Eighth Abdominal Segment Research Articles

Female sex pheromone release and the timing of male flight in the red bollworm Diparopsis castanea Hmps. (Lepidoptera, Noctuidae), measured by pheromone traps

AbstractThe female sex pheromone gland of Diparopsis castanea Hmps. consists of modified intersegmental tissue between the eighth and ninth abdominal segments. Glands contain an average of 12·73 ×10–3 μg of pheromone consisting of 80·4±2·0% trans-9, 11-dodecadien-l-yl acetate (range 72·7–86·7%) and 19·6±2·0% 11-dodecen-l-yl acetate (range 13·3–27·3%). Although no significant correlation exists between female body weight and pheromone content of the gland, the duration of sex pheromone release over the lifespan of a female is positively correlated with its weight on emergence. Six behavioural steps may be recognised in the precopulatory behaviour of females but the frequency and duration of sex pheromone release is strongly influenced by both temperature and light intensity. At 25°C females typically ‘call’ on two or more occasions for 41–50% of the night, calling commencing earlier at cool (13·4°C) temperatures than at moderate (19·4°C) or warm (25·0°C) temperatures. Calling by mated females increases considerably from four to five nights after mating but is typically of shorter duration than for virgins. The dispersal flight of Diparopsis males in cotton crops commences almost immediately after sunset and before the end of dusk, with peak male catches in sex pheromone traps occurring earlier in the cooler months of May and June (20.00–22.00 h) than in November (02.00–04.00 h). The Diparopsis synthetic sex pheromone, dicastalure, traps a greater proportion of males and females both earlier and later in the night than virgin females and this ‘timing advantage’ may be important in a pheromone control programme based on disruption of communication between the sexes.

Ultrastructure of sex-pheromone gland cells and cuticle before and during release of pheromone in female eastern spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae).

The sex-pheromone-producing gland of Choristoneura fumiferana, as in other moths, is a modified intersegmental membrane between the eighth and ninth abdominal segments. Gland cells differ from epidermal cells in unmodified intersegmental membranes in their size, shape, and structure. One to 2 days before emergence of the adult, the gland cells have few microvilli and the cytoplasm contains mainly rough endoplasmic reticulum. By 1 h before emergence, the cells have the adult characteristics. The basal region below the nucleus contains Golgi complexes, lipid droplets, glycogen deposits, and rough endoplasmic reticulum. The apical region contains many microbodies and extensive smooth tubular endoplasmic reticulum. The apical surface has numerous well-developed microvilli, each of which contains a core of smooth endoplasmic reticulum. In contrast to gland cells, unmodified epidermal cells only contain rough endoplasmic reticulum and their apical projections are small and ill-defined. Cuticle of the gland and unmodified intersegmental membrane does not change after deposition but continues to resemble that of the developing gland 1 to 2 days before emergence. Pore canals are present as gaps in the endocuticle and follow the helicoidal arrangement of the microfibrils. Near the microvilli the pore canals contain a filamentous structure which is replaced by epicuticular filaments near the first lamella of the endocuticle. Groups of epicuticular filaments terminate at an oval depression in the dense epicuticle. Each oval depression opens at the surface of the inner cuticulin. Epicuticular filaments are not the immediate precursors of the pheromone. The probable role of the epicuticular filaments in pheromone synthesis and release is discussed.

Characters for determining the sex of cutworms and other noctuid larvae (Lepidoptera: Noctuidae)

External structures were found which permitted the accurate determination of males, or females, or both in the larvae of each of 40 species of noctuids.In males, the developing genitalia arise from a pyriform histoblast attached to the ventral cuticle near the anterior margin of the ninth abdominal segment. The cuticle is invaginated into this structure, which is visible externally as a slit, or as a depression, but it is often obscure. In some species the invaginated cuticle is strongly melanized, and consequently very distinct, but in most it is either colorless or too variable to be useful as the definitive sexual character.In females there is one pair of ovoid histoblasts attached to the ventral cuticle in each of the eighth and the ninth abdominal segments. Externally, the cuticle corresponding to these areas of attachment is modified; usually the cuticular sculpturing is reduced or absent, about, and sometimes beyond, these areas. Each area is usually recessed and forms a more or less distinct pit. These structures proved reliable for sexing larvae and in every species were located between the ventral and subventral setae in the eighth and ninth abdominal segments.

