红火蚁蚁巢表层各虫态数量与蚁丘大小的关系

采用挖巢取样法调查广州市番禺区6个地点的红火蚁蚁巢表层各虫态数量,分析各虫态数量与蚁丘大小的相互关系。结果表明,在调查的180个蚁巢中,占蚁巢总数57.78%的红火蚁蚁丘体积5000 cm~3,占蚁巢总数20.56%的红火蚁蚁丘体积介于5000~10000 cm~3,占蚁巢总数21.67%的红火蚁蚁丘体积10000 cm~3;占蚁巢总数32.78%的红火蚁蚁巢蚁丘表面基部面积500 cm~2,占蚁巢总数42.78%的红火蚁蚁巢蚁丘表面基部面积在500~1000 cm~2,占蚁巢总数24.44%的红火蚁蚁巢蚁丘表面基部面积1000 cm~2。平均1cm~3有效蚁丘体积中有3头红火蚁,1 cm~2蚁丘表面基部面积有22头红火蚁。红火蚁各虫态数量和蚁群总数均明显地随着蚁丘体积和表面基部面积的增大而增大,工蚁数量与蚁丘体积及表面基部面积的正相关性较其他虫态强;红火蚁数量与蚁丘体积的相关性强于该蚁数量与蚁丘表面基部面积的相关性。     

红火蚁蚁丘大小与诱集工蚁数量的关系

采用诱饵诱集法研究了荒地、绿化带生境中红火蚁蚁丘体积、蚁丘表面基部面积与诱集工蚁数量之间的关系.结果表明：在荒地生境中,随着蚁丘体积的增大,诱集工蚁数量表现为先迅速增加、后增大减缓、最终趋于平衡的规律,当蚁丘体积、蚁丘表面基部面积分别为11634 cm³、1308 cm²时,诱集工蚁数达到最大值,为每诱饵291 头;在绿化带生境中,随着蚁丘体积的增大,诱集工蚁数量动态与荒地生境相似,当蚁丘体积>18089 cm³时,诱集工蚁数量的增幅明显变缓,当蚁丘体积为25974 cm³时,诱集工蚁数达到最大值,为每诱饵232头.韦布尔函数方程可较好地描述诱集的红火蚁工蚁数量与蚁丘体积、蚁丘表面基部面积间的关系.     

药剂灌巢剂量对红火蚁蚁巢迁移的影响

为了明确药剂灌巢剂量对红火蚁蚁巢迁移的影响。本研究利用不同剂量的锐劲特药液对红火蚁进行灌巢处理,在野外条件下观察了药剂灌巢后红火蚁蚁巢的迁移情况。结果表明:(1)当药液量与蚁巢体积的比例低于1.6时,会出现蚁巢迁移,药液量较大时,灌巢防治红火蚁可取得较好的防效;(2)随着灌巢药液量的增加,新蚁巢出现的个数明显减少,出现比例明显降低,新蚁巢的体积明显减小;(3)随着灌巢药液量的增加,新蚁巢出现的时间会延迟,处理药液量为2.5 L时,新蚁巢一般出现在1-3 d内,而药液量增加后,新蚁巢一般在3-5 d出现;(4)药剂灌巢防治后,红火蚁会在距处理蚁巢1-7 m范围内建立新蚁巢,不同药液量处理之间没有明显差异,新蚁巢出现的位置没有明显的方位取向。为避免灌巢不彻底导致蚁巢迁移,应保证灌巢用药量充足,推荐药液量为蚁巢体积的2倍以上。     

