Dopaminergic control of foregut contractions in Locusta migratoria

Tyrosine hydroxylase-like immunoreactivity is present in cell bodies and processes in the brain and optic lobes of Locusta migratoria, with processes projecting along the frontal connectives to form a neuropile within the frontal ganglion. Immunoreactive cell bodies and processes are also evident in the hypocerebral and ventricular ganglia with processes extending over the foregut. Tyrosine hydroxylase is the rate-limiting enzyme in dopamine biosynthesis, and high-performance liquid chromatography coupled to electrochemical detection was used to confirm the presence of dopamine in the innervation to the foregut. Spontaneous foregut contractions are under the control of the ventricular ganglia and are absent when these ganglia are removed. Dopamine leads to an inhibition of both the amplitude and frequency of phasic contractions of the foregut that are produced when the ventricular ganglia are left attached. Dopamine has direct effects on the foregut muscle in the absence of the ventricular ganglia, inhibiting a proctolin-induced contraction in a dose-dependent manner.     

Juvenile hormone-controlled vitellogenin synthesis in Locusta migratoria fat body. Hormonal induction in vivo.

Biosynthetic processes related to the production of vitellogenin (yolk precursor protein) have been examined in the fat body of adult female Locusta migratoria. Vitellogenin-producing capacity was assayed by incubation of fat body with [³H]leucine, followed by precipitation from the medium with specific antiserum. In normal development, vitellogenin synthesis began at about Day 7 after emergence and became maximal at about Day 13, when this protein accounted for 60% of the total fat body protein output. The production of other proteins increased to a lesser extent, becoming maximal at about Day 6. The incorporation of uridine into fat body RNA rose to a maximum at Day 8, which coincided with a marked increase in tissue RNA content. The DNA content in adult female fat body approximately doubled between Days 3 and 8. Vitellogenin synthesis, and the increases in RNA and DNA, were prevented by removal of the corpora allata (the source of juvenile hormone). In allatectomized locusts, vitellogenin synthesis was induced by JH or an analog, ZR-515. Applied topically in acetone, these gave steep dose-response curves, half-maximal at 75 and 150 μg, respectively. After a single treatment with ZR-515, fat body vitellogenin production rose slowly during 48 hr, then steeply to a maximum at 72 hr, but after decay of this effect during 10 days, a second application of ZR-515 induced renewed synthesis with little initial lag. Hormone treatment produced a smaller increase in the output of other proteins, and an increase in incorporation into RNA which preceded the major rise in vitellogenin synthesis. Male fat body produced little or no vitellogenin. These results are consistent with action of JH at the gene level.     

东北地区亚洲飞蝗染色体核型分析

采用常规压片法对吉林省亚洲飞蝗Locusta migratoria migratoria(L.)的染色体核型进行分析.研究结果表明:亚洲飞蝗性别决定机制为X0型,染色体数目为2n♂=23,染色体组式4L+4M+3S+X,全部为端部着丝粒染色体,NF=23.染色体中最长(L1)与最短(S11)染色体之比大于4:1,臂比大...     

Cuticle protein in Locusta migratoria

• 1.1. The total protein content and the soluble proteins of the cuticle of male fifth instar and newly moulted adult locusts were analysed.
• 2.2. Protein was deposited in cuticle in a stepwise manner whereas chitin deposition was continuous.
• 3.3. Resorption of cuticular protein preceded resorption of chitin following apolysis.
• 4.4. Immunological and electrophoretic analyses indicated that certain cuticular proteins were also present in the haemolymph.
• 5.5. Certain water soluble proteins appeared to be characteristic of the newly deposited cuticle and were presumably bound to the cuticular matrix as development continued.
• 6.6. Despite an increase in total soluble protein following apolysis, no evidence of new proteins was detected. It was deduced that the initial step in protein resorption from the old cuticle is the release of the protein from its cuticular bonds.

     

The physiological control of drinking behaviour in nymphs of Locusta migratoria

ABSTRACT. The changes in behaviour of nymphs of Locusta migratoria in relation to free water, during the course of two different deprivation regimes are described. With no access to food or water for 24 h at 30°C, the insects responded positively to free water when it was provided. If dry food was provided during water deprivation, positive responses occurred in 8 h. The physiological changes associated with the behavioural change indicate that positive responses were correlated with a reduction in abdominal volume; experimentally induced changes confirmed this. Increased osmotic pressure did not influence the onset of drinking, but the amount of water ingested was directly correlated with the size of osmotic pressure increases.     

