ISSN:0739-4462    

DOI:10.1002/arch.940130302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractTeratocytes, derived from extra‐embryonic tissues of parasitic Braconidae, Trichogrammatidae, and Scelionidae, play several important roles in the parasitoid‐host interaction. It is clear from the literature that the specific role (s) vary among species. Only recently have the biochemical and endocrinological roles of these cells been considered. This overview examines the recent literature on teratocytes and stresses the importance of in vitro procedures to elucidate the functional roles (trophic, immunosuppression, secretory) of teratocytes in the parasitoid‐host relatio

ISSN:0739-4462    

DOI:10.1002/arch.940130303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractEvidence for the role of host components in the growth and development of parasitoids is briefly reviewed, and implications concerning the development of in vitro culture media are discussed. In vitro development of the entomophagous parasitoidsEucelatoria bryaniSabrosky (Diptera: Tachinidae) andTrichogramma pretiosumRiley (Hymenoptera: Trichogrammatidae) is dependent on low‐molecular‐weight host chemicals. Asparagine, but not aspartic acid, and several other free amino acids are essential dietary ingredients forE. bryani. From insect hemolymph, small, unidentified polar molecules with characteristics similar to sugars are needed for pupation ofT. pretiosum. Both adaptive and nonadaptive changes likely are responsible for the dependence of parasitoids on host factors. The genetic changes have no apparent adverse effect unless the parasitoids are fed artificial media devoid of certain chemicals that are obtained in vivo from host insects. The rearing of at least several species of important entomophages to control pest insects of great economic importance is dependent on the identification of constituents from host insects and inclusion of these chemicals in artifical di

ISSN:0739-4462    

DOI:10.1002/arch.940130304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractA number of theories have been proposed concerning the means of avoiding host's encapsulation by parasitoid larvae. Our available data, however, are still not sufficient to explain the encapsulation–inhibiting effects of the gregarious endoparasitoidCotesia( =Apanteles)glomerataon its larval host,Pieris rapae crucivora. This study was prompted initially by the observation that the hemolymph obtained from parasitized fifth instar larvae failed to melanize. Phenoloxidase (PO) activity in the hemolymph of parasitized and nonparasitizedPierislarvae was determined spectrophotometrically by measuring the degree of dopachrome formation in diluted hemolymph with Ca2+‐free saline. PO activity was inhibited in host hemolymph containing young‐phase teratocytes, 1.5‐day‐old cells 40–45 μm in diameter, but not in that containing old‐phase teratocytes, 7‐day‐old cells 90–100 μm in diameter. Similar results with young‐phase teratocytes were obtained in vitro. Our data suggest that young teratocytes may suppress PO activity in the host hemolymph and interfere with encapsulation ofC.glomeratalarvae by the host. However, the mechanism of PO suppression r

ISSN:0739-4462    

DOI:10.1002/arch.940130305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractEggs and larvae ofApanteles kariyaiavoid the host defense reactions ofPseudaletia separatadue to the action of calyx and venom fluids injected by females during oviposition and the teratocytes originated from the embryonic serosal cells 3.5 day postoviposition. Phenoloxidase (PO) activity in host larvae was unaffected during early stages of parasitization (4–6 days postoviposition), relative to unparasitized larvae, but was greatly reduced to 25% during the late stage of parasitization (days 7–10). Hemolymph PO activity was not affected, in vitro, by calyx and venom fluids but was reduced in the presence of teratocytes. An apparent PO inhibitor was detected in older teratocyte cells. First instar parasitoid larvae implanted into unparasitized hosts, following transfer of either young teratocytes (4 day postoviposition) or old teratocytes (8 day post‐oviposition) with calyx and venom fluids resulted in avoidance of encapsulation only when calyx and venom fluids with young (4 day) teratocytes were injected. These results indicated that during early parasitization of the host, teratocytes just released from the embryonic serosal cells (4 day) function in conjunction with calyx and venom fluids injected into the host with the parasitoid egg to prevent its encapsulation by host hemocytes. During late parasitization, the older teratocytes (8 day) may also function in preventing host encapsulation by producing an PO inhibitor suppresses host hemolymph PO activity at the time of parasitoid egre