红火蚁的巢间相容性

在室内条件下通过将红火蚁Solenopsis invicta Buren异巢不同品级的个体置于同一容器中,对红火蚁的巢间相容性进行研究。结果表明,蚁后与异巢幼蚁共处时,异巢幼蚁的羽化率为33.3%,与对照处理的38.3%(蚁后与同巢幼蚁共处)无显著差异。工蚁与异巢幼蚁共处时,异巢幼蚁的羽化率为53.7%,与对照处理的72.2%(工蚁与同巢幼蚁共处)无显著差异。蚁后与异巢工蚁共处时,异巢蚁后的存活率为45%,与对照处理的61.7%(工蚁与同巢蚁后共处)无显著差异。有翅繁殖雌蚁与异巢工蚁共处时,异巢工蚁的存活率为86.7%与对照处理的99.4%(工蚁与同巢有翅繁殖雌蚁共处)存在显著差异;异巢有翅雌蚁的存活率为22.2%,与对照处理的88.9%(工蚁与同巢有翅繁殖雌蚁共处)存在显著差异。由此可见,同区域内红火蚁异巢各品级间存在一定程度的相容性,并巢行为有可能发生。     

不同品级红火蚁体内生物碱含量的比较

本文旨在比较不同有机溶剂,不同浸泡时间对红火蚁体内生物碱的提取效率以及同巢蚁群中不同品级的红火蚁体内生物碱之间的差异。选用红火蚁整体浸泡法,获取生物碱样品,利用GC-FID技术进行定量分析。结果表明利用正己烷浸泡1 h即可获得红火蚁体内大部分的生物碱。同巢蚂蚁种群中,雌性生殖蚁体内生物碱含量最高,约为82μg/头,而工蚁体内的生物碱含量与个体大小呈正相关。     

红火蚁搬尸信号物质的初步研究

蚂蚁死亡后在密闭、潮湿的巢穴环境内非常容易滋生病原菌,威胁巢穴健康。为了防止尸体的存在危害健康个体,工蚁识别尸体上的“死亡信号”并将其搬离巢穴。本研究采用溶剂提取法提取工蚁尸体化合物,并利用化学方法转化尸体提取物,然后测试红火蚁Solenopsis invicta工蚁对4种主要提取成分——酯、脂肪酸、表皮碳氢化合物以及哌啶生物碱的行为反应。结果表明,红火蚁尸体的正己烷提取物具有很强的搬尸活性,高达76%的滤纸条被搬运到弃尸堆。酯、自由脂肪酸和结合态脂肪酸都能引起红火蚁的搬尸行为,搬尸活性分别为40%、28%和19%。自由脂肪酸转化成甲酯后搬尸活性不变,但结合态脂肪酸转化成甲酯后搬尸活性丧失。此外,红火蚁尸体还释放出多种能够诱导搬尸行为的未知成分,说明“死亡信号”具有复杂性。     

蚁巢受到干扰后红火蚁工蚁的连续性活动变化

红火蚁Solenopsis invicta Buren工蚁活动能力与蚁群健康、环境条件等密切相关,对蚁群进行干扰会引起工蚁防卫和攻击行为。本文采用标尺插入法对蚁巢进行干扰破坏,测定了工蚁活动性指数,结果显示在相同干扰程度下活动性指数随蚁巢体积增大而增大,相同蚁巢时随着干扰程度增加而活动性指数先迅速增大后基本保持不变。间隔5 min对蚁巢实施连续干扰后工蚁活动性呈明显连续下降趋势,第5次干扰后工蚁的响应活动变得很弱,工蚁活动性指数与干扰时间之间关系符合二次曲线方程。     

红火蚁防控药剂使用后对草坪节肢动物群落的影响

【目的】化学防治是目前控制红火蚁Solenopsis invicta为害的最有效的方法。化学药剂在对红火蚁起到良好防效时,也会对发生区的其他节肢动物群落造成一定的影响。本文研究了红火蚁常用防治药剂施用后对红火蚁典型发生区域-草坪生境中节肢动物群落的影响。【方法】使用网捕法和陷阱取样法调查处理和对照区的节肢动物。【结果】调查表明,施用推荐剂量的0.015%多杀菌素饵剂35 g/巢、0.045%茚虫威饵剂5 g/巢、0.096%氟虫腈粉剂30 g/巢和4.5%高效氯氰菊酯乳油2 000倍液后,对草坪上节肢动物群落产生不同的影响。研究发现,在农药处理后,各处理区节肢动物的Shannon-Wiener多样性指数得到不同程度的提高,在处理后45 d后,多杀菌素饵剂、茚虫威饵剂、氟虫腈粉剂和高效氯氰菊酯乳油处理区的Shannon-Wiener多样性指数分别为2.1、2.0、1.8和2.1,显著高于对照区的1.5。通过主成份分析得到施用30 g/巢0.096%氟虫腈粉剂和2 000倍液的高效氯氰菊酯乳油灌巢对节肢动物群落恢复产生一定的负面影响,即造成节肢动物群落中的非靶标生物的死亡。【结果】红火蚁种群在被药剂压制后,各药剂处理区中的生物多样性得到不同程度的恢复;35 g/巢的0.015%多杀菌素饵剂和5 g/巢的0.045%茚虫威饵剂对节肢动物群落相对安全,节肢动物群落相比对照区在防治后表现为物种相对丰富和群落结构稳定。     

