Caste-specific modulation of juvenile hormone III content and ecdysteroid titer in postembryonic development of the stingless bee,Scaptotrigona postica depilis

Summary Juvenile hormone III content and ecdysteroid titer were analyzed for larval and pupal development of the stingless bee,Scaptotrigona postica depilis. Castespecific differences in juvenile hormone III content were detected at three developmental phases: at the transition from the fourth to the fifth larval stadium, in the spinning phase of the fifth larval stadium, and shortly after the imaginal moult. During the fifth larval stadium, juvenile hormone content closely reflects corpora allata activity. Juvenile hormone synthesis may thus be responsible for the elevated hormone titer in spinning-phase queen larvae, a phase of known sensitivity for induction of queen characters by exogenous juvenile hormone. For ecdysteroids, two phases of caste-specific differences were found: in the pre-pupal phase, and shortly after the imaginal moult. In both periods the titer in queens is distinctly higher compared to workers.Abbreviations Im imago 1 day after eclosion - L3, L4, L5 larval instars 3, 4, and 5 - L5F1, L5F2 substages of feeding phase in fifth larval instar - L5S1, L5S2, L5S3 substages of spinning phase in fifth larval instar - PP1, PP2 substages of prepupal phase - Pw white eyed pupa - Pp pink eyed pupa - Pr red eyed pupa - Pd dark eyed pupa - Pdl, Pdm, Pdd dark eyed pupa with progressive tanning of cuticle - RIA radioimmunoassay     

Comparative analysis of bacterial community and antibiotic-resistant strains in different developmental stages of the housefly (Musca domestica)

The housefly (Musca domestica) is an important host for a variety of bacteria, including some pathogenic and antibiotic-resistant strains. To further investigate the relationship between the housefly and the bacteria it harbors, it is necessary to understand the fate of microorganisms during the larval metamorphosis. The major bacterial communities in three developmental stages of the housefly (maggot, pupa, and adult fly) were investigated by a culture-independent method, polymerase chain reaction–denaturing gradient gel electrophoresis (PCR?DGGE) analysis of 16S rRNA genes. The bacteria that were identified using DGGE analysis spanned phyla Proteobacteria, Firmicutes, and Bacteroidetes. Changes in the predominant genera were observed during the housefly development. Bacteroides, Koukoulia, and Schineria were detected in maggots, Neisseria in pupae, and Macrococcus, Lactococcus, and Kurthia in adult flies. Antibiotic-resistant bacteria were screened using a selective medium and tested for antibiotic susceptibility. Most resistant isolates from maggots and pupae were classified as Proteus spp., while those from adult flies were much more diverse and spanned 12 genera. Among 20 tested strains across the three stages, 18 were resistant to at least two antibiotics. Overall, we demonstrated that there are changes in the major bacterial communities and antibiotic-resistant strains as the housefly develops.     

16S rDNA-based phylogeny of non-symbiotic bacteria of Entorno-pathogenic nematodes from infected insect cadavers

Using 16S rDNA gene sequencing technique, three different species of non-symbiotic bacteria of entomopatho-genic nematodes (EPNs) (Steinernema sp.and Heterorhabditis sp.) were isolated and identified from infected insect cadavers(Galleria mellonella larvae) after 48-hour post infections.Sequence similarity analysis revealed that the strains SRK3, SRK4 and SRK5 belong to Ochrobactrum cytisi,Schineria larvae and Ochrobactrum anthropi,respectively.The isolates O.anthropi and S.larvae were found to be associated with Heterorhabditis indica strains BDU-17 and Yer-136,respectively,whereas O.cytisi was associated with Steinernema siamkayai strain BDU-87. Phenotypically, temporal EPN bacteria were fairly related to symbiotic EPN bacteria (Photorhabdus and Xenorhabdus genera). The strains SRK3 and SRK5 were phylogeographically similar to several non-symbionts and contaminated EPN bacteria isolated in Germany(LMG3311T) and China (X-14),while the strain SRK4 was identical to the isolates of S.larvae (L1/57,L1/58, L1/68 and L2/11) from Wohlfahrtia magnifica in Hungary.The result was further confirmed by RNA secondary structure and minimum energy calculations of aligned sequences.This study suggested that the non-symbionts of these nematodes are phylogeographically diverged in some extent due to phase variation.Therefore,these strains are not host-dependent, but environment-specific isolates.     

