Pathogenicity of Metarhizium rileyi (Hypocreales: Clavicipitaceae) against Tenebrio molitor (Coleoptera: Tenebrionidae).

Tenebrio molitor L., also known as the mealworm, is a polyphagous insect pest that infests various stored grains worldwide. Both the adult and larval stages can cause significant damage to stored grains. The present study focused on isolating entomopathogenic fungi from an infected larval cadaver under environmental conditions. Fungal pathogenicity was tested on T. molitor larvae and pupae for 12 days. Entomopathogenic fungi were identified using biotechnological methods based on their morphology and the sequence of their nuclear ribosomal internal transcribed spacer (ITS). The results of the insecticidal activity indicate that the virulence of fungi varies between the larval and pupal stages. In comparison to the larval stage, the pupal stage is highly susceptible to Metarhizium rileyi, exhibiting 100% mortality rates after 12 days (lethal concentration 50 [LC50] = 7.8 × 106 and lethal concentration 90 (LC90) = 2.1 × 1013 conidia/mL), whereas larvae showed 92% mortality rates at 12 days posttreatment (LC50 = 1.0 × 106 and LC90 = 3.0 × 109 conidia/mL). The enzymatic analyses revealed a significant increase in the levels of the insect enzymes superoxide dismutase (4.76-10.5 mg-1) and glutathione S-transferase (0.46-6.53 mg-1) 3 days after exposure to M. rileyi conidia (1.5 × 105 conidia/mL) compared to the control group. The findings clearly show that M. rileyi is an environmentally friendly and effective microbial agent for controlling the larvae and pupae of T. molitor.

Diversity of bacteria in different life stages and their impact on the development and reproduction of Zeugodacus tau (Diptera: Tephritidae).

Fruit flies usually harbor diverse communities of bacteria in their digestive systems, which are known to play a significant role in their fitness. However, little information is available on Zeugodacus tau, a polyphagous pest worldwide. This study reports the first extensive analysis of bacterial communities in different life stages and their effect on the development and reproduction of laboratory-reared Z. tau. Cultured bacteria were identified using the conventional method, and all bacteria were identified by high-throughput technologies (16S ribosomal RNA gene sequencing of V3-V4 region). A total of six bacterial phyla were identified in larvae, pupae, and male and female adult flies, which were distributed into 14 classes, 32 orders, 58 families and 96 genera. Proteobacteria was the most represented phylum in all the stages except larvae. Enterobacter, Klebsiella, Providencia, and Pseudomonas were identified by conventional and next-generation sequencing analysis in both male and female adult flies, and Enterobacter was found to be the main genus. After being fed with antibiotics from the first instar larvae, bacterial diversity changed markedly in the adult stage. Untreated flies laid eggs and needed 20 days before oviposition while the treated flies showed ovary development inhibited and were not able to lay eggs, probably due to the alteration of the microbiota. These findings provide the cornerstone for unexplored research on bacterial function in Z. tau, which will help to develop an environmentally friendly management technique for this kind of harmful insect.

Promotion of Metabolite Synthesis in Isaria cicadae, a Dominant Species in the Cicada Flower Microbiota, by Cicada Pupae.

Cicada flowers, which are edible and medicinal mushrooms, are the fruiting bodies of Isaria cicadae, a fungus that is parasitic on the larvae of cicada pupae. We hypothesize that host factors might possess stimulatory activity on metabolite synthesis in Isaria cicadae. Here, we first compared the microbial community structures of different wild cicada flowers across geographical regions, compartments, and growth stages via high-throughput sequencing. Isaria cicadae TZC-3, an isolate of the most abundant operational taxonomic unit (OTU6782) in all the fungal communities, was isolated from wild cicada flowers. Furthermore, the effects of cicada pupae on metabolite synthesis in Isaria cicadae TZC-3 were studied in submerged culture. The contents of intercellular polysaccharides, adenosine, N6-(2-hydroxyethyl)-adenosine, free amino acids, and hydrolyzed monosaccharides in the mycelia cultured with cicada pupa powder (4%) were significantly increased as compared with the contents in the control group. This indicates that a cicada pupa can act as an elicitor for metabolite synthesis in Isaria cicadae.

High Diversity of Bacterial Communities in Developmental Stages of Bactrocera carambolae (Insecta: Tephritidae) Revealed by Illumina MiSeq Sequencing of 16S rRNA Gene.

