小癭蚊 ( Feltiella minuta (Felt)) (雙翅目:癭蚋科) 生活史、捕食量及其在茄園的季節變動

Abstract

小癭蚊( Feltiella minuta (Felt) )產卵於茄子葉背纖毛上，幼蟲捕食葉蟎，老熟後做繭化蛹葉脈邊上，常在葉脈交會處。卵0.22 mm長，老熟幼蟲1.42 mm 長，蛹1.08 mm長，繭1.50 mm長。在15、20、25、28及30℃及13：11( L：D)小時光暗週期之定溫箱中，以神澤氏葉蟎(Tetranychus Ranzawai Kishida)之卵為食，雌蟲自卵發育至成蟲平均需32.9、15.1、10.1、9.0、9.5日，雄蟲之發育期分別需32.8、15.3、10.3、9.0、9.2日其發育極整齊，同一日所產卵幾乎在同一日羽化為成蟲。低溫時，卵及蛹期在發育期中所占比例略高，成蟲壽命甚短，各溫度下平均皆未及5日。飼以蜂蜜水，雌蟲產卵量分別為7.8、17.2、13.2、16.3、11.2粒。幼蟲可捕食各齡期的葉蟎，食量隨發育生長而急速上升。雌性幼蟲可分別捕食神澤氏葉蟎卵195.3、187.5、167.6、165.0、142.5粒，雄性幼蟲則捕食173.3、153.5、132.0、140.7、122.1粒葉蟎卵。每日捕食量隨溫度上升而增加，以28℃為例，其捕食量介於黃角小黑隱翅蟲(Oligota flavicornis (Boisduval & Lacordaire))與溫氏捕植蟎(Amblyseius womersleyi Schicha)之間。連續4年調查不施藥茄園，本蟲均隨葉蟎族群發生，與黃角小黑隱翅蟲、印度食蟎薊馬(Scolothrips indicus Priesner )、捕植共同抑制葉蟎族群。發展IPM系統中應將癭蚊的保育及利用列入考慮。 Feltiella minuta (Felt) oviposits on hairs on the back of eggplant oeaf. The larva feeds on spider mites, and pupates in a loosely spun cocoon, usually along the leafvein, often at the intersection of 2 veins. The lengths of egg, mature larva, pupa, and cocoon averaged 0.22 mm, 1.42 mm, 1.08 mm, and 1.50 mm, respectively. Reared in an incubator at 15, 20, 25, 28, and 30℃, with a photoperiod of 13:11 (L:D), and fed with eggs of Tetranychus Ranzawai Kishida, the developmental period, from egg to adult, averaged 32.9, 15.1, 10.1, 9.0, 9.5d for female flies, and 32.8, 15.3, 10.3, 9.0, 9.2 d for male flies, respectively. This midge developed uniformly. Eggs deposited on the same day emerged to adult almost on the same date. The egg and pupal stages occupied a larger proportion of the whole developmental period at lower temperatures. The adult life span was short, usually less than 5 d. Fed with diluted honey, an adult female laid 7.8, 17.2, 13.2, 16.3, and 11.2 eggs at the respective temperatures. Larvae could feed on any stage of the spider mite. The feeding amount increased sharply as age increased. Each female larva consumed 195.3, 187.5, 167.6, 165.0, and 142.5 spider mite eggs, while each male larva consumed 173.7, 153.6, 132.0, 140.7, and 122.1 spider mite eggs, at the respective temperatures. Daily consumption increased as temperature increased. At 28℃, its feeding amount was less than that of Oligota flavicornis Boisduval & Larcodaire, but greater than that of Amblyseius womersleyi Schicha. Weekly surveys made consecutively for 4 yr in eggplant fields which received no acaricide or insecticide application showed this midges always occurred and fluctuated after the spider mite population. It regulated the spider mite population together with O. flavicornis, Scolothrips indicus Priesner, and A. womersleyi. The conservation of this midge should be included in the IPM system.