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Toshiharu Tanaka - One of the best experts on this subject based on the ideXlab platform.
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Development of Meteorus pulchricornis and regulation of its noctuid host, Pseudaletia separata
Journal of Insect Physiology, 2007Co-Authors: M. Suzuki, Toshiharu TanakaAbstract:Abstract The solitary endoparasitoid Meteorus pulchricornis can parasitize many lepidopteran host species successfully. In the case of parasitization of Pseudaletia separata , developmental duration of M. pulchricornis was 8–9 days from egg to larval emergence and 6 days from prepupa to adult emergence. Successful parasitism by M. pulchricornis decreased with host age. Following parasitization of day-0 4th host instar, the parasitoid embryo, whilst still enclosed in serosal cell membrane, hatched out of the egg chorion 2 days after oviposition. Subsequently, the 1st instar parasitoid emerged from the surrounding serosal cell membrane. Serosal cells dissociated and developed as Teratocytes 3.5 days after oviposition. One embryo of M. pulchricornis gave rise to approximately 1200 Teratocytes, a number that remained constant until 6 days after parasitization, but decreased drastically to 200 at 7 days post-oviposition. The Teratocytes of M. pulchricornis were round- or oval-shaped and grew from 65 μm at 4 days to 200 μm in the long axis at 6 days post-parasitization. At 4 days post-parasitization, many cells or cell clusters with lipid particles were observed in the hemocoels of parasitized hosts. In addition, paraffin sections of parasitized hosts revealed that many Teratocytes were attached to the host's fat body and contributed to disrupting the fat body tissue. Further, examination of the total hemocyte count (THC) during parasitization revealed that THC was maintained at low levels. Surprisingly, a temporal decrease followed by restoration of THC was observed in hosts injected with virus-like particles of M. pulchricornis (MpVLPs) plus venom, which contrasts with the constant THC suppression seen in parasitized hosts. This indicates that MpVLP function is temporal and is involved in regulation of the host during early parasitism. Therefore, Teratocytes, a host regulation factor in late parasitism, could be involved in keeping THC at a low level.
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larvae of an endoparasitoid cotesia kariyai hymenoptera braconidae feed on the host fat body directly in the second stadium with the help of Teratocytes
Journal of Insect Physiology, 2002Co-Authors: Yutaka Nakamatsu, S Fujii, Toshiharu TanakaAbstract:Larvae of a gregarious endoparasitoid, Cotesia kariyai (Watanabe), grew rapidly during the second stadium in the host. The fat body of a Pseudaletia host parasitized by C. kariyai was completely consumed by 10 d, just before larval emergence. It seemed hard to explain the growth of the second instar parasitoids and the rapid consumption of the fat body only by ingestion of hemolymph converted from the fat body or other organs of the host. Paraffin sections of the parasitized host revealed that many Teratocytes were attached to the surface of the fat body in many sites and destroyed the fat body tissue locally. Zymography of proteins released from the Teratocytes revealed that the Teratocytes 4 to 9 days after parasitization showed collagenase activity (as a gelatinase). Further, 1st instar parasitoids which were transplanted together with Teratocytes into unparasitized hosts preconditioned with C. kariyai polydnavirus (CkPDV) plus venom, grew normally to the 2nd stadium. Abnormal growth of parasitoid larvae was observed when parasitoid larvae were transplanted without Teratocytes. These results suggest that the Teratocytes attach to the outer sheath of the fat body, secrete an enzyme that makes a hole in the matrix of the fat body, thus allowing the second instar parasitoid to ingest the content of the fat body.
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Cotesia kariyai Teratocytes: growth and development
Journal of Insect Physiology, 2001Co-Authors: Masashi Hotta, Takashi Okuda, Toshiharu TanakaAbstract:The growth and development of Teratocytes was examined in the Cotesia kariyai-Pseudaletia separata system. Cotesia kariyai embryos released an average of 163 Teratocytes at the time of hatching, 3.5 days after oviposition. The cells increased in diameter from 30 to 77 μm until 7 days post-parasitization, after which there was no significant increase in average diameter. However, there was significant variation in diameter within the population of Teratocytes during the later developmental stages of the parasitoid larvae. The DNA contents increased up to day 7. The ploidy level of Teratocytes increased 4-fold (2C to 8C) from days 4 to 7 and thereafter remained the same. Scanning electron microscopy (SEM) revealed that the surface of the Teratocytes was covered with microvilli during all developmental stages, although on days 9 to 10 post-parasitization, bleb structures were also observed on a few. In vitro analysis of the proteins secreted from Teratocytes following labeling with 35 S-methionine showed that many proteins were synthesized de novo and secreted by the cells until 9 to 10 days post-parasitization. These results indicate that Teratocytes in later stages of development maintain their activity and regulate the physiological state of the host. © 2000 Elsevier Science Ltd. All rights reserved.