Bactrocera carambolae is a highly polyphagous fruit pest of agricultural importance. This study reports the bacterial communities associated with the developmental stages of B. carambolae. The microbiota of the developmental stages were investigated by targeted 16S rRNA gene (V3-V4 region) sequencing using the Illumina MiSeq. At 97% similarity, there were 19 bacterial phyla and unassigned bacteria, comprising 39 classes, 86 orders, 159 families and 311 genera. The bacterial composition varied among the specimens of developmental stage and across developmental stages as well as exuviae. Four phyla of bacteria (with relative abundance of ≥1% in at least one specimen)-Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria-were recovered from the larva, pupa, adult stages and exuviae. Proteobacteria was the predominant phylum in all the developmental stages as well as the exuviae. Enterobacteriaceae (Proteobacteria) was the predominant family in the adult flies while the family [Weeksellaceae] (Bacteroidetes) was predominant in the larval and pupal stages. Among the genera occurring in more than one developmental stage of B. carambolae, Erwinia was more abundant in the larval stage, Halomonas more abundant in adult female, Stenotrophomonas more abundant in adult male, and Chryseobacterium more abundant in the larval and pupal stages. The results indicate transmission of bacteria OTUs from immatures to the newly emerged adults, and from exuviae to the environment.

Comparison of Major Bioactive Compounds of the Caterpillar Medicinal Mushroom, Cordyceps militaris (Ascomycetes), Fruiting Bodies Cultured on Wheat Substrate and Pupae.

In this study, the main bioactive compounds of the fruit bodies of Cordyceps militaris-such as adenosine, cordycepin, polysaccharides, mannitol, superoxide dismutase (SOD), and carotenoids-were cultivated on wheat and pupae, as well as sclerotium (the pupae portion) and sclerotium with fruiting bodies. The amounts of adenosine and polysaccharide in all the tested samples (except for the polysaccharides of sclerotium) are higher than the quality standards (adenosine ≥0.055% and polysaccharide ≥2.5%) determined by the Ministry of Health of the People's Republic of China. As the most important bioactive compound in C. militaris, cordycepin is the highest in the fruiting bodies on pupae than in other samples, whereas it is the lowest in the sclerotium. The amounts of cordycepin, carotenoids, and SOD were higher in the fruiting bodies on pupae than that in the fruiting bodies on wheat, whereas the amounts of adenosine, polysaccharides, and mannitol were higher in the fruiting bodies on wheat than in the fruiting bodies on pupae. There was no significant difference in the amounts of cordycepin, carotenoids, and SOD in the sclerotium with fruiting bodies and the fruiting bodies on wheat. The adenosine, polysaccharide, and mannitol contents in the sclerotium with fruiting bodies were significantly lower than those of the fruiting bodies on wheat. Overall, the results of this evaluation could not distinguish which is better: the fruiting bodies on pupae or those on wheat; each has its own merits. The fruiting bodies of C. militaris cultivated on both wheat and pupae are important candidates for medicinal and tonic use for the welfare of humankind.

Assemblage of filamentous fungi associated with aculeate hymenopteran brood in reed galls.

Monotypic stands of common reed and the reed-gall-associated insect assemblages are distributed worldwide. However, fungi associated with these assemblages have not been characterized in detail. Here we examined 5200 individuals (12 species) of immature aculeate hymenopterans or their parasitoids collected at 34 sampling sites in Central Europe. We noticed fungal outgrowth on exoskeletons of 83 (1.60%) larvae and pupae. The most common host was eudominant Pemphredon fabricii. However, the less abundant aculeate hymenopteran reed gall inquilines were infected at higher prevalence, these included Trypoxylon deceptorium, Trypoxylon minus, Hoplitis leucomelana and Hylaeus moricei (all considered new host records). We identified three fungal species, Penicillium buchwaldii (72% of cases), Aspergillus pseudoglaucus (22%) and Penicillium quebecense (6%). When multibrooded nests were affected, only a part of individuals was infected in 62% of cases. The sampling site-specific infection rate reached up to 13%, thus fungal infections should be considered an important variable driving the abundance of gall inquilines. Infections of generalist host species were more frequent than those of reed gall specialists, suggesting that suboptimal conditions decreased the immunocompetence of non-specialized species, which only occasionally nest in reed galls and feed in reed beds.

Epiphyas postvittana (Lepidoptera: Tortricidae)-Botrytis cinerea (Helotiales: Sclerotiniaceae)-Vitis vinifera (Vitales: Vitaceae) Interaction: The Role of B. cinerea on the Development of E. postvittana in Synthetic Nutritional Media.