Insect haemolymph: Cooperation between humoral and cellular factors in Locusta migratoria

In Locusta migratoria, prophenoloxidase is present in the plasma and serum, but in reduced amounts relative to the haemocytes. This phenoloxidase activity cannot be induced by either heating or freezing and thawing and it is lost by heating at 70°C for 30 min. Both lipopolysaccharides and laminarin can elicit the prophenoloxidase activating system. These elicitors of prophenoloxidase activation are active in haemocyte lysate and in serum but never induce any phenoloxidase activity in plasma. In haemocyte lysate, the activating system is not heat resistant, and heating at 56°C for 30 min prior to incubation with laminarin or lipopolysaccharide precludes any phenoloxidase activity. Plasma contains a strong inhibitor of the prophenoloxidase activating system but serum does not. This inhibitor does not affect the phenoloxidase enzyme itself. The possible role of the activating system in immune recognition and the strategies evolved by parasites or pathogens to escape being recognized by their host are discussed.     

Phase polymorphism in Locusta migratoria: the relative effects of geographical strains and albinism on morphometrics

An albino strain, which had originated from Okinawa, Japan, and a normally coloured strain, which had originated from West Africa, have been used to study density‐dependent morphometric phase characteristics and their changes in adults of the migratory locust, Locusta migratoria (L.). By repeated crossings we also obtained congenic albinos and normal phenotypes and investigated their morphometrics with increasing West African genome, eventually reaching 99.6% West African and 0.4% Okinawa gene pool. The data were analysed by the classical morphometric ratios (F/C and E/F; F = length of the hind femur, C = maximum width of the head, E = length of the fore wings), as well as by canonical discriminant (multivariate) analysis. The latter was based on measurements of F, C and E (as above), as well as of M (minimum width of the pronotum) and H (maximum height of the pronontum). Okinawa albinos showed more solitarious morphometrics and a smaller amplitude of morphometric phase change than West African normal phenotypes. Both the morphometric ratios and the canonical discriminant analysis demonstrated clearly that these differences were caused primarily by the strain (Okinawa vs. West African). However, the pigmentation (albino vs. normal colouration) also affected morphometric phase differences; albinos showed more solitarious morphometrics and somewhat more restricted morphometric phase change than congenic normal phenotypes. The effect of the pigmentation was considerably smaller than that of the strain. The results refute Nolte's claim that albino locusts constitute an extreme solitarious phase, even under crowding. However, Nolte's less extreme claim, that albino locusts have more solitarious morphometrics than normally coloured locusts, is validated by the present results.     

Neuroendocrine control of blood lipids in the locust, Locusta migratoria

In order to determine the best conditions, the influence of various parameters on the haemolymph lipid concentration were studied. These parameters are the age, the sex and the feeding of the animals, the time and the number of the haemolymph sample-taking and the temperature of the locust culture. A large in vivo increase in haemolymph lipid concentration was obtained in locusts which received extracts of the whole CC and of their glandular or neurohemal lobes. Reversely, a decrease in this concentration was obtained in locusts operated 7 days before (cardiacectomy or glandular lobe removal). Moreover the pars intercerebralis extracts increased the level of haemolymph lipids. We conclude that adipokinetic factors are present, both in the glandular lobes of the CC and in their neurohemal lobes. It is likely that the latter partly originate from the pars intercerebralis. Results of allatectomy and injections of corpora allata extracts led to the conclusion that corpora allata contain an adipokinetic factor, the juvenile hormone. and factors that inhibit the haemolymph lipid concentration. Finally, from different injections of neurotransmitters and drugs it is argued that it is mainly octopamine which is involved in the mechanism governing the increase of the level of haemolymph lipids.     

Chiasma distribution in asynaptic Locusta migratoria

The formation of chiasmata in six full sib male partially asynaptic individuals of Locusta migratoria has been studied. The mean chiasma frequency per cell was 2.3 both at diplotene and metaphase I. Chiasmata tended to be distributed evenly among the bivalents. The frequency and distribution of the chiasmata in each type of bivalent (L, M, or S) depended on the level of asynapsis and on interference between the bivalents. Short bivalents were the most affected by interference, while M bivalents associated independently of L and S bivalent behaviour.     

Ecdysteroids During Embryogenesis in Locusta migratoria

SYNOPSIS. Ovaries of Locusta migratoria synthesize large amountsof ecdysteroids at the end of oöcyte maturation. The predominantecdysteroids in mature ovaries are conjugated 2-deoxyecdysone(100 µM) and conjugated ecdysone (50 µM) which outnumberthe corresponding free compounds by 50–100 fold. Thesevarious ecdysteroids persist during ovulation and are recoveredfrom newly-laid eggs. The conjugated maternal ecdysteroids aregradually metabolized as embryonic development proceeds; theyhave disappeared as such on day 6 after oviposition, that isafter blastokinesis and shortly after dorsal closure. Concomitantlyto this metabolism of the maternal conjugated ecdysteroids,other ecdysteroid conjugates appear in the eggs which have differentchromatographic behaviors and some of which are conjugates ofecdysone metabolites formed by the embryo. The data availableso far are compatible with the hypothesis that the maternalconjugates are hydrolysed to free 2-deoxyecdysone and ecdysoneby the embryo during early stages of development and subsequentlyconjugated to inactivation compounds. During the later stagesof embryonic development however, a de novo synthesis of ecdysoneis probable, the maternal conjugates having been metabolizedduring the earlier stages.     

