Karsten Seidelmann - Academia.edu (original) (raw)

Papers by Karsten Seidelmann

Web Ecology

Ulbrich, K. and Seidelmann, K. 2001. Modeling population dynamics of solitary bees in relation to... more Ulbrich, K. and Seidelmann, K. 2001. Modeling population dynamics of solitary bees in relation to habitat quality. - Web. Ecol. 2: 57-64. To understand associations between habitat, individual behaviour, and population de- velopment of solitary bees we developed an individual-based model. This model is based on field observations of Osmia rufa (L) (Apoideae: Megachilidae) and describes population dynamics of solitary bees. Model rules are focused on maternal investment, in particular on the female's individual decisions about sex and size of progeny. In the present paper, we address the effect of habitat quality on population size and sex ratio. We examine how food availability and the risk of parasitism influence long-term popu- lation development. It can be shown how population properties result from individual maternal investment which is described as a functional response to fluctuations of envi- ronmental conditions. We found that habitat quality can be expressed in terms o...

Physiological Entomology, 2014

ABSTRACT Phengaris (Maculinea) butterflies are social parasites of Myrmica ant colonies. Larvae o... more ABSTRACT Phengaris (Maculinea) butterflies are social parasites of Myrmica ant colonies. Larvae of the parasite are adopted by the ant workers into the colonies. Apparently, chemical signals are used by Phengaris nausithous Bergsträsser larvae to mimic those of the host brood to be recognized by the ants. In the present study, chemical extracts of ant brood and butterfly larvae using four different solvents are tested in behavioural choice assays in search of compounds involved in the adoption process. Tetracosane is the main shared compound in all brood extracts of Myrmica rubra L. and in all larvae of P. nausithous. The attractiveness of tetracosane for M. rubra workers is confirmed by testing synthetic tetracosane in behavioural choice assays, suggesting that the adoption ritual may be initiated by tetracosane.

Journal of Insect Behavior, 1999

The ecology of a species strongly influences the strategies with which males and females maximize... more The ecology of a species strongly influences the strategies with which males and females maximize their lifetime reproductive success. When males and females do not invest equally in offspring, the sex with the higher parental investment becomes a rare resource for the other. The spatial and temporal distribution of the limiting sex forms the basis of the mating system. In

Apidologie, 2006

... Corresponding author: karsten.neumann@zoologie.uni-halle.de 1 Manuscript editor: Walter S.She... more ... Corresponding author: karsten.neumann@zoologie.uni-halle.de 1 Manuscript editor: Walter S.Sheppard ... female bees from 10 European O. rufa populations col-lected in Germany (Halle - HALL, Schkopau - SCHK, Leau - LEAU, Oranienbaum - ORAN, Gatersleben - GATE ...

Physiological Entomology, 2008

ABSTRACT Abstract The haemolymph titre of the phase-related 6-kDa peptide is determined in fourth... more ABSTRACT Abstract The haemolymph titre of the phase-related 6-kDa peptide is determined in fourth- and fifth-instar larvae, as well as in adults, by high-performance liquid chromatography. In larvae, the concentration of this peptide slowly increases towards the end of the instar to reach a maximum just before the moult. The titre is slightly higher in the fifth instar than in the fourth instar. In adults, it reaches an average concentration of 0.8 μg μL−1 of the haemolymph. In females, a peak is found at day 15 whereas, in males, there are two peaks, the first at day 9 and the second at day 15 after fledging. The role of the peptide in inducing yellow protein mRNA synthesis is investigated, as is its effect on the production of the pheromonal compound phenylacetonitrile (PAN). The peptide stimulates yellow protein mRNA synthesis, but its injection causes no change in yellow colouration. No effect on PAN production is found.

Physiological Entomology, 2003

Desert locusts, Schistocerca gregaria (Forska˚l) (Orthoptera: Acrididae), exhibit a population de... more Desert locusts, Schistocerca gregaria (Forska˚l) (Orthoptera: Acrididae), exhibit a population density-dependent phase polymorphism which includes the gradual change of many morphological, physiological and behavioural characteristics. Many volatiles associated with desert locusts have been identified recently and it is assumed that they are involved in pheromonal control of behaviour and development of locusts. Ovipositing females deposit with their egg pods several volatiles that appear to be attractive to other females resulting -possibly in combination with environmental factors -in an aggregated oviposition. Mature males release several volatiles, among them phenylacetonitrile, which are reported to accelerate sexual maturation in young males. Also, aggregation pheromone systems for hoppers and adults have been described. However, recent studies and publications shed a new light on the postulated effects of some of these volatiles. Gregarious behaviour can undoubtedly be induced by mechanical stimuli. Furthermore, the main component of the adult aggregation pheromone system, phenylacetonitrile, is found to be a repellent obviously not involved in aggregation. Comprehensive studies have demonstrated that phenylacetonitrile is used by mature gregarious males as a courtship inhibition pheromone to enhance mate guarding. Recent progress, contradictory results and perspectives in desert locust pheromone research related to reproduction are summarized and discussed in this paper.