AN ANALYSIS OF GEOGRAPHICAL VARIATION IN THE DAMSELFLY, ARGIA APICALIS (ZYGOPTERA: COENAGRIONIDAE)

AbstractThe paper describes and maps stripe pattern variability in the damselfly Argia apicalis (Say) along the periphery of its southeastern distribution. Two major variations exist. One, the broad-striped form, has a wide, full-length humeral stripe and, in females, a well-developed middorsal thoracic stripe. Broad-striped specimens also possess larger areas of black pattern on the dorsum of the head and, in males, on the eighth and ninth abdominal segments. The second, typical form, has a reduced pattern characterizing populations west and north of southeast Georgia and northern Florida. The southeastern margin of distribution consists of broad-striped populations representing four groups of isolated populations. Isolation results from low interchange between colonies of different river systems and, within the southeast, lack of colonies on lakes, ponds, smaller streams, and river headwaters. One intergradation area between typical and broad-striped populations is known. A discussion follows relating origin of the variability to Pleistocene habitat changes.

STUDIES OF PHYSIOLOGICALLY ACTIVE ARTHROPOD SECRETIONS: VI. EVIDENCE FOR A SEX PHEROMONE IN FEMALEORGYIA LEUCOSTIGMA(LEPIDOPTERA: LYMANTRIDAE)

AbstractThe results of behavioural, chemical, and histological studies are reported showing the presence of a sex attractant in femaleOrgyia leucostigmaJ. E. Smith. A method of bioassaying the attractancy of the female moths by the use of 4-ft-long glass tubes is given. Extraction of female abdominal tips with dichloromethane yields material biologically active when tested against maleO.leucostigma.The pheromone-producing gland is a dorsally situated, crescent-shaped structure formed by modification of the epidermal cells in the intersegmental membrane between the eighth and ninth abdominal segments. The glandular cells are goblet-shaped and are arranged in an unusual manner.

The nervous system of the desert locust,Schistocerca gregaria(Orthoptera: Acrididae) with a discussion on muscle innervation

Summary A detailed illustrated account of the nervous system in S. gregaria is given. The central, peripheral and sympathetic nervous systems have been described. The central and peripheral nervous systems comprise the brain, ventral nerve cord, suboesophageal, three thoracic and five abdominal ganglia and their nerves to different parts of the body. The brain consists of proto, deuto and tritocerebrum. The suboesophageal ganglion lies below the oesophagus and is connected to the tritocerebral lobes by a pair of connectives. This ganglion gives off a pair of recurrent nerves and seven pairs of nerves supplying the mouthparts, cervical muscles, salivary ducts and prothoracic ventral longitudinal muscles. The first or prothoracic ganglion gives off a pair of recurrent nerves and five pairs of nerves supplying different prothoracic muscles, sensillae of the prosternum and forelegs. The second or mesothoracic ganglion also gives off a pair of recurrent nerves and five pairs of nerves innervating hypodermis, forewings, middle legs, different muscles of the mesothorax and the chordotonal organ. The third or metathoracic ganglion gives off five pairs of metathoracic nerves and six pairs of abdominal nerves; the thoracic nerves supply the hindwings, metasternal sensillae, various muscles and hindlegs while the abdominal nerves include dorsal and ventral nerves of the first, second and third abdominal segments supplying the abdominal muscles, pleuron, tympanum and spiracles. The dorsal nerves of the second to eighth abdominal segments form VNABIC which supply the lateral muscles and spiracle in the respective segment. The first four abdominal ganglia, i.e. fourth, fifth, sixth and seventh abdominal ganglia give off one dorsal and one ventral nerve supplying the dorsal and ventral muscles in the respective segment. In the female the ventral nerve of the seventh abdominal ganglion also innervates the oviduct. The eighth abdominal ganglion gives off six pairs of nerves which supply the muscles of the eighth, ninth and tenth abdominal segments, epiproct, paraproct, cerci and rectum. This ganglion in the male also supplies the complex genital organ and in the female sends nerves to different valves of the ovipositor. The sympathetic nervous system is divisible into stomatogastric nervous system consisting of frontal ganglion, oesophageal ganglion, hypocerebral ganglion and their nerves and ventral sympathetic nervous system comprising a single median nerve, transverse nerves and paramedian nerves.

