著者

中尾 舜一

出版者

九州大学

雑誌

九州大學農學部學藝雜誌 (ISSN:03686264)

巻号頁・発行日

vol.14, no.3, pp.319-328, 1954-03

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In spite of its rare occurrence, Agriosphodrus dohrni Signoret is widely spread over all prefectures of Kyushu, Japan, except Kagoshima Prefecture, from where not a single specimen has hitherto been collected (Fig.1). The favourite habitat of the nymphs of this Reduviid seems to be restricted to a certain narrow and extremely limited place, viz., a slightly hollowed or folded site on the east or south side of a fairly large or large trunk of such trees as Celtis sinensis japonica Nakai, Prunus yedoensis Matsumiara, Pinus thubergii Parlatore, Cinnamomum camphora Siebold, Cyclobalanopsis gilva Oersted, Podocarpus chinensis Blume, Shiia sieboldi Makino, Diospyros kaki domestica Makino, etc., about 2 3 meters above the ground, where the nymphs are making aggregations except their foraging times and often hibernate during winter and from where the nymphs move away to all directions in search for their prey. Therefore, such favourite sites become isolated from one another and are very few even on a single tree-trunk or in a given area where their aggregations are represented by more or less accidental collections. Contrary to the nymphs the adults are always solitary in habit, chiefly living on the shoots or trunks of the tree in question where they have spent their nymphal stage, but seldom fly away or migrate to another tree. From such observations it becomes apparent that the characteristic feature of its distribution may be attributed to its occurrence in isolated areas in the state of isolated populations. The adults are said occassionally attracted to light. The nymphs have been observed to feed on the larvae of Psychidae and Arctiidae (Lithosiinae), an adult fly of about 5 mm in body-length and a small Chrysomelid (?) beetle, which were pierced with their strong rostrum. The habitat of this Reduviidae on the trunk of Celtis sinensis japonica Nakai in the campus of the Kyushu University consists of clumps of moss, in which there are living a number of Arctiid (Lithosiinae) larvae of three different species. So far as the author's observation goes, these larvae seem to represent the chief food of this Reduviid. Gyotoku (1951) and Hasegawa (unpublished data) reared this Reduviid with caterpillars, aphides on Chrysanthemum, adults of Nezra antennata Scott, Nephotettix bipunctus cincticeps Uhler and the last instar nymphs of Poecilocoris lewisi Distant in the laboratory. Early hatched or moulted nymphs have been observed to feed on the lately hatched or moulted ones voraciously. The fact that the foraging area of such younger nymphs is very narrow is directly correlated with the habit of cannibalism and is the reason why the population of this Reduviid in nature becomes reduced to some extent during their first and scecond nymphal stages. On the other hand, such phenomenon as cannibalism has not been detected on the nymphs of the third, fourth and fifth instars in nature, Consequently the population size at the third nymphal stage reaches nearly the final size seen at the fifth stage. Of course natural enemies and other factors, if present, may cause the declination of population but those effects seem to be slight in the case of this Reduviid. In case the maximum temperature of the day become higher than 10℃, some of the overwintering nymphs become active and wander about beyond the boundaries of the favourite hibernation site and feed on their prey. This Reduviid seems to withstand starvation for considerable duration days. The eggs are deposited on favourite sites on the surface of the trunk. The site represents the most suitable environment, where the nymphs would aggregate themselves after ward. Oviposition takes place both in the morning and evening. The eggs are laid in batches of 30 to 80, and each ootheca is covered with a thin yellowish resin-like substance which is secreted by the female.1. 本報文に於て筆者は, ヨコズナサシガメ AgriosPhodrus dohrni Signoretの幼虫期における集団形成現象の手懸りとしての棲息環境・食性及び産卵習性を究明すると共に, 本種の日本に於ける分布についてもあわせ報告した. 2.日本に於ける分布は,鹿児島県を除く九州の各県である. 3.本種は樹幹上に極く限定された狭い棲息環境をもち, 従つて棲息場所は隔離された非常に孤立的なものとなつている. 4.一定の産卵好適場所に産卵された卵塊は,樹脂に似た物質で覆われ, 1卵塊は30~80個の卵からなる. 5.食物は多岐にわたり, 鱗翅類の各種幼虫, 小さな蝿の成虫, 小甲虫成虫, 蛎虫等各種の小昆虫の殆んどを食する. 筆者の観察した棲息場所における主な食物は, コケガの幼虫及びミノガの幼虫であつた. 弟1・2齢幼虫は肖然状態にても盛んに共食いをする.