Flagellar Segments Research Articles

On the [formula omitted] for calculating Bayes credible intervals for fraction noncomforming : B. J. Nicholson. IEEE Trans. Reliab.R-34(3), 227 (1985)

Five biotypes of Ephedrus plagiator (Nees, 1811) were investigated on the basis of three meristic and nine ratio characters, using numerical methods. The attribution of biotypes was given by Unweighted Pair-Group Method Arithmetic Average Cluster Analysis and Canonical Variates Analysis. Specimens of Ephedrus plagiator reared from Dysaphis Börner spp. on Malus domestica Borkh., 1803 showed clear distinction from other Ephedrus plagiator biotypes by the number of longitudinal placodes on the first and second flagellar segments, respectively, the shape of metasomal tergum I and the host range. On the basis of the above-mentioned characters we are presenting the formal description of the new species, Ephedrus dysaphidis n. sp. which belongs to Ephedrus plagiator species group.

Architecture of a lamellicorn flagellum (Phyllopertha horticola, scarabaeidae, coleoptera, insecta).

The distal three of the seven flagellar segments of the scarabaeid beetle Phyllopertha horticola are lamelliform, gathered into a club, and possess five sensillar fields that are packed with sensilla placodea. The most proximal surface of the club bears only hair-shaped sensilla. On the inner four sensillar fields a narrow central elongated zone houses pit organs and cavities with sunken sensilla placodea and other sensilla. The most distal, fifth sensillar field is smooth. The sensilla placodea seem to be of several types. The only distinct difference between the sexes is the shorter and more rounded lamellae of the female. The total count of sensilla placodea in males outnumbers that of the females by about 60%.

The antennal thermoreceptor of the camel cricket, Tachycines asynamorus

The antennal thermoreceptors of the camel cricket, Tachycines asynamorus, were investigated electrophysiologically and with the scanning electron microscope. In addition, the behaviour of the camel cricket was examined in a temperature gradient. The thermoreceptors were found in coeloconic sensilla together with a pair of antagonistic hygroreceptors. This sensillum comprises a pit (opening dia: ca. 5 μm) and a swollen-tipped and cone-shaped peg (tip dia: ca. 0.5 μm) at the bottom. The sensilla are distributed on the flagellar segments laterally to the body axis. The response to a rapid temperature drop occurred in a phasic-tonic manner. The magnitude of the response increased with an increasing drop in the temperature. The static response was dependent on the adaptation temperature (range of 20–40°C) and was largest when the receptor was adapted to 20–30°C. The sensitivty to rapid temperature drop is also dependent on the adaptation temperature, i.e. it is high when the receptor is adapted to temperatures giving a large static activity. The animals crowded together in an area which was at 20–25°C when subjected to a temperature gradient (10–35°C). The temperature “preferred” by the animals was the same as the temperature at which the receptor was most active and most sensitive.

Sensilla on the Antennal Flagellum of the Bertha Armyworm Moth, Mamestra configurata Walker (Lepidoptera: Noctuidae): a Scanning Electron Microscope Study

The antennae of male bertha armyworm moths, Mamestra configurata Walker, are setiform and possess, on average, 72 flagellar segments. A terminal organ is found at the tip of the scape as well as three types of sensilla trichodea on each flagellar segment. One type of sensillum chaeticum, two types of sensilla basiconica, one type of sensillum coeloconicum, one type of sensillum styloconicum, and one type of sensillum auricillicum are also found on each segment. Female antennae differ from male antennae in possessing two additional short sensilla chaetica on each flagellar segment and in lacking the long, hooked, sensilla trichodea.

Fine structure of antennal mechanosensilla of adult Rhodnius prolixus stål (Hemiptera: Reduviidae).