Anatomy and histology of the circulatory system of the desert locust,Schistocerca gregaria(Forskål) (Orthoptera: Acrididae)

Summary The dorsal diaphragm extends from first to the tenth abdominal segment while the ventral diaphragm from prothorax to the eighth abdominal segment. Eight pairs of alary muscles are located in second to ninth abdominal segment. The dorsal vessel, extending from the frons to the tenth abdominal segment, is divisible into heart and aorta. There are eight heart chambers located in the second to ninth abdominal segment. The aorta in the mesothorax, metathorax and first abdominal segment bears ampullae; it extends into the head and ends in a funnel appressed to the frons. A membranous flap-like, triradiate structure is attached to the dorsal wall of the aorta near the oesophageal ganglia. The dorsal vessel bears seven pairs of ventro-lateral excurrent ostia and twelve pairs of dorso-lateral incurrent ostia, the latter bearing internal valves. In the neck region the dorsal vessel is supported by a median dorsal septum. The caudal end of the last heart chamber is attached to the tenth abdominal tergite by ...

STUDIES OF PHYSIOLOGICALLY ACTIVE ARTHROPOD SECRETIONS: I EVIDENCE FOR A SEX PHEROMONE IN FEMALEVITULA EDMANDSAE(LEPIDOPTERA: PHYCITIDAE)

AbstractEvidence is presented for the presence of a sex attractant in femaleVitula edmandsae(Packard). The ability of the virgin female to attract the male varies with age, reaching a maximum 2 days after emergence.The pheromone-producing gland is a ring-shaped structure formed by modification of the epidermal cells in the intersegmental membrane between the eighth and ninth abdominal segments.

Sex Pheromone Specificity Tests in the Tortricidae—an Introductory Report1

Laboratory and field tests were conducted with female sex pheromone extracts in 11 species of tortricids. These included Grapholitha molesta (Busck), Hedia nubiferana Haworth, Carpocapsa pomonella (L.), Paralobcsia viteana (Clemens), Ancylis comptana fragariae (Walsh & Riley), of the subfamily Olethreutinae, and Argyrotaenia velutinana (Walker) A. quadrifaciana Fernald, Archips argyrospilus (Walker), A. mortuanus Kearfott, Choristoneura rosaceana (Harris), and Pandcmis limitata (Robinson) of the Tortricinae. A slight male response to pheromone extracts of females in other species suggested similar but not identical pheromone structures. Field tests showed male specificity in all species with the exception of some attractancy of Archips mortuanus males to Argyrotaenia velutinana female extracts. Negative male stimulation was recorded in the field and laboratory with strawberry leaf roller, Ancylis c. fragariae female extract. Histological studies on the female pheromoneproducing glands revealed significant development of glandular epithelium between the eighth and ninth abdominal segments with all species except strawberry leaf roller moths.

Sex Pheromones of Noctuid Moths. X. The Morphology and Histology of the Female Sex Pheromone Gland of Trichoplusia ni (Lepidoptera: Noctuidae)12

The gland that produces the female sex pheromone of Trichoplusia ni (Hübner) is an eversible sac of glandular epithelium situated dorsally in the intersegmental membrane between the eighth and ninth abdominal segments. Histological studies indicate that the pheronione is continuously secreted by females 1–7 days old. Dissection and chemical assay confirmed that the organ described produces the pheromone.

Notched Sternite: a Mutant of Blattella germanica, with Possible Implications for the Homology and Evolution of Ventral Abdominal Structures1