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cotesia kariyai Teratocytes growth and development
Journal of Insect Physiology, 2001Co-Authors: Masashi Hotta, Takashi Okuda, Toshiharu TanakaAbstract:Abstract The growth and development of Teratocytes was examined in the Cotesia kariyai-Pseudaletia separata system. Cotesia kariyai embryos released an average of 163 Teratocytes at the time of hatching, 3.5 days after oviposition. The cells increased in diameter from 30 to 77 μm until 7 days post-parasitization, after which there was no significant increase in average diameter. However, there was significant variation in diameter within the population of Teratocytes during the later developmental stages of the parasitoid larvae. The DNA contents increased up to day 7. The ploidy level of Teratocytes increased 4-fold (2C to 8C) from days 4 to 7 and thereafter remained the same. Scanning electron microscopy (SEM) revealed that the surface of the Teratocytes was covered with microvilli during all developmental stages, although on days 9 to 10 post-parasitization, bleb structures were also observed on a few. In vitro analysis of the proteins secreted from Teratocytes following labeling with 35S-methionine showed that many proteins were synthesized de novo and secreted by the cells until 9 to 10 days post-parasitization. These results indicate that Teratocytes in later stages of development maintain their activity and regulate the physiological state of the host.
E M Hegazi - One of the best experts on this subject based on the ideXlab platform.
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growth patterns of microplitis rufiventris hym braconidae Teratocytes in spodoptera littoralis lep noctuidae larvae treated with a chitin synthesis inhibitor
Journal of Applied Entomology, 2001Co-Authors: E M Hegazi, W E KhafagiAbstract:The influence of sublethal dietary levels (0.4 p.p.m.) of a chitin synthesis inhibitor lefenuron {N-[2,5-dichloro-4-(1,1,2,3,3,3-hexafluoropropoxy)-phenylaminocarbonyl]-2,6-difluorobenzamide} on the development of Microplitis rufiventris Teratocytes was investigated. Observations and data were taken on maturing Teratocytes, i e. at the end of parasitoid development. When embryogenesis of the parasitoid eggs was initiated in treated hosts, the dissociated cells of the embryonic membrane of some of the parasitoid larvae did not liberate in the haemolymph of the host, whereas in the other hosts, the released ones as individual cells scored the largest mean number per host larva. When young Teratocytes were exposed to the treatment they were found in some cases clumping in masses or clustered around the parasitoid larvae. In treated hosts, different size classes of Teratocytes co-existed. Larger and morphological abnormal cells were more common in hosts which contained older Teratocytes at the time of treatments. Abnormal Teratocytes were associated with developmental abnormalities of parasitoid larvae, possibly due to deterioration of the host environment. This observation was common in treated hosts and in few cases of untreated ones. A significant decrease in teratocyte size occurred 24 h after parasitoid emergence, Observations and results obtained in the present work suggested that: (1) teratocyte may function in controlling the growth and successful development of parasitoid larvae; (2) they might have a protective function through sequestering abnormal materials issuing in the haemolymph of the host either during the course of parasitoid development or due to external stress; and (3) number of teratocyte cells liberated from the embryonic membrane of parasitoid egg is not constant.
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studies on the mature Teratocytes in the body cavity of spodoptera littoralis boisd attacked by microplitis rufiventris kok
Archives of Phytopathology and Plant Protection, 1999Co-Authors: E M Hegazi, W E Khafagi, A M Elminshawy, N ElsingabyAbstract:Number, diameter and distribution of the mature Teratocytes of Microplitis rufiventris wasp were studied before and after parasitoid egression. The evidence obtained in this study indicated that the Teratocytes have no role in providing nutrition at least by ingestion to the parasitoid larvae. Teratocytes lose about one‐third of their diameter at the end of the parasitoid development. About 75% of the total count of Teratocytes was found in the posterior region of the host larva in which the posterior part of the parasitoid larva is located “anal vesicle”;. Occurrence of a significant number of Teratocytes in the cephalic haemolymph of host larva has led to a suggestion that the Teratocytes might be responsible for depriving the host larva from some biological products necessary for the host development for successful development of the parasitoid.