广东吴川红火蚁消长规律

采用系统调查的方法研究广东吴川红火蚁Solenopsis invicta Buren蚁巢数量、蚁丘体积和工蚁的年度变化规律,结果表明1年之中红火蚁活动蚁巢密度出现2个高峰期,分别在6~8月和10~12月;4~7月和10~11月新增活动蚁巢数量较大;蚁巢自然消亡出现在多个时间,其中以9月最多。4~11月红火蚁工蚁活动旺盛,用诱饵诱集法监测,5、6月和10、11月红火蚁工蚁出现2个明显盛期,而陷阱法中工蚁数量为单峰型,高峰出现在7月。2种监测方法获得的工蚁数量间相关系数为0.88,达到极显著相关。气温、地表温度、5cm土壤温度与2种方法获得的工蚁数量间相关系数分别为0.88,0.88,0.86和0.93,0.94,0.95,均达极显著水平。红火蚁蚁丘体积4~6月、9~12月增大幅度较大,其中6月份蚁巢增长最为明显。     

三种植物源药剂对红火蚁的防治效果评估及其对本地蚂蚁群落影响

红火蚁Solenopsis invicta Buren是一种危险性入侵害虫,可对人类健康、农林业生产、公共安全和生态系统产生严重的负面影响。目前,化学农药是防治红火蚁的主要方法。然而,大多数化学农药并不适用于有机农场、水产养殖区等生态敏感区。为筛选出用于生态敏感区红火蚁防治的药剂,本文结合室内和田间试验评估了植物源杀虫剂苦参碱Matrine、鱼藤酮Rotenone和除虫菊素Pyrethrin对红火蚁的防治效果。室内试验结果表明,苦参碱、鱼藤酮和除虫菊素对红火蚁均具有较高的毒性。田间试验表明,25.00 mg/L和12.50 mg/L苦参碱、250.00 mg/L 和125 mg/L鱼藤酮、75.00 mg/L和37.50 mg/L除虫菊素灌巢处理,红火蚁蚁巢减退率分别达到100%、81.25%、87.50%、79.17%、71.73%和66.67%。然而,除25.00 mg/L苦参碱外,其他处理均导致在被灌巢的蚁巢周围短期内出现新蚁巢。灌巢处理后,处理区的蚂蚁多样性指数和均匀度指数升高,优势度指数下降。综上所述,苦参碱、鱼藤酮和除虫菊素适合灌巢处理防治红火蚁,其中0.5%苦参碱可溶性液剂能有效降低红火蚁种群数量,使得蚁巢减退率达100%,同时对本地蚂蚁群落没有负面影响,因此该商品制剂在红火蚁防治方面具有较好的开发潜力。     

Prevalence of a koinobiont endoparasitoid Misotermes mindeni (Diptera: Phoridae) in colonies of the fungus-growing termite Macrotermes gilvus (Blattodea: Termitidae) in Malaysia