Evidence from various sources indicates that blattids are dose to the stem which gave rise to the Pterygota. In addition, they still retain morphologic characteristics present in the more generalized of the living Apterygota. The notched-sternite mutation of Blattella germanica (L.) results in the appearance of additional body structures resembling those which presumably characterized ancestral insects, and which are found today among the Apterygota. These include 2 pairs of valvulae (gonapophyses) in females, styli on the eighth abdominal segment, apparent rudiments of styli on some of the pregenital segments, and a partial or complete division of the abdominal sterna into 3 plates. Mutant females are also characterized by mid-ventral membranous outgrowths in the pregenital segments. The only structures present in living insects to which these outgrowths seem at all comparable are the eversible sacs of apterygotes. A detailed study of the development and morphology of the mutant structures leads to a number of suggestions concerning the homology and evolution of some of the ventral abdominal structures. These include the proposals that structures of the genital chamber which lie anteriorly to the genital papilla belong to the seventh segment, that the first valvifer arms are homologous with the laterosternal shelf, and the first and second valvulae are homologous with eversible sacs in the sense that they appear to have developed from common antecedent structures. It is suggested also that the coxopodites or coxosternites of blattids may be composite structures, in that they include the fused elements of the telopodite as well as the coxopodite of a primitive appendage.

Studies on the hormonal control of tanning in the American cockroach—I. Release of an activation factor from the terminal abdominal ganglion

Neck ligatures placed on freshly ecdysed cockroaches fail to alter the tanning process. However, ligatures placed between the thorax and abdomen, and between various abdominal segments, always confined the cuticular darkening to the posterior portions. Freezing and thawing experiments showed that the activation factor is released within the seventh and eighth abdominal segments. Subsequent investigations on various glandular tissues within this region revealed that the terminal abdominal ganglion contained the factor. Extirpation of the ganglion does not completely abolish tanning. However, injection of ganglionic homogenates into the untanned thorax results in the tanning of abdominal ligated cockroaches and neck ligated houseflies and faceflies.

PROCTODONE, AN INSECT DEVELOPMENTAL HORMONE

1. Diapause development in larvae of the European corn borer, Ostrinia nubilalis, was shown to be dependent on a physiological factor originating in the seventh and eighth abdominal segments.2. Under conditions of an experimentally accelerated diapause development schedule (long-day photoperiod plus ammonium acetate treatment), the action of the abdominal system was required for about two days, the brain system for about five days, and the prothoracic system for about six days, in order to complete diapause and prepupal postdiapause development.3. The influence of the abdominal system was shown to be transmitted by the blood stream, rather than via, the ventral nerve cord.4. The abdominal system was postulated to elaborate and release a hormone whose physiological action is to stimulate the neuroendocrine system of the brain.5. Because the abdominal system hormone was found to originate in the epithelial cells of the anterior portion of the hindgut, it was named proctodone.6. Proctodone production was fou...

The Nervous System of Certain Abdominal Segments and the Innervation of the Male Reproductive System and Genitalia of Hyalophora cecropia (Lepidoptera: Saturniidae)1

The musculature and its innervations in the fourth pregenital abdominal segment of the adult male cecropia moth are described. Dorsal, ventral, and transverse pairs of nerve roots arising from the pregenital segmental abdominal ganglion seem homologous with those described for the pregenital segments of certain Orthoptera, the neuropteran Chauliodes formosanus , and the cecropia larva. In this lepidopteran, as in those other orders, the dorsal nerve fuses with the transverse nerve of the preceding ganglion, and the spiracular muscles are innervated from the fused branches of the dorsal and transverse nerves. The ventral nerve in this species and in some Orthoptera fuses with the transverse nerve of its own segmental ganglion. The homologies in such widely separated insect orders support the concept of a basic segmental nerve pattern within the Hexapoda. The terminal abdominal ganglion lies in the sixth abdominal segment in the cecropia male and gives rise to the lateral nerves of the sixth, seventh, and eighth abdominal segments, as well as the trunk giving rise to the branch nerves that innervate the reproductive system and the genital musculature. The vasa deferentia loop beneath the lateral nerves innervating the rectum, anal tube, and body wall in the anal area. If these relationships are homologous with the position of the lateral nerves of the 11th abdominal segment in Orthoptera, the nerves passingabove the vasa deferentia in this moth are the lateral nerves of the 11th abdominal segment, which is no longer recognizable as a segment in Hyalophora cecropia (L.).

