Piyaratne M K, Amerasinghe P H, Amerasinghe F P, Konradsen F
International Water Management Institute, Battaramulla, Sri Lanka.
J Am Mosq Control Assoc. 2005 Dec;21(4):387-94. doi: 10.2987/8756-971X(2006)21[387:FOLACA]2.0.CO;2.
No previous studies have been conducted on the natural food of larval Anopheles culicifacies s.l. (the major malaria vector) and An. varuna (a secondary vector) in Sri Lanka. The present study analyzed the contents of guts dissected from larvae collected from pools in a natural stream-cum-irrigation conveyance channel in the Upper Yan Oya watershed in the North Central Province of the country during August-September 1997 and July 1998. Determinations of physicochemical and biological parameters of the pools and their water were done at the same time. A fluorochromatic stain, 4',6-diamidino-2-phenylindole, was used to stain larval gut contents. Quantitative estimates of different categories of food types were made by analyzing the gut contents of 95 An. culicifacies (26 second instars and 69 fourth instars) and 52 An. varuna (21 second instars and 31 fourth instars). Detritus was the most frequent food type, comprising >74% of the gut contents in both species. Other food types included bacteria (cocci and rods), filamentous algae, diatoms, and desmids. Overall, bacteria constituted a significantly higher proportion of the gut contents in An. culicifacies than in An varuna. Significantly more detritus, bacteria, and total particulate matter occurred in 4th instars of An. culicifacies than in An. varuna, indicating a greater food intake in the former species. Second instars of An. culicifacies and An. varuna did not differ significantly in any parameter. A significant increase in food intake between 2nd and 4th instars was seen for An. culicifacies, but not An. varuna. Food indices were lower in An. varuna than in An. culicifacies when the 2 species co-occurred, indicating competition for food, and the implications of this to adult body size, survival, and fecundity are discussed.
此前尚未对斯里兰卡嗜人按蚊复合组幼虫（主要疟疾传播媒介）和瓦氏按蚊（次要传播媒介）的天然食物开展过研究。本研究分析了1997年8月至9月以及1998年7月从该国中北部省上亚诺亚河流域一条天然溪流兼灌溉输水渠道中的水塘采集的幼虫肠道内容物。同时对水塘及其水体的理化和生物学参数进行了测定。使用荧光染色剂4',6-二脒基-2-苯基吲哚对幼虫肠道内容物进行染色。通过分析95只嗜人按蚊（26只二龄幼虫和69只四龄幼虫）和52只瓦氏按蚊（21只二龄幼虫和31只四龄幼虫）的肠道内容物，对不同类别的食物类型进行了定量估计。碎屑是最常见的食物类型，在这两个物种的肠道内容物中均占>74%。其他食物类型包括细菌（球菌和杆菌）、丝状藻类、硅藻和鼓藻类。总体而言，嗜人按蚊肠道内容物中细菌所占比例显著高于瓦氏按蚊。嗜人按蚊四龄幼虫中的碎屑、细菌和总颗粒物明显多于瓦氏按蚊，表明前者的食物摄入量更大。嗜人按蚊和瓦氏按蚊的二龄幼虫在任何参数上均无显著差异。嗜人按蚊二龄幼虫和四龄幼虫之间的食物摄入量有显著增加，但瓦氏按蚊没有。当这两个物种同时出现时，瓦氏按蚊的食物指数低于嗜人按蚊，表明存在食物竞争，并讨论了其对成虫体型、生存和繁殖力的影响。
