Search results for "juvenile"
showing 10 items of 366 documents
Case of unilateral wing formation in the female of the glowwormLampyris noctiluca
2003
On July 27, 1999, the first author found a unilaterally winged adult glowworm in a park in the city of Mainz. Except for the wings on the left side, the specimen exhibited female characteristics that extended to external sexual appendages, the lantern and the gonads. The internal organization showed some remarkable differences between right (wingless) and left (winged) side. The right ovary contained three times more mature eggs than the left side and the volume of the corpus allatum of this side was about one-third larger than that of the left side. This suggests that aptery and egg maturation are affected by corpus allatum activity, i.e., juvenile hormone production. The findings do not s…
Ontogeny of Heterocypris bosniaca (Ostracoda: Cyprididae): description of postembryonic instars and rediscovery of the neglected A-9 stage
2013
Despite being the most common and widespread family of Ostracoda in fresh water, the Cyprididae are still poorly known with respect to species ontogeny. The full series of eight juvenile instars has been described in detail for just five of the approximately 1000 living species, and only in one case did this include the earliest A-9 stage. We aimed to fill this gap with a morphological study of the post-embryonic development of Heterocypris bosniaca Petkowski, Scharf and Keyser, 2000, a species with unusual morphological traits within the genus, including putatively paedomorphic characters such as valves without tubercles and the narrow calcified inner lamella on both valves. Inside the egg…
The influence of smoke volatiles on sexual maturation and juvenile hormone biosynthesis in the black army cutworm, Actebia fennica (Lepidoptera: Noct…
2000
0965-1748 (Print) Journal Article Research Support, Non-U.S. Gov't; Outbreaks of the black army cutworm, Actebia fennica, are associated with recently burned sites, where larvae feed on early successional plants. In the present paper we show that smoke volatiles stimulate juvenile hormone biosynthesis in virgin females, resulting in a more rapid rate of oocyte maturation and a significant advance in the age of first calling (the release of the sex pheromone) compared to control females. The ecological implications of this physiological effect are discussed.
Fruit Colour Preferences of Redwings (Turdus iliacus): Experiments with Hand-Raised Juveniles and Wild-Caught Adults
2004
Certain fruit colours and their contrast with the background coloration are suggested to attract frugivorous birds. To test the attractiveness of different colours, we performed three experiments in laboratory with controlled light conditions. In the first two experiments, we studied the fruit colour preferences of naive juvenile redwings. In the third experiment, we continued to investigate whether the contrast of the fruit colour with the background coloration affects the preference of both naive juveniles and experienced adult redwings. In the first experiment, juvenile birds preferred black, UV-blue and red berries, to white ones. In pairwise trials, a new set of juveniles still preferr…
Sexual cannibalism in Nephila plumipes as a consequence of female life history strategies
2002
The evolution of sexual cannibalism has been modelled as both an adaptive and nonadaptive female strategy. Recent evidence from several species suggests a connection between female foraging and sexual cannibalism, but the precise benefits for females have remained obscure. Here, we investigate the difference between cannibalistic and noncannibalistic female Nephila plumipes by removing the potential nutritional benefit of cannibalism. Courting and mating males that were killed by a female were immediately removed so that the female could not consume them. Nevertheless, cannibalistic females gained more mass from maturation to oviposition and produced larger first clutches than noncannibalis…
Microbiological transformations. 30. Enantioselective hydrolysis of racemic epoxides: the synthesis of enantiopure insect juvenile hormone analogs (b…
1993
Abstract The enantioselective epoxide biohydrolysis of the racemic benzodioxole 6,7-epoxygeraniol derivative 1 has been achieved using the fungus A. niger . This new type of preparative scale bioconversion allows the synthesis of both enantiomers of Bower's compound, an analogue of insect juvenile hormone. Biological tests showed that the 6(R) enantiomer was about ten times more active than the 6(S) enantiomer against the yellow meal worm Tenebrio molitor .
Preparation and preliminary biological screening of cholic acid–juvenoid conjugates
2020
Abstract Steroidal compounds have been utilized as carriers and for modification of physico-chemical properties of model biologically active secondary alcohols – juvenoids. Juvenoids are juvenile hormone analogues – environmentally safe insecticides, possessing significant biological activity towards different arthropods groups in focus on insect pest species. Structure modification of juvenoids plays important role to control the rate of liberation and decomposition of juvenoid in digestive system and can also play important role in the mode of action towards selected insect. This study presents an approach to the synthesis of steroidal monomers and dimers carrying one and two molecules of…
Wing feather moult and age determination of Snowy Owls Bubo scandiacus.
2012
Moult of primary and secondary flight feathers of Snowy Owls Bubo scandiacus was studied from 53 museum specimens retaining some juvenile feathers. There were no ringed Snowy Owls of known age in the skin material, and the moult pattern has thus been interpreted using the moult of Eagle Owls Bubo bubo as a model. The difference between juvenile and adult primaries is described. Greater coverts may facilitate age determination of single flight feathers. Snowy Owls start their first flight feather moult M1 by shedding the innermost 2-6 secondaries during their second summer (as 2C birds). A majority of the owls also shed primary P7 during this first moult, occasionally also P8. This moult pro…
Experimental conditions for respiration and growth studies of F0 and F1 larval and juvenile European seabass Dicentrarchus labrax
2022
Water parameters in the 2 years before spawning of F0 (08.02.2016-06.03.2018) and during larval and juvenile phase of F1: Larval period until 17.05.2018 (48 dph, 900 dd) and 01.06.2018 (63 dph, ~900 dd) for warm and cold life condition respectively, for the juveniles until 28.09.2018 (180 dph, ~4000 dd) and 12.02.2019 (319 dph, ~5100 dd) for warm and cold conditioned fish respectively. Means ± s.e. over all replicate tanks per condition. Temperature (Temp.), pH (free scale), salinity, oxygen and total alkalinity (TA) were measured weekly in F1 and monthly in F0; sea water (SW) measurements were conducted in 2017 and 2018. Water parameters during larval and early juvenile phase of F0: Larval…
Localization of quantitative trait loci for diapause and other photoperiodically regulated life history traits important in adaptation to seasonally …
2015
Seasonally changing environments at high latitudes present great challenges for the reproduction and survival of insects, and photoperiodic cues play an important role in helping them to synchronize their life cycle with prevalent and forthcoming conditions. We have mapped quantitative trait loci (QTL) responsible for the photoperiodic regulation of four life history traits, female reproductive diapause, cold tolerance, egg-to-eclosion development time and juvenile body weight in Drosophila montana strains from different latitudes in Canada and Finland. The F2 progeny of the cross was reared under a single photoperiod (LD cycle 16:8), which the flies from the Canadian population interpret a…