Super-size flies

The increasing prevalence of obesity and other nutrition-related chronic diseases has prompted considerable efforts to understand their pathogenesis and treatment. One experimental approach is to overexpress, inactivate, or manipulate specific genes that regulate energy metabolism and fat storage. Many such techniques are fully established, routine tools in Drosophila and C. elegans, which provide elegant models for dissecting endocrine problems and metabolic pathways.     

Plastic flies

Individuals within species and populations vary. Such variation arises through environmental and genetic factors and ensures that no two individuals are identical. However, it is clear that not all traits show the same degree of intraspecific variation. Some traits, in particular secondary sexual characteristics used by males to compete for and attract females, are extremely variable among individuals in a population. Other traits, for example brain size in mammals, are not. Recent research has begun to explore the possibility that the extent of phenotypic variation (here referred to as “variability”) may be a character itself and subject to natural selection. While these studies support the concept of variability as an evolvable trait, controversy remains over what precisely the trait is. At the heart of this controversy is the fact that there are very few examples of developmental mechanisms that regulate trait variability in response to any source of variation, be it environmental or genetic. Here, we describe a recent study from our laboratory that identifies such a mechanism. We then place the study in the context of current research on the regulation of trait variability, and discuss the implications for our understanding of the developmental regulation and evolution of phenotypic variation.     

Asymmetric flies

What are the sources of phenotypic variation and which factors shape this variation are fundamental questions of developmental and evolutionary biology. Despite this simple formulation and intense research, controversy remains. Three points are particularly discussed: (1) whether adaptive developmental mechanisms buffering variation exist at all; (2) if yes, do they involve specific genes and processes, i.e., different from those involved in the development of the traits that are buffered?; and (3) whether different mechanisms specifically buffer the various sources of variation, i.e., genetic, environmental and stochastic, or whether a generalist process buffers them all at once. We advocate that experimental work integrating different levels of analysis will improve our understanding of the origin of phenotypic variation and thus help answering these contentious questions. In this paper, we first survey the current views on these issues, highlighting potential sources of controversy. We then focus on the stochastic part of phenotypic variation, as measured by fluctuating asymmetry, and on current knowledge about the genetic basis of developmental stability. We report our recent discovery that an individual gene, Cyclin G, plays a central role—adaptive or not—in developmental stability in Drosophila.¹ We discuss the implications of this discovery on the regulation of organ size and shape, and finally point out open questions.     

Origin,acquisition and diversification of heritable bacterial endosymbionts in louse flies and bat flies

The γ‐proteobacterium Arsenophonus and its close relatives (Arsenophonus and like organisms, ALOs) are emerging as a novel clade of endosymbionts, which are exceptionally widespread in insects. The biology of ALOs is, however, in most cases entirely unknown, and it is unclear how these endosymbionts spread across insect populations. Here, we investigate this aspect through the examination of the presence, the diversity and the evolutionary history of ALOs in 25 related species of blood‐feeding flies: tsetse flies (Glossinidae), louse flies (Hippoboscidae) and bat flies (Nycteribiidae and Streblidae). While these endosymbionts were not found in tsetse flies, we identify louse flies and bat flies as harbouring the highest diversity of ALO strains reported to date, including a novel ALO clade, as well as Arsenophonus and the recently described Candidatus Aschnera chinzeii. We further show that the origin of ALO endosymbioses extends deep into the evolutionary past of louse flies and bat flies, and that it probably played a major role in the ecological specialization of their hosts. The evolutionary history of ALOs is notably complex and was shaped by both vertical transmission and horizontal transfers with frequent host turnover and apparent symbiont replacement in host lineages. In particular, ALOs have evolved repeatedly and independently close relationships with diverse groups of louse flies and bat flies, as well as phylogenetically more distant insect families, suggesting that ALO endosymbioses are exceptionally dynamic systems.     

The orientation behaviour of horse flies and deer flies (Tabanidae, Diptera)

The Manitoba Fly Trap is illustrated and described and its uses in behaviour studies, surveys, insect control and perhaps population studies are enumerated. Its advantages over other traps for diurnal biting flies are discussed.

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Zusammenfassung Die Manitoba-Fliegenfalle wird abgebildet und beschrieben. Ihre Verwendungsmöglichkeiten bei der Verhaltensforschung, Sammlung und Bekämpfung von Insekten und vielleicht bei Massenwechselstudien werden aufgezählt und ihre Vorteile vor anderen Fallen für den Fang diurnaler Stechfliegen diskutiert.

     

实蝇类昆虫的引诱剂和诱捕器

实蝇科昆虫的许多种类是重要的入侵物种, 在国际植物检疫领域具有重要地位。联合国粮农组织（FAO）和《国际植物保护公约（IPPC）》积极倡导国际合作实施对实蝇类害虫的有效控制, 不断完善和出版实蝇控制技术手册并制定相关的国际植物检疫标准。引诱剂和诱捕器是实蝇类害虫监测、调查和防治中最重要的手段之一, 被广泛采用。国际上普遍认可的实蝇诱剂主要包括蛋白质诱剂（PA)、甲基丁香酚（ME）、诱蝇酮（CUE）、乙酸铵诱剂（AA）、乙酸铵盐诱剂（AS）、TML 诱剂、己酸丁酯诱剂（BuH）、吡嗪诱剂（MVP）等, 我国也研发了大量植物型和食物型诱剂。国际上常用实蝇诱捕器有20多种, 依据捕获实蝇的不同方式分为干型诱捕器、湿型诱捕器和干湿综合型诱捕器3类。同时, 我国利用各种塑料瓶研制了多种多样的诱捕器。本文对国际、国内实蝇诱剂和诱捕器等研究和利用情况进行了总结, 提出我国在建设外向型水果非疫区的实蝇监测中应使用国际标准的诱剂和诱捕器, 以便获得国际认可并促进我国优势农产品顺利进入国际市场, 在研发诱剂和诱捕器时做到标准化并及时申请专利保护、推向国际市场以便获得国际有关标准的采用和认可。     

Fruit flies and intellectual disability

Mental retardation - more commonly known nowadays as intellectual disability - is a severe neurological condition affecting 3% of the general population. As a result of analysis of familial cases and recent advances in clinical genetic testing great strides have been made in our understanding of the genetic etiologies of mental retardation. Nonetheless, no treatment is currently clinically available to patients suffering from intellectual disability. Several animal models have been used in the study of memory and cognition. Established paradigms in Drosophila have recently captured cognitive defects in fly mutants for orthologs of genes involved in human intellectual disability. We review here three protocols designed to understand the molecular genetic basis of learning and memory in Drosophila and the genes identified so far with relation to mental retardation. In addition, we explore the mental retardation genes for which evidence of neuronal dysfunction other than memory has been established in Drosophila. Finally, we summarize the findings in Drosophila for mental retardation genes for which no neuronal information is yet available. All in all, this review illustrates the impressive overlap between genes identified in human mental retardation and genes involved in physiological learning and memory.