A survey of the infestation rate of colonies of Macrotermes gilvus (Hagen) (Termitidae: Macrotermitinae) with the koinobiont endoparasitoid Misotermes mindeni Disney & Neoh (Diptera: Phoridae) was conducted in Malaysia from September 2009 to January 2011 in the states of Kedah, Penang, Perak, Selangor, Kuala Lumpur, Johor, Terengganu, and Sarawak. Of the 1,125 M. gilvus mounds surveyed, 12.4% contained termites parasitized by M. mindeni and these mounds occurred only in the states of Penang and Perak. High frequencies of mounds containing parasitized termites were found at sites in Penang: Bayan Lepas (21.1%), Minden Campus of Universiti Sains Malaysia ([USM]; 24.5%), Teluk Bahang (28.0%), and Bukit Mertajam (35.0%); the lowest frequency (4.0%) was recorded from Gelugor. The parasitized colonies at all sites were classified as healthy, with exception of several from the Minden Campus of USM (96.4% healthy) and Ayer Itam (87.5% healthy). Most parasitized colonies (71.2%) had a low level of M. mindeni infestation. Only 16.7 and 12.1% of the infested colonies had moderate or high parasite infestation levels, respectively. The height of infected mounds was significantly higher than that of the healthy mounds, but there was no difference between the mound diameters of infested and uninfested mounds. Parasite infestation level was not significantly correlated with mound height or mound diameter. The ambient light intensity at sites with infested mounds was significantly lower than that of uninfested mounds. There was also a significant negative relationship between light intensity and degree of parasitism.     

Studies on a population of large termite mounds in Uganda

• 1 Two study-sites near Kampala were mapped and all of the termite mounds within them were measured. Changes were recorded in the three succeeding years. A method was developed for estimating mound volumes from height and diameter.
• 2 Macrotermes bellicosus mounds reached a volume of about 2.4 m³ in 3 years after which they grew more slowly to a maximum from 4 to 6 m³. Growth in volume during the first 3 years was approximately linear and its rate did not vary seasonally, probably because growth is related to temperature which was nearly constant throughout the year.
• 3 M.bellicosus mounds had an average length of life of about 10 years, although colonies survived on average only 4 years. The corresponding figures for Pseudacanthotermes spp. were 5 and 2 1/2 years. Some mounds were recolonized after the death of the original colony.
• 5 Fresh earth was brought up at a minimum rate of about 10 m³ ha^-1 yr^-1 but more was lost by erosion and destruction and the populations of mounds were decreasing.
• 4 The number of ventilation shafts in M.bellicosus mounds increased with the volume of the mound. Many mounds, both dead and alive, supported vegetation.
• 6 Local opinion is that Pseudacanthotermes are harmless but M.bellicosus is regarded as a pest and attempts are made to destroy its mounds.

     

Multi-scale pattern analysis of a mound-building termite species

Termite mounds are a widespread feature in most African savannas. These structures exhibit high nutrient contents and often host a special vegetation composition. In this study, we analysed mound distribution patterns of a fungus-growing termite species, Macrotermes michaelseni, an important ecosystem engineer in the savannas of Namibia. Inhabited mounds taller than 0.7 m were regularly distributed. We view this pattern as a result of intraspecific competition. The heights of mounds taller than 0.7 m were correlated positively with their distance, such that mounds closer together, i.e. up to inter-mound distances of approximately 50 m, tended to be smaller than average. This indicates that intraspecific competition for foraging areas controls mound distribution pattern and colony size. Differences between mound heights increased on the spatial scale up to inter-mound distances of 80 m. We assume that the foundation of new colonies is only possible in unoccupied patches. In such patches, young colonies are able to occur close together as they have a relatively low foraging demand and therefore a low spatial demand. In contrast, their critical distance to taller colonies with higher foraging demands is rather large, which leads to the observed increasing difference of mound heights with increasing distances between them.     

