SGER: Preliminary Assessment of Extinction of Crickets by Ants in Hawaii

0TTE 9815919 这项建议的目的是评估从非洲引入夏威夷的大头蚁（Pheidole megacephala）的影响，这种蚂蚁现在似乎直接威胁到蟋蟀和其他昆虫的多样性，并间接威胁到动物群的其他组成部分（蟋蟀是鸟类食物的主要组成部分）。 虽然引进的确切日期仍然不确定;报告表明这种蚂蚁的存在早在世纪和它的特别破坏性的影响节肢动物。 蚂蚁捕食的证据仍然是间接的，但它是强有力的。 最近对蟋蟀流行情况的观察（1997年10月和1998年1月）表明，在以前富饶的地区，蟋蟀突然严重减少。 这一悲观评估所依据的基线数据是在19年期间收集的。 奥特研究了整个夏威夷岛的蟋蟀的分类学和系统学，收集了644个地理点，记录了超过11，000首蟋蟀歌曲，并描述了大约190个新物种。 在过去的9年里，Shaw一直在研究Laupola属的繁殖、物种边界和行为，目的是了解新物种是如何在这个岛上的实验室里出现的。 在此期间，她访问了Otte（1994）描述的许多板球丰富的地区。 在1997年10月，发现以前有大量蟋蟀种群的地区几乎没有蟋蟀。 对栖息地的检查发现了大量的大头蚁。 1998年1月再次进行了观察，当时没有听到蟋蟀的声音。 奥特在考艾岛的207个地点记录了蟋蟀。 这些地点中的大多数包括Laupala属的成员。 10月和1月的调查只包括一个长样带。 该提案的目的是评估蚂蚁对若干低地和高地生境的影响。 厄尔尼诺现象的影响必须牢记。 由于20世纪80年代的厄尔尼诺现象对蟋蟀没有明显的影响（除了相当大的干旱），目前的人口下降可能与天气无关。 引进植物的影响也必须考虑在内。 在受影响的样带中，某些杂草植物的存在是显而易见的。 但是，由于蟋蟀不是特定于植物的宿主，并且生存在外来植物密度高的地区，因此植被变化并不是种群崩溃的可能原因。 必须考虑到自然的捕食者-被捕食者循环正在发生的可能性。 由于这种蚂蚁在夏威夷已经存在了90多年，目前的激增令人困惑。 这是经典的捕食循环吗？ 这些地区过去有蚂蚁入侵过吗？ 会有任何人口崩溃和随后的蟋蟀复苏？ 蚂蚁灭绝蟋蟀物种的可能性很大。 塔希提岛的调查显示，在过去曾有过特有动物区系的穆里亚，现在已经没有高地蟋蟀动物群了。 引进的蚂蚁是如此丰富，设置蟋蟀陷阱是不可能的诱饵是由蚂蚁在几分钟内设置。 将确定六种Laupala的当前分布，并与过去研究的基线数据进行比较。 将评估种群水平，并将其与蚂蚁的存在或不存在相关联。 将在哈佛大学和罗格斯大学建立蟋蟀和蚁群，以评估蚂蚁对处于各个发育阶段的蟋蟀的影响。 蟋蟀种群也将被保存在几个实验室，直到可以评估野外种群的命运。

0TTE 9815919 The goal of this proposal is to assess the effect of the ant, Pheidole megacephala (the big-headed ant) which has been introduced into Hawaii from Africa and now appears to threaten the diversity of crickets and other insects directly, and other components of the fauna indirectly (crickets are a major component of bird diet). Although the exact date of introduction remains uncertain; reports suggests the presence of this ant early in the century and its particularly devastating effect on arthropods. Evidence of ant predation is still indirect, but it is strong. Recent observations on the prevalence of crickets (October 1997 and January 1998) indicate a sudden and severe reduction of crickets in formerly rich areas. The baseline data upon which this pessimistic assessment is based was collected over a 19 year period. Otte studied the biogeography and systematics of crickets on all Hawaiian Island, collected at 644 geographic points, recorded more than 11,000 cricket songs, and described approximately 190 new species. Over a 9 year period Shaw has researched the phylogeny, species boundaries and behavior of the genus Laupola, with the goal of understanding how new species arise in this island laboratory. During that time she visited many of the cricket rich areas described by Otte (1994). In October 1997 areas previously having huge cricket populations were found to have virtually no crickets at all. Examination of the habitat revealed large numbers of big-headed ants. Observations were conducted again in January 1998 at which time no crickets were heard. Otte recorded crickets at 207 sites on the Island of Kauai. The majority of these sites included members of the genus Laupala. October and January surveys included only one long transect. The goal of this proposal is to assess the impact of ants at a number of lowland and highland habitats. The effect of El Nino must be kept in mind. Because an earlier El Nino in the 1980's had no visible effect on crickets (d espite considerable drought ) the current population decline may not be weather related. The effect of introduced plants must also be kept in mind. The presence of certain weedy plants in the affected transect is noticeable. but, because crickets are not host specific on plants and survive in areas with a high density of exotic plants, vegetational changes are not the likely cause of populations crashes. The possibility that a natural predator-prey cycle is occurring must be considered. Since the ants have been present in Hawaii for over 90 years, the current surge is baffling. Is this classical predator prey cycle? Have these areas been invaded by ants in the past? Will there be any populations crash and subsequent revival of crickets? The possibility that ants will exterminate cricket species is a high possibility. Surveys in Tahiti show that there is now no upland cricket fauna on Moorea-an area known to have had an endemic fauna in the past. Introduced ants are so abundant that the setting of cricket traps is impossible-baits are removed by ants within minutes of setting. The current distribution of six species of Laupala will be determined and compared to baseline data from past studies. Population levels will be assessed and correlated with presence or absence of ants. Crickets and ant colonies will be established at Harvard and Rutgers Universities to assess the effect of ants on crickets in various developmental stages. Cricket colonies will also be kept in several laboratories until the fate of field populations can be assessed.