Journal of Insect Physiology, 2002

Male desert locusts in the gregarious phase release phenylacetonitrile (PAN) on becoming sexually... more Male desert locusts in the gregarious phase release phenylacetonitrile (PAN) on becoming sexually mature. It has been assumed that this chemical is responsible for aggregation of adult desert locusts. However, PAN has repellent characteristics and is involved in sexual behavior. Mature males release PAN as a volatile to serve as a kind of olfactory concealment during mating and to prevent competing males from homosexual encounters. We conclude that PAN is a courtship-inhibiting pheromone exclusively used under crowded conditions in dense populations when high sperm competition occurs among desert locust males. By chemically enhancing their mate guarding, gregarious males improve the protection of their mate from rivals and ensure their reproductive success. 

Journal of Insect Physiology, 2003

Mature gregarious male desert locusts, Schistocerca gregaria, emit the courtship inhibition phero... more Mature gregarious male desert locusts, Schistocerca gregaria, emit the courtship inhibition pheromone phenylacetonitrile. Wings and legs, in particular the fore wings, have been identified as the main releasing sites. Abdomen and head emit only trace amounts of this pheromone. In contrast veratrole, another typical component of male volatiles, is emitted by all body parts. Epidermal gland cells in the identified phenylacetonitrile releasing appendages are the putative sites of its biosynthesis. Incubation of these body parts in the presence of (14)C-phenylalanine results in the production of (14)C-phenylacetonitrile. Some of the phenylacetonitrile appears to be degraded to HCN and benzaldehyde presumably enhancing the repellent character of phenylacetonitrile. HCN is only detectable in volatiles of mature gregarious male desert locusts. Possible advantages of the observed distribution of the phenylacetonitrile release sites and of the cyanogenesis in relation to mating behaviour are discussed.

Journal of Chemical Ecology, 2013

Pheromones serve key functions in the biology of swarming locusts. However, research has focused ... more Pheromones serve key functions in the biology of swarming locusts. However, research has focused largely on the mass-swarming desert locust, Schistocerca gregaria. We extended these investigations to the pheromonal profile of the rarely swarming American bird grasshopper, S. americana (Drury). The headspace of mature gregarious S. americana males contained three characteristic electroantennogram-active components: (Z)-3-nonen-1-ol, (Z)-2-octen-1-ol, and nonanal. These substances were accompanied by aromatics such as phenol that are also released by females and immatures. Male-specific pheromone components were released independently from epidermal gland cells, with the highest emission rate being for (Z)-3-nonen-1-ol from the abdomen and legs. The emission of the major compound, (Z)-3-nonen-1-ol, is stress-sensitive, and coincides with sexual maturity and crowding. The emission pattern strongly supports a role of (Z)-3-nonen-1-ol in the reproductive biology of S. americana. The pheromone is involved in courtship-inhibition and is used as mate assessment pheromone in cryptic female choice. In double mating experiments, females choose sperm of males with high (Z)-3-nonen-1-ol emission. Furthermore the pheromone accelerated maturation of immature adults and supports synchronization of sexual development.

Journal of chemical ecology, 2000

... and benzyl cyanide (Nolte et al., 1973; Fuzeau-Braesch et al., 1988; Luber et al., 1993; Fere... more ... and benzyl cyanide (Nolte et al., 1973; Fuzeau-Braesch et al., 1988; Luber et al., 1993; Ferenz et al., 1994; Obeng-Ofori et ... in the reservoir tube by log-linear analysis of a three-dimensional contingency table according to Adam and Enke (1972) and Warnstorff and D¨orfel (1998 ...

Chemoecology, 2005

... et al. (1994). It should be noted that guaiacol and phenol have been shown to be produced by ... more ... et al. (1994). It should be noted that guaiacol and phenol have been shown to be produced by bacteria in the locust gut (Dillon et al. 2000; Dillon & Charnley 2002). All chemicals were purchased from Sigma (Germany). 1 µl ...

Behavioral Ecology and Sociobiology, 2010

Trivers' and Willard's hypothesis that natural selection favors sex allocation in relation to mat... more Trivers' and Willard's hypothesis that natural selection favors sex allocation in relation to maternal condition assumes iteropary. Though this assumption is not met in most solitary Aculeata, the reproductive life span of semelparous females may be divided into discrete successive cycles by the risk of open-cell parasitism. Females can avoid losing their investment to parasites attacking the open cell only by limiting the provision time for each cell. The restriction of time available for the investment in a single progeny irrespective of the condition of the female leads to de facto iteropary. Moreover, in Hymenoptera, there are no costs for sex allocation due to the haplodiploid mode of sex determination. In sexually size dimorphic species, females in poor condition are predicted to invest in the smaller sex and vice versa. The resulting prediction of a conditional sex allocation in solitary Aculeata was tested in the Red Mason bee, Osmia rufa (Osmia bicornis), a stem or hole-nesting, polylectic, univoltine megachilid bee. Body size is a key component of condition in females of nest-constructing solitary bees. Large females collect the same amount of pollen and nectar in a shorter time than small ones and should suffer less from parasitism. We found that small females dealt with their handicap of a low provisioning performance by shifting the sex ratio toward sons (the smaller sex) and by reducing the body size of daughters. Large females, however, shifted their offspring sex ratio toward daughters, the sex that depends more on body size in its reproductive value. The sex ratio in the population met the expected Fisherian sex ratio. Although females allocated their investment in the sexes according to their body mass, the population-level investment was balanced.