Epiphyas postvittana (Walker) (light-brown apple moth) is a polyphagous herbivore of economic significance, which also feeds on Vitis vinifera L. The E. postvittana-V. vinifera interacting system also involves the participation of the fungus Botrytis cinerea Persoon ex Fries. We have been exploring the relationship among E. postvittana-V. vinifera-B. cinerea over the past two years. In this article, we report the preference and performance of the larvae of E. postvittana raised solely on a synthetic diet incorporated with the mycelial material of B. cinerea (Diet B). To characterize the effect of fungus on the development of E. postvittana, another synthetic diet was prepared that included the lyophilized leaf material of V. vinifera (Diet C). When raised on Diets B and C, a decrease in the duration of larval development and an increase in the survival and fecundity rate of E. postvittana occurred. Diet B influenced the pupal mass, but a significant increase occurred when the larvae were fed on Diet C. The larval emergence rate was the greatest in E. postvittana raised on Diet B, followed by those on Diet C. The F(2) generation of the larvae reared on Diet B showed similar effects as F(1) on the life-history performance of the larvae. Diet B enhanced the life-history performance of E. postvittana, although the larvae of E. postvittana showed little preference to Diet B. The greater fertility rate of E. postvittana reared on Diet B suggests the importance of sterols as shown in Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae) and in a few Myrmicinae (Hymenoptera: Formicidae), which serve as precursors to different ecdysteroids that regulate many critical processes through embryonic development.

Studies on larvicidal and pupicidal activity of Leucas aspera Willd. (Lamiaceae) and bacterial insecticide, Bacillus sphaericus, against malarial vector, Anopheles stephensi Liston. (Diptera: Culicidae).

The efficacy of whole plant extracts of Leucas aspera and Bacillus sphaericus has been proven against larvicidal and pupicidal activities of the malarial vector, Anopheles stephensi. The present study investigated the larvicidal and pupicidal activity against the first to fourth instar lavae and pupae of the laboratory-reared mosquitoes, A. stephensi. The medicinal plants were collected from the area around Maruthamalai hills, Coimbatore, Tamil Nadu, India. L. aspera whole plant was washed with tap water and shade dried at room temperature. The dried plant materials were powdered by an electric blender. From the powder, 100 g of the plant materials was extracted with 300 ml of organic solvents of ethanol for 8 h using a Soxhlet apparatus. The extracts were filtered through a Buchner funnel with Whatman number 1 filter paper. The crude plant extracts were evaporated to dryness in a rotary vacuum evaporator. The plant extract showed larvicidal and pupicidal effects after 24 h of exposure. All larval instars and pupae have considerably moderate mortality; however, the highest larval mortality was the ethanolic extract of whole plant L. aspera against the first to fourth instar larvae and pupae values of LC(50) = I instar was 9.695%, II instar was 10.272%, III instar was 10.823%, and IV instar was 11.303%, and pupae was 12.732%. B. spaericus against the first to fouth instar larvae and pupae had the following values: I instar was 0.051%, II instar was 0.057%, III instar was 0.062%, IV instar was 0.066%, and for the pupae was 0.073%. No mortality was observed in the control. The present results suggest that the ethanolic extracts of L. aspera and B. sphaericus provided an excellent potential for controlling of malarial vector, A. stephensi.

Comparative evaluation of phenoloxidase activity in different larval stages of four lepidopteran pests after exposure to Bacillus thuringiensis.

Microbial entomopathogen-based bioinsecticides are recognized as alternatives to synthetic pesticides. Insects defend themselves against microbial pathogens by innate mechanisms, including increased phenoloxidase (PO) activity, but its relationship with microbial bioinsecticides efficacy is little known. This study evaluated the differences in PO activity at different developmental stages of the tobacco budworm Heliothis virescens Fabricius (Lepidoptera: Noctuidae), Indian meal moth Plodia interpunctella (Hübner) (Pyralidae), beet armyworm Spodoptera exigua (Hübner) (Noctuidae), and cabbage looper Trichoplusia ni (Hübner) (Noctuidae). Additionally, 2(nd)- and 4(th)-instars were exposed to the LC(50) value of the commercial Bacillus thuringiensis (Bt) spray, Biobit(®). The percentage of insecticidal activity (IA%) on 2(nd)-instar Biobit-exposed larvae was approximately the predicted 50 % mortality for all species except S. exigua. With all 4(th) instar Biobit-exposed larvae, mortality was not significantly different from that of unexposed larvae. Unexposed insects had a significantly higher PO activity in pre-pupae and pupae than early-instar larvae and adults, whereas PO activity was higher in adult females than in males. Correlation analysis between IA% and PO activity revealed significant r-values (p < 0.01) in 2(nd) instar H. virescens (r = 0.979) and P. interpunctella (r = 0.930). Second instar Biobit-exposed P. interpunctella had 10 times more PO activity than unexposed larvae. Similarly, the amount of total protein was lower in 4(th) instar Biobit-exposed H. virescens and higher in S. exigua. Therefore, the results indicated a relationship between Biobit susceptibility and PO activity in some cases. This information may be useful if the Biobit application period is timed for a developmental stage with low PO activity. However, more studies are needed to determine the correlation of each insect with a particular bioinsecticide.

