Uta Seibt

Sex Pheromone of the Queen Bufferfly: Electroantennogram Responses

Olfactory receptor responses (electroantennograms) were recorded from antennae of danaid butterflies. Antennae of male and female queen butterflies (Danaus gilippus berenice) respond equally strongly to the hairpencil of queen males, to its crude extract, and to one of its two identified secretory components (the ketone). Responses to the second component (the diol) are weak. Hairpencils of a related species, Lycorea ceres, which also contain the ketone, are equally effective in eliciting electroantennograms from both sexes of the queen. Antennae of another related species, the monarch (Danaus plexippus), respond to the same stimuli as does the queen. Monarch hairpencils, which lack the ketone, do not elicit electroantennograms in monarch or queen antennae.

Instrumentaldialekte der KlapperlercheMirafra rufocinnamomea (Salvadori)

Ein- bis vierteilige Klappermuster von der BaumklapperlercheMirafra rufocinnamomea, die ich in Kenia und Tanzania in den Jahren 1971–74 aufgenommen habe (Abb. 1), werden beschrieben und mit ähnlichen Befunden vonPayne (1973) verglichen. Innerhalb eines Areals ist das Muster benachbarter Lerchen gleich und außerdem über mehrere Jahre konstant; gewöhnlich antiphonieren die Tiere. Vergleiche mit Instrumentaldialekten anderer Tierarten und die Frage nach Entstehung und Weitergabe dieser Lautäußerungen innerhalb der Ontogenese werden diskutiert. Bei der Klapperlerche handelt es sich wahrscheinlich um einen Gruppendialekt. Five different types of wing-flap dialects in the flappet larkMirafra rufocinnamomea were found in Kenia and Tanzania during 1971–1974: in one area wing-flap songs consist of 1 part (fig. 1, 5), in other areas of 2 parts (fig. 1, 4) or 3 parts (fig. 1, 1 + 2) or 4 parts (fig. 1, 3). The special type of flappet-pattern is constant in one area for several years. Neighbouring individuals share the same pattern.Payne (1973) recorded similar dialects of this lark in Nigeria and Zambia (fig. 2), but he found smaller differences. Wing-flap dialects are compared with other vocal and instrumental dialects and the question of their development is discussed.

Pharmacophagy in grasshoppers?. Zonocerus attracted to and ingesting pure pyrrolizidine alkaloids

Zonocerus elegans has been found to be attracted to pure pyrrolizidine alkaloids and to ingest them. This finding makes the species likely to be pharmacophagous; also, it might provide means of controlling Zonocerus, and it indicates the importance of olfaction for localizing and recognizing host‐plants in grasshoppers.

The protective function of the compact silk nest of social Stegodyphus spiders (Araneae, Eresidae)

SummaryThis study investigates the suggested protective function of the compact silken nest of two species of social Stegodyphus spiders (S. dumicola and S. mimosarum), as a possible ultimate factor for their sociogenesis. Being inhabitants of African dry thornbush country, these spiders are endangered by overheating and desiccation. In the laboratory, both species were found to avoid temperatures >40° C. In the field, temperature in the nest between 7:00 and 21:00 h tends to be higher than air-temperature outside, and between 13:00 and 15:00 h even tends to exceed 40° C. The nest thus is of no value in temperature regulation. Nor is it effective in protecting the spiders from desiccation: Both species have a body water content of 65.2±3.8% and are extremely desiccation resistant; they survived 9 days at 37°C in an exciccator with P2O5, with a daily average % liveweight reduction of 4.94(±1.1). In the field, relative humidity inside the nest between 11:00 and 19:00 h tends to be lower than that of the air outside. Inspection of burnt areas showed that the nest does not protect the spiders from bushfire. The nest does protect from wind, hail, and direct sun-radiation; but available natural retreats, or a simple silken shield, or the funnel-shaped silk tube inhabited by solitary Stegodyphus, have the same effect.

Population history in social spiders repeated: colony structure and lineage evolution in Stegodyphus mimosarum (Eresidae).

Social cooperative spiders from diverse taxonomic families share life‐history and demographic traits, including highly inbred colony structure. The combination of traits suggests constrained pathways for social evolution in spiders. The genus Stegodyphus has three independently evolved social species, which can be used as replicate samples to analyse population constraints in evolutionary time. We tested colony structure and population history of the social S. mimosarum from South and East Africa using mitochondrial DNA variation, and we compared the results to published data for the independently evolved social congener S. dumicola. S. mimosarum had many and diverse haplotypes (5–7% sequence divergence for ND1) but colonies were monomorphic and genealogically similar haplotypes occurred in abutting regions. These findings are nearly identical to results for S. dumicola and imply similar colony‐level processes over evolutionary time in independently evolved social species. These population dynamics are discussed with respect to the apparent lack of cladogenesis in social spiders.

Structure, geography and origin of dialects in the traditive song of the Forest weaver Ploceus bicolor sclateri in Natal, S. Africa

From a 21-year-long combined field and laboratory study we describe the general song structure and local song dialects of this species. These dialects differ in syntactic and phonological charateristics. Within its first 24 months the individual learns a song from its parents and keeps that song constant throughout life. In free-living populations dialects remained constant over the total study period. We could exclude that the dialects are an acoustic window phenomenon. We found individual song variations within dialects which suggest a derivation of local dialects from family-specific songs, enhanced by man-induced habitat fragmentation.

Species cohesion despite extreme inbreeding in a social spider

Colonial social spiders experience extreme inbreeding and highly restricted gene flow between colonies; processes that question the genetic cohesion of geographically separated populations and which could imply multiple origins from predecessors with limited gene flow. We analysed species cohesion and the potential for long‐distance dispersal in the social spider Stegodyphus dumicola by studying colony structure in eastern South Africa and the cohesion between this population and Namibian populations previously published. Data from both areas were (re)analysed for historic demographic parameters. Eastern South African S. dumicola were closely related to an east Namibian lineage, showing cohesion of S. dumicola relative to its sister species. Colony structure was similar in both areas with mostly monomorphic colonies, but haplotype diversity was much reduced in eastern South Africa. Here, the population structure indicated recent population expansion. By contrast, Namibia constitutes an old population, possibly the geographic origin of the species. Both the comparison of the eastern South African and Namibian lineages and the distribution within eastern South Africa show the potential for long‐distance dispersal in few generations via colony propagation.

Einflüsse auf Paarpartner und Rivalen in „Duett-Kämpfen“ revierverteidigender Vögel

Wenn Duettieren bei Vögeln der Revieranzeige und Revierabgrenzung dient, sollte man besondere Duett-Abläufe erwarten, sobald sich Paare — an der Reviergrenze oder im Revier — begegnen. Bislang sind nur wenige solcher Fälle beschrieben. Daß ein Individuum im Duett auf ein anderes als den Paarpartner Bezug nimmt, läßt sich am ehesten erkennen, wenn jedes Paar mehrere motivlich verschiedene Duette singen kann. Entgegen früheren Angaben in der Literatur fanden wir beim OrgelwürgerLaniarius aethiopicus, daß ein Duett-Duell Paar gegen Paar nicht chaotisch verlief. Ein Individuum kann seine Rufe zeitlich und motivlich sowohl auf den Partner abstimmen wie auch auf den gleichgeschlechtlichen Rivalen; Duettbeziehungen zum andersgeschlechtlichen Nachbarn kamen nicht vor, schienen sogar vermieden zu werden. Motivliche Beeinflussung zwischen konterduettierenden Paaren ist für mehrere Arten(Cisticola, Laniarius) nachgewiesen. Sie fehlt dem BartvogelTrachyphonus usambiro, der in jedem Geschlecht nur über ein Motiv verfügt, fehlt aber auch dem Drongo (Günnigmann 1973), obwohl er extrem motivreich duettiert. Solche Analysen scheinen uns vielversprechend für die Beantwortung der Frage nach der biologischen Funktion des Duettierens. Duetting as part of birds territorial behaviour in some species shows the form of conterduetting between pairs. Such performances can be analyzed with respect of partners versus rivals influencing each other. Influences upon the individual become apparent by its choice of motiv and the timing of its calls with respect to the vocalizations of another bird. For the African tropical boubou,Laniarius aethiopicus, we show that the individual during a conter-duet in fact adresses its calls to its mate and its rival, respectively. Although careful analyses are still lacking for other species, it is apparent from literature that different species differ with respect to these inter-pair influences. A closer analysis might be helpful to get insight into the more subtile functions of duetting in birds.

Ein Stimmfühlungs-Duett beim Hornraben, Bucorvus leadbeateri (Vigors)

Hornraben,Bucorvus leadbeateri, äußern, wenn sie paarweise auf Nahrungssuche durch die Steppe schreiten, in monotoner Folge dumpfe Töne (um 200 Hz). Die Partner rufen streng abwechselnd. Aus den physikalischen Eigenschaften der Laute und der Situation, in der sie auftreten, schließen wir, daß es sich um Stimmfühlungslaute handelt. Da jedes Tier den Ruf des Partners beantwortet, ändert sich die Rufgeschwindigkeit — gemäß der Laufzeit des Schalls — mit dem Abstand zwischen den Partnern. Sie haben also die Möglichkeit, aus ihrem eigenen Ruftempo (oder dem Abstand zwischen eigenem Ruf und Partner-Antwort) auf die Entfernung zum Partner zu schließen, den sie im hohen Gras nicht sehen können. The East African Ground Hornbill,Bucorvus leadbeateri, spends much of its time walking slowly through the grass searching for food. The birds are usually seen in pairs. In tall grass the pair members easily loose sight of each other. While walking they constantly utter deep (about 200 Hz) sounds, male and female strictly alternating. From the physical characteristics of these sounds some suggestions concerning their function can be deduced: 1. The low frequency contrasts well with the background noise in grassland; 2. The sound is easy to identify and to locate because of its pure tone quality and its rhythmical interruptions; 3. The only useful information that can be drawn from a monotonous repetition of identical calls is about the senders position. We therefore suggest this peculiar antiphonal duetting to be a mean of keeping contact between the partners; 4. Since each bird answers the call of its partner, the time interval between call and answer, as well as between successive calls of the same individual, carries information about the metric distance between the individuals. The call repetition rate decreases with increasing distance between the partners. The low frequency contrasts well with the background noise in grassland; The sound is easy to identify and to locate because of its pure tone quality and its rhythmical interruptions; The only useful information that can be drawn from a monotonous repetition of identical calls is about the senders position. We therefore suggest this peculiar antiphonal duetting to be a mean of keeping contact between the partners; Since each bird answers the call of its partner, the time interval between call and answer, as well as between successive calls of the same individual, carries information about the metric distance between the individuals. The call repetition rate decreases with increasing distance between the partners.

Suggested pharmacophagy of the African bushhopper Phymateus leprosus (Fabricius) (Pyrgomorphidae, Orthoptera)

The bushhopper Phymateus leprosus (Fabricius) in the field shows a special appetite for the milkweed Asclepias fruticosa. Asclepiadaceae, like Apocynaceae and Scrophulariaceae, contain cardiac glycosides. Raw and purified extracts of these plants phagostimulate larval and adult P. leprosus. We also screened natural and half-synthetic compounds found in those plant extracts. While saponins and sapogenins did not stimulate the animals, many cardiac glycosides and aglycones, offered on filter paper, proved to be phagostimulants.