Assembly of Myrmelachista Roger (Formicidae: Formicinae) in twigs fallen on the leaf litter of Brazilian Atlantic Forest

The nests of Myrmelachista are found in tree trunk cavities and branches. The biology of these arboreal ants is still relatively unknown. We investigated the nesting behaviour of this genus in fallen dry twigs in the Atlantic rainforest of southeastern Brazil. Physical characteristics of the nests, colony demographics, presence of breeders and ant worker sizes were recorded. Samples were collected weekly for 12 months, along open, sunny and undisturbed trails within forest remnants. In all, 202 nests were collected and six species were recorded. Myrmelachista ruszkii had the highest population of immatures and the greatest number of nests found. Myrmelachista nodigera had the smallest workers, was the least populous and the colony was housed in the finest branches. These results expand the current knowledge about the diversity and biology of Myrmelachista in the Brazilian Atlantic forest, and describe polydomic nests and competitive behaviour of M. ruszkii.     

Enhanced ants system and its application

1 .INTRODUCTIONAnts system(AS) is one newtype of si mulative evo-lution algorithmfirst developed by Italian scholar M.Dorigo[1 ~5]et al . in recent years . Based on AS,there exist versatile types ,such as ant colonysystem,Max-Min ants system,ants algorithm[ 1 ,2] , which isone bionic algorithm originating from the biologyworld and achieves pronounced effect in a series ofdifficult combinational opti mization problem, espe-cially TSP problem[ 5 ,8 ~1 0].AS has made full development si…     

密度对蚁群自组织聚集的影响

在生物及人类社会中,自组织聚集是十分普遍而且重要的集群行为,也是近年来蓬勃发展的交叉领域.为了定量地深入研究自组织聚集的宏观规律,我们用实验方法研究了草地铺道蚁的自组织聚集与其密度之间的关系,采用层次社会熵和样方法的统计手段测量蚂蚁群体的聚集度,以定量度量其自组织聚集程度.精确控制的实验以及基于实验数据的统计分析表明,蚂蚁群体在低密度下呈现近随机分布状态,高密度下稳定于显著的聚集状态,即蚂蚁聚集的程度是密度依赖的.实验给出的佐证在后续探究蚂蚁聚集的微观机制研究中将起到至关重要的作用,能够引起聚集行为涌现的简单机制是与密度密切相关的.     

实验平台装置边缘影响和蚁群聚集程度研究

为深入研究自组织聚集的微观机制, 采用日本弓背蚁作实验材料, 在二维正方形平面和二维圆形平面实验台上进行蚁群实验, 通过高速摄像机视频跟踪并进行定量统计分析. 实验结果表明, 实验装置边缘对蚂蚁有“吸引”作用, 随着群体规模增加, 装置边缘对蚁群吸引减弱. 通过研究蚂蚁速度, 发现因为装置边缘的吸引, 蚂蚁在边界和非边界运动状态不同. 在边界, 蚂蚁主要状态是“停止”和“低速运动”; 在非边界, 蚂蚁主要状态是“低速运动”. 本文首次提出用层次社会熵定量测量蚁群聚集程度, 发现其随着蚁群群体规模增加呈现先上升后下降趋势, 表明蚁群聚集程度随着蚁群群体规模增加先下降后上升.      

一种基于蚁群算法特征建模与分类的肺结节检测方法

根据肺结节的特征模型对感兴趣区域(ROI)进行分类来检测肺结节。首先,使用蚁群算法构造初步的规则集合,根据条件元素的相关度对规则进行修改确定最终的规则集合。然后,对规则集合中的特征进行建模,定义特征变量表示选定特征。最后,根据ROI的这些特征变量值以及总体特性,利用蚁群算法对ROI进行分类。分类中根据蚂蚁尸体堆积模型确定分类中心,采用蚂蚁觅食模型进行分类。仿真结果表明,该算法检测肺结节具有较高的敏感性,对医生后续的肺癌诊断有指导意义。     

堤坝蚁穴通道的可灌性及浆液配比

堤坝蚁穴通道的可灌性极不均匀。通过对渗流条件和制浆材料性能的详细分析,配制出了两种浆液,1#号浆液适用于细小孔道和裂缝的充灌,2#浆液适用于粗大空腔的充填固结,只有配合使用两种浆液,才能达到灭蚁防渗的目的。     

