The origin and evolution of social life in the Stenogastrinae (Hymenoptera,Vespidae)

The Stenogastrinae are a subfamily of the Vespidae. The main difference between these and other social wasps (Polistinae and Vespinae) is a jelly-like substance that the Stenogastrinae secrete from the Dufour 's gland and use in many functions of their biology. It is suggested that this substance greatly contributed to the evolution of social life in these wasps by making it possible to nourish the brood with liquid food and store it in the nest, thus favoring also the evolution of the behavioral mechanisms which facilitated interactions between adults. Social organization of the colonies may have been kept at a low level through a basic system of continuous temporary helper replacement, while the evolution of large colonies was restrained, as well as by the poor quality of construction material, low egg-laying capacity and limited production of abdominal substance, imperfect social regulatory mechanisms, and the absence of defensive mechanisms of the colonies against large predators.     

Social behavior and brood decline in reproductive-phase colonies ofBelonogaster petiolata (Degeer) (Hymenoptera: Vespidae)

Colonies ofBelonogaster petiolata in Gauteng (South Africa) produced reproductive offspring (gynes and males) in late January and early February of each nesting season; their appearance was associated with a decline in worker and brood numbers. Brood decline could commence in the presence of a dominant, reproductively active queen, and loss or removal of the queen was not followed directly by cessation of nest growth and brood care. An older worker usually took over the α-position in queenless colonies. Several factors appear to contribute to brood decline and, ultimately, termination of the colony cycle in this species. These include (1) cessation of the supply of solid food to colonies (and particularly their larvae) during the reproductive phase, (2) a decrease in the worker/larva ratio during the latter phase due to the progressive loss of workers, (3) increasing number of gynes and males, and (4) an adult priority over food reception from foragers.     

The role of flavonoids in the establishment of plant roots endosymbioses with arbuscular mycorrhiza fungi,rhizobia and Frankia bacteria

Flavonoids are a group of secondary metabolites derived from the phenylpropanoid pathway. They are ubiquitous in the plant kingdom and have many diverse functions including key roles at different levels of root endosymbioses. While there is a lot of information on the role of particular flavonoids in the Rhizobium-legume symbiosis, yet their exact role during the establishment of arbuscular mycorrhiza and actinorhizal symbioses still remains unclear. Within the context of the latest data suggesting a common symbiotic signaling pathway for both plant-fungal and plant bacterial endosymbioses between legumes and actinorhiza-forming fagales, this mini-review highlights some of the recent studies on the three major types of root endosymbioses. Implication of the molecular knowledge of endosymbioses signaling and genetic manipulation of flavonoid biosynthetic pathway on the development of strategies for the transfer and optimization of nodulation are also discussed.     

Investigations on ecdysteroids and juvenile hormones and on morphological aspects during early embryogenesis in the ovoviviparous cockroach Nauphoeta cinerea

During early embryogenesis, which is from ovulation (day 0) until dorsal closure (day 19), the quantity of free and conjugated ecdysteroids in the egg cases, as measured by radioimmunoassay (RIA), increases. Thin-layer chromatography (TLC) and high-performance-liquid-chromatography (HPLC) analyses combined with RIA suggest that 20-hydroxy-ecdysone is the predominant ecdysteroid. Hydrolysis of the highly polar products of day-0 and day-17 egg cases by Helix pomatia enzymes indicates the presence of some conjugates of 20-hydroxy-ecdysone, hydrolyzable under these conditions. However, important quantities of RIA-reactive highly polar products are not hydrolyzed particularly in day-17 egg cases. These results demonstrate that the highly polar products of day-0 egg cases are qualitatively as well as quantitatively different from the highly polar products of day-17 egg cases. Morphological investigations show that the peak of 20-hydroxy-ecdysone at the time of the dorsal closure coincides with the synthesis of an embryonic cuticle. Using the Galleria wax test only traces, or no juvenile hormone activity could be detected in embryos during the entire period of early embryonic development. Morphological investigations of the brood sac suggest that this organ is very important to facilitate the initial uptake of water into the eggs. Thereafter the embryos can develop independently of the female when kept in a humid environment.     

Ungulate saliva inhibits a grass–endophyte mutualism

Fungal endophytes modify plant–herbivore interactions by producing toxic alkaloids that deter herbivory. However, studies have neglected the direct effects herbivores may have on endophytes. Antifungal properties and signalling effectors in herbivore saliva suggest that evolutionary pressures may select for animals that mitigate the effects of endophyte-produced alkaloids. Here, we tested whether saliva of moose (Alces alces) and European reindeer (Rangifer tarandus) reduced hyphal elongation and production of ergot alkaloids by the foliar endophyte Epichloë festucae associated with the globally distributed red fescue Festuca rubra. Both moose and reindeer saliva reduced the growth of isolated endophyte hyphae when compared with a treatment of distilled water. Induction of the highly toxic alkaloid ergovaline was also inhibited in plants from the core of F. rubra''s distribution when treated with moose saliva following simulated grazing. In genotypes from the southern limit of the species'' distribution, ergovaline was constitutively expressed, as predicted where growth is environmentally limited. Our results now present the first evidence, to our knowledge, that ungulate saliva can combat plant defences produced by a grass–endophyte mutualism.     