Positive interactions between desert granivores: localized facilitation of harvester ants by kangaroo rats

Facilitation, when one species enhances the environment or performance of another species, can be highly localized in space. While facilitation in plant communities has been intensely studied, the role of facilitation in shaping animal communities is less well understood. In the Chihuahuan Desert, both kangaroo rats and harvester ants depend on the abundant seeds of annual plants. Kangaroo rats, however, are hypothesized to facilitate harvester ants through soil disturbance and selective seed predation rather than competing with them. I used a spatially explicit approach to examine whether a positive or negative interaction exists between banner-tailed kangaroo rat (Dipodomys spectabilis) mounds and rough harvester ant (Pogonomyrmex rugosus) colonies. The presence of a scale-dependent interaction between mounds and colonies was tested by comparing fitted spatial point process models with and without interspecific effects. Also, the effect of proximity to a mound on colony mortality and spatial patterns of surviving colonies was examined. The spatial pattern of kangaroo rat mounds and harvester ant colonies was consistent with a positive interspecific interaction at small scales (<10 m). Mortality risk of vulnerable, recently founded harvester ant colonies was lower when located close to a kangaroo rat mound and proximity to a mound partly predicted the spatial pattern of surviving colonies. My findings support localized facilitation of harvester ants by kangaroo rats, likely mediated through ecosystem engineering and foraging effects on plant cover and composition. The scale-dependent effect of kangaroo rats on abiotic and biotic factors appears to result in greater founding and survivorship of young colonies near mounds. These results suggest that soil disturbance and foraging by rodents can have subtle impacts on the distribution and demography of other species.     

Termite cohabitation: the relative effect of biotic and abiotic factors on mound biodiversity

1. Termites are important ecosystem engineers that improve primary productivity in trees and animal diversity outside their mounds. However, their ecological relationship with the species nesting inside their mounds is poorly understood. 2. The presence of termite cohabitant colonies inside 145 Cornitermes cumulans mounds of known size and location was recorded. Using network‐theoretical methods in conjunction with a suite of statistical analyses, the relative influence of biotic and abiotic drivers of termite within‐mound diversity on the composition and species richness of the termite community was investigated, specifically builder presence and physical aspects of the mound. 3. We found that richness inside the mound increases with mound size, and the species similarity between mounds decreases with distance. The physical attributes (abiotic drivers) of termite mounds (size and relative distance to other mounds) are the strongest predictors of termite species richness and composition. The biotic driver (presence of a builder colony) has an important, though smaller, negative effect on within‐mound termite species richness. 4. The findings suggest that the termites' physical manipulation of their environment is an important driver of within‐mound community diversity. More generally, the approach taken here, using a combination of statistical and network‐theoretical methods, can be used to determine the relative importance of abiotic and biotic drivers of diversity in a wide range of communities of interacting species.     

Reproductive success of Macrotermes bellicosus (Isoptera, Macrotermitinae) in two neighbouring habitats

The fungus-cultivating, mound-building termite Macrotermes bellicosus can reach high densities in African savannah habitats, whereas in forests it is comparatively rare and is only found in relatively open areas. Earlier studies in the Comoé National Park (Côte d'Ivoire, West Africa) suggested that this might be because ambient temperatures are lower in the forest than the savannah. Therefore, forests seem to be suboptimal habitats. During 3 consecutive years we measured relevant fitness parameters in both habitats to test this hypothesis. Colonies in the savannah had higher reproductive outputs. They reproduced annually, producing high numbers of offspring (alates), whereas forest colonies reproduced on average only once every 3?years and even then only low numbers of alates were produced. Annual growth of mound height, which can be regarded as an indicator of colony growth, varied considerably between individual colonies and years. Nevertheless, in two years the growth rate of mounds in the shrub savannah was higher than that of mounds in the gallery forest. Unexpectedly, survival probability as calculated by Kaplan Meier analysis was much lower for colonies in the shrub savannah than for colonies in the gallery forest. Using these data in a computer simulation we calculated lifetime reproductive success (LRS) for an average colony in both habitats. As LRS was much higher for colonies in the shrub savannah than in the gallery forest, these results confirmed our suggestion that the forest is a suboptimal habitat for M. bellicosus.     

The harvester ant (Pogonomyrmex badius) midden: refuse or boundary?