The neural control of spermathecal contractions in the locust,Locusta migratoria

The innervation of the spermatheca and demonstration of neural control of spermathecal contractions in Locusta migratoria was illustrated using anterograde and retrograde fills, combined with electrophysiological stimulation and recording. The anterior portion of the spermatheca receives innervation via the receptaculum seminis nerve (N2B2) from two large ventral neurons and one dorsal neuron. All were bilaterally paired and situated in the VIIIth abdominal ganglion. Three ventral bilaterally paired neurons situated in the VIIIth abdominal ganglion also provide innervation to the posterior portion of the spermatheca via the ductus seminalis aperture nerve (N2B3). Six DUM neurons, located in the VIIIth abdominal ganglion, in addition to two centroposteriorly situated DUM neurons in the VIIth abdominal ganglion, are also associated with these two nerves. N2B4 also provides innervation to the posterior portion of the spermatheca. N2B6b is associated with sensory cells identified in the anterior lateral regions of the genital chamber. The spermatheca contracts spontaneously, with peristaltic contractions beginning at the spermathecal sac and continuing along the length of the spermathecal duct. However electrical stimulation of the ventral ovipositor nerve (VON or N2B), receptaculum seminis nerve (N2B2) and the ductus seminalis aperture nerve (N2B3) indicates that contractions are also under neural control. In particular contractions of the spermathecal sac, coil duct and anterior straight duct are initiated via motor projections from the receptaculum seminis nerve (N2B2) and posterior straight duct contractions are controlled by motor input from the ductus seminalis aperture nerve (N2B3). The results suggest that spermathecal contractions of the anterior and posterior portions of the spermatheca are under separate neural control.     

亚洲飞蝗不同发育阶段取食习性的研究

为探明亚洲飞蝗食物选择机制及寄主植物对其生长发育的影响,基于对比称重法、取食频数测定和人工饲喂方式,对亚洲飞蝗不同龄期食量变化、对不同寄主植物喜食程度及主要寄主植物对其生长发育的影响进行研究。结果表明:雌性飞蝗4龄至成虫阶段日取食量分别为0.39±0.02、0.50±0.02、0.75±0.07 g/d。雄性飞蝗4龄至成虫阶段的日取食量分别为0.30±0.06、0.41±0.03、0.71±0.11 g/d。同性别亚洲飞蝗不同发育阶段日取食量间均存在极显著差异。选取小麦、玉米、芦苇、早熟禾、苜蓿、冷蒿等植物,进行取食频数测定。亚洲飞蝗3龄蝗蝻喜食小麦和芦苇,少食苜蓿和早熟禾,偶食玉米,不食冷蒿。4龄蝗蝻嗜食玉米,喜食小麦,少食芦苇,偶食早熟禾,不食苜蓿和冷蒿;5龄蝗蝻喜食小麦,少食芦苇、玉米和早熟禾,偶食苜蓿,不食冷蒿。成虫喜食小麦和玉米,少食芦苇和早熟禾,不食苜蓿和冷蒿。分别以小麦、玉米、芦苇及三者同比例混合物饲养亚洲飞蝗3龄、4龄、5龄蝗蝻后,不同龄期蝗蝻发育历期、交配次数、产卵次数均存在极显著差异。亚洲飞蝗随着年龄段的增长取食量逐渐增加,而亚洲飞蝗同一发育阶段雌性与雄性取食量之间没有显著差异。亚洲飞蝗在每个年龄段对不同的寄主植物具有选择性,主要取食的寄主植物为小麦、玉米和芦苇。与单种饲料饲养相比,以混合饲料饲养的亚洲飞蝗发育历期最短,交配次数最少,产卵次数最多。不同寄主植物对其生长发育有显著的影响。     

Flight orientation of swarming Locusta migratoria

ABSTRACT. High-speed films of four swarms of Locusta migratoria in Australia and one swarm in New Guinea were analysed. Measurements were made of the locust's body orientation and flight track in the horizontal relative to wind direction, and of height and speed of flight. In all swarms mean course angle and mean track angle in relation to wind direction were significantly different from zero, although all indicated an upwind direction. No evidence was found for orientation to compass direction or sun. Considerable fluctuations in flight direction were measured in some individuals as they traversed the field of view. A modification of Kennedy's (1951) theory is adopted to explain the angled orientations to wind. It is suggested that this could be the result of an optical orientation mechanism.     

