Morpho-ecological characteristics of the xylobiont larvae of the genus Phaonia Robineau-Desvoidy, 1830 (Diptera, Muscidae) with a description of the larva of Ph. canescens Stein, 1916

The first data on the biology and morphology of the larva and puparium of Phaonia canescens Stein, with additional data on Ph. exoleta (Meig.) and Ph. cincta (Zett.), are given. Keys to the larvae and puparia of the three species studied are compiled.     

A comparative characterization of immature stages of the species of the Phaonia palpata group (Muscidae, Diptera)

The morphology of immature stages of the xylobiont Phaonia palpata Stein, Ph. tiefii Schn., and Ph. ishizuchiensis Shin. et Kano was studied. Differences in the structure of the cephalopharyngeal organ of the larvae and of the ultimate puparial segment were found. Keys to the species considered are given.     

The calcified puparium of the face fly, Musca autumnalis (Diptera: Muscidae)

The general composition of the calcified puparium of Musca autumnalis was determined. Ash-weight analyses show that 62% of the puparium is inorganic material. The major components of the puparium are calcium, magnesium, phosphate and carbonate. Calcium and magnesium phosphate are the predominant salts in the puparium, with a lesser contribution by their respective carbonates. Scanning electron microscopy revealed that the exocuticle was the site of calcification in the puparium. Inorganic analyses of the insoluble salt isolated from face fly larvae showed it to be compositionally identical with the puparial salt. Major organic components of the puparium are lipid, chitin and protein. The presence of carbonic anhydrase and alkaline phosphatase activity in post-feeding larvae was confirmed.     

On the ecology of Phaonia larvae (Diptera, Muscidae)

The composition and ecological associations of predaceous larvae of more than 20 species of the genus Phaonia Rob.-Desv. from xylobiont communities were studied. The groups of phloeobionts and xylobionts are distinguished, and their associations with the principal wood destroying insects are discussed. Data on autecology of 22 species are presented.     

Analysis of metamorphosis in Drosophila melanogaster: Characterization of giant,an ecdysteroid-deficient mutant

The mutant allele giant of Drosophila melanogaster affects the timing and the level of increase in ecdysteroid titer normally occurring at puparium formation. The third larval instar is extended by 4 days in phenotypically “giant” individuals during which the imaginal discs mature slower than normal and finally take on the folding pattern characteristic of maturity at a time when normal individuals have already formed puparia. After puparium formation, development occurs at the same rate in giant and wild-type animals. Feeding 20-hydroxyecdysone at 94 hr after oviposition allows giant larvae to develop at the same rate as wild-type larvae and to produce normal-sized adults (although at 94 hr the imaginal discs of giant lack much of the folding pattern of mature discs). Radioimmunological determination of ecdysteroid titers in giant and normal individuals indicates that the peak of ecdysteroid activity associated with puparium formation is lower in giant and occurs 4 days later than normal. These results indicate that giant is an ecdysteroid-deficient mutant with major effects on metamorphosis. Unlike previously reported ecdysteroid-deficient mutants, however, giant larvae eventually develop into adults and may be induced to undergo complete metamorphosis at the same time as wild type by feeding 20-hydroxyecdysone.     

Mode of action of an insect neuropeptide leucopyrokinin (LPK) on pupariation in fleshfly (Sarcophaga bullata) larvae (Diptera: Sarcophagidae)

An insect neuropeptide leucopyrokinin (LPK) (pQTSFTPRLamide) accelerates pupariation in wandering larvae of the fleshfly Sarcophaga bullata. The period of sensitivity to the action of LPK begins approximately 4 h before pupariation. Within this period the degree of acceleration of contraction into the shape of a puparium is practically independent of the age at which the larvae are injected, while acceleration of tanning is distinctly more age dependent. From ligation experiments we conclude that intact central innervation is essential for the action of LPK on puparial contraction, whereas central neurones take no part in mediation of LPK action on tanning of the cuticle. An analysis of tensiometric recordings of muscular activity revealed that the actual time of LPK accelerated puparial contraction coincides with the beginning of the immobilisation/retraction phase. LPK accelerates the switch from wandering behaviour to immobilisation/retraction behaviour but has no effect on the onset and duration of motor patterns that normally underlie puparial contraction in controls. The morphology of an accelerated puparium is normal but its formation is temporally dissociated from normal ‘contraction patterns’ that are performed a long time after the puparium has contracted. It means that neuromuscular activity of larvae accelerated by LPK does not cease upon formation of the white puparium, but continues until the whole motor programme of pupariation behaviour is completed. Apparently the peptide acts on the integument by stimulating it to contract and shrink, and no specific patterns of muscular contractions are needed to properly shape the puparium. This finding sheds a new light on our understanding of the mechanism of puparium formation.     