THE POSTEMBRYONIC DEVELOPMENT OF THE FEMALE REPRODUCTIVE SYSTEM IN LIMOTHRIPS CEREALIUM HALIDAY (THYSANOPTERA: THRIPIDAE)

In the early second‐instar larva the reproductive system comprises a pair of undifferentiated ovary‐rudiments, each produced posteriorly into a solid strand of cells—the mesodermal lateral oviduct rudiments. Later in the second instar a spermathecal rudiment arises from the epidermis of the eighth abdominal segment and ovipositor valve rudiments from the eighth and ninth sterna. By the early prepupa the lateral oviducts acquire ampullae and the ectodermal structures are supplemented by a common oviduct rudiment (from the seventh sternum) and an accessory gland rudiment (from the ninth sternum). Further growth of these is followed in the pupa by the development of the vagina through ventral closure of a mid‐sternal groove on the eighth segment and by the division of the ovary rudiment into ovarioles. Meanwhile the ovipositor valves have increased in length and some of their muscles have arisen by differentiation of previously unorganized masses of myoblasts; the remaining ovipositor muscles are formed from larval muscles which change their positions but are otherwise unaltered. Though the reproductive system of Limothrips is morphologically comparable to that of less specialized Exopterygota, its development is shown to be delayed in a manner more reminiscent of the endopterygote insects.

The Internal Anatomy of the Silverfish Ctenolepisma campbelli and Lepisma saccharinum (Thysanura: Lepismatidae)1

The several organ systems of these two species are described, compared, and illustrated. Differences were found in the tracheation of the eye, the disposition of vestigial stylal tracheae, and the absence in L. saccharinum of the ventral tracheal commissure of the eighth abdominal segment. The digestive system follows a generalized plan, similar to that of Orthoptera. In C. campbelli , but not in L. saccharinum , the first five abdominal ganglia have migrated one segment forward, but each continues to innervate the segment from which it came, whether a tracheal connection with that segment is preserved or not; the different behavior of tracheae and nerves in relation to such migrated ganglia seems a result of the sequence of their formation in the embryo. In both species the dorsal vessel is pulsatile for its whole length, but little or no peristalsis was observed; instead, systoles occur alternately in an anterior and a posterior chamber which are separated by a thoracic valve. Ten pairs of ostia were observed with difficulty through the transparent integument of living C. campbelli; probably those of L. saccharinum are similar. Pericardial cells were less numerous in the former than in the latter species. Each ovary consists of five ovarioles, connected to a common duct near the base of the ovipositor; the spermatheca lies beneath the eighth abdominal ganglion and communicates with the oviduct, ovipositor, and genital pore above the eighth sternite. Males have three pairs of testes on each side of the body, each pair discharging through a common vas efferens into a vas deferens which leads to one of the two seminal vesicles; and from this a long tube, with accessory glands apparently built into it, runs to the base of the acdeagus. Apical cells, not previously known in Thysanura, were found present in the testes. Histological sections of the aedeagus and its base provide, for the first time, evidence for a paired origin of this organ in Apterygota.

POSTEMBRYONIC DEVELOPMENT OF THE REPRODUCTIVE SYSTEMS OF THE PRAIRIE GRAIN WIREWORM, CTENICERA AERIPENNIS DESTRUCTOR (BROWN) (COLEOPTERA: ELATERIDAE)

In the male larva of Ctenicera aeripennis destructor (Brown), the reproductive system consists of paired mesodermal gonads situated in one of the second to fifth segments of the abdomen, an ectodermal genital capsule and paired mesodermal ampullae situated in the ninth segment of the abdomen, and a pair of mesodermal cell strands that connect the gonads to the ampullae. In the female larva, the reproductive system consists of paired mesodermal gonads situated similarly to those of the male, paired mesodermal ampullae situated at the posterior margin of the seventh segment, and a pair of mesodermal cell strands that connect the gonads to the ampullae. During the larval stage, prepupal period, and pupal stage, the gonads and cell strands of the male develop into testes and vasa deferentia, respectively, and those of the female, into ovaries and lateral oviducts, respectively. In the male, during the prepupal period and pupal stage, the ampullae develop into the paired spermatophoral and accessory glands and the seminal vesicles; the genital capsule develops into the ejaculatory duct and external genitalia. In the female, during the prepupal period and pupal stage, the ampullae develop into the common oviduct; the vagina forms from a groove in the ventral epidermis of the eighth and ninth abdominal segments; the uterus, spermatophoral receptacle, spermatheca, accessory gland, and its duct develop from invaginations in the vaginal groove in the eighth abdominal segment; the external genitalia develop from ridges on the sternal epidermis of the ninth abdominal segment.