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effect of mating status and age of microplitis rufiventris hym braconidae females on the growth pattern and number of their Teratocytes
Journal of Applied Entomology, 1999Co-Authors: E M Hegazi, W E KhafagiAbstract:The effect of mating status and age of the female of Microplitis rufiventris parasitoid on the growth pattern of its Teratocytes during the larval development is described as well as the changes in the number of these cells. The growth pattern of Teratocytes derived from haploid eggs significantly differed from that of eggs deposited by mated females. Both cell diameter and the number of maturing M. rufiventris Teratocytes was fertilization-dependent. Following the parasitization of Spodoptera littoralis larvae with virgin parasitoid females, the host larvae hosted a large number of cells of smaller size at the end of parasitoid development. The opposite effect was seen when the host larvae contained female parasitoid larvae. The age of the female at parasitization had an effect on the maximum cell size attained prior to parasitoid emergence. It seems that there are two factors other than mating which affect the number of Teratocytes: degeneration inside the host haemolymph and to some degree accidental ingestion by parasitoid larva.
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prediction studies on number of Teratocytes and eggs of microplitis rufiventris kok hym braconidae parasitoid in superparasitized host larvae
Journal of Applied Entomology, 1999Co-Authors: W E Khafagi, E M Hegazi, S ShowailAbstract:1 Introduction Microplitis rufiventris Kok. (Hym., Braconidae) is an internal solitary parasitoid of many noctuid caterpillars including the cotton leafworm Spodoptera littoralis (Boisd.) ( Kokujev 1914; Hammad et al. 1965 ; Gerling 1969), the lesser cotton worm S. exigua Hbn. ( Meier 1929; Thompson 1946; El-Minshawy 1963); S. latebrosa Lederer ( Hammad et al. 1965 ) and American bollworm Heliothis armigera Hbn. ( Meier 1929; Ibrahim & Tawfik 1975). When the egg of M. rufiventris hatches in its host, S. littoralis, spherical cells from the serosa that envelope the parasitoid embryo are released into the host’s haemolymph. Approximately 400 cells are liberated from an egg of the parasitoid. These cells increase in size, reaching a maximum average diameter of 137 μm at the completion of parasitoid development ( Khafagi 1997). These cells are most frequently called ‘Teratocytes’ ( — 1968 , 1971; Vinson 1970). It is reported that the presence of large numbers of the Teratocytes is indicative of superparasitism but their number does not give an indication to the exact number of parasitoid eggs from which the cells have been derived ( —, — Khafagi et al. 1998 ) . Therefore, it was of interest to initiate prediction studies on egg and teratocyte numbers in superparasitized host larvae.
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precocene ii and possible function of microplitis rufiventris kok hym brac Teratocytes
Archives of Phytopathology and Plant Protection, 1998Co-Authors: E M Hegazi, Wedad E KhafagiAbstract:Different developmental ages of Microplitis rufiventris Kok. Teratocytes were exposed to a topical dose (70 μg/5 μl) of an anti‐juvenile hormone (Precocene II) via Spodoptera littoralis larvae and inspected just prior parasitoid egression. Application of PII exerted significant reduction in both cell number and size. Whatever the teratocyte age at treatment, treated host larvae contained smaller sized cells than untreated ones, i.e., the effect seems to be permanent. The results suggested that: (1) the teratocyte may be involved in sequestering host's juvenile hormone, (2) healthy Teratocytes may act in inhibiting the ability of host to produce melanin, and (3) PII‐treatment might have an effect on the absorptive function of the Teratocytes.
Michael R Strand - One of the best experts on this subject based on the ideXlab platform.