Each antenna of both sexes of adult Rhodnius prolixus has approximately 570 mechanosensitive neurons that innervate five morphologic types of cuticular mechanosensilla: campaniform sensilla, tapered hairs, trichobothria, and type I and type II bristle sensilla. Each campaniform sensillum and tapered hair is presumably innervated by one mechanosensitive bipolar neuron and probably functions in proprioception. The campaniform sensilla being located at the base of the scape could monitor the position of the antenna. Tapered hairs are found at the distal margin of flagellar segment I and projecting laterally from the bases of the pedicel and scape. They probably provide information about the relative positions of the antennal segments. Seven trichobothrium are located on the pedicel and three on flagellar segment I. Each trichobothrium has a long filamentous hair inserted into the base of a socket that extends inwardly as a cuticular tube and is innervated by one bipolar neuron with a tublar body, a parallel arrangement of microtubules associated with electron-dense material. The trichobothria may respond to small variations in air currents. Type I bristles occur at the base of the antenna and are the most numerous type of mechanosensillum; an average of 452 occur on each antenna of females and 440 on males. The bristle is curved toward the antennal shaft and is serrated distally. Type II bristles are located distally and are the second most numerous type of mechanosensillum; an average of 88 were counted on each antenna of females and 94 on males. The type II bristle is straight with small, longitudinal, external grooves and projects laterally from the antennal shaft. Each type I and II bristle sensillum is innervated by a bipolar neuron whose dendrite is divided into an inner and outer segment. The outer segment is encased by a dendritic sheath which may be highly convoluted and distally contains a tubular body. Two sheath cells are associated with each sensillum. Both types of bristle sensilla have a tactile function. The tubular bodies of both types of bristle sensilla have a complex structure indicating that they are very sensitive. Variations in the amount and arrangement of the electron-dense material at the tip of the tubular bodies may reflect differences in viscoelastic properties that underlie functional characteristics.

Sensory organs inIps typographus (Insecta: Coleoptera) ? Fine structure of antennal sensilla

The antennal sensilla inI. typographus are almost exclusively confined to the flattened terminal flagellar segment. The sensillar types have distinct distribution patterns in the three areas where they are found. Judging from the ultrastructural characteristics the following functions can be assigned to the sensillar types: chemoreception, single-walled and double-walled sensilla; chemoreception/mechanoreception, terminal-pore sensillum. Moreover there are two types of mechanoreceptors, one of which is connected to a bristle, whereas the other terminates within the cuticle of the flagellar segment.

Morphology and Distribution of Sensilla on the Antennae and Mouthparts of Hypochlora alba (Orthoptera: Acrididae)

Sensilla on antennae and mouthparts of immature and adult Hypochlora alba (Dodge), a monophagous grasshopper, were observed with a scanning electron microscope. The antenna contains sensilla trichodea (s.t.) on the scape and pedicel and four types of sensilla brasiconica (s.b.) on the flagellum. The s.b. include long, thick-walled uniporous and short, multiporous chemoreceptors. Males have 50 to 80% more s.b. types I to III than females. Sensilla coeloconica with strongly ribbed pegs are abundant. Rows of cuticular plates with apical papillae ring the distal margins of flagellar segments. A rosette of cuticular plates occurs on the dorsal side of the antepenultimate segment. Maxillary and labial palpi have the same types and distribution of sensilla which include long s.t. primarily on the distal segment and four types of s.b. Types III and IV s.b. are terminal chemoreceptors on the distal segment; the predominant type III is ribbed and uniporous. The total number of terminal sensilla is less than that on polyphagous species of grasshoppers. The posterior surface of the clypeo-labrum contains three asymmetrical pairs of hair tracts, a central hair group and three types of s.t. Four types of chemoreceptor groups occur (A1 to A3, A10) which consist of pegs, domes or bulbous sensilla. Other bulbous sensilla present are types 9, 11, and 12, the latter forming longitudinal strands of pillow-like structures. Type 13 hairs are elongations of swollen areas on longitudinal strands.

Effect of temperature on the duration of egg development, and moulting and growth in juveniles of Crangonyx pseudogracilis (Crustacea: Amphipoda) in the laboratory

SUMMARY. The interval between moults is an extension of egg development time, increasing from birth to sexual maturity which is probably reached at instar 6 or 7. The duration of each instar increased with the animal's age. Incubation time for eggs and the intermoult interval have the same curvilinear inverse relationship with water temperature in the range 3.5–25°C. Results are expressed as degree‐days above predicted threshold temperatures of 3.8°C for eggs and 3.2°C for instar 1 after birth, but inverse power‐law relationships were a better fit to the results, with exponents of ‐ 1.355 for eggs, ‐ 1.263 for instar 1 and ‐ 1.37 to ‐ 1.92 for instars 2–4. Temperature — dependence apparently altered in instars 5 and 6 at 15–25°C. From a multiple regression of geometric mean moult interval (Mi, days) against mean age (A) and temperature (T, °C), Mi= 56.4 T−0.7 e0.016A, with mean ages of 106 days at 15°C and 85 days at 25°C after six moults.The mean number of primary flagellar segments on the antennules increased from 4.0 in instar 1 to 6.0 in instar 2 and 8.0 in instar 3. Thereafter, segments were added less regularly to give a mean of 13.2 in instar 7. In a natural population, when the sexes became distinctive they had 11–13 flagellar segments.From birth at c. 0.05 mg wet wt, individual growth rates were highly variable; mean growth rates (Gs, % wet wt day−1) were similar in animals fed on dried, leached elm leaves and living, green leaves of Callitriche; there was a power‐law relationship with temperature in the range 3.5–25°C, (Gs= 0.27 T0.59). Faster growth rates were obtained on living leaves of Elodea. Sexual maturity is reached at c. 0.4–0.5 mg wet wt. A brief comparison is made with Gammarus pulex; C. pseudogracilis may be better adapted to warm‐water habitats.