Long-term preservation, regeneration, and cultivation of Paecilomyces tenuipes (Peck) Samson (Ascomycetes), an entomopathogenic fungus inoculated into the silkworm larva of Bombyx mori.

Paecilomyces tenuipes reportedly have anticancer and immune activities, along with various other medicinal uses. Cultured products with P. tenuipes are certified for use in food in South Korea, and processed goods containing this fungus have been developed in many countries, particularly South Korea, Japan, and China. Research on mass production technology-procured raw materials for the manufacture of P. tenuipes is very important; however, cultures of the fungus have been unstable. This study identified stable cultivation conditions, focusing on growth inhibition and revitalization. Moisture regulation and preservation of pupae inoculated with P. tenuipes were used to control growth inhibition and revitalization. When inoculated silkworm pupae were dehydrated to 4% moisture and preserved freeze-dried or at -70 degrees C, -20 degrees C, or 4 degrees C, the mycelia in their bodies were able to survive for 14 d. Inoculated silkworm pupae were rehydrated for 3 h and the mycelia within their bodies were recovered at 94.3-96.3%. Silkworm pupae at 4% moisture were able to survive for 135 d at temperatures < 4 degrees C and for 1 y after freeze-drying. Optimal conditions for synnemata induction were 25 degrees C and 100-300 1x.

Pathogen resistance in the moth Orgyia antiqua: direct influence of host plant dominates over the effects of individual condition.

The role of pathogens in insect ecology is widely appreciated but remains insufficiently explored. Specifically, there is little understanding about the sources of the variation in the outcome of insect-pathogen interactions. This study addresses the extent to which immune traits of larvae and pupae of the moth Orgyia antiqua L. (Lepidoptera: Lymantriidae) depend on the host plant species and individual condition of the insects. The two host plants, Salix myrsinifolia Salisb. and S. viminalis L., were chosen because they differ in the concentration of phenolic glycosides, harmful to most polyphagous insects. Individual condition was assumed to be reflected in body weight and development time, and was manipulated by rearing larvae either singly or in groups of four. The resistance traits recorded were survival and time to death after fungal infection in the larval stage and the efficiency of encapsulating a nylon implant by the pupae. The survival of the infected larvae was mainly determined by the species of the host plant. Encapsulation response was not associated with the resistance to the pathogen, suggesting that the host plant affected the pathogen rather than the immune system of the insect. Interestingly, the host plant supporting better larval growth led to inferior resistance to the pathogen, indicating a trade-off between different aspects of host plant quality.

PGPR and entomopathogenic fungus bioformulation for the synchronous management of leaffolder pest and sheath blight disease of rice.

BACKGROUND: The biological control of plant pests and diseases using a single organism has been reported to give inconsistent and poor performance. To improve the efficacy, bioformulations were developed possessing mixtures of bioagents. RESULTS: Bioformulations combining Pseudomonas fluorescens Migula strains Pf1 and AH1 and Beauveria bassiana (Balsamo) Vuill. isolate B2 were developed and tested for their efficacy against leaffolder pest and sheath blight disease on rice under glasshouse and field conditions. The combination of Pf1, AH1 and B2 effectively reduced the incidence of leaffolder insect and sheath blight disease on rice compared with other treatments. An in vitro assay of leaffolder preference to rice leaf tissues treated with Pf1 + AH1 + B2 biformulation showed variation from normal growth and development of leaffolder larvae. Plants treated with the Pf1 + AH1 + B2 combination showed a greater accumulation of enzymes, lipoxygenase and chitinase activity against leaffolder insect compared with other treatments. Similarly, the plants showed a higher accumulation of defence enzymes, peroxidase and polyphenol oxidase activity against sheath blight pathogen in Pf1 + AH1 + B2 treatment compared with the untreated control. The bioformulation mixture attracted the natural enemy population of leaffolder under field conditions. In addition, a significant increase in rice grain yield was observed in Pf1 + AH1 + B2 treatment compared with the untreated control. CONCLUSION: The combination of P. fluorescens strains and B. bassiana isolate effectively reduced the incidence of leaffolder insect and sheath blight disease on rice plants and showed the possibility of controlling both pest and disease using a single bioformulation.

Effects of Wolbachia on sperm maturation and architecture in Drosophila simulans Riverside.

Wolbachia is an intracellular obligate symbiont, that is relatively common in insects and also found in some nematodes. Cytoplasmic incompatibility (CI) is the most commonly expressed form, of several sex altering phenotypes caused by this rickettsial-like bacterium. CI is induced when infected males mate with uninfected females, and is likely the result of bacterial-induced modification of sperm grown in a Wolbachia-infected environment. Several studies have explored the dynamics of Wolbachia bacteria during sperm development in Drosophila. This study confirms and extends these earlier investigations of Wolbachia's distribution and proliferation in male germ cell lines. We examined Wolbachia population dynamics during testis development of Drosophila simulans (Riverside) by studying their distribution during the early mitotic divisions of secondary spermatogonial and subsequent meiotic cyst cells. Wolbachia are found in lower concentration in spermatogonial than in spermatocyte cells. Cytoplasmically incompatible crosses result in low levels of viable embryos despite the occurrence of fairly high levels of uninfected cysts. During meiotic divisions Wolbachia organize themselves at the poles during prophase and telophase but arrange themselves in equatorial bands during metaphase and anaphase. Moreover, during meiosis Wolbachia are asymmetrically divided between some daughter cells. There is no strong relationship between the fusome and Wolbachia and we have not found evidence that bacteria cross the ring canals. Wolbachia were observed at the distal and proximal sides of individualization complexes. Multiple altered sperm structures were observed during the process of individualization of infected sperm.

Actividades enzimáticas en aislamientos bacterianos de tractos digestivos de larvas y del contenido de pupas de Automeris zugana y Rothschildia lebeau (Lepidoptera: Saturniidae)

Enzymatic activities of bacteria isolated from the digestive tract of caterpillars and the pupal content of Automeris zugana and Rothschildia lebeau (Lepidoptera: Saturniidae). The enzymatic activities of bacteria isolated from the digestive tracts of caterpillars and the pupal contents of Automeris zugana and Rothschildia lebeau was studied. This digestive tract represents an extreme microenvironment due to its high pH and presence of antimicrobial substances secreted by the insect or derived from ingested plant tissue. At the same time, it contains large amounts of nutrient-rich food, for which microbes may compete among themselves and with the caterpillar. There is little information about the microbiota associated with tropical caterpillar guts, although bacteria from different genera have been isolated from gut and pupae samples. The study of the enzymatic activities generated by these organisms constitutes a starting point to understand their metabolic and physiological relationships with their hosts, and to find enzymes that have potential biotechnological applications. In this study we evaluated several enzymatic activities in two collections of bacteria isolated from caterpillar guts and pupae of the tropical lepidopteran species A. zugana and R. lebeau. Bacteria grown under aerobic conditions were tested for an array of enzymes, including gelatinases, caseinases, lipases, esterases, cellulases, xylanases, amylases and chitinases. Both collections displayed similar patterns of enzymatic activity. No isolate showed activity for all enzymatic tests, but as a whole, at least some bacteria in each collection were able to degrade each substrate tested. Isolates with the same taxonomic identification obtained from caterpillar guts and pupae had almost the same enzymatic activities. In both collections, it was possible to group bacterial isolates according to their enzyme activity pattern. In addition to a heterogeneous ensemble of isolates exhibiting two or less enzymatic activities, there were two groups with at least five activities that showed an apparent specialization for the substrates they were able to use. The first consisted exclusively of isolates of the family Enterobacteriaceae, which were positive for lipolytic and chitinolytic activities, but completely lacked amylasic, cellulolytic and xylanolytic activities. The second group, composed mainly of Gram-positive rods, exhibited the opposite pattern: they were positive for amylasic, cellulolytic and xylanolytic activities, lacked chitinolytic activity and had few isolates with lipolytic activity. This work forms the foundation for future research to explore the biotechnological potential of bacterial isolates from caterpillar guts. Rev. Biol. Trop. 55 (2): 401-415. Epub 2007 June, 29.

El tracto digestivo de orugas constituye un microambiente extremo, debido a su elevado pH y presencia de sustancias antimicrobianas secretadas por el insecto o derivadas del tejido vegetal ingerido. Al mismo tiempo, el intestino alberga gran cantidad de alimento, por el cual los microorganismos presentes podrían competir entre sí y con su hospedero. Existe poca información sobre la microbiota asociada con el intestino de orugas tropicales, aunque se ha demostrado la presencia de bacterias de diversos géneros tanto en el intestino como en el interior de pupas. El estudio de las actividades enzimáticas de estos microorganismos constituye un punto de partida en la comprensión de la posible relación metabólica y fisiológica que establecen con sus hospederos, a la vez que permite investigar enzimas con potenciales aplicaciones biotecnológicas. En este trabajo se evaluó la presencia de actividades gelatinolítica, caseinolítica, esterásica, lipolítica, quitinolítica, amilásica, celulolítica y xilanolítica en dos colecciones de aislamientos bacterianos provenientes de tractos digestivos de orugas y de pupas de los lepidópteros Automeris zugana y Rothschildia lebeau. Se utilizaron ensayos bioquímicos tradicionales para detectar enzimas secretadas en condiciones aerobias, en las que ambas colecciones exhibieron un comportamiento enzimático similar. Ningún aislamiento produjo un resultado positivo en todas las pruebas, pero como conjunto ambas colecciones fueron capaces de utilizar todos los sustratos evaluados. Los aislamientos obtenidos de pupas presentaron prácticamente las mismas actividades que sus homólogos provenientes de intestinos. En ambas colecciones fue posible agrupar los aislamientos de acuerdo con su patrón de producción de enzimas. Además de un conjunto heterogéneo de aislamientos poco activos (dos o menos actividades), se destacan dos grupos muy activos (al menos cinco actividades), que manifiestan una aparente especialización en los sustratos que utilizan. El primero de ellos está constituido exclusivamente por miembros de la familia Enterobacteriaceae, los cuales exhibieron un alto porcentaje de positividad en actividades lipolítica y quitinolítica, pero no demostraron la expresión de las actividades amilásica, celulolítica ni xilanolítica. El segundo grupo, formado en su gran mayoría por bacilos Gram-positivos, presenta la situación opuesta: alta positividad en actividades amilásica, celulolítica y xilanolítica, no detección de actividad quitinolítica y pocos aislamientos con actividad lipolítica. Este trabajo pretende ser la base de futuras investigaciones que exploren el potencial biotecnológico de aislamientos bacterianos provenientes del tracto digestivo de orugas.

Two new isolates of Bacillus thuringiensis pathogenic to Spodoptera litura.

Both the standard Bacillus thuringiensis kurstaki (HD-1) and the formulated commercial product resulted from this strain have shown limited pathogenicity against the tobacco cutworm (Spodoptera litura). However, two new isolates of Bacillus thuringiensis (K-2074 and K-2178) isolated from Taiwan have been identified through an active screening program to be highly pathogenic against the tobacco cutworm. In this paper, we present results of characterization and the pathogenicity of these two new isolates.

Identification of virus-specific polypeptides and translatable mRNAs in the isolated pupal abdomens of the silkworm, Bombyx mori, infected with nuclear polyhedrosis virus.

Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that infection of the isolated pupal abdomens of the silkworm, Bombyx mori, with B. mori nuclear polyhedrosis virus (BmNPV) caused generation of a number of polypeptides with a concomitant decrease of cellular polypeptides. These generated polypeptides were not identified as viral structural polypeptides, but were characterized as the degradation products of cellular polypeptides, as evidenced by the reaction with specific antiserum against storage proteins 1 and 2. Immunoblot analysis using anti-BmNPV serum identified at least 14 virus-specific polypeptides in the BmNPV-structural polypeptides of the virus. In vitro translation and subsequent immunoprecipitation with anti-BmNPV serum showed that translation yielded at least 15 polypeptides at the expense of cellular polypeptides. Time-course experiments showed that the viral structural polypeptides and virus-specific translatable mRNAs were not detectable until 3 days postinoculation. On the basis of the fact that the isolated pupal abdomens are in an arrested state of development, the delayed onset of virus-specific macromolecule production in the infected isolated pupal abdomens, as compared with that in the developing intact pupae, implies that some cellular function associated with the pupal-adult development is an important prerequisite for the efficient commencement of BmNPV replication.