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cotesia vestalis Teratocytes express a diversity of genes and exhibit novel immune functions in parasitism
Scientific Reports, 2016Co-Authors: Qijuan Gu, Michael R Strand, Fei Li, Zehua Wang, Qisheng Song, Xue-xin ChenAbstract:Some endoparasitoid wasps lay eggs that produce cells called Teratocytes. In this study, we sequenced and analyzed the transcriptome of Teratocytes from the solitary endoparasitoid Cotesia vestalis (Braconidae), which parasitizes larval stage Plutella xylostella (Plutellidae). Results identified many teratocyte transcripts with potential functions in affecting host immune defenses, growth or metabolism. Characterization of teratocyte-secreted venom-like protein 8 (TSVP-8) indicated it inhibits melanization of host hemolymph in vitro, while two predicted anti-microbial peptides (CvT-def 1 and 3) inhibited the growth of bacteria. Results also showed the parasitized hosts lacking Teratocytes experienced higher mortality after immune challenge by pathogens than hosts with Teratocytes. Taken together, these findings indicate that C. vestalis Teratocytes secrete products that alter host immune functions while also producing anti-microbial peptides with functions that help protect the host from infection by other organisms.
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Teratocytes and their functions in parasitoids
Current opinion in insect science, 2014Co-Authors: Michael R StrandAbstract:Some endoparasitoid wasps (Hymenoptera) produce Teratocytes, which are a type of cell that is released into host insects when wasp eggs hatch. In this short review I first summarize the different taxa of wasps that produce Teratocytes, the embryonic origin of these cells, and key features of teratocyte growth. Then I discuss the known or hypothesized functions of Teratocytes, and the range of teratocyte gene products that have been identified including recent transcriptome and proteome data.
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the growth and role of microplitis demolitor Teratocytes in parasitism of pseudoplusia includens
Journal of Insect Physiology, 1991Co-Authors: Michael R Strand, E A WongAbstract:Abstract The growth and function of Microplitis demolitor Teratocytes in Pseudoplusia includens larvae was investigated. An average of 542 Teratocytes was produced per M. demolitor egg. The number of Teratocytes present per host declined during the course of parasitoid development, but the size of individual cells increased. The ploidy levels of Teratocytes ranged from 2 to 8C at hatching, but had increased to 128–256C at the completion of parasitoid development. Injection of in vitro cultured Teratocytes into fourth stadium P. includens larvae had an inconsistent effect on development. Most larvae pupated without delay when injected with a physiological dose of 600 Teratocytes, but 54% of larvae failed to pupate when injected with a superphysiological dose of 2400 Teratocytes. Examination of Teratocytes indicated most cells were encapsulated by P. includens haemocytes within 24 h of injection. However, prior injection of larvae with M. demolitor calyx fluid or polydnavirus plus venom suppressed the encapsulation response. Further, 87% of larvae injected with polydnavirus plus venom and 600 Teratocytes exhibited alterations in growth that were very similar to parasitism by M. demolitor .
D L Dahlman - One of the best experts on this subject based on the ideXlab platform.
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extended in vitro culture of microplitis croceipes Teratocytes and secretion of tsp14 protein
Journal of Insect Physiology, 2002Co-Authors: H L Hoy, D L DahlmanAbstract:Teratocytes, cells which originate from the serosal membrane of some Braconidae and Scelionidae, can be found in the hemocoel of permissive hosts during part or all of the developmental time of the parasitoid larva. Teratocytes from Microplitis croceipes are known to secrete biologically active proteins, which contribute to developmental arrest and failure to pupate of Heliothis virescens larvae. One such protein, which has a molecular weight of approximately 14 kDa is called TSP14. The presence of parasitoid larvae is essential to maintain Teratocytes under in vitro conditions with protein-free EX-CELL 400. The teratocyte viability was maintained in vitro for at least 12 days in the presence of larvae when medium was exchanged every three days. Western blots show that TSP14 was secreted during the entire period of exchanges. In the absence of parasitoid larvae, teratocyte viability was only 30% by day 6 and no TSP14 had been secreted. In the absence of parasitoid larvae, Teratocytes maintained in vitro in EX-CELL 400 medium supplemented with 10% FBS remained viable for at least nine days and secreted TSP14 for at least six days. This suggests that parasitoid larval secretions are sufficient but not uniquely essential to maintain teratocyte viability. Parasitoid larvae maintained in the absence of Teratocytes did not secrete TSP14 and their secretory products did not inhibit pupation of H. virescens larvae.