On the taxonomy of Rhynchophora larvae: Adelognatha and Alophinae (Insecta: Coleoptera)

Summary.Problems of phylogeny and adult classification as well as the need for identifying the numerous noxious species of short‐nosed weevils in the larval stage, which is usually polyphagous and feeds externally on roots, and therefore identifiable only by taxonomic methods, have prompted this piece of research. Some of the subfamilies used in classifying adult short‐nosed weevils are not reflected in larval taxonomy, but the current system for adults is probably not entirely natural.A general discussion of morphology shows that pigmented ocellar spots are often present, but that ocelli with a cornea are exceptional. The antenna1 segments have disappeared, only some sensorial cones and the main sensorial appendage, which in Adelognatha is wider than long and dorso‐ventrally compressed, being preserved. The mandibular cutting edge is toothed only in three systematically isolated groups. The terminology of the labial parts is discussed and “mentum” is accepted for the cardines region of the second maxillae. The chaetotaxy is amazingly similar in all forms but supplies important taxonomic characters, if not only the number of setae on a segment but their size and exact arrangement are used. On the eighth and ninth abdominal segments the number of setae is successively reduced, the second seta of the posttergnm being the first to disappear, and the first (i.e. the one nearest median line), or fourth the second. In very few genera increased numbers of setae or fissile ventral setae are found. The main seta of the spiracular area tends to be shifted caudad on the posterior segments. In many genera the apical abdominal segments show distinctive sclerotizations, three types of which are distinguished. In Maleuterpes a dorsal disc surrounded by a crown of setae is present, and a few other genera have bare flattened discs with a central pit onsome of theepipleurites.Biology and breeding methods are treated together. Parthenogenesis is frequent, and males are often unknown. Apart from a few oligophagous genera the adults show feeding preferences for young leaves more than for definite species or systematic groups of plants, and are thus polyphagous. This combination of parthenogenesis, polyphagy, and, probably frequent reproduction in several successive years renders i t easy for some species to establish themselves wherever they may be introduced. Eggs are deposited between, and glued to, two adjacent surfaces in the majority of species (Rrachyderes‐type), but Sitona, Alophus and some others drop eggs singly and a t random (Sitona‐type). The latter become black after one to two days, both types and transitions occurring within Otiorrhynchus. For oviposition of the Brachyderes‐type “pleated” strips of blotting paper can be used conveniently to receive the eggs, and this may indicate a possibility for control. The size of the eggs in proportion to the adult is discussed. At room temperature larvae hatch after ten to thirty‐two days, Sitona and some Otiorrhynchus requiring only a short incubation period, Barynotus and Alophus a long one. The young larvae of all but a few genera drop to the ground and burrow into the soil in search of roots. The first instar is almost always characterized by a clavate tip to seta w; egg‐bursters are not present, except perhaps in Calomycterus. Five to ten larval instars have been ascribed to Adelognatha.The main part of the paper is systematic and contains keys to the principal groups of weevil larvae, to three genera and species of Alophinae and to fifty genera of Adelognatha. Where several species are available or have been suitably described, the distinguishing characters are set out, mostly in keys, 102 species (among them twelve species of Otiorrhynchus and eight of Sitona) being characterized. Detailed descriptions of the fifty‐three genera and short descriptive notes on the species are appended.

Studies of British Anthomyiid Flies

A study of the immature stages of the Anthomyiid flies, Delia cilicrura, D. trichodactyla, Erioischia brassicae, E. floralis and Pegohylemyia fugax, associated with injury to cruciferous crops, has shown that the several species can be distinguished. The egg stage can be identified by the sculpturing of the chorion, except in the case of the closely related species E. brassicae and E. floralis where the sculpturing is similar but there is a considerable difference in size.The larvae can be distinguished by differences in the shape and character of the head and in its relation to the prothorax, and in the form of the mouth-parts in the three instars. The number of finger-like processes of the anterior spiracles and the number and arrangement of the tubercles of the eighth abdominal segment also contribute to the identification of the larvae.

The Post-embryonic Development of Hanseniella agilis (Symphyla)

The Post-embryonic Development of Hanseniella agilis (Symphyla)