Brutph?nologie und Morphometrie des Schwarzbauchmeerl?ufers (Fregetta tropica) auf King George Island, Antarktis

Zusammenfassung Im Jahre 1995/96 wurden brutphänologische und biometrische Daten des Schwarzbauchmeerläuferes (Fregetta tropica) auf King George Island, Antarktis, erhoben.Die Vorbrutzeit erstreckte sich bis Ende Dezember, dem Beginn der Hauptlegephase. Während der Inkubationszeit (Gesamtdauer 39–42 Tage) verweilten die Weibchen im Mittel 1,6 Tage (Männchen 1,8 Tage) auf dem Gelege. Die Häufigkeit von Brutunterbrechungen (Dauer 1,9 Tage) nahm im Laufe der Inkubationszeit drastisch ab. Hauptschlupfzeit der Küken war Anfang bis Mitte Februar. Das Kükenwachstum zeichnete sich durch individuell differenzierte Massezunahme aus. Nach 20–25 Tagen wurde die Adultmasse erreicht; die Maximalmasse eines Kükens lag bei 193% der Adultmasse. Der Wachstumsverlauf der Küken wurde mit logistischen Gleichungen beschrieben.Signifikante geschlechtsspezifische Größenunterschiede der Altvögel ließen sich nur für die Flügellänge nachweisen. Die mittlere Ausbildung des Brutflecks der untersuchten Kolonie sank innerhalb einer fünfteiligen Skala von 3,7 (BF vollständig ausgebildet) während der Vorbrutzeit auf 1,4 (BF sehr gering ausgebildet) am Ende der Nestlingszeit.Vögel unterschiedlicher BF-Kategorien unterschieden sich in ihren Massen signifikant. Am Ende der Inkubationszeit wiesen nur noch Brüter einen gut ausgebildeten Brutfleck auf. Eine kombinierte Betrachtung von BF-Ausbildung und Masse läßt daher schon zu einem frühen Zeitpunkt verläßliche Rückschlüsse auf den Status eines Vogels (Brüter oder Nichtbrüter) zu. Am Ende der Brutsaison lag der so errechnete Nichtbrüter-Anteil bei 67%.

---

Breeding and biometrics of Blackbellied Stormpetrel (Fregetta tropica) at King George Island, Antarctic

Summary During the austral summer of 1995/96 breeding aspects and biometrics of Blackbellied StormpetrelsFregetta tropica at King George Island, South Shetlands, were observed. The pre-laying period lasted until the end of December when the main laying time began. In the incubation period (duration 39–42 days) the breeding shifts of females and males were on average 1.6 and 1.8 days, respectively. Frequencies of breeding spells decreased dramatically towards the end of the incubation period. The chicks mainly hatched in the beginning/middle of February. Chick development was characterized by individually differing increases of body mass. After 20–25 days they reached adult body mass; the observed mass maximum was 109.9 g (193% of adult body mass). The development of body mass, wing length and tarsus length could be approximated using sigmoidal regression curves. 28 sexed adult birds showed significant differences only in wing length but not in tarsus length. From the pre-laying till the end of the hatching period the mean brood patch scores decreased from 3.7 (complete brood patch) to 1.4 (broodpatch weakly developed). Birds with well developed brood patches weighed on average 57.3 ± 4.0 g whereas birds with hardly visible brood patches weighed 53.5 ± 2.8 g. Because only breeders show brood patches at the end of the incubation period a consideration of both brood patchand body mass allows a reliable classification into breeders or nonbreeders. At the end of the hatching period 67% of all captured birds were nonbreeders.

     

Internal incubation and early hatching in brood parasitic birds

The offspring of brood parasitic birds benefit from hatching earlier than host young. A proposed but little-known strategy to achieve this is 'internal incubation', by retaining the egg in the oviduct for an additional 24 h. To test this, we quantified the stage of embryo development at laying in four brood parasitic birds (European cuckoo, Cuculus canorus; African cuckoo, Cuculus gularis; greater honeyguide, Indicator indicator; and the cuckoo finch, Anomalospiza imberbis). For the two cuckoos and the honeyguide, all of which lay at 48 h intervals, embryos were at a relatively advanced stage at laying; but for the cuckoo finch (laying interval: 24 h) embryo stage was similar to all other passerines laying at 24 h intervals. The stage of embryo development in the two cuckoos and honeyguide was similar to that of a non-parasitic species that lay at an interval of 44-46 h, but also to the eggs of the zebra finch Taeniopygia guttata incubated artificially at body temperature immediately after laying, for a further 24 h. Comparison with the zebra finch shows that internal incubation in the two cuckoos and honeyguide advances hatching by 31 h, a figure consistent with the difference between the expected and the observed duration of incubation in the European cuckoo predicted from egg mass. Rather than being a specific adaptation to brood parasitism, internal incubation is a direct consequence of a protracted interval between ovulation (and fertilization) and laying, but because it results in early hatching may have predisposed certain species to become brood parasitic.     