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microplitis croceipes Teratocytes in vitro culture and biological activity of teratocyte secreted protein
Journal of Insect Physiology, 1998Co-Authors: Eric J Schepers, D L Dahlman, Deqing ZhangAbstract:Abstract Teratocytes originate from the dissociation of the extraembryonic serosal membrane in some Braconidae and Scelionidae. Methods used to culture Teratocytes in vitro are described and the yield of teratocyte secreted proteins (TSP) was measured. Although 90% are viable after 6 days, in vitro Teratocytes reached only half the diameter (32 μ m) of the same age Teratocytes obtained in vivo . Teratocytes cultured in vitro secrete as much as 0.7 μ g of protein per day per larval equivalent (≈900 cells). Presence of parasitoid larvae enhanced teratocyte viability while periodic exchange of medium did not. However, medium exchange significantly increased the total amount of protein secreted. Size and viability were improved with the addition of 10% FBS to the Ex-cell 400 culture medium. Non-denaturing PAGE showed at least 15 proteins with molecular sizes estimated to be between 24 to 347 kDa in medium containing Teratocytes. An in vitro fat body assay was developed to measure the effect of TSP on protein synthesis and juvenile hormone esterase (JHE) activity. Crude TSP inhibited in vitro incorporation of [ 35 S]-methionine into protein synthesized by the fat body. The amount of JHE released from in vitro fat body treated with crude TSP was significantly less than controls, most likely caused by the inhibition of general protein synthesis. The active fraction of TSP passed through a 30 kDa molecular weight cutoff filter but was retained by a 3 kDa filter. SDS-PAGE revealed four proteins with molecular weights between 8 and 20 kDa not present in control medium incubated without Teratocytes.
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effects of microplitis croceipes Teratocytes on host haemolymph protein content and fat body proliferation
Journal of Insect Physiology, 1997Co-Authors: Deqing Zhang, D L Dahlman, Ulla JarlforsAbstract:Abstract Qualitative and quantitative changes in haemolymph proteins in Heliothis virescens were observed in larvae injected with either Microplitis croceipes Teratocytes or teratocyte secreted proteins (TSP). Haemolymph protein titres in hosts receiving either 0.5 or 1 larval equivalent (LE) of Teratocytes were similar to those of parasitized larvae, whereas a single injection of 4 LE of TSP was required to induce a similar response. SDS-PAGE showed that the 82 kDa monomer of riboflavin-binding protein and the 74/76 kDa monomers of storage proteins were significantly reduced in parasitized larvae and in nonparasitized larvae treated with TSP. Concentrations of a 155 kDa monomer (insectacyanin chromoprotein) also were reduced in parasitized larvae and those injected with either Teratocytes or TSP. Two monomers (56 and 60 kDa) were unique to parasitized larvae. Treated larvae required several days longer than controls to reach a comparable premetamorphic stage (burrowing–digging). Reductions in fat body proliferation similar to those seen in parasitized larvae were observed in larvae treated with either 1 LE of Teratocytes, or with 2 or 4 LEs of TSP. Perivisceral fat body weights from larvae treated with either 0.25 or 0.5 LE of Teratocytes were significantly reduced, but less so than those which received 1 LE. Thus, fat body proliferation in both teratocyte- and TSP-treated larvae was inhibited in a dose-dependent manner. Both light- and transmission electron microscopy observations revealed cytological differences in fat body tissues of larvae injected with either Teratocytes or TSP from the condition observed in parasitized larvae and noninjected controls. Gross dissection of periviseral fat body from parasitized, teratocyte-injected and TSP-injected larvae showed tissue much less developed and differing considerably in appearance from controls. Observed differences included reduced size and/or number of lipid bodies and qualitative and quantitative changes in other cytoplasmic organelles.
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ultrastructure of microplitis croceipes cresson braconidae hymenoptera Teratocytes
International Journal of Insect Morphology & Embryology, 1994Co-Authors: Deqing Zhang, D L Dahlman, Ulla Jarlfors, H H Southgate, Scott P WileyAbstract:Abstract The developing embryo of the braconid, Microplitis croceipes (Braconidae : Hymenoptera), is encased in an extraembryonic serosal membrane. Hatching of the parasitoid within the larva of its habitual host, Hehothis virescens (Noctuidae : Lepidoptera), is initiated about 40 hr after oviposition when held at 25 ± 2°C. At this time, the monolayered serosal membrane begins to dissociate into individual cells (Teratocytes). After dissociation, Teratocytes become dispersed in the hemolymph of the host. The average number of Teratocytes released from each parasitoid embryo is 914 ± 43. Teratocytes average 14.1 ± 2.4 μm in diameter when first released, and reach a maximum average diameter of 68.1 ± 4.6 μm 6 days after liberation. Newly released Teratocytes have ovoid nuclei, simple mitochondria and a limited number of profiles of the endoplasmic reticulum, all of which indicate relative metabolic inactivity. The ramified nuclei, extensive endoplasmic reticulum, polymorphic mitochondria and accumulation of glycogen granules and lipid droplets observed in older Teratocytes provide circumstantial evidence that protein synthesis is occurring. Within hours after dissociation, microvilli begin to cover the surface of the Teratocytes. Anatomical deformation (blebs) that occurred on some older (8-day-old) Teratocytes probably resulted from enlargement or expansion of microvilli.