Lysozymelike lytic enzyme of Streptococcus faecalis and its role in the larval development of wax moth, Galleria mellonella

The predominant type of bacteria present in the gut of larval Galleria mellonella were streptococci group D identified as Streptococcus faecalis which showed bacteriolytic activity. Young larvae usually contained mixed populations with a marked dominance of fecal streptococci while normally developed mature larvae most frequently contained large uniform populations of S. faecalis. Pupal stages were found to contain the highest percentage of individuals with pure cultures of fecal streptococci.The author suggests a hypothesis that, owing to its bacteriolytic properties, S. faecalis can be considered as a component of the natural, nonspecific defense mechanism of G. mellonella against bacterial infections. The lytic enzyme released in the exponential growth phase of S. faecalis participates in the selection process stabilizing the microbial flora of wax moth larvae; it limits the population of other forms of bacteria. Larval resistance to bacterial infections to a large extent depends on the magnitude of the populations and thus on S. faecalis muramidase concentration. Bacterial lysozyme inhibited the growth of the ingested organisms and in consequence it prevented the proliferation of undesired bacteria in the digestive tract of Galleria larvae.The lytic enzyme proved to be identical with autolysin, a β-N-acetylmuramide glycanhydrolase (EC 3.2.1.17) which has been isolated from trypsin-speeded wall autolysates of S. faecalis by Shockman and Cheney (1969).     

Bacteria associated with Lucilia sericata larvae reared on fish wastes

The green blowfly, Lucilia sericata (Meigen) (Diptera: Calliphoridae), is a cosmopolitan species of great medical, veterinary, and forensic importance. In addition, their larvae are among the most promising agents for the bioconversion of low-quality biomass, such as organic waste, into sustainable and nutritionally valuable proteins for farmed fish and poultry. Despite the considerable medical and economic importance, the current literature provides limited information about microbiota associated with larvae. The present study aims to fill this knowledge gap. Freshly harvested L. sericata larvae (maggots) grown on fish wastes were investigated by conventional and molecular approaches to evaluate culturable microbial numbers and unculturable microbial diversity associated with the larval cuticle (external samples) and the internal body. In total 200 bacterial isolates were obtained; 46% of the strains originated from external samples and 58% originated from internal body samples produced extracellular protease enzymes, which may be involved in the digestion of proteins during larval feeding. In total 12 predominant bacteria with high proteolytic activity were further identified by morphological, physiological, biochemical, and molecular tools. Proteolytic bacteria in internal samples included Proteus, Providencia, Micrococcus, Deinococcus, whereas in external samples Providencia, Pseudomonas, and Acinetobacter were found. 16S rRNA clone library analysis revealed that the majority of internal bacteria (35%) were taxonomically assigned as Xanthomonadaceae (Schineria, Xylella, Ignnatzchineria), 28% Morganellaceae (Proteus, Providencia, Serratia), and 14% Enterobacteriaceae (Vagococcus, Serratia). Less abundant were bacteria of the genera Clostridium (3%), Erypelothrix (3%), and Oceanispherum (2%). This knowledge will be useful for biotechnological application of L. sericata.     

The bacterial flora of the midgut of two Danish populations of healthy fifth instar larvae of the turnip moth, Scotia segetum

Examination of the midgut bacteria of two Danish populations of healthy fifth instar turnip moth larvae, Scotia (=Agrotis) segetum, living on potatoes and celery gave the following results. The total number of living microorganisms in the midgut varied between 1.0 × 10⁴ and 4.0 × 10⁵. Larvae from celery in N. W. Zeeland always contained Streptococcus faecalis and six members of Enterobacteriaceae, viz., Citrobacter freundii, Klebsiella pneumoniae, Hafnia alvei, Proteus mirabilis, P. vulgaris, and Erwinia amylovora. In larvae from potatoes in E. Jutland, the species consistently present were Streptococcus faecalis and four species of Enterobacteriaceae, viz., Escherichia coli, Erwinia amylovora, E. carotovora var. atroseptica, and one other, probably a member of the E. carotovora group. Streptococcus faecalis is supposed to occur as a mutualist in the alimentary tract, suppressing Gram-positive bacteria.     

