Intra- and interspecific sex-pheromone communication in the genus Yponomeuta

ABSTRACT. Male behaviour in pheromone attraction was observed in a wind tunnel for eight species of the genus Yponomeuta Latreille. Interspecific responses and the effect of some combinations of female pheromones were also investigated. The results show that the species Yponomeuta cagnagellus (Hübner), Y. malinellus Zeller, Y. rorellus (Hübner) and Y. plumbellus (Den. & Schiff.) are isolated by the specificity of their female pheromones. The other four species, Y. evonymellus (L.), Y. padellus (L.), Y. irrorellus (Hübner) and Y. vigintipunctatus (Retz.), exhibited interspecific pheromone attraction.     

Role of host-plant stimuli in sexual behaviour of small ermine moths (Yponomeuta)

ABSTRACT. 1. Studies involving experiments with olfactometers and field experiments have shown that the release of sex-pheromone by females of Yponomeuta spp. is stimulated by the presence of host plants.
2. While in Y.evonymellus L. less females emitted pheromone in the absence of host plants, in Y.padellus L. the initiation of pheromone release was delayed.
3. Females of Y.evonymellus, Y.cagnagellus Hüb., Y.padellus and Y.plumbellus D. & S. all preferred a place with host-plant odour to one with non-host odours for sex-pheromone release.
4. Male preference for host-plant odour was demonstrated in the laboratory only for Y.cagnagellus.
5. Trap catches in the field indicated a reinforcement of female attractiveness by host-plant stimuli.     

Small-scale variation in sexual size dimorphism and sex ratio in the aquatic moth Acentria ephemerella Denis and Schiffermüller, 1775 (Lepidoptera: Crambidae)

The aquatic herbivorous and capital-breeding moth Acentria ephemerella Denis and Schiffermüller, 1775 feeds on submerged pondweeds, Potamogeton spp., and is highly preyed upon by fish in the littoral zone. We studied the spatiotemporal within-lake variability of length, sexual size dimorphism (SSD) and sex ratio of A. ephemerella pupae and of larval population densities. Population densities at three sampling sites strongly increased from July to August and were significantly higher at the Reichenau site in July. Acentria ephemerella sex ratio was male-biased at the Güttingen and Hagnau sites, but showed unbiased or slightly biased sex ratios at Reichenau. The SSD was strongly female-biased. Female size and SSD declined during summer, possibly due to reduced food quantity/quality. The SSD was highest at Reichenau, with little to no differences between Hagnau and Güttingen. At Reichenau, the high population size in July coincided with an unbiased sex ratio, and large SSD/female size due to multiple, possibly interacting factors, including fish predation.     

Sex-limited expression of ornamental feathers in birds

Extravagant secondary sexual characters show sexual size dimorphismin some species but are completely sex limited in others. Sexualornamentation has been hypothesized to benefit mainly malesthrough sexual selection, but the costs of secondary sexualcharacters initially would be experienced by both sexes. Theevolution of sexual size dimorphism of ornaments and, eventually,the complete sex-limited expression of these characters, willdepend on the effects of sexual and natural selection on thetwo sexes. A phylogenetic analysis controlling for similaritiesdue to common ancestry of 60 independent evolutionary originsof feather ornamentation in birds was used to investigate ecologicalfactors correlated with sexual size dimorphism and sex-limitedexpression of secondary sexual characters. When the size ofan ornament is large relative to body size, the trait willbe particularly costly for females, resulting in selectionfor increased sexual size dimorphism of the ornament. Indeed,sexual size dimorphism of ornaments was positively relatedto the relative size of male ornaments but was unrelated torelative size of female ornaments. Species with polygynousand lekking mating systems with little or no male parentalcare (in particular nest building and incubation) demonstratedsex-limited expression of ornaments as compared to monogamousspecies. Species with no food provisioning of offspring by themale showed a trend for increased sexual size dimorphism ofornaments. Therefore, large natural selection costs duringreproduction imposed by the expression of secondary sexualcharacters are related to the evolution of sexual size dimorphismof ornaments and eventually their complete loss from females.     

Sexually dimorphic eggs, nestling growth and sibling competition in American Kestrels Falco sparverius

1. American Kestrel ( Falco sparverius ) nestlings are sexually dimorphic, with daughters larger than sons. The larger daughters have an advantage during sibling competition for food in excess of their higher per capita food requirements, and we predicted that parents would reduce this competitive disparity by differentially enhancing the growth of sons, specifically by laying them in larger eggs.
2. In a captive breeding population, eggs producing sons were significantly larger than eggs producing daughters; laying order effects were controlled.
3. The influence of sibling egg size ratios on post-natal size relationships persisted through the nesting period, providing parents with a tool to manipulate size-related phenomena in their offspring.     

The courtship behaviour of Yponomeuta padellus

The sequence of behavioural steps from male attraction until copulation is described and analyzed for Yponomeuta padellus L. (Yponomeutidae, Lepidoptera). Males respond to a pheromone emitting female with wing fanning followed by upwind zigzagging flight. Males will land near the females and then walk while wing fanning. The antennae drum onto the substratum and the abdominal-hair pencils are displayed. When in contact with a female the male drums with his antennae onto wings, head and antennae. Mostly a clasping attempt follows. A male has a higher chance to be accepted when he firt encounters the rear of a female instead of the head. Females refuse males by walking away or wing fanning or a combination of both.