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Teratocytes and host parasitoid interactions
Biological Control, 1991Co-Authors: D L DahlmanAbstract:Abstract Teratocytes, derived from extraembryonic tissues of parasitic Braconidae, Platygasteridae, and Scelionidae, play several important roles in parasitoid-host interactions. Teratocytes have trophic, immunosuppressive, and secretory functions but their specific activities depend upon the life stage of the host, the time spent by the parasitoid within the host, and the individual species of parasite and host. Teratocytes have immunosuppressive, trophic, and secretory functions. Teratocytes from the braconid, Microplitis croceipes, were obtained at various times from the hemolymph of its host, Heliothis virescens, or from preparations obtained from M. croceipes eggs hatched in vitro. The Teratocytes were viewed using scanning electron microscopy and were found to possess a dense coat of microvilli. In vitro cultures of Teratocytes secrete proteins and these teratocyte secretory products, when injected into H. virescens larvae, produce many of the same developmental abnormalities observed when larvae are injected with intact Teratocytes or are truly parasitized. Finally, it was demonstrated that DNA from the M. croceipes polydnavirus hybridizes with DNA extracted from Teratocytes and various other tissues of M. croceipes. Potential implications of the teratocyte/host/polydnavirus interactions are discussed with respect to biological control applications.
W E Khafagi - One of the best experts on this subject based on the ideXlab platform.
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growth patterns of microplitis rufiventris hym braconidae Teratocytes in spodoptera littoralis lep noctuidae larvae treated with a chitin synthesis inhibitor
Journal of Applied Entomology, 2001Co-Authors: E M Hegazi, W E KhafagiAbstract:The influence of sublethal dietary levels (0.4 p.p.m.) of a chitin synthesis inhibitor lefenuron {N-[2,5-dichloro-4-(1,1,2,3,3,3-hexafluoropropoxy)-phenylaminocarbonyl]-2,6-difluorobenzamide} on the development of Microplitis rufiventris Teratocytes was investigated. Observations and data were taken on maturing Teratocytes, i e. at the end of parasitoid development. When embryogenesis of the parasitoid eggs was initiated in treated hosts, the dissociated cells of the embryonic membrane of some of the parasitoid larvae did not liberate in the haemolymph of the host, whereas in the other hosts, the released ones as individual cells scored the largest mean number per host larva. When young Teratocytes were exposed to the treatment they were found in some cases clumping in masses or clustered around the parasitoid larvae. In treated hosts, different size classes of Teratocytes co-existed. Larger and morphological abnormal cells were more common in hosts which contained older Teratocytes at the time of treatments. Abnormal Teratocytes were associated with developmental abnormalities of parasitoid larvae, possibly due to deterioration of the host environment. This observation was common in treated hosts and in few cases of untreated ones. A significant decrease in teratocyte size occurred 24 h after parasitoid emergence, Observations and results obtained in the present work suggested that: (1) teratocyte may function in controlling the growth and successful development of parasitoid larvae; (2) they might have a protective function through sequestering abnormal materials issuing in the haemolymph of the host either during the course of parasitoid development or due to external stress; and (3) number of teratocyte cells liberated from the embryonic membrane of parasitoid egg is not constant.