New record of the genus Ithytrichia (Trichoptera: Hydroptilidae) for South America,with descriptions of male,larva and pupa of a new species from northwestern Argentina

Ithytrichia is a small genus of Hydroptilidae, recorded from Europe, North America, and north Central Mexico. The first record of Ithytrichia for South America is presented here. A new species of this genus Ithytrichia ferni is described from northwestern Argentina. Diagnostic characters of the male imago, pupa and larva are described and illustrated. Biological notes are included.     

Records of chironomids of the tribe Pentaneurini (Diptera: Chironomidae) in the Eastern Himalayas of India

Larva, pupa and female imago of Paramerina ampliseta n. sp. and Rheopelopia tuberculata (Chaudhuri & Debnath 1987), pupa and male imago of Paramerina clara n. sp. and pupa of Ablabesmyia (Ablabesmyia) alba Chaudhuri, Debnath & Nandi 1983 and Paramerina inficia Chaudhuri & Debnath 1985 are described from the Eastern Himalayas of India.     

Dynamic changes of gut bacterial communities present in larvae of Anoplophora glabripennies collected at different developmental stages

The Asian long-horned beetle, Anoplophora glabripennies (Motschulsky), is a destructive wood-boring pest that is capable of killing healthy trees. Gut bacteria in the larvae of the wood-boring pest is essential for the fitness of hosts. However, little is known about the structure of the intestinal microbiome of A. glabripennies during larval development. Here, we used Illumina MiSeq high-throughput sequencing technology to analyze the larval intestinal bacterial communities of A. glabripennies at the stages of newly hatched larvae, 1st instar larvae and 4th instar larvae. Significant differences were found in larval gut microbial community structure at different larvae developmental stages. Different dominant genus was detected during larval development. Acinetobacter were dominant in the newly hatched larvae, Enterobacter and Raoultella in the 1st instar larvae, and Enterococcus and Gibbsiella in the 4th instar larvae. The microbial richness in the newly hatched larvae was higher than those in the 1st and 4th instar larvae. Many important functions of the intestinal microbiome were predicted, for example, fermentation and chemoheterotrophy functions that may play an important role in insect growth and development was detected in the bacteria at all tested stages. However, some specific functions are found to be associated with different development stages. Our study provides a theoretical basis for investigating the function of the intestinal symbiosis bacteria of A. glabripennies.     

In vitro antibacterial activity and physicochemical properties of a crude methanol extract of the larvae of the blow fly Lucilia cuprina

The emergence of multidrug‐resistant bacterial strains has prompted the reintroduction of maggot therapy in the treatment of chronic, infected wounds. Many previous studies have demonstrated the potent antibacterial activity of larval excretions/secretions of the blowfly Lucilia sericata (Meigen) (Diptera:Calliphoridae) against bacteria. However, the antibacterial activity of its sibling species, Lucilia cuprina (Wiedemann) (Diptera:Calliphoridae) against a wide range of pathogenic bacteria has never been determined. The aim of this study was to develop a new procedure to produce whole body extract of larvae of L. cuprina via methanol extraction as well as to demonstrate the in vitro antibacterial activity of this extract against seven selected wound pathogens (Staphylococcus aureus, methicillin‐resistant S. aureus, S. epidermidis, Streptococcus pyogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli). The turbidimetric assay demonstrated that L. cuprina larval extract was significantly potent against all bacteria tested (P < 0.001). Additionally, colony‐forming unit (CFU), agar well diffusion and minimum inhibitory concentration assays have confirmed the apparent potency of larval extract against P. aeruginosa. The reconstituted larval extract was highly robust and thermally stable. These observations substantiated the feasibility of the methanol extraction method in the production of larval extract.     

The culturable bacterial community of frass produced by larvae of Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) in the Canary island date palm

Aims: Larvae of the red palm weevil (RPW) Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) feed inside palm stem tissues, making galleries and producing a wet fermenting frass. We characterized the culturable bacteria associated with frass produced by tunnelling larvae inside the Canary island date palms and investigated the role of frass and gut bacteria in plant polymers breakdown. Methods and Results: A culture‐dependent method was used to isolate bacteria from frass and noninfested palm tissues. Bacterial isolates were grouped into operational taxonomic units based on polymorphisms in the ITS‐PCR profiles, and representative isolates were identified by partial sequencing of the 16S rRNA gene. Frass bacteria were dominated by 2,3‐butanediol fermenter Enterobacteriaceae. None of the bacterial isolates was able to degrade cellulose; however, cellulolytic and hemicellulolytic bacteria were isolated from the larval gut enrichment cultures. Conclusions: Frass bacteria are specifically associated with the RPW larvae and might play beneficial roles for RPW, other than nutritional, that deserve further investigations. Breakdown of plant polymers probably occurs inside the larvae digestive system. Significance and Impact of the Study: Frass and gut micro‐organisms of R. ferrugineus should be included in studies of the interactions between RPW, its plant hosts, and its enemies.     

Influence of ionizing radiation on the formation of adult antennae in large fruit-tree tortrix <Emphasis Type="Italic">Archips podana</Emphasis> Scop. (Lepidoptera,Tortricidae)

The influence of sterilizing doses of X-radiation on the formation of adult antennae during the pupa period of development of Archips podana was studied. We found a change in the number of coeloconic and auriculate sensilla in those imago whose pupae were exposed to radiation. A slow-down in the process of antennae formation at the pupal stage was registered after the irradiation of instar five larvae and newly formed pupae.     

A danaid mullerian mimic, Euploea core amymone (Cramer) lacking cardenolides in the pupal and adult stages

Euploea core amymone , a Mullerian Mimic, when reared on Serium oleander and Asclepias curassavica , stores emetic cardiac glycosides only in the larval stages, and not as pupa and adult. Danaus plexippus erippus. which exhibits less cardioactivity if tested on the isolated rat heart than E. c. amymone , nevertheless stores them at all three stages of development; polar cardenolides not present in its food plant A. curassavica , were found in the pupa and imago.     

Dynamics of the intestinal bacterial community in black soldier fly larval guts and its influence on insect growth and development

Black soldier fly (BSF), Hermetia illucens (Diptera: Stratiomyidae), is a prominent insect for the bioconversion of various organic wastes. As a saprotrophic insect, the BSF inhabits microbe-rich environments. However, the influences of the intestinal microorganisms on BSF growth and development are not very clear. In this study, the dynamics of the intestinal bacterial community of BSF larvae (BSFL) were analyzed using pyrosequencing. Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria were the most prevalent bacterial phyla in the intestines of all larval instars. The dynamic changes in bacterial community compositions among different larval instars were striking at the genus level. Klebsiella, Clostridium, Providencia, and Dysgonomonas were the relatively most abundant bacteria in the 1st- to 4th-instar BSFL, respectively. Dysgonomonas and Providencia also dominated the 5th- and 6th-instar larvae, at ratios of 31.1% and 47.2%, respectively. In total, 148 bacterial strains affiliated with 20 genera were isolated on different media under aerobic and anaerobic conditions. Among them, 6 bacteria, BSF1–BSF6, were selected for further study. The inoculation of the 6 isolates independently into germ-free BSFL feeding on an artificial diet showed that all the bacteria, except BSF4, significantly promoted BSF growth and development compared with the germ-free control. Citrobacter, Dysgonomonas, Klebsiella, Ochrobactrum, and Providencia promoted BSF development significantly by increasing the weight gains of larvae and pupae, as well as increasing the prepupae and eclosion rates. In addition, Citrobacter, Klebsiella and Providencia shortened the BSF life cycle significantly. The results illustrate the promotive effects of intestinal bacteria on BSF growth and development.     