Ecdysteroid synthesis by the ring gland of Drosophila melanogaster during late-larval,prepupal and pupal development

Radioimmunoassay has been used to determine the characteristics of ecdysteroid synthesis by ring glands and brain-ring gland preparations from late 3rd-instar larvae of Drosophila melanogaster cultured in vitro. The rate of synthesis and secretion is linear for at least 4 hr in culture. Using a 4-hr culture period, variation in the rate of ecdysteroid synthesis by brain-ring gland preparations during larval, prepupal and pupal development has been examined. The rate of synthesis and secretion is highest in late 3rd-instar larvae and decreases after puparium formation. During pupal development, at a time when the endogenous ecdysteroid titre is again increasing, the rate of ecdysteroid synthesis by brain-ring gland preparations remains low and is only 10% of that prior to puparium formation. It is, therefore, likely that the ring gland is not a major source of ecdysteroids during this period.     

Metabolism of β-alanyl-l-tyrosine in Sarcophaga bullata

Soluble enzymes have been demonstrated in extracts of Sarcophaga bullata larvae and pupae which both synthesize and hydrolyze the dipeptide β-alanyl-l-tyrosine (β-AT). In vitro assays for the synthesis and hydrolysis of β-AT were developed using thin-layer chromatography and (1-¹⁴C)β-alanine.The fat body was identified as the tissue origin of both the synthetase and hydrolase enzymes. The specific activity of β-AT synthetase in fat body extracts was constant throughout larval development, whereas hydrolytic activity in fat body extracts rose sharply after completion of the white puparium, reached a maximum in 12 to 18 hr, and then fell to its initial level. The rôle of the two enzymic activities in the formation of the puparium of S. bullata is discussed.     

Larvae of phoronids (Phoronida) from Terpeniya Bay (Southeastern Sakhalin)

Phoronid larvae were found in planktonic samples from the northern coast of Terpeniya Bay. In some samples, their density was up to 220 specimens/m³. Larval stages having 10, 12, 16, 20, and 22 tentacles are described. Larvae were identified as Actinotrocha branchiata and belong to the species Phoronis muelleri Selys-Longchamps, 1903. However, unlike the Ph. muelleri larvae described in the literature, the larvae we found are smaller (not more than 900 μm) before metamorphosis and have fewer tentacles (24). They lack paired vacuolated diverticula of the stomach, which are characteristic of Ph. muelleri larvae. However, judging by all other characters, namely transparency, the absence of coelomic cylinder in the preoral lobe, and the presence of adult tentacle primordia, one pair of blood cell aggregations, and a pyriform organ, these larvae are similar to the previously described larvae of Ph. muelleri. Adult forms of Ph. muelleri were previously found in Terpeniya Bay and described by Mamkaev (1962) and Emig (1984).     

Some effects of low oxygen partial pressures on the development of Calliphora vomitoria;

The influence of wet conditions and low pO₂ on the survival and development of non-feeding final instar larvae and puparia of Calliphora vomitoria has been investigated. The larvae delay the formation of the puparium in wet conditions in air and in dry or wet conditions in 10 and 5% oxygen. This may be related to the susceptibility of the newly formed puparia to oxygen shortage. The pupal respiratory horns play an important part in maintaining O₂ uptake when the puparia are surrounded by particles covered with a film of water but are not involved in aiding survival in low pO₂. Zero age puparia are killed by a 2 day exposure to 10% O₂ but later stages can continue to develop in this gas. Fifty per cent of the 0, 1 and 9 day old puparia are killed by about a 12 hr exposure to 1% O₂ whereas 50 per cent of the 2 to 8 day old puparia can survive over 1·5 days exposure to this gas. Development, as measured by respiration rates and the timing of the emergence of the adults, is delayed by 1% O₂ by the amount of time that the insects spend in that gas. However, the first phase of elongation of the pharate adult longitudinal flight muscle, occurring between the third and fourth day of puparial life, is only slightly slowed down in 1% O₂. The variations in susceptibility to 1% O₂ and the growth of the muscles are discussed in relation to published accounts of protein synthesis in the puparium.     