Interaction between octopamine and proctolin on the oviducts of Locusta migratoria

The biogenic amine octopamine and the pentapeptide proctolin are two important neuroactive chemicals that control contraction of the oviducts of the African locust Locusta migratoria. The physiological responses and signal transduction pathways used by octopamine and proctolin have been well characterized in the locust oviducts and this therefore provides the opportunity to examine the interaction between these two pathways. Octopamine, via the intracellular messenger adenosine 3',5'-cyclic monophosphate (cyclic AMP), inhibits contraction of the oviducts, while proctolin, via the phosphoinositol pathway, stimulates contraction. We have examined the physiological response of the oviducts to combinations of octopamine and proctolin and also looked at how combinations of these affect one of the main intracellular mediators of the octopamine response, namely cyclic AMP. It was found that application of octopamine to the oviducts led to a dose-dependent reduction in tonus of the muscle and also a decrease in the amplitude and frequency of spontaneous phasic contractions. Octopamine-induced relaxation was enhanced in the presence of the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX). Octopamine was also able to inhibit proctolin-induced contractions of the oviducts in a dose-dependent manner. A 10(-9) M proctolin-induced contraction was inhibited by 83% in the presence of 10(-5) M octopamine, and was completely inhibited in the presence of 10(-5) M octopamine plus 5x10(-4) M IBMX. Octopamine led to a dose-dependent increase in cyclic AMP content as measured by radioimmunoassay. In the presence of 10(-9) M proctolin, this octopamine-induced increase in cyclic AMP was reduced by as much as 60%. Proctolin also caused a dose-dependent decrease in the cyclic AMP elevation produced by 5x10(-6) M octopamine. These results indicate that octopamine and proctolin can antagonize each other's physiological response when added in combination, and that proctolin is able to modulate the response of the oviducts to octopamine by influencing cyclic AMP levels.     

X-linkage of a vitellogenin gene in Locusta migratoria

Hybridization of a cloned DNA probe to blots of restriction digests of Locusta migratoria genomic DNA showed that a vitellogenin gene is present at one copy per haploid genome in females, and at only one-half that number in males. The genomic region encompassing the 3′-coding end of the gene is polymorphic, as revealed by blots of DNA from individual locusts. DNA from some female locusts yielded two variants in this region, whereas a series of male locusts showed one variant or the other, but never both. The results demonstrate that the vitellogenin gene, which is normally expressed only in females, is X-linked in L. migratoria.     

Endocrine mechanisms controlling body-color polymorphism in locusts.

The present article reviews recent published and unpublished findings on the hormonal mechanisms for the control of body-color polymorphism in locusts. Emphasis is placed on the dark color-inducing factors and their role in the induction of various types of body coloration observed under different environmental conditions. Implantation of corpora cardiaca (CC) taken from normal nymphs of Locusta migratoria induced dark color in nymphs of an albino strain. Using the albino strain for the bioassay, a neuropeptide, [His7]-corazonin, was identified as a dark color-inducing factor for L. migratoria and Schistocerca gregaria. In the former, depending upon the dose and timing of the injection, this peptide and juvenile hormone developed various body colors looking like those found in nature. The body coloration characteristic of gregarious forms was also induced in isolated albino nymphs and field-collected solitary nymphs. In S. gregaria, on the other hand, the peptide induced black patterns, but the orange or yellow background color observed in gregarious forms was not induced when the peptide was injected into solitary individuals. [His7]-corazonin also induced darkening in other grasshoppers and locusts, but not in katydids. Albino L. migratoria developed dark color when implanted with brains or CC taken from other insects belonging to 10 major insect orders, but not with those from Coleoptera. [His7]-corazonin or a similar compound is widespread among insects and plays a pivotal role in controlling body color in some species and presumably other physiological roles in other species. Arch.     

Ultrastructure of the colon of Locusta migratoria

The ultrastructure of the colon of Locusta migratoria is described. The colon is lined by a thick cuticle that, for the most part, adheres to the underlying epithelium. The cuboid epithelial cells are characterized by moderate invaginations of the apical and, to a lesser extent, basal plasma membranes; the lateral plasma membranes are relatively flat. The bulk of the mitochondria are located in the apical region of the cell and are not particularly associated with any of the plasma membranes. The basal region of the cells contains much rough endoplasmic reticulum, glycogenlike granules, and a predominance of spherical, electron-dense bodies of various sizes. Where muscle fibers make contact with the epithelium, the cells are much reduced; the cytoplasm is usually less electron-dense, and, typically, the nucleus has a thick layer of granular material associated with the inner nuclear membrane. The apical and basal plasma membranes of the reduced epithelial cells contain numerous hemidesmosomes. The apical hemidesmosomes occur in pairs around an extracellular space that contains electron-opaque material. The latter forms tonofibrillae that extend into the endocuticle. Bundles of microtubules are associated with the hemidesmosomes. The tubules traverse the cell from the apical to the basal region. The possible significance of these findings is discussed.