Abstract. 1. P.badius Latreille, a harvester ant of the southern U.S.A., surrounds its nest mound with small bits of charcoal, previously believed to be incidental refuse, along with other components of the colony's midden.
2. Charcoal middens were removed from the nest mounds of colonies in northern Florida. These colonies collected new charcoal and replaced the middens within 7 days.
3. Activity rhythms, use of space, and interspecific aggression were compared in experimental and control colonies. When middens were removed, the frequency of invasions of the nest mounds by other species of ants increased. Foreign ants circled the nest mound and interfered with colony activities. Increased numbers of invading ants led to an increase in patrolling and defensive behaviour by the P.badius colonies.
4. The charcoal midden is not merely refuse. Instead, it acts as a boundary that deters ants of other species from coming onto the P.badizls nest mound. Ants may use charcoal bits as a repository of a chemical substance functioning as a territorial marker.     

Microsatellite genotyping of red imported fire ant (Hymenoptera: Formicidae) colonies reveals that most colonies persist in plowed pastures

Our study focused on colony dynamics of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), in relation to the standard practice of planting rye grass (i.e., plowing) in the fall in Louisiana. Microsatellite molecular markers were used to determine genotypes of individuals from red imported fire ant colonies. These markers allowed us to monitor treatment effect by detecting changes in number and location of colonies in response to disking of pasture plots. Previous research on mound disturbance as a form of cultural control in pastures has produced mixed results. We found that the majority of colonies persisted on plots after plowing. Mound density and mound area, 5 mo after plowing, were not significantly different among treatments. In contrast, April measurements of mound volume were significantly smaller on plowed plots compared with control plots. A closer look at the rebuilding of mounds on plowed plots, during the 5 mo, showed that mound heights stayed below pretreatment measurements and they were significantly smaller than those of undisturbed mounds. Whether plowing has potential for use as a cultural control technique in reducing the impact of red imported fire ant mounds on agricultural practices in pastures remains to be seen. Conceivably, the best application of this technique will be in combination with other control measures in an integrated pest management approach to control red imported fire ants in pastures.     

Clonal variation in colony morphology and growth of CHO cells cultured on agar

Single Chinese hamster ovary (CHO) cells plated on agar form macroscopic colonies with high efficiency. Colonies produced by cells from the uncloned cell line increase in diameter continuously for 10–12 days after plating to form mounds of cells about 1 mm in diameter. With further incubation, some of these colonies do not increase in diameter (arrested dome), some form an expanding annular monolayer of cells around the central mound (fried egg), and some grow by enlarging the central mound into a low multilayered disc (saucer).These colony types on agar appear to be clonal characteristics of the CHO cell line. Cloning the line gives two kinds of isolates: one forms a mixture of arrested dome and fried egg colonies in an inheritable ratio, and the other forms saucer colonies. Cells from saucer colonies form saucer colonies when replated on agar. Cells from all colony types replate with similar efficiency on plastic or agar, and exhibit the same growth rate and cell size in liquid suspension culture. On plastic substrate, all these CHO cells form colonies which increase continuously in diameter for as long as 21 days, and little clonal difference in the morphology of colonies or of single cells is observed.These observations reveal a previously unsuspected heterogenieity in an established line of cultured mammalian cells and provide a method for studying new classes of In vitro growth control phenomena. These control phenomena may help in the building an in vitro model for tumor growth.     

高原鼢鼠土丘对矮嵩草草甸植被演替及土壤营养元素的作用

本文研究了矮蒿草草甸上高原酚鼠土丘的出现率及其对植被的覆盖状况,土丘高度的下降及其直径的变化,土丘植物地上生物量和土丘营养元素含量。高原鼢鼠土丘出现率为242个/只/年,合土壤干重为1023.82公斤/只/年,对植被的覆盖面积高达22.53平方米/只/年。土丘在地表滞留时间约1年,处于不同演替阶段植被区域内出现的土丘,其植物地上生物量间的差异显著。5月前,在原生植被区出现的土丘,经4个月后,土丘边缘形成环状富草区,士丘边缘至中心区形成环状贫草区,而土丘中心仍处于无草状况。在次生植被区上的土丘则无此现象。新土丘除速效钾的含量与对照区无显著差异外,速效氮、磷的含量显著地高于对照区。旧土丘土壤中的速效氮、磷、钾含量均低于新土丘,但氮、磷的含量仍高于对照区。