Effect of the Entomogenous Nematode Nemplectana carpocapsae on the Tachinid Parasite Compsilura concinnata (Diptera: Tachinidae)

The entomogenous nematode Neoaplectana carpocapsae and its associated bacterium, Xenorhabdus nematophilus, could not infect the pupal stage of the tachinid Compsilura concinnata through the puparium. N. carpocapsae had an adverse effect on 1-, 2- and 3-day-old C. concinnata larvae within the armyworm host in petri dish tests. All 1-day-old larvae treated with nematodes died in their hosts, whereas 61% and 69% of 2- and 3-day-old larvae treated with nematodes, respectively, died. However, the survivors developed to adults. Nine to thirty-seven percent of adult tachinids which emerged from nematode-treated soil (50 nematodes/cm²) were infected with N. carpocapsae. The nematode adversely affects C. concinnata directly by the frank infection of the tachinid and indirectly by causing the premature death of the host which results in tachinid death.     

A biochemical study of the scarlet eye-color mutant of Drosophila melanogaster

3-Hydroxykynurenine is virtually absent from st larvae but accumulates during adult development in the puparium. Over the period of adult emergence, the accumulated 3-hydroxykynurenine is excreted so that st adults contain none. Larvae of st fed on tryptophan-C ¹⁴ medium produce labeled 3-hydroxykynurenine, at a reduced rate, perhaps, compared to wild type. Xanthurenic acid levels in st pupae are similar to those in wild type. Thus the failure of st larvae to accumulate 3-hydroxykynurenine does not seem to be due either to an inability to synthesize this compound or to an excessive rate of its conversion to xanthurenic acid. Rather, it appears that the mechanism of 3-hydroxykynurenine storage during larval life is defective, so that this compound is excreted at an abnormally high rate. The inability of the pigment cells of the eyes of st to synthesize xanthommatin may result from a similar defect in their ability to take up or store 3-hydroxykynurenine.     

Alkaline phosphatase of Drosophila melanogaster. III. Tyrosine-O-phosphate as substrate

Tyrosine-O-phosphate was used as a substrate for two allelic forms (APH-4 and-6) of alkaline phosphatase of late third instar larvae of Drosophila melanogaster. Two findings of particular interest are (1) lack of inhibition by 1mm inorganic phosphate and (2) severe substrate inhibition. The accumulated evidence that, in vivo, alkaline phosphatase catalyzes the conversion of tyrosine-O-phosphate into tyrosine, which is then utilized for puparium formation, is discussed.     

Ultrastructure of salivary glands of Drosophila lebanonensis during normal development and after in vivo ecdysterone administration

Changes in the morphology of the salivary glands of Drosophila lebanonensis have been followed at both the light and electronmicroscopic level during a period of 30 hr before puparium formation and during puparium formation itself. Three striking differences were observed in comparison to other Drosophila species studied: (1) the secretion product of Drosophila lebanonensis has a different stainability to PAS reagent and uranyl acetate and no internal structures or “caps” can be observed; (2) the release of this secretion product is not restricted to a time period shortly before puparium formation but is a continuous process starting about 24 hr before puparium formation; and (3) the histolysis of these glands starts immediately after puparium formation, whereas in other Drosophila species this event starts 5 hr later.Puparium formation of Drosophila lebanonensis is controlled by the circadian oscillation. Injection of ecdysterone before the “gate” period results in changes in the cuticle as observed during normal development, but is not followed by the histolysis of the glands. Injection of ecdysterone after the “gate” is not followed by changes in the cuticle but histolysis is induced.     

Penetration and persistence of an insect growth regulator in the pupa of the stable fly, Stomoxys calcitrans.

An insect growth regulator, (E)-6,7-epoxy-1-(p-ethylphenoxy)-3,7-dimethyl-2-octene (Stauffer R-20458) with insect juvenile hormone activity readily penetrated the puparium of white pharate pupae of Stomoxys calcitrans. The quantity and the persistence of the chemical in the puparium and in the developing pharate adult were determined over a 168 hr post-treatment period. The loss of chemical from the pharate stage was almost total within 168 hr, but over 20 per cent of the applied dose was still present in the puparium after the same interval.     

Circadian control of the cellular response to β-ecdysone in Drosophila lebanonensis

Drosophila lebanonensis displays a strict circadian rhythm with regard to the puparium formation and the occurrence of ecdysone-specific puffs in the salivary gland chromosomes. In normal development these puffs occur 3–4 hours before puparium formation. Injection of β-ecdysone at periods before ecdysone puffs are present, induces in all instances their appearance within 30 minutes, irrespective of the phase of the circadian oscillation at the time of injection. In spite of the appearance of the hormone specific puffs following β-ecdysone injection, puparium formation did not occur 3–4 hours after the puffs became active. Depending upon the time of injection within the circadian cycle, puparium formation occurred 5–6 hours after injection (when injection was performed close to a “gate” period), or occurred during the next “gate” of the circadian oscillation.     

