Ecological immunology of mosquito-malaria interactions: Of non-natural versus natural model systems and their inferences

There has been a recent shift in the literature on mosquito/Plasmodium interactions with an increasingly large number of theoretical and experimental studies focusing on their population biology and evolutionary processes. Ecological immunology of mosquito-malaria interactions - the study of the mechanisms and function of mosquito immune responses to Plasmodium in their ecological and evolutionary context - is particularly important for our understanding of malaria transmission and how to control it. Indeed, describing the processes that create and maintain variation in mosquito immune responses and parasite virulence in natural populations may be as important to this endeavor as describing the immune responses themselves. For historical reasons, Ecological Immunology still largely relies on studies based on non-natural model systems. There are many reasons why current research should favour studies conducted closer to the field and more realistic experimental systems whenever possible. As a result, a number of researchers have raised concerns over the use of artificial host-parasite associations to generate inferences about population-level processes. Here I discuss and review several lines of evidence that, I believe, best illustrate and summarize the limitations of inferences generated using non-natural model systems

Gene flow among populations of Anopheles gambiae: a critical review

The success of genetic-control programmes aimed at introducing genes into wild Anopheles gambiae populations depends on our understanding of the genetic structure of these populations. Population-genetic studies are required for identifying discrete population groups across Africa, determining their geographical distribution and evaluating the degree to which they may be reproductively isolated. Population studies are also needed to estimate the rate at which genes may spread within and between populations at various spatial scales and to identify biological and physical features of the environment that may interfere with their movement. Studies of the mechanisms of reproductive isolation between molecular/chromosomal forms of An. gambiae can be used to validate the results of population-genetic approaches and aid in the development of reproductively competitive laboratory strains. In the following, we review past and recent studies that cover these aspects of An. gambiae population genetics and ecology. We critically discuss the validity of the designs and methodologies involved in an attempt to provide a sound basis for future undertakings. We also discuss new directions and priorities in the light of the recent developments toward a genetic-control strategy for An. gambia

Ein Instrument der parlamentarischen Mitwirkung im Bereich der schweizerischen Aussenpolitik : die Information und Konsultation gemäss Art. 152 Parlamentsgesetz

Dass der Weg der parlamentarischen Mitwirkung im Bereich der Aussenpolitik steinig werden sollte, widerspiegelte sich bereits in der Entstehungsgeschichte der Aussenpolitischen Kommissionen (APK). Diese haben zum heutigen Zeitpunkt unter anderem dafür zu sorgen, dass das Parlament seine Mitwirkungsrechte in auswärtigen Angelegenheiten frühzeitig und wirk¬sam wahrnehmen kann. Nebst verschiedensten Instrumenten auf Verfassungs- und Gesetzesebene steht den APK ein wichtiges Mitwirkungsinstrument zur Verfügung: die Information und Konsultation gemäss Art. 152 Parlamentsgesetz (ParlG). Seit Inkrafttreten dieser Bestimmung im Dezember 2003 offenbart sich jedoch, dass sich die praktische Umsetzung des Gesetzesartikels mit den damaligen Vorstellungen des Gesetzgebers anlässlich der Erarbeitung dieses parlamentarischen Instrumentes nicht deckt. Der Gesetzgeber wies seiner¬zeit auf das für die Umsetzung bedeutende Vertrauensverhältnis zwischen Bundesrat und Parlament hin. Allerdings beeinflussen nun Spannungen und Konkurrenz zwischen der Exekutive und der Legislative die Umsetzung von Art. 152 ParlG. Die vorliegende Arbeit versucht, die geschichtlichen Hintergründe, die Entstehung, den Sinn und Zweck sowie die Praxis von Art. 152 ParlG vor dem Hintergrund des erwähnten Spannungsfelds und im Zusammenspiel mit den weiteren Mitwirkungsinstrumenten im Bereich der Aussenpolitik darzulegen. Comme le montre déjà l'historique des Commissions de politique extérieure (CPE), la participation du Parlement à la politique extérieure n'est pas dénuée d'obstacles. A l'heure actuelle, les CPE doivent notamment faire en sorte que le Parlement puisse faire valoir, en amont et avec efficacité, son droit de participation dans le domaine de la politique étrangère de la Suisse. Outre divers instruments figurant dans la Constitution et les lois, les CPE disposent d'un important moyen de participation: l'information et la consultation au sens de l'art. 152 de la loi sur le Parlement (LParl). Depuis l'entrée en vigueur de cette disposition en décembre 2003, il s'avère toutefois que l'application concrète de cet article de loi ne ré¬pond pas entièrement aux attentes du législateur lors de l'élaboration de cet instrument parlementaire. En effet, le législateur s'était alors basé sur la relation de confiance entre le Conseil fédéral et le Parlement, relation essentielle à la mise en oeuvre de cet article. La pratique montre cependant que la mise en oeuvre de l'art. 152 LParl est influencée par des tensions et par une relation de concurrence existant entre l'exécutif et le législatif. Le présent travail entend exposer le contexte historique de l'art. 152 LParl, son élaboration, son but et sa mise en oeuvre, tout en tenant compte des éléments de tension et des autres instruments permettant la participation en matière de politique extérieure

