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In aerial animals, flight morphology needs to be designed to allow daily behavioural activities. Within species differences in behaviour can therefore be expected to relate to differences in flight morphology, not only between males and females but also between same-sex members when they use different behavioural strategies. In female polymorphic damselflies, one female morph is considered a male mimic that resembles the male's body colour and behaviour (andromorph), whereas the other is dissimilar (gynomorph). Here, we questioned whether males, andromorphs, and gynomorphs of the damselfly Enallagma cyathigerum (Charpentier, 1840) differ in flight morphology, with andromorphs being more similar to males than gynomorphs. In addition, we evaluated whether differences in flight morphology are consistent or whether some morphs are more plastic in response to seasonal environmental fluctuations. Most morphometrics showed similar seasonal plasticity for males and both female morphs, which could only partly be explained from allometry. Consistent with high manoeuvrability in flight, males had broader wings and lower wing loading than females. Variation between female morphs was less pronounced, with no consistent differences in length, aspect ratio, total surface, and wing loading. However, we detected morph-specific differences in shape and width, with andromorphs having broader wings than gynomorphs similarly to males. Chez les animaux qui vivent en milieu aerien, la morphologie du vol doit etre organisee de fargon a permettre les activites comportementales quotidiennes. An sein d'une meme espece, on pent donc s'attendre a ce que les differences de comportement soient reliees a des differences de morphologie du vol, non seulement entre les males et les femelles, mais aussi entre les membres d'un meme sexe qui utilisent des strategies comportementales differences. Chez les demoiselles polymorphes femelles, une des formes femelles (l'andromorphe) est consideree etre un mime du male et sa couleur corporelle et son comportement ressemblent a ceux du male, alors que l'autre forme (la gynomorphe) est differente du male. Nous recherchons ici si les males, les andromorphes et les gynomorphes de la demoiselle Enallagma cyathigerum (Charpentier, 1840) different dans leur morphologie du vol et si les andromorphes sont plus semblables aux males que les gynomorphes. De plus, nous evaluons si les differences de morphologie du vol sont stables on si certaines formes d'individus ont plus de plasticite en reaction aux fluctuations environnementales saisonnieres. La plupart des donnees morphometriques affichent une plasticite saisonniere semblable chez les males et les deux formes de femelles, qui ne pent s'expliquer qu'en partie par l'allometrie. En accord avec leur plus grande manoeuvrability an vol, les males possedent des ailes plus larges et une charge alaire plus faible que les femelles. La variation entre les formes femelles est moins prononcee et il n'y a pas de differences constantes dans la longueur, l' allongement d' wile, la surface totale et la charge alaire. Nous avons decele, cependant, des differences specifiques a la sorte de femelle dans la forme et la largeur de l'aile; comme les males, les andromorphes possedent des ailes plus larges que celles des gynomorphes. [Traduit par la Redaction], Introduction In aerial animals, the design of the flight apparatus is expected to have a strong effect on fitness, since activities such as predator avoidance, foraging, and courtship behaviour are [...]

A discussion to integrate the current approach for studying host selection by phytophagous insects based on the optimal oviposition theory that is the preference-performance hypothesis with the optimal foraging theory is presented. It is concluded that optimal foraging may shape host preference patterns of phytophagous insects and an integration of the two theories in plant-insect research may provide a better understanding of plant-insect interactions.

The [C.sub.3]-[C.sub.4] hypothesis states that plants possessing the [C.sub.4] photosynthetic pathway are a poorer food resource for herbivores than those possessing the [C.sub.3] pathway, and that this difference is reflected in a tendency for herbivores to avoid feeding on [C.sub.4] species. We tested this hypothesis by studying host preference of two oligophagous grass miners, Chromatomyia milii and C. nigra (Diptera: Agromyzidae). Multiple-choice experiments between four [C.sub.3] and four [C.sub.4] grasses, two-choice experiments between combinations of [C.sub.3] and [C.sub.4] grasses, and no-choice experiments demonstrated a clear feeding and oviposition preference for [C.sub.3] grasses by both miners. Feeding and oviposition were very rare to absent on all [C.sub.4] grasses. Nutritional-quality analyses showed that water, protein, amino acid, and lignin content did not differ between [C.sub.3] and [C.sub.4] grasses; only the soluble carbohydrate content proved to be significantly lower in [C.sub.4] grasses. We postulated and tested a new explanation for [C.sub.4] avoidance, the 'physical-constraint hypothesis,' which states that physical constraints imposed by a smaller interveinal distance in [C.sub.4] grasses may cause [C.sub.4] avoidance. Interveinal distances of [C.sub.4] grasses were significantly smaller than those of [C.sub.3] grasses, and their ranges did not overlap. Several observations strongly suggested that interveinal distance influences feeding and oviposition patterns. Firstly, the ovipositor and eggs of both miners were too wide to fit between two adjacent veins of [C.sub.4] grasses. Secondly, feeding punctures initiated on [C.sub.4] grasses were smaller than on [C.sub.3] grasses, and feeding-puncture size was correlated with interveinal distance. Regression analysis showed that feeding and oviposition preference were positively related to interveinal distance but not to carbohydrate content. We conclude that our observations are consistent with the physical-constraint hypothesis rather than the nutritional-quality hypothesis. Key words: [C.sub.3]-[C.sub.4] hypothesis; [C.sub.3] and [C.sub.4] plants, anatomical differences; [C.sub.3] and [C.sub.4] plants, nutritional differences; Chromatomyia; grass miners; grasses; herbivore preference and performance: [C.sub.3] vs. [C.sub.4]; interveinal distance as a physical constraint; leaf miners; photosynthetic pathway; plant-insect interactions; venation in plants.

Red Lists are used to assess the extinction risk of species. Regional IUCN criteria were applied to categorise 42 indigenous freshwater fish species in Flanders into Red List categories. As such, three species are assessed as Regionally Extinct, eight as Critically Endangered, two as Endangered and eight as Vulnerable. A further five species are considered Near Threatened, 15 species as Least Concern and one species is Data Deficient. Five species disappeared from the Regionally Extinct category compared with the previous Red List (1988) as a consequence of improved water quality of estuaries and reintroduction programmes. In total, 62% of the freshwater fish species in Flanders was considered extinct or threatened. This is higher than neighbouring regions and Europe as a whole (44%). This new Red List of freshwater fishes in Flanders can be used to inform conservation actions. [ABSTRACT FROM AUTHOR]