Number of flagellar segments and moulting in the amphipod Gammarus pulex

SUMMARY. The number of flagellar segments on the antennules of Gammarus pulex was quantitatively related to body size in animals from natural populations and to moulting and instar number of isolated animals grown from birth in the laboratory. The number of segments was 5.0 at birth increasing to means of 19–20 in females and 21–22 in males at sexual maturity or c. 5 mg wet wt reached after nine or ten moults. Addition of segments to the paired flagellae of juveniles was not regular and the number of segments cannot be used to identify particular instars of individuals or to determine their age. The mean interval (days) between moults progressively increased in the later juvenile instars and was exponentially related to moult number, age and the number of flagellar segments; the moult interval is also exponentially related to these variables in adults.

Fine structure of sense organs on the antennal pedicel and scape of the male cockroach, Periplaneta americana

The ultrastructure of five types of sensory organs has been examined on the pedicel and scape of the male cockroach Periplaneta americana. Two of the five, chaetic sensillum B and campaniform sensilla, are located on both flagellar and basal segments. Chaetic sensilla B appear to be mechano- and contact chemoreceptive, and are distributed sparsely on the pedicel and scape. Campaniform sensilla are arranged circularly around the distal margin of the pedicel. The remaining three are found only on the basal segments. (i) Chaetic sensillum A: This sensillum possesses a hair bearing no pores either at the tip or the side wall. It contains one receptor cell, the cilium of which has a mechanoreceptive structure and ends near the base of the hair. Chaetic A hairs are distributed all over the surface of the pedicel and scape. (ii) Pedicelar connective chordotonal organ: This organ is an elongated mass lying under the ventral epithelium. The mass is a bundle of about 50 scolopidia. Each scolopidium contains two receptor cells. Sensory cilia of these receptor cells are capped by an attachment cell, which extends distally and joins the hypodermis ventrally beneath the pedicel—meriston joint. (iii) Johnston's organ: This organ also consists of 150 or more scolopidia. Scolopidia lie in the hypodermis of the pedicel. Each scolopidium contains three receptor cells positioned in the distal half of the pedicel. One of the three cilia extends distally and enters the canal within the pedicel—meriston joint articulation. These results suggest that a majority of sense organs on the pedicel and scape are joint mechanoreceptors.

Sensilla of the antennae and the labial and maxillary palps of Blattella germanica (L.) (Dictyoptera: Blattellidae): Their classification and distribution.

The various sensilla on the antennae and on the labial and maxillary palps of Blattella germanica (L.) were studied. Thick-walled chemoreceptors with fluted shafts and articulated bases are located on the antennae and on the labial and maxillary palps. Thin-walled chemoreceptors, without fluted shafts or articulated bases, are restricted to the flagellar segments of the antennae and to the distal segments of the palps. Antennae of adult males have more thin-walled chemoreceptors than do those of females. Hair-plate sensilla are found at the scape-head and scape-pedicel joints, and at the joints of segments on the palps. Campaniform sensilla are concentrated as a ring around the distal margin of the pedicel, and are also scattered singly on the scape, pedicel, and flagellar segments of the antennae, and on the first segment of the maxillary palps. Occasionally, a few sensilla coeloconica and cold receptor sensilla are found on the antennal flagellum.

Changes in intramembranous particle distribution in the plasma membrane of Didelphis virginiana spermatozoa during maturation in the epididymis.