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studies on the mature Teratocytes in the body cavity of spodoptera littoralis boisd attacked by microplitis rufiventris kok
Archives of Phytopathology and Plant Protection, 1999Co-Authors: E M Hegazi, W E Khafagi, A M Elminshawy, N ElsingabyAbstract:Number, diameter and distribution of the mature Teratocytes of Microplitis rufiventris wasp were studied before and after parasitoid egression. The evidence obtained in this study indicated that the Teratocytes have no role in providing nutrition at least by ingestion to the parasitoid larvae. Teratocytes lose about one‐third of their diameter at the end of the parasitoid development. About 75% of the total count of Teratocytes was found in the posterior region of the host larva in which the posterior part of the parasitoid larva is located “anal vesicle”;. Occurrence of a significant number of Teratocytes in the cephalic haemolymph of host larva has led to a suggestion that the Teratocytes might be responsible for depriving the host larva from some biological products necessary for the host development for successful development of the parasitoid.
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effect of mating status and age of microplitis rufiventris hym braconidae females on the growth pattern and number of their Teratocytes
Journal of Applied Entomology, 1999Co-Authors: E M Hegazi, W E KhafagiAbstract:The effect of mating status and age of the female of Microplitis rufiventris parasitoid on the growth pattern of its Teratocytes during the larval development is described as well as the changes in the number of these cells. The growth pattern of Teratocytes derived from haploid eggs significantly differed from that of eggs deposited by mated females. Both cell diameter and the number of maturing M. rufiventris Teratocytes was fertilization-dependent. Following the parasitization of Spodoptera littoralis larvae with virgin parasitoid females, the host larvae hosted a large number of cells of smaller size at the end of parasitoid development. The opposite effect was seen when the host larvae contained female parasitoid larvae. The age of the female at parasitization had an effect on the maximum cell size attained prior to parasitoid emergence. It seems that there are two factors other than mating which affect the number of Teratocytes: degeneration inside the host haemolymph and to some degree accidental ingestion by parasitoid larva.
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prediction studies on number of Teratocytes and eggs of microplitis rufiventris kok hym braconidae parasitoid in superparasitized host larvae
Journal of Applied Entomology, 1999Co-Authors: W E Khafagi, E M Hegazi, S ShowailAbstract:1 Introduction Microplitis rufiventris Kok. (Hym., Braconidae) is an internal solitary parasitoid of many noctuid caterpillars including the cotton leafworm Spodoptera littoralis (Boisd.) ( Kokujev 1914; Hammad et al. 1965 ; Gerling 1969), the lesser cotton worm S. exigua Hbn. ( Meier 1929; Thompson 1946; El-Minshawy 1963); S. latebrosa Lederer ( Hammad et al. 1965 ) and American bollworm Heliothis armigera Hbn. ( Meier 1929; Ibrahim & Tawfik 1975). When the egg of M. rufiventris hatches in its host, S. littoralis, spherical cells from the serosa that envelope the parasitoid embryo are released into the host’s haemolymph. Approximately 400 cells are liberated from an egg of the parasitoid. These cells increase in size, reaching a maximum average diameter of 137 μm at the completion of parasitoid development ( Khafagi 1997). These cells are most frequently called ‘Teratocytes’ ( — 1968 , 1971; Vinson 1970). It is reported that the presence of large numbers of the Teratocytes is indicative of superparasitism but their number does not give an indication to the exact number of parasitoid eggs from which the cells have been derived ( —, — Khafagi et al. 1998 ) . Therefore, it was of interest to initiate prediction studies on egg and teratocyte numbers in superparasitized host larvae.
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Teratocytes of microplitis rufiventris in superparasitized host larvae
Archives of Phytopathology and Plant Protection, 1998Co-Authors: E M Hegazi, W E Khafagi, A M Elminshawy, N ElsingabyAbstract:The effects of superparasitism on the size and number of Teratocytes (giant cells released by the serosa of braconid eggs after hatching) found in the host Spodoptera littoralis at the completion of development of the solitary endoparasitoid Microplitis rufiventris were assessed. Although the number of Teratocytes increased, on average, with parasitoid load (1, 2 or 3 parasitoid eggs), this increase was lower than predicted, based on the number of parasitoids (i.e., is not proportional to parasitoid load). Similarly, the size of the Teratocytes decreased as a function of parasitoid load. The total volume of the Teratocytes (mm3) is reduced by 39.1 and 66.4% in hosts parasitized twice and three times, respectively. It is concluded that, in superparasitized hosts, some form of competition likely takes place among the Teratocytes, or between these cells and the first‐hatched larva, possibly through the action of a chemical (released by the latter) that inhibits the growth of Teratocytes from supernumerary pa...