Heterosis Increases Fertility, Fecundity and Survival of Laboratory-Produced F1 Hybrid Males of the Malaria Mosquito Anopheles coluzzii

The success of vector control strategies aiming to decrease disease transmission via the release of sterile or genetically-modified male mosquitoes critically depends on mating between laboratory-reared males and wild females. Unfortunately, mosquito colonization, laboratory rearing, and genetic manipulations can all negatively affect male competitiveness. Heterosis is commonly used to produce domestic animals with enhanced vigor and homogenous genetic background and could therefore potentially improve the mating performance of mass-reared male mosquitoes. Here, we produced enhanced hybrid males of the malaria mosquito Anopheles coluzzii by crossing two strains colonized 35+ and 8 years ago. We compared the amount of sperm and mating plug proteins they transferred to females, as well as their insemination rate, reproductive success and longevity under various experimental conditions. Across experiments widespread adaptations to laboratory mating were detected in the older strain. In large-group mating experiments, no overall hybrid advantage in insemination rates and the amount of sperm and accessory gland proteins transferred to females was detected. Despite higher sperm activity, hybrid males did not appear more fecund. However, individual-male mating and laboratory-swarm experiments revealed that hybrid males, while inseminating fewer females than older inbred males, were significantly more fertile, producing larger mating plugs and drastically increasing female fecundity. Heterotic males also showed increased longevity. These results validate the use of heterosis for creating hybrid males with improved fitness from long-established inbred laboratory strains. Therefore, this simple approach could facilitate disease control strategies based on male mosquito releases with important ultimate benefits to human health

Behavioural and electrophysiological responses of female Anopheles gambiae mosquitoes to volatiles from a mango bait

Attractive Toxic Sugar Baits (ATSB) are used in a “lure-and-kill” approach for management of the malaria vector Anopheles gambiae, but the active chemicals were previously unknown. Here we collected volatiles from a mango, Mangifera indica, juice bait which is used in ATSBs in Tanzania and tested mosquito responses. In a Y-tube olfactometer, female mosquitoes were attracted to the mango volatiles collected 24–48 h, 48–72 h and 72–96 h after preparing the bait but volatiles collected at 96–120 h were no longer attractive. Volatile analysis revealed emission of 23 compounds in different chemical classes including alcohols, aldehydes, alkanes, benzenoids, monoterpenes, sesquiterpenes and oxygenated terpenes. Coupled GC-electroantennogram (GCEAG) recordings from the antennae of An. gambiae showed robust responses to 4 compounds: humulene, (E)-caryophyllene, terpinolene and myrcene. In olfactometer bioassays, mosquitoes were attracted to humulene and terpinolene. (E)-caryophyllene was marginally attractive while myrcene elicited an avoidance response with female mosquitoes. A blend of humulene, (E)- caryophyllene and terpinolene was highly attractive to females (P < 0.001) when tested against a solvent blank. Furthermore, there was no preference when this synthetic blend was offered as a choice against the natural sample. Our study has identified the key compounds from mango juice baits that attract An. gambiae and this information may help to improve the ATSBs currently used against malaria vectors