Structural specializations in the plasma membrane of opossum spermatozoa obtained from different levels of the epididymis have been analyzed in thin sections and freeze-fracture replicas. The maturation process was accompanied by a redistribution of intramembranous particles in the flagellar midpiece region. Caput epididymal spermatozoa are immotile, and freeze-fracture replicas of the midpiece plasma membrane reveal a random arrangement of intramembranous particles. As spermatozoa transit the corpus epididymis, the intramembranous particles in the midpiece plasma membrane are redistributed from a random arrangement to an organized packing pattern. This redistribution apparently involves the formation of chains of intramembranous particles which gradually increase in length, orient parallel to the flagellar long axis, and ultimately form numerous parallel rows, each three to five particles wide. In cauda epididymal spermatozoa the intramembranous particles within the rows are packed in an organized manner, and few free intramembranous particles are noted between rows. Analysis of thin sections revealed that the reorganization of intramembranous particles is accompanied by the deposition of a mat of amorphous material at the cytoplasmic face of the membrane. No striking changes in intramembranous particle distribution during epididymal maturation were found in other flagellar segments or in the plasma membrane overlying the sperm head.

Morphology of the elongate sensillum placodeum on the antennae of Aphidius smithi (Hymenoptera: Aphidiidae)

Elongate placoid sensilla were present on all 20 flagellar segments in five male Aphidius smithi and all but the basal 1 of 17 segments in five females. They are oriented longitudinally, approximately equidistant around the circumference of a segment. Scanning electron microscopy of the internal cuticular surface disclosed lamellae which divide the sensillum into lateral and median channels. Many transverse ridges are present in the ceiling of the median channel. Unlike other species, there is no cuticular floor of the sensillum. Numerous nerve cell bodies in the subcuticular tissue give rise to dendritic processes, a ciliary region, and a region of dendritic branches which lie parallel to each other within the 1-μm-wide median channel underneath the 0.1- to 0.25-μm-thick dome. Each dendritic branch is composed of a neurotubule surrounded by a plasma membrane. The ascending dendrites are flanked by the microvilli of the trichogen cell. A tormogen cell encloses the trichogen cell and extends into the lateral channels of the sensillum. The relationship of minute pores in the dome with the underlying dendritic branches is unclear. The hypothesis is advanced that the sensilla may be involved in host finding through perception of infrared radiation.

The antennal movement apparatus in the small tortoiseshell (Aglais urticae L., Insecta, Lepidoptera)

1. The club-shaped antenna ofAglais urticae L. consists of 34–37 segments (scape, pedicel, and flagellar segments; Fig. 1) covered by hairs and scales (Fig. 4a). Only the scape and the pedicel can be moved by muscles (Fig. 6). 2. The head-scape joint may be compared to a ball-and-socket joint. The scape can be moved in various directions by four muscles of the head (Fig. 6a). The scape-pedicel joint functions like a hinge joint, about which axis G3-G4 the pedicel together with the flagellum can be turned upwards by one muscle and downwards by two muscles of the scape (Figs. 6b and 7). This axis, when the antenna is in resting position, makes an angle of ca. 40° (pointing forwards) with the longitudinal body axis when projected into the horizontal plane (Fig. 14). 3. The pedicel-flagellum joint, as all the successive joints, is of almost radial symmetry (Fig. 2). The flagellar segments can only be moved passively by a relatively small amount. 4. Aglais has in its pedicel a highly developed Johnston's organ (Figs. 8–10), the sense cells of which can probably perceive passive movements of the flagellum in relation to the pedicel. The active movements of the antenna can be controlled by Bohm's bristles on the scape and the pedicel (Figs. 3–7). 5. The Johnston's organ, the Bohm's bristles and the antennal muscles are supplied by nerves which arise in the deutocerebrum (Figs. 11 and 12). 6. During flight the antennae are stretched forward almost horizontally (Fig. 1). The adjustment of this antennal flight position is discussed (Figs. 13 and 14).

Flagellar sensilla of two species of Andrena (hymenoptera: Andrenidae)

The flagellar sensilla of both sexes of Andrena tibialis and A. vaga were surveyed by scanning electron microscope (SEM). The first flagellar segment is very long in both sexes of A. vaga and in females of A. tibialis. The females of both species have abundant s. basiconica, which males lack. Other sensilla found in both males and females were s. placodea, s. campaniformia, s. trichodea (of at least 3 types) and pit organs. Setae are also numerous.

L'equipement sensoriel de l'antenne d'un coleoptere troglobie, Aphaenops cryticola linder (Coleoptera : Trechinae)

The types, number and the spatial arrangement of the sensilla on the antennae of the cave beetle, Aphaenops crypticola, have been determined by scanning electron microscope. The antenna is composed of 11 segments. There are 3 types of sensilla chaetica and s. trichodea, s. basiconica, s. ampullacea, s. campaniformia, tuberculated-peg, and proprioreceptors; a special type of chemoreceptor is described and named s. basiconica inflata. The antenna has about 1800 sensilla; their number increases from the scape to the distal segment. On the flagellar segments the long s. chaetica type 1 are located on a sub-distal ring, except on the 11th segment where there are 2 rings; the short s. chaetica type 3 are distal; the chemoreceptors appear on the 3rd, 4th and 8th segments. The peg morphology of the sensillum ampullaceum is described.