Action of juvenoids on the metamorphosis of cyclorrhaphous Diptera

Administrations of high doses of juvenoids to the last instar larvae of cyclorrhaphous flies cause occasionally lethal defects in puparium formation but mostly affect only the pupal-adult transformation. In pupae, juvenoids impede proliferation and differentiation of the imaginal disks and of abdominal histoblasts: at low doses they cause incomplete rotation of male genitalia and deformations of the ovipositor, at higher doses their effects gradually spread from the tip of abdomen towards the middle of the body. The highest amounts influence the entire abdomen, size and pigmentation of the eyes, and development of hairs and sclerotization of the integument on the head and thorax. Various species slightly differ in the pattern of morphological effects produced, in the ability of affected insects to leave the puparium, and in the sensitivity to juvenoids of different types. A uniform scale for classification of morphological effects in the species examined is described in this paper. The most potent juvenoids are effective at doses around one nanogramme per specimen. Out of 29 selected compounds tested, isopropyl 11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate is the most active juvenoid for Drosophila, Musca, and Sarcophaga; methyl 10,11-epoxy-3,7,11-trimethyl-2,6-tridecadienoate is the most active juvenoid for Ceratilis; and isopropyl 11-chloro-3,7,11-trimethyl-2-dodecenoate possesses the highest activity for Calliphora.     

Cyclic AMP levels in Drosophila during postembryonic development and in the adults.

The physiological content of Drosophila melanogaster tissues in cyclic AMP has been determined and its variations studied during postembryonic development and in the adults. Marked variations were observed, especially during metamorphosis where the ratio between the lowest and highest values (0·35 to 17·25 pmoles/mg protein) was $\text{1}\text{44}$. In larvae the variations of cyclic AMP level were not clearly related to the larval ecdyses, but the steps of metamorphosis, i.e. formation of the puparium, larval-pupal apolysis, and pupal-adult apolysis, were accompanied with rapid and drastic rises of cyclic AMP, up to the highest value mentioned. We therefore deduce that cyclic AMP is involved in the metamorphosis of D. melanogaster as a chemical signal. In adults, the cyclic AMP level was remarkably constant and was around 7 pmoles/mg protein.     

Remarks on the morphology and biology of Cleigastra apicalis (Meigen, 1826) (Diptera, Scathophagidae)

The egg, second‐ and third‐instar larvae and puparium of Cleigastra apicalis are described for the first time. All pre‐imaginal stages are found on stems of the common reed affected by flies of the genera Lipara and Platycephala and the butterfly Arenostola phragmitidis. The larvae feed on dead plant and animal tissue and the excreta of other insects that live inside the stems of the common reed. Exceptionally they will scrape living plant tissue. The pupa is the overwintering stage.     

Changes in dry weight, protein, and nucleic acid content during diapause and normal development of the blowfly, Lucilia sericata

Dry weight (D.W.), protein, RNA, and DNA have been determined in the blowfly, Lucilia sericata, throughout all stages of normal development in long and short photoperiod regimes and during larval diapause. During normal development protein/D.W. levels fluctuate markedly during the larval and puparial stages, increased levels being correlated with the synthesis of new cuticle, etc. prior to ecdysis and the histogenesis of adult tissues prior to emergence. Protein levels remain relatively high and constant during adult life to senescence. RNA/D.W. levels are highest in first instar larvae but decline rapidly during larval development until just before puparium formation. Sharp increases are found prior to pupation and then again prior to adult emergence. In the adult stage, the levels decline steadily throughout the life span. DNA/D.W. levels are very low in the egg but rach their highest levels in early first instar larvae. They then decline during larval development, with small increases being found prior to puparium formation and adult emergence. Adult levels remain relatively constant throughout the life span. The ratio has extremely high values in the egg, indicating the high degree of synthetic activity that takes place during embryogenesis. There is a steady decline in values during adult life to senescence in both sexes, suggesting that physiological ageing in L. sericata is accompanied by a decrease in protein synthesis potential.During larval diapause all parameters, with the exception of the ratio, are maintained at low and constant levels, reflecting the fact that diapause is a period when synthetic and mitotic activity are minimal. The great variations in levels, however, indicate that individuals within a group of larvae can terminate diapause spontaneously at 24°C and return to the normal processes of morphogenesis.