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Résumé Les séquences du comportement depuis l'attraction du mâle jusqu'à la copulation ont été décrites et analysées chez Y. padellus (L.). Les mâles réagissent à une femelle émenttant une phéromone par un hattement d'ailes suivi d'un vol en zigzag contre le vent. Les mâles atterriront près des femelles et marcheront avec leurs ailes en battement. Les antennes tambourinent le substrat et les pinceaux abdominaux sont déplyés. Lorsqu'il est au contact de la femelle, le mâle tambourine avec ses antennes les ailes, la tête et les antennes. Généralement suit une tentative d'étreinte. Les chances de succès sont les plus élevées quand les premiers contacts du mâle sont avec la partie postérieure de la femelle plutôt qu'avec la tête. Les femelles refusent les mâles en s'écartant ou en battant des ailes ou les deux à la fois.Il semble qu'en plus des stimuli cliniques, des stimuli mécaniques fournis par les écailles sont nécessaires pour que les mâles localisent la femelle et s'orientent pour une tentative d'étreinte.

     

褐巢蛾属分类修订(鳞翅目,巢蛾科,巢蛾亚科)

对褐巢蛾属 Metanomeuta Meyrick进行了修订,重新描述了模式种,讨论了其形态变异;记述2个新种,即岳西褐巢蛾 Metanomeuta yuexiensis sp.nov.和疏刺褐巢蛾 Metanomeutaspinisparsula sp.nov..文中提供了成虫和外生殖器特征图,给出了分种检索表及分布图.模式标本保存在南开大学昆虫标本室.岳西褐巢蛾,新种 Metanomeuta yuexiensis sp.nov.(图3,10,13)该种与金冠褐巢蛾 Metanomeuta fulvicrinis Meyrick外部相似,但可通过外生殖器特征区别:颚形突卵圆形,末端钝圆;雌性后阴片中部微凹,前阴片不明显,囊导管基部2/3具瘤突,交配囊长卵形.正模♂,安徽岳西温泉(30°52'N,116°22'E),1995-08-08,胡祥富采,外生殖器玻片号JQ07191.副模：8♂♂,1♀,安徽岳西温泉,1995-07-25～08-22,胡祥富采. 疏刺褐巢蛾,新种Metanomeuta spinisparsula sp.nov.(图4,11,14)该种与金冠褐巢蛾Metanomeuta fulvicrinis 相似,区别在于:体为深褐色,翅面无任何斑纹;雄性颚形突略呈舌状,末端突出,抱器腹除端部有一枚较大刺突外,无明显小刺或小刺束;雌性导管端片小且非杯状,囊导管仅基部1/2 具瘤突.正模♂,湖南石门县壶瓶山江坪(29°35'N,111°22'E;480m),2002-01-05,于海丽采,外生殖器玻片号JQO6091;副模1♀,采集资料同正模.     

Macroevolutionary patterns of sexual size dimorphism in copepods

Major theories compete to explain the macroevolutionary trends observed in sexual size dimorphism (SSD) in animals. Quantitative genetic theory suggests that the sex under historically stronger directional selection will exhibit greater interspecific variance in size, with covariation between allometric slopes (male to female size) and the strength of SSD across clades. Rensch''s rule (RR) also suggests a correlation, but one in which males are always the more size variant sex. Examining free-living pelagic and parasitic Copepoda, we test these competing predictions. Females are commonly the larger sex in copepod species. Comparing clades that vary by four orders of magnitude in their degree of dimorphism, we show that isometry is widespread. As such we find no support for either RR or for covariation between allometry and SSD. Our results suggest that selection on both sexes has been equally important. We next test the prediction that variation in the degree of SSD is related to the adult sex ratio. As males become relatively less abundant, it has been hypothesized that this will lead to a reduction in both inter-male competition and male size. However, the lack of such a correlation across diverse free-living pelagic families of copepods provides no support for this hypothesis. By comparison, in sea lice of the family Caligidae, there is some qualitative support of the hypothesis, males may suffer elevated mortality when they leave the host and rove for sedentary females, and their female-biased SSD is greater than in many free-living families. However, other parasitic copepods which do not appear to have obvious differences in sex-based mate searching risks also show similar or even more extreme SSD, therefore suggesting other factors can drive the observed extremes.     

黄基歧角螟雌雄异形现象及其雌性的发现(鳞翅目,螟蛾科)

黄基歧角螟Endotricha luteobasalis Caradja,1935广泛分布在我国南部,自发表以来未见雌性报道。本文依据采自浙江、贵州、广西和四川等四省的113只标本(其中82只为雌性)证明该种为雌雄异形种,首次报道黄基歧角螟的雌性个体,比较了雌雄外形差异,提供了成虫和雌雄性外生殖器特征图。研究标本(除指明的外)保存于南开大学生命科学学院昆虫标本室。