Moist and dry hygroreceptors for relative humidity of the cockroach,Periplaneta americana L.

Antennal hygroreceptors of the cockroach,Periplaneta americana L. have been electrophysiologically investigated. 1. The moist and dry hygroreceptors, together with a thermal receptor, are contained in a sensillum capitulum, which is located on alternating flagellar segments (Fig. 3). 2. The responses of both hygroreceptors are of a phasic-tonic manner, and following the cessation of stimulation, decrease to a level lower than the prestimulation level (Figs. 4, 5). 3. The humidity-response relationship of the hygroreceptors is independent of stimulus flux (Fig. 7). 4. The responses of the hygroreceptors, when the whole animal and stimulus air are changed simultaneously, are larger at higher than at lower temperatures. The normalized humidity-response relationship of the hygroreceptors at different temperatures are coincident when plotted against relative humidity but not when plotted against absolute humidity (Figs. 8, 10). 5. The humidity-response relationships at different temperatures are coincident when plotted against relative humidity, but not when plotted against absolute humidity, provided that only the stimulus temperature is changed (Figs. 9, 11). 6. We conclude that the responses of the hygroreceptors depend on the relative humidity and that the mechanism of the primary process of hygroreception is non-chemical.

Antennal sensilla of three parasitic Hymenoptera

Scanning electron microscopy studies were conducted on the antennal sensory sensilla of 3 species of parasitoid Hymenoptera which utilize Heliothis virescens (Fab.) as their habitual host. Two of the species, Cardiochiles nigriceps Viereck and Microplitis croceipes (Cresson), are braconids, while the third, Campoletis sonorensis (Cameron), is an ichneumonid. Two uniquely shaped basiconic sensilla—curved non-fluted and fluted bent-tipped—are present only on the antennal flagella of C. nigriceps. Trichoid sensilla are the most abundant sensory receptors on all species studied. Placoid and fluted basiconic sensilla are numerous on all flagellar segments. Smooth basiconic sensilla are restricted in number to one per flagellar segment in each of the 3 species. An analysis of the sensory sensilla seems to indicate that the ability to search for more than one host species is not dependent upon any one morphologically unique chemoreceptor.

A comparative ultrastructural and behavioral study of the antennal sensory sensilla of the parasitoid Cardiochiles nigriceps (hymenoptera:Braconidae).

Scanning and transmission electron microscopy studies were conducted on the antennal sensory sensilla of the hymenopteran parasitoid, Cardiochiles nigriceps Viereck, of the family Braconidae. Distinct morphological differences were found between the chemoreceptors of the male and female. Curved, non-fluted, thin-walled sensilla were found to be very abundant on the male and restricted in location and number on the female. Trichoid, placoid and fluted basiconic sensilla were numerous on the antennal flagella of both sexes. Smooth basiconic sensilla were restricted in number to one per flagellar segment in both sexes. Behavioral data suggest that bent-tipped, thick-walled sensilla unique to the female are involved in detecting a chemical(s) emitted from the host, Heliothis virescens (Fab.).

Patterns of genetic mosaicism in the antennae and legs of Habrobracon juglandis

Habrobracon females which are homozygous for the mutant ebony produce a high frequency of mosaics in their progeny. This is probably due to a delay in the migration of pronuclei, which may result in a prefertilization cleavage of one or both of them. The mosaics are zygogenetic-androgenetic, zygogenetic-gynogenetic, or gynogenetic-androgenetic in origin. The distribution of phenotypes in the adult mosaics is nonrandom, probably corresponding to the original relative positions of the pronuclei. Mosaicism patterns were studied in the legs and antennae, both of which show longitudinal clonal patterns presumably resulting from oriented cell divisions during development. Mosaicism frequencies for the appendages are similar to those found in Drosophila, indicating that the imaginal discs are initiated as similar-sized groups of cells in the two insects. The Habrobracon antenna shows sexual dimorphism, containing 19 flagellar segments in the male and 12 in the female. Gynandromorphic antennae contain male, female and mixed segments, but female segments are never found distal to the twelfth segment. The gynandromorphic antennae show a high frequency of incomplete or helical segments, occurring most frequently in segments 10–13. The data are discussed in relation to the problem of appendage segmentation.