ISSN:0739-4462    

DOI:10.1002/arch.940130306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAs a prelude to a study in vitro of the function of the embryonic serosa of the parasitic waspBiosteres longicaudatus(Braconidae), the ultrastructure of serosas of different ages reared in vivo and in vitro were compared. The evidence suggests that the serosal capsule consists of one to three cell layers. The innermost (internal cells) which line the serosal capsule and the outermost (external) cells which are bathed by the host's hemolymph are secretory. Large, coated vesicles in the internal cells increase in number and size with age and, likely, take up and transport molecules into the serosa. Multivesicular bodies, Known for their enzyme‐degradative function, occur in external cells and are eventually extruded into the surrounding environment. Distinctive electrondense, rod‐shaped particles appear in external cells within 8 h after larvae hatch, increase in number with larval age, and occur at the bases of microvilli. The latter appear electron dense with age and eventually they and the lobulated microvilli in internal cells fragment into the surrounding environment. To determine whether parasites and/or their serosas release substances into the hostAnastrepha suspensa(Diptera: Tephritidae), hemolymph from unparasitized and superparasitized (>1 parasite/host) pharate pupae was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Serosas and/or parasite larvae were incubated in artificial media and each of these was subjected to SDS‐PAGE. A polypeptide, approximately 24 kilodaltons (Kd) occurred in the hemolymph of 24‐h‐old superparasitized pharate pupal hosts but not in the control. A similar polypeptide was observed in medium cultured with parasite larva and serosa as well as serosa alone, but was not in their respective control media. This approximately 24‐Kd band in SDS‐PAGE gels corresponds to a band in the serosa homogenate and may be identical to it. Serosas and parasite larvae in vivo and in vitro have similar protein profiles. Based upon these ultrastructural and electrophoretic studies, it appears that the serosa ofB.longicaudatushas a synthetic function, as has been reported for the extra‐embryonic membrane of other parasitic Hymenoptera. It may sequester and degrade molecules from the host hemolymph and likely release newly synthesized as well as degraded produ

ISSN:0739-4462    

DOI:10.1002/arch.940130307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe behavior, development, morphology, and ecology of parasitic insects are known to be influenced by various aspects of their hosts. These aspects include chemical cues emanating from the potential host that influence host location and acceptance by the ovipositing parasite female, as well as the age, size, and general physiological state of the host in which the immature parasite develops. Some parasitic insects develop optimally in the host egg, others in early to mid‐larval instar hosts, and still others in late‐larval to pupal stage hosts. This niche partitioning among parasites likely reflects parasite strategies to minimize competition. However, important biochemical conditions mediated by endocrine and nutritional factors within the hosts themselves dictate the extent to which these strategies are successful. In this paper I suggest that endocrine‐mediated metabolic events in late‐larval through pupal stage insects render these stages to be a nutritionally distinct resource from the early through mid‐larval stage. Consequently, members of these two groups are exploited by insect parasites which themselves have different nutritional requirements. To support this hypothesis, selected aspects of insect nutrition and endocrinology that may influence the suitability of early to mid‐stage larval hosts vs. late‐larval to pupal hosts for parasite development are reviewed. The possible impact of host suitability on aspects of parasite ecology, e.g., sex ratios and voltinism, is also brie

ISSN:0739-4462    

DOI:10.1002/arch.940130308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe facultative diapause ofAscogaster quadridentatadepends upon the photoperiod experienced by its host. A host exposed to short day lengths (12L:12D) ceases development in its fourth stadium, spins a cocoon, and remains dormant throughout the winter. A first stadium parasitoid larva overwinters in a true diapause, within its dormant host.Dormancy of both animals is due to a failure of the host's endocrine system. Upon transfer of the host from dormancy‐maintaining (OL:24D, 4°C) to dormancy‐terminating conditions (DTC = 16L:8D, 25°C) a host cephalic factor is released. The cephalic factor blocked by host ligation within 48 h of transfer to DTC was circumvented by an injection of the host with 20‐hydroxyecdysone. Parasitoid larvae that were either isolated within the abdomen of 20‐hydroxyecdysone‐injected hosts or held in vitro with the molting hormone initiated apolysis.An increased titer of hemolymph juvenile hormone, which was present 48 h after the host was transferred to DTC, may have had a prothoracicotropic effect upon the host/parasitoid unit. A topical application of 1 ng of methoprene, concurrent to host transfer to DTC, accelerated parasitoid development. No parasitoid development was evident if the host was neck‐ligated at the time of its methoprene treatment and transfer to DTC. These data suggest that the prothoracicotropic effect of methoprene was via the host head, rather than directly on the host prothoracic glands, or the para

ISSN:0739-4462    

DOI:10.1002/arch.940130309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractCrowding ofDrosophilalarvae modifies their suitability to the cynipid endoparasitoidLeptopilina boulardi. The success of parasitic development rises from 40% in uncrowded host larvae to 90% in crowded ones. Crowding reduces the imaginal size of both wasps and uninfested hosts, but it has opposite effects on their development time: That of flies is increased, whereas that of wasps is reduced.

ISSN:0739-4462    

DOI:10.1002/arch.940130310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe mode of penetration of parasitoids belonging to the genusEretmocerusinto whitefly larvae and their immature development were examined. Examination included scanning electron microscopy and light microscopy of stained and unstained whole mounts and sections.TheEretmoceruslarva pierces the venter of its host shortly after hatching, and subsequently enters the host through the same hole. The host reacts by forming a cellular capsule around theEretmoceruslarva. This capsule is incomplete, with an opening in its ventral side opposite the penetration hole. The capsule remains intact during most of the second instar of the parasitoid. It then disintegrates, but its remnants are still visible around the third instar. Whenever twoEretmoceruslarvae penetrate, they are surrounded by two capsules. The capsule does not prevent parasitoid development, but it apparently precludes contact of cellular elements of the host's blood with the developing parasitoid larva.Adaptive features ofEretmoceruslarval biology include the early contact with the host's internal medium that permits host regulation; and the delay of contact with the host's blood cells that may preclude the need to confront host immunological systems.

ISSN:0739-4462    

DOI:10.1002/arch.940130311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY