Male search behavior of the stonefly,Pteronarcella badia (hagen) (Plecoptera: Pteronarcyidae), in relation to drumming

The mating system of many northern hemisphere stoneflies involves vibrational duetting, yet searching behavior in relation to the percussive communication has remained unreported. The communication-search system of a Colorado population of the ubiquitous western stonefly Pteronarcella badiain an experimental arena entails (1) a ranging search by calling virgin or polygynous males until duet establishment with virgin females, (2) continued intermittent duetting while the male engages in a local search and the female remains stationary, and (3) a tactile-based find of the female, followed by immediate mounting and mating. The average 234-s find time for pairs engaging in strong, continuous duets was significantly shorter than those for nonduetting or anomalously duetting pairs. Males of strongly duetting pairs made significantly more turns toward the female during search than in anomalously duetting pairs, and their local search pattern appears to be a triangulation aided by resource-specific (female) vibrational cues. Males displayed a wide range of fitness, based on searching time, and an increased number of duets significantly reduced finding time. Potential female selection and possible extrapolation of these experimental results to natural field conditions are discussed.     

A comparison of buttress drumming by male chimpanzees from two populations

Wild chimpanzees (Pan troglodytes) produce low-frequency sounds by hitting the buttresses and/or trunks of trees. This buttress drumming occurs in discrete bouts that may be integrated into the phrase sequence of the chimpanzees long-distance vocalization, the pant hoot. The aim of this study was to investigate whether regional variation exists in the drumming behavior of male chimpanzees from Kibale National Park (Kanyawara community), Uganda, and Taï National Park, Ivory Coast. Recordings were made during a 6-month field season at Taï in 1990, and a 12-month field season at Kanyawara in 1996–1997. Acoustic analysis revealed the following: (1) Kanyawara males drummed significantly less frequently in conjunction with a pant hoot or hoot than did Taï males; (2) drumming bouts by Kanyawara males included significantly fewer beats, and were significantly shorter in duration, than those of Taï males; these differences disappeared when only those bouts produced in conjunction with a call were compared; (3) when Kanyawara chimpanzees did call and drum together, they tended to integrate drumming into the vocalization at a later point than did Taï males; and (4) individual differences in the temporal patterning of drumming bouts were not apparent for Kanyawara males, whereas a previous analysis revealed individual differences among Taï males.     

Study of the sound produced byPimpla instigator [Hymenoptera,Ichneumonidae] during host selection

When females ofPimpla instigator inspect objects as possible oviposition sites, they use their antennae to make the objects resonate. The antennae are not used as drum sticks, but serve merely to transmit shock waves generated within the female's body. Transmission of the shock waves to the substrate is mediated through vesicles situated at the extreme tip of the distal segment of each antenna. The present results support the hypothesis that acoustical inspection of the environment is a part of the exploratory behaviour of this insect.      

Physical and chemical characteristics of Aloe ferox leaf gel

Aloe ferox leaf gel differs substantially from that of Aloe vera but almost no commercially relevant data is available this species. Leaf dimensions, gel yields and gel compositions were studied, based on samples from several natural populations. Glucose is the only free sugar in aloe gel (0.1 to 0.4 mg ml^− 1 in A. ferox). Monosaccharides released after hydrolysis show potential for gel fingerprinting and allow for a distinction between A. ferox and A. vera. The former yields various combinations of glucose and galactose as main monosaccharides, while the latter yields only mannose. Further variation studies are recommended because A. ferox appears to have three different gel chemotypes. Conductivity shows species-specific ranges — in A. ferox below 3000 μS cm^− 1 in fresh gel and above 3100 μS cm^− 1 in aged gel (corresponding values for A. vera were 1670 and 1990 μS cm^− 1). The level of phenolic (bitter) compounds in A. ferox gel can be reduced by treatment with activated charcoal, resulting in a small loss of total dissolved solids. Alcohol precipitable solids and insolubility are useful variables for quality control of gel powder. The methods and data presented are the first steps towards developing quality criteria for A. ferox leaf gel.     

Apparent influences of host-plant distribution on the structure and the genetic variability of local populations of the Purple Clay (Diarsia brunnea)

Diarsia brunnea (Lepidoptera, Heterocera, Noctuidae, Denis and Schiffermuller, 1775) is an abundant oligophagous moth occurring in the French Pyrenees. No or little influence of the forest type was found on population densities. In order to study the genetic structure of two separate moth populations in a natural forest and in a plantation, genomic fingerprinting with ISSR markers (Inter Simple Sequence Repeats) was used. The goal was to search for potential spatial structuring which could be influenced by differences in forest type.     

Temperature and enzymic control of malate metabolism in berries of Vitis vinifera

The specific activities of grape enzymes concerned with malic acid metabolism were determined at various stages of berry development under two temperature regimes. It was found that the lower acidity levels occurring in high temperature grapes at maturity are due to a changed pattern in acid breakdown rather than to reduced malic acid accumulation. The differences in acid disappearance cannot be explained by a shift in relative enzyme activities towards malate consumption with rising temperature.     

Parturition in the tsetse fly Glossina morsitans: Pattern of activity,sound production and evidence for control by the mother's brain

The mature tsetse larva descends slightly in the uterus causing a protrusion of the female's abdomen and a thrusting open of the female vulva 5–6 h before parturition. Coinciding with larval descent, the female becomes conspicuously restless. The activity pattern monitored by measuring oxygen consumption shows a progression of four discrete stages of activity before and after parturition. Immediately following parturition, the female emits a low frequency sound of 5.8 min duration that differs markedly from sounds produced during feeding or mating. Parturition can be blocked by neck-ligation of the female, thus suggesting a crucial role for the brain. Both neural and hormonal pathways appear to be involved. Transection of the nerve that innervates the uterine muscles reduces the incidence of successful parturition, and parturition in neck-ligated females can be stimulated by transfusion of haemolymph from females that have recently given birth. When parturition is blocked, larvae are retained in utero but eventually pupariate after a delay of 2.3 days.     

Lateralization and motor stereotype of song production in the brown-headed cowbird

Song production in adult brown-headed cowbirds(Molothrus ater ater) is lateralized, with a slight right syringeal dominance. The left size of the syrinx produces low-frequency (200–2000 Hz) notes within the introductory note clusters, while the right side produces the higher-frequency (1500–6000 Hz) introductory notes, the interphrase unit (10–12 kHz), and the final high-frequency whistle (5–13 kHz). Cross-correlation analyses reveal that individual cowbirds produce each of their four to seven song types with a distinct stereotyped motor pattern–as judged by the patterns of syringeal airflow and subsyringeal pressure. The acoustic differences across song types are reflected in the differences in the bronchial airflow and air sac pressure patterns associated with song production. These motor differences are particularly striking within the second and third introductory note clusters where there is a rapid switching back and forth between the two sides of the syrinx in the production of notes. These motor skills may be especially important in producing behaviorally effective song. 1994 John Wiley & Sons, Inc.     

Sexual Dimorphism of the Larynx of the Mongolian Gazelle (Procapra gutturosa Pallas, 1777) (Mammalia, Artiodactyla, Bovidae)