Bacteria associated with four species of Dacus (Diptera: Tephritidae) and their role in the nutrition of the larvae

Summary The bacteria associated with Dacus tryoni (Froggatt), Dacus jarvisi (Tryon), Dacus neohumeralis (Hardy) and Dacus cacuminatus (Hering) were examined. Bacteria were isolated from the surface of freshly-laid eggs, from within surface sterilised pupae, from heads and abdomens of wild and laboratory-maintained flies, and from decomposed fruits in which the wild larvae were feeding. A more diverse flora was associated with D. tryoni and D. jarvisi (15 and 14 species, respectively) than with D. neohumeralis and D. cacuminatus (9 and 6 species, respectively). Most of the bacteria belonged to the family Enterobacteriaceae and while there were similarities of bacterial associations between fly species there was no evidence of a strict symbiotic association of a particular bacterium or bacteria with each species of fly. The larvae of D. jarvisi were unable to develop normally in an artificial medium containing unhydrolysed protein and free of bacteria and on a medium containing casein and Serratia liquefaciens (isolated from the flies and shown to secrete protease) the larvae died. On the same casein medium containing Enterobacter cloacae (isolated from the flies and shown to be protease negative) the larvae developed normally. Larvae of D. tryoni and D. jarvisi were devoid of protease and cellulase activity, but contained some amylase activity. The significance of these results in terms of current hypotheses concerning symbioses between tephritids and bacteria is discussed.     

Description of the xylobiont larvae and pupae of the genus <Emphasis Type="Italic">Achyrolimonia</Emphasis> (Diptera,Limoniidae)

The larva and pupa of Achyrolimonia basispina (Alex.) are described for the first time. New data on the morphology of the larva and pupa of A. decemmaculata (Loew) are discussed, and the morphological characteristics of the genus are defined more exactly. The larvae of these species develop in the dead wood of deciduous trees and in the old carpophores of wood fungi.     

Hormonal Effects on the in vitro Larval Growth of the Swine Intestinal Roundworm,Ascaris suum

Summary

Several biogenic amines and insect juvenile hormone III were tested in a growth bioassay of the parasitic nematode, Ascaris suum. Compounds (1 to 1000μzmol) were placed in culture with third-stage larvae for 24 hr, larvae were then rinsed several times, and larval cultures were returned to incubators for 6 more days. By this time, larvae had developed to the fourth-stage. The larvae were fixed in hot formalin, and their lengths were measured. Epinephrine and norepinephrine oxidized and were nematocidal under these culture conditions. Histamine and serotonin had no effect on length of the larvae. Octopamine (10–50μmol) exposure resulted in a significant dose-dependent increase in length. When incubated with octopamine (10μzmol) for 7 days, larvae grew more slowly than controls without octopamine (P< 0.05). Juvenile hormone III stimulated a dose-dependent (0 to 10μmol) increase in length after a 24 hr exposure. No synergism was detected between juvenile hormone III and ecdysone when co-incubated with larvae. These results indicate that Ascaris larvae are growth-insensitive to low concentrations of biogenic amines of host origin. Conversely, biological transmitters of invertebrate origin are potent stimulators of larval growth.     

Description of the type species of the genus Goerodes and generic assignment of three East Asian species (Trichoptera, Lepidostomatidae)

After critical examination of specimens from several localities in Japan, I synonymize Goerodes toyotamaensis (Kobayashi) with G. corniger Ulmer, the type species of the genus. I redescribe the male, female, larva, and larval case of G. corniger and describe the pupa and egg for the first time. I reconfirm the generic assignment of G. albardanus (Ulmer), G. elongatus (Martynov), and G. sinuatus (Martynov), which were placed in Dinarthrodes by some authors, based on the similarity of their larvae with those of other species of Goerodes, including the type species. I synonymize Crunobiodes koreaensis Kobayashi, originally described from Korea, with G. sinuatus. Received: February 18, 2000 / Accepted: May 31, 2000