率ともに高かった．一部のハチ類はゴルフ場の土地利用計画における2つの「生態系保全ゾーン」から外れた区域でのみ記録された．

In a Bornean rain forest, we conducted food preference tests with 11 arboreal and 8 ground ant species (26 colonies), which belonged to the genera Leptogenys, Odontoponera, Gnamptogenys, Aenictus, Cataulacus, Crematogater, Dolichoderus, Oecophylla, Camponotus, and Polyrhachis. Three types of food (honey solution, cheese and dead insect) were offered to foraging ants on trail. In five species, solid particles carried by returning workers were picked up near the nest entrance, and identified in the laboratory. Food preference tests indicated that all arboreal ants except Crematogaster sp. 2, which was a resident of Macaranga winkleri trees, accepted soild protein food (cheese and dead insects). Observations at the nest entrance, however, showed that animal items were scarcely or never carried to the nest. In at least some species, insects offered to foraging workers were not carried to the nest, but sucked of their body fluid at the sites where they were placed. In all the ground ants studied, including Aenictus spp., the acceptance of honey solutions was observed.

The skeletomusculature of the anterior abdominal segments in Aculeata was examined to discuss the relationships among Formicidae, Vespidae (s.l.) and Scoliidae, and phylogeny among Formicidae. On the basis of ground plan for Aculeata hypothesized, the present study indicated 3 types of apomorphic states associated with the formation of an additional petiole. The abdominal characters showed that Vespidae is more closely related to Formicidae than to Scoliidae. The tiphiid-like abdominal appearance of Amblyoponini may be secondary modification for increasing the length of tergal muscles. A close relationship between the ponerine tribe Ectatommini and Myrmicinae was proposed in the present study, because among the aculeates these formicid groups alone had a lobe for attachment of tergal muscles developed on the pretergum of the third segment.