Lang J D
Vector Surveillance and Control Division, San Diego County Department of Environmental Health Services, CA 92123, USA.
J Med Entomol. 1996 Sep;33(5):790-804. doi: 10.1093/jmedent/33.5.790.
Abiotic and biotic factors affecting the seasonal abundance of 3 species of sylvatic fleas on their hosts were examined at 7 sites in San Diego County, California. Indices for Oropsylla (Diamanus) montana (Baker) were usually highest on Spermophilus beecheyi nudipes (Huey) when < 18.4 degrees C (October-December), whereas those for Hoplopsyllus anomalus (Baker) were highest when > 18.4 degrees C (July-September). O. montana was affected most by ambient temperature (inversely for the coastal site [134 m] and directly for most mountain sites [> 1,183 m]). O. montana was affected most (directly) by relative humidity at the inland valley site, which concurs with this flea being most abundant in other areas during periods yielding higher relative humidties and moderate ambient temperatures. H. anomalus was influenced most (directly) by ambient temperature at lower sites (< 1,183 m) and by host activity at higher ones (> 1,456 m). Usually nonrandom distribution findings, when indices for each squirrel flea were higher on some hosts, indicate that flea numbers are correspondingly higher in some nests and burrows because of more favorable microconditions. Data also indicated that plague may persist at higher sites in southern California or in other areas where climatic conditions permit increased and prolonged interactions between more abundant O. montana and its host during spring through summer. Whereas, plague may have less chance of persisting at lower sites because these interactions are decreased and shortened during the warmer months. Squirrels may become infected with plague following hibernation and again when reoccupying colonial burrows. The flea Orchopeas sexdentatus was affected most (inversely) by relative humidity at a coastal site, with higher indices occurring on fewer Neotoma lepida Thomas and on more abundant Neotoma fuscipes macrotis Thomas during colder months. Such increased flea/Neotoma fuscipes Baird activity at lower sites may favor plague amplification during the winter which may involve ground squirrels and other rodents in the spring.
在加利福尼亚州圣地亚哥县的7个地点，研究了影响3种野生跳蚤在其宿主上季节性丰度的非生物和生物因素。当温度低于18.4摄氏度（10月至12月）时，蒙塔那山蚤（Diamanus montana，贝克）（现归入山蚤属Oropsylla）在加州地松鼠指名亚种（Spermophilus beecheyi nudipes，休伊）上的指数通常最高，而异常角叶蚤（Hoplopsyllus anomalus，贝克）的指数在温度高于18.4摄氏度（7月至9月）时最高。蒙塔那山蚤受环境温度影响最大（沿海地点[134米]呈负相关，大多数山区地点[>1183米]呈正相关）。在内陆山谷地点，蒙塔那山蚤受相对湿度影响最大（呈正相关），这与该跳蚤在其他地区相对湿度较高且环境温度适中的时期最为丰富的情况相符。异常角叶蚤在较低地点（<1183米）受环境温度影响最大（呈正相关），在较高地点（>1456米）受宿主活动影响最大。当每种松鼠跳蚤在某些宿主上的指数较高时，通常会发现非随机分布，这表明由于更有利的微环境，某些巢穴和洞穴中的跳蚤数量相应更高。数据还表明，在南加州的较高地点或其他气候条件允许在春季至夏季期间蒙塔那山蚤与其宿主之间增加并延长相互作用的地区，鼠疫可能会持续存在。而在较低地点，鼠疫持续存在的可能性较小，因为在温暖月份这些相互作用会减少并缩短。松鼠在冬眠后以及再次重新占据群居洞穴时可能会感染鼠疫。在一个沿海地点，六齿近鬃蚤（Orchopeas sexdentatus）受相对湿度影响最大（呈负相关），在较冷月份，在较少的托马斯林鼠（Neotoma lepida Thomas）上且指数较高，而在较多的大耳林鼠（Neotoma fuscipes macrotis Thomas）上指数较高。在较低地点这种跳蚤/大耳林鼠活动的增加可能有利于冬季鼠疫的传播，这在春季可能涉及地松鼠和其他啮齿动物。
