汽水域に成立したヨシ群落に生息するヒヌマイトトンボと,隣接する淡水の放棄水田に出現したアオモンイトトンボおよびアジアイトトンボ,モートンイトトンボの卵および幼虫の塩分耐性を比較した.卵を0‰(蒸留水),5‰,10‰,15‰,20‰の濃度の塩水に入れ,4齢幼虫になるまで飼育した.どの種も高い塩分濃度で孵化率が低下し,アジアイトトンボとモートンイトトンボは20‰の塩分濃度で全く孵化しなかった.この2種は15‰における幼虫の生存率も低かった.一方ヒヌマイトトンボとアオモンイトトンボにおける塩分濃度に対する孵化率と幼虫の生存率の変化は,ほとんど同じで,この2種は汽水環境で十分生息できると考えられた.これらの結果から,ヒヌマイトトンボの保全を行うためには,幼虫の生息場所の塩分濃度の調節とともに,成虫の生息空間も考慮すべきであると指摘した.

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従来,近畿地方以西に分布していたムラサキツバメは,近年,関東地方のほぼ全域で発生している.現段階での本種の定着北限に近いと考えられる関東地方北部において,2002〜2003年に野外における発生経過と幼生期の捕食寄生者および随伴するアリ類について調査した.1.野外における成虫・卵・幼虫の個体数調査の結果から,茨城県つくば市では,本種は部分4化であることが示唆された.第二〜第四世代の卵数のピークは,それぞれ6月下旬〜7月上旬,8月下旬,9月中旬であった.また第一世代に相当すると思われる卵が4月上旬に発見された.2.これまで,本種は4齢幼虫が終齢であるとされていたが,飼育観察と野外で採集された幼虫の頭幅の測定結果から,蛹化するまでに5齢を経過することが明らかとなった.3.幼虫あるいは蛹化後の蛹には,7種のアリ類が随伴していた.4,本種の卵期における捕食寄生者はこれまでに報告されていなかったが,本研究によって少ないながら卵が寄生されていることが明らかになった.また,幼虫期の寄生は確認できず,蛹期の寄生も数例のみに限られた.

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The nesting biology of Andrena (Plastandrena) japonica (Smith) was studied at a personal garden of about 100m² in Matsue (35°29'N), southwestern Honshu, Japan, in 1984. This species is bivoltine. Therefore, A. (P.) fukaii Cockerell becomes a junior synonym, as the spring morph of A. japonica. The biological features of A. japonica are as follows: 1) The nesting period of the overwintering generation (G₀) and the first generation (G₁) is nearly the same, about 1.5 months, the former lasts from the middle of April to early June, and the latter from the middle of June to late July. 2) Immatures of G₀ develop into adults by the middle of October. 3) The nest density at maximum reaches up to 300 nests/m² (total in the garden was 4,736 nests) in G₀, and 252 nests/m² (5,688 nests) in G₁. 4) The nest type is linear-branched. One or two lateral burrows connect to the main burrow, each containing 1-7 serially arranged provisioned cells. 5) The number of cells in completed nests is 6.3±0.9 (n=3) in G₀, and 7.0±1.4 (n=5) in G₁. 6) The mean number of foraging trips performed per day is 2.7, spending 54 minutes/trip in G₀, and 3.4, for 42 minutes/trip in G₁. 7) One pollen loaf for both males and females was made by respectively 4 and 6 foraging trips. These values, mentioned in 6) and 7), suggest that one bee makes one cell every two days under favorable conditions. 8) Nesting duration is 31.7±3.9 days (n=13) in G₀. 9) Some bees (4/31) rarely make two nests. 10) The female ratio (females/(females+males)) is around 0.75 in both generations, indicating that the sex ratio is female-biased. 11) As natural enemies of A. japonica, the bee, Nomada rengino Tsuneki, and flies, Myopa buccata (L.), M. testacea Krober, and Bombylius sp. were found in nests.

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The impact of the ant Lasius niger attending the cotton aphid, Aphis gossypii, on the number of emerging adults of this aphid's primary parasitoid, Lysiphlebus japonicus, and its hyperparasitoids in the presence of predators was assessed experimentally at a no-pesticide mandarin grove. Aphid colonies were artificially initiated on young citrus shoots in spring. L. japonicus females were observed foraging more frequently in ant-attended aphid colonies than in colonies where ants were excluded using tanglefoot. They were often attacked by ants, but oviposited successfully by avoiding encounters with approaching ants. In ant-excluded colonies, L. japonicus parasitized a small number of aphids, with most of them being subject to intraguild predation mainly by the coccinellid Harmonia axyridis. Attending ants drove away large predators, including H. axyridis, from aphid colonies through aggressive behavior, so that the aphid numbers were consistently greater in ant-attended colonies. Ants disregarded parasitized aphids, thereby incidentally protecting them against large predators. Consequently, L. japonicus-mummies were abundant in ant-attended colonies, but scarce in ant-excluded colonies. In addition, significantly more adults of L. japonicus and hyperparasitoids emerged in ant-attended colonies. Many larvae of a small coccinellid, Scymnus posticalis, foraged in ant-attended colonies, but were ignored by ants. The number of mummies in ant-attended colonies was reduced when S. posticalis larvae were abundant, but the difference was insignificant. Ant-exclusion after mummy formation revealed that ants reduced intraguild predation and hyperparasitism on immature L. japonicus within mummies. Thus, L. niger attending A. gossypii increases the number of emerging adults of this aphid's primary parasitoid and hyperparasitoids by repelling large intraguild predators, although ants do disturb ovipositing parasitoids.

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Part 1: Generic characteristics, phylogenetic relationships and a brief review of the biology of the genus Dipogon are presented. Three species of the conspersus group of the subgenus Deuteragenia occurring in Japan are treated: Dipogon (Deuteragenia) conspersus is redescribed, and two new species, D. (Deu.) sperconsus and D. (Deu.) inconspersus, are described. Part 2: Two species-groups of the subgenus Deuteragenia, genus Dipogon, occurring in Japan are treated. In the Dipogon vechti species-group, D. vechti and D. romankovae are recorded from Japan and redescribed, and D. albithrix sp. nov. is described. In the D. granulifrons species-group, D. granulifrons sp. nov. and D. carychroceraeus sp. nov. are described. Part 3: Three species belonging to two species-groups of the subgenus Deuteragenia, genus Dipogon, occurring in Japan are revised: Dipogon immarginatus (D. immarginatus group), D. bifasciatus and D. nipponicus (D. bifasciatus group). Detailed descriptions and illustrations of their characteristics, including those of the genitalia, are provided for all species. Keys to five species-groups in Japan, as well as all species treated in this series, are presented.

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