蚂蚁有效成分的提取及性能研究

用超声波法对蚂蚁有效成分进行提取,通过正交实验法确定了最佳提取条件,并研究了该条件下蚂蚁提取液对亚硝胺合成的阻断作用及对亚硝酸根离子的清除作用。实验结果表明:蚂蚁提取液对亚硝胺合成的阻断率和对亚硝酸根离子的清除率高达90%。     

Phoretic behaviour of Attacobius attarum (Roewer, 1935) (Araneae: Corinnidae: Corinninae) dispersion not associated with predation?

Attacobius attarum spiders exhibit a phoretic behaviour on the winged sexual of Atta leaf-cutting ants during their mating flight. However, it is unclear if this behaviour is for dispersion or to facilitate the predation of ants in the new colonies. A nest of Atta sexdens was monitored on the day of the mating flight, and the winged ants, as well as the spiders, were collected. The results obtained corroborate the hypothesis that phoretic behaviour is commonly used for dispersion of the spider A. attarum, predominantly females. Of these spiders, 64 individuals of A. attarium were collected, of which 62 were females (96.9%) and two were males (3.1%). Regarding the winged leaf-cutting ants sampled, 378 females and 361 males were collected, totaling 739 individuals. Of these, 64 individuals (8.7%) had a spider attached to its back for phoretic dispersal and none was observed on the queens after the nuptial flight. In our study, A. attarum females perform phoretic dispersal into the environment on winged leaf-cutting ants but do not settle in the new nests.     

A synopsis of the subterranean mealybug genus Neochavesia Williams and Granara de Willink (Hemiptera: Pseudococcidae: Rhizoecinae)

The neotropical mealybug genus Neochavesia, associated with the ant genus Acropyga Roger, is discussed and placed in the tribe Xenococcini on the bases that it lacks dorsal ostioles, the distal end of the circulus is depressed and cup-shaped, and the third-instar female is a pupa. These are characters shared by Xenococcus Silvestri and Eumyrmococcus Silvestri, also in the tribe Xenococcini, and differ from those in the tribe Rhizoecini, the other tribe in the subfamily Rhizoecinae. Two new species, Neochavesia iwokramae sp. nov. and N. lapollai sp. nov., are described from Guyana, and the female pupal instar and adult male of N. lapollai and the adult male of N. caldasiae (Balachowsky) are described and illustrated. A key to adult females is provided.     

Polygyny,oviposition, life cycle and longevity of the three subspecies of leaf-cutting ants,Acromyrmex subterraneus (Hymenoptera: Formicidae)

ABSTRACT

Research related to the comparative biology of phylogenetically close ant species has received little attention, although it is the basis for understanding the systematics of some sibling groups. The objective was to study the polygyny, oviposition, life cycle and longevity of the three subspecies of leaf-cutting ants. For that, we studied: oviposition rate – queens from three colonies were individually placed in plastic containers, and at 24-hour intervals, the laid eggs were quantified over a period of 96 hours; the workers’ life cycle – the development of immature ants was observed every 24 hours and, as a result, the duration of each stage of development was determined; the workers’ longevity – newly emerged adults were tagged and returned to the fungus chamber of their respective nests, and daily observations were made in each of the nest’s chamber. Laying rates were variable in the three queens studied, with a mean of total eggs laid of 271 for Acromyrmex subterraneus brunneus, 113 for Acromyrmex subterraneus subterraneus and 119 for Acromyrmex subterraneus molestans.The incubation period was 21.2 days in A. s. brunneus, 22.8 days in A. s. subterraneus and 20.4 days in A. s. molestans. The larval phase and pupal phase lasted on average 22.5 and 21.2 days in A. s. brunneus, 22.8 and 15.8 days in A. s. subterraneus and 17.2 and 14.2 days in A. s. molestans, respectively. Life cycle was different in the studied taxa, from 62 to 77 days in A. s. brunneus, from 59–68 days in A. s. subterraneus and from 51 to 55 days in A. s. molestans. The workers’ longevity varied between subspecies A. s. brunneus, A. s. subterraneus and A. s. molestans.