Social wasps and bees captured in carrion traps in a rainforest in Brazil

Information is presented on social wasps and bees caught in carrion traps in ‘terra firme’ rainforest in Caxiuanã, PA, Brazil. Six species of epiponine wasps were captured. Angiopolybia pallens was the most frequent species, being caught in approximately 43.5% of the trials, followed by Angiopolybia paraensis (15.8%), Agelaia fulvofasciata (5.6%) and Agelaia angulata (3.3%). Agelaia pallipes and Agelaia cajennensis both had only a single individual captured. Twelve species of social bees were captured. The genera Trigona, Partamona and Melipona had similar numbers of species, but frequencies varied considerably. One individual of Apis mellifera was captured.     

贵州钝颚白蚁（蜚蠊目：白蚁科：象白蚁亚科）线粒体基因组测序及分析

钝颚白蚁属Ahmaditermes隶属白蚁科Termitidae象白蚁亚科Nasutitermitinae,该属物种较为丰富,分布较广,但目前关于其线粒体基因组的研究较少。为丰富钝颚白蚁的线粒体基因组特征认识及探究其系统发育地位,本研究测定分析贵州钝颚白蚁Ahmaditermes guizhouensis全线粒体基因组序列,并基于143条白蚁线粒体基因组序列的37个编码基因,利用最大似然法和贝叶斯法构建系统发育树。研究结果如下：（1）贵州钝颚白蚁线粒体基因组全长15 836 bp,核苷酸组成呈现AT偏向性（A+T=68.8%）。除nad2使用非常规的GTG作为起始密码子之外,其余蛋白质编码基因均使用典型的起始密码子或终止密码子。线粒体基因组控制区的重复单元类型为Bp-B。（2）钝颚白蚁属比较线粒体基因组揭示,线粒体基因组基本特征较为相似,13个蛋白质编码基因中nad5的进化速率最快,cox1和cox2进化最保守。基于白蚁通用条形码基因cox2,贵州钝颚白蚁与宽头钝颚白蚁Ahmaditermes laticephalus的P-distance遗传距离为0,推断两者可能存在同物异名关系。（3）象白蚁亚科内部发现考登白蚁属Kaudernitermes、象白蚁属Nasutitermes、缩狭白蚁属Coarctotermes、针白蚁属Aciculitermes、锥白蚁属Subulitermes和冢白蚁属Tumulitermes共6个属为非单系群。钝颚白蚁属与象白蚁属Nasutitermes的部分支系互为姐妹群关系。     

On the origin of brood parasitism in altricial birds

The probability that obligate interspecific brood parasitism(OP), among altricial birds evolved directly from the normalbreeding (no parasitism, NP) mode or indirectly through intraspecificnest parasitism (INP) was examined by using maximum-likelihoodand parsimony approaches. We examined the probability of ancestralstates at 24 key nodes in order to test our hypotheses. Thestate of the most basal node in a tree of 565 genera of altricialbirds is equivocal; however, the state probability of NP atthis node is about 5.5-fold more likely than the state of obligateparasite. A similar trend was observed for basal nodes of mostfamilies examined. The INP state was supported only in the Hirundinidae.The high incidence of INP among martins and swallows explainsthis finding. Contrary to our predictions, even in other groupswhere there is a high incidence of INP and OP, such as in thetribe Icteri and the Old World finches, the probability of NPbeing ancestral was very high. We conclude that in all casesbut one (Hirundinidae) obligate, and probably facultative, broodparasitism evolved directly from normal breeding mode ratherthan indirectly through some other form of parasitism.     

Development of non-reproductive castes in the neotropical termite generaCornitermes,Embiratermes andRhynchotermes (Isoptera,Nasutitermitinae)

Summary The developmental pattern of the neuter castes was studied in the mandibulate nasute generaCornitermes, Embiratermes andRhynchotermes. InCornitermes walkeri, all the workers and soldiers are male. There are two larval and a single worker instar. Workers can molt into presoldiers. InEmbiratermes chagresi andRhynchotermes perarmatus, both sexes are present among the neuters. A slight sexual dimorphism (males > females) is discernible among both larval instars and among workers ofE. chagresi; female workers can molt into presoldiers. InR. perarmatus, the sexual dimorphism is conspicuous from the first larval instar on. Male larvae go through two instars, then give rise to workers, which do not molt. InR. perarmatus, there is no worker stage in females, but a third larval instar, preceding the presoldier. Hypotheses are proposed as to the evolution of these caste patterns, attempting to conciliate present knowledge of Nasutitermitinae phylogeny and known evolutionary trends affecting termite caste patterns, according to the species' ecology.Research Associate: National Fund for Scientific Research (Belgium).