The larynges (except for the epiglottis) of two adult Mongolian gazelles, one male and one female, were dissected. This species is characterized by a pronounced sexual dimorphism of the larynx. Dimorphism with regard to the size of the entire larynx and of the thyroid cartilage is about 2:1 whereas the difference of mean body mass is about 1.3:1 between males and females. Unexpectedly, and in contrast to other bovids, the larynx of the male Mongolian gazelle has a paired lateral laryngeal ventricle. However, in contrast to horse, dog, pig and many primate species also possessing such a paired ventricle, its rostral opening in the Mongolian gazelle is situated lateral to the corniculate process of the arytenoid cartilage. The neck of the laryngeal ventricle is embraced by the bifurcated cuneiform process of the epiglottis. Despite the enlarged laryngeal cartilages, the vocal process of the male arytenoid cartilage is relatively shorter than that of the female. The male thyroarytenoid muscle is clearly separated into a rostral ventricular muscle and a caudal vocal muscle whereas the female's, as in other bovids, is almost uniform. The lateral sac of the two-chambered laryngeal ventricle in the male projects laterally between the ventricular and the vocal muscle. As in the domestic bovids and in many other artiodactyls the larynx of the male Mongolian gazelle is lacking any rostrally directed membraneous portion of the vocal fold. Instead, the thick and tough bow-like vocal fold projects caudally into the infraglottic cavity and is supported by a peculiar pan-like fibroelastic pad. This resilient element, situated medial to the bipartite thyroarytenoid muscle, might be a homologue of the vocal ligament, eventually including lateral portions of the elastic cone. A fibroelastic pad is absent in the female. The resilient floor of the laryngeal vestibulum, ventral to the fibroelastic pad, is rostrally and caudally subducted by tube-like spaces. Evolutionary enlargement of the male larynx, including the vocal folds, and of the caudal portions of the vocal tract may have shifted the fundamental and formant frequencies to a lower register. The paired lateral laryngeal ventricle might produce an amplitude increase of the vocalizations assisted by differential action of the bipartite thyroarytenoid muscle. In addition, the peculiar shape, size and tough consistency of the male vocal folds may, as in roaring felids, assist in producing high amplitude and low frequency vocalizations. Perhaps the biological role of the enlarged male larynx of Procapra gutturosa has evolved in relation to its mating system. In the rutting season, dominant males establish individual territories and maintain harems. During prolonged courtship prior to mating, these males perform an acoustic display uttering loud and guttural bellows. In addition, the bulging ventral neck region of males may serve as an optical attractant for the females. Thus, the evolution of the enlarged larynx of the male Mongolian gazelle may have been favoured by sexual selection.     

Pathophysiological influences of the Heterorhabditis bacteriophora complex on seventh-instar larvae of Galleria mellonella: Effect on silk production

Oral introduction of invasive juveniles of Heterorhabditis bacteriophora results in an inhibition of silk production by seventh-instar larvae of Galleria mellonella. The inhibition can be duplicated by intrahemocoelic injection of its bacterial associate alone. The inhibition varies directly with dose and is correlated with a progressive increase in hemolymph bacterial titer.     

Temporal patterns of intra- and interspecific acoustic signals differ in two closely related species of Acanthoplus (Orthoptera: Tettigoniidae: Hetrodinae)

Males of the closely related African tettigoniids Acanthoplus discoidales and Acanthoplus longipes produce a long-lasting calling song and a short disturbance sound. The temporal patterns of the sounds were analysed in respect to species differences and song type differences. The calling songs of both species consist of impulses which are separated into verses of two syllables, with fewer impulses in the first syllable. A. longipes produces more impulses in each syllable than A. discoidales and has longer verse durations, verse intervals and syllable intervals. Also, the disturbance sounds, produced after mechanical stimulation, contain distinct verses of impulses. The disturbance sound of A. longipes has a higher number of impulses per verse than that of A. discoidales. The frequency spectra of the songs in both species have similar peak frequencies (around 12.5 kHz) and both species have their greatest hearing sensitivity in the range between 5 and 10 kHz. Females of A. longipes perform phonotaxis only to songs with a species-specific temporal pattern. By contrast, females of A. discoidales react positively to calling songs of both species.     

Infectivity of a microsporidium of mosquitoes (Nosema algerae) to larval stages of Schistosoma mansoni in Biomphalaria glabrata

Lai P. F. and Canning E. U. 1980. Infectivity of a microsporidium of mosquitoes (Nosema algerae) to larval stages of Schistosoma mansoni in Biomphalaria glabrata. International Journal for Parasitology10: 293–301. Nosema algerae derived from a closed colony of Anopheles stephensi was fed to Biomphalaria glabrata infected with Schistosoma mansoni. Mother and daughter sporocysts became hyperinfected but the snail tissues remained free of the microsporidia except for rare small aggregates of spores. These lay close to the sites occupied by mother or daughter sporocysts and were probably liberated from them. Irrespective of dose, fewer snails contained infected sporocysts when spores were given at 7 days post-miracidial infection than when given at 14 days. These periods corresponded respectively to stages when mother sporocysts only or daughter sporocysts as well were present in the snails. Infection of the sporocysts began in the tegumental cells, spread to the brood chamber and ultimately to the cercariae themselves. Heavily infected sporocysts contained fewer developing embryos. Doses of 10⁶ and 10⁷ spores/snail caused significant depression of cercaria output when given at 14 days but not at 7 days.