ISSN:0739-4462    

DOI:10.1002/arch.940130102

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

年代:1990

数据来源: WILEY

摘要:

AbstractInsects have evolved many mechanisms that reduce their potential for serving as hosts for entomophagous species. Some of these mechanisms involve escape, mimicry, and repellancy, which are effective defense mechanisms against both predators and parasitoids. But, insects have a second line of defense against parasitoids and parasites. These may include repellancy and a cuticular barrier to invasion but they include several internal defenses that are collectively referred to as immune mechanisms.The current understanding of insect immunity is reviewed as background to examining the ways in which insect parasitoids have evolved to successfully handle the immune system of the host. The various means that parasitoids utilize to handle the insect immune systems have been divided into five approaches. These five approaches are described and current knowledge of the mechanisms used by parasitoids to deal with the immune system of their host is explored.

ISSN:0739-4462    

DOI:10.1002/arch.940130103

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

年代:1990

数据来源: WILEY

摘要:

AbstractHeliothis virescensparasitized byMicroplitis croceipesstop development at a predictable point prior to parasite emergence. The objectives of this study were to examine several factors which might contribute to the syndrome by comparing parasitized and nonparasitized larvae at specific and correspondingly similar physiological points in their development. Fifth stadium nonparasitized larvae experience a small pupal commitment burst of ecdysone followed by a large burst. In contrast, ecdysteroid titers in parasitized larvae remained at the pupal commitment level during the entire 5th stadium. Data shows that ecdysone 20‐monooxygenase and sterol precursors are not limiting factors, with the possible exception of limited hemolymph sterol at the end of parasitoid development. In addition, isolated prothoracic glands from parasitized larvae produce amounts of ecdysteroid comparable to controls when stimulated with a crudeManduca sextaprothoracicotropic hormone preparation. Juvenile hormone esterase titers in parasitized larvae are low throughout the 5th stadium. They do not show the major rapid increase in activity normally associated with the latter part of the active feeding period in the nonparasitized 5th instar. Possible explanations for the low ecdysteroid titers in parasitized larvae include failure to synthesize and release prothoracic gland stimulatory factor by the poorly developed fat body, insufficient sterol precursors at the critical time of ecdysteroid synthesis, inhibition of the release of PTTH, failure of the prothoracic gland to respond to PTTH, and the consequences of abnormally high juvenile hormone titer

ISSN:0739-4462    

DOI:10.1002/arch.940130104

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

年代:1990

数据来源: WILEY

摘要:

AbstractTrichoplusia niparasitized byCopidosoma floridanumweighed more in the fourth and fifth instar than unparasitized controls. While parasitized and unparasitized fourth‐instar larvae molted at the same time, parasitized fifth‐instar larvae ceased feeding and initiated wandering 1 day later than unparasitized fifth‐instar larvae. Measurement of hemolymph ecdysteroid, juvenile hormone esterase (JHE), and protein titers suggested that the delay in wandering had an endocrinological basis. Ecdysteroid titers of parasitized and unparasitized fourth‐instar larvae were similar, but the ecdysteroid titer in parasitized fifth‐instar larvae rose about 24 h later than in unparasitized fifth‐instar larvae. Two major peaks of JHE activity occurred in unparasitized fifth‐instar larvae, but only one occurred in parasitized fifth‐instar larvae. JHE activity coincided on the first day of the fifth instar (L5D1) in both parasitized and unparasitized fifth‐instar larvae; however, activity peaked and fell later in parasitized individuals. Few differences were noted in the hemolymph protein levels of parasitized and unparasitized hosts. Ligation of parasitizedT. nibetween the head and prothorax adversely affectedC. floridanumdevelopment. Ligation before or immediately after ecdysis to the fourth instar inhibited differentiation of theC. floridanummorulae.C. floridanumecdysed to the second instar or pupated in hosts ligated prior to wandering in the fifth instar, but the number of progeny that pupated and emerged as adult wasps was reduced relative to unl

ISSN:0739-4462    

DOI:10.1002/arch.940130105

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis is the first report of a juvenile hormone (JH) in the Caribbean fruit fly,Anastrepha suspensa(Diptera: Tephritidae). JH III was identified in whole body extracts of L3 (final instar) larvae and pharate pupae (PhP) by using a physicochemical method. JH III was also found in PhP superparasitized (up to 11.3 ± 3.5 S.D. parasites/host) by the solitary waspBiosteres longicaudatus(Hymenoptera: Braconidae) and in first instars of the parasite. The levels of JH III in hosts were up to 15 × higher than those of the controls. The JH esterase (JHE) levels in the hemolymph of 1‐day‐old PhP controls were significantly (P<0.05) higher than those of superparasitized individuals. These results suggest that the elevated JH III levels induced by superparasitism may arise from JH buildup due either to decreased JHE activity to continued synthesis of JH by the ring gland or to secretion of JH III by the parasites into the host's hem

ISSN:0739-4462    

DOI:10.1002/arch.940130106

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

年代:1990

数据来源: WILEY

摘要:

AbstractFactors produced in Hymenopteran parasitoids from their poison gland or from calyx region of the ovary or from both effect changes in host growth. In this review, the sources of these factors from parasitoids ofHeliothisspp. (Lepidoptera: Noctuidae) are described and their effects on host growth are compared. An evaluation of protein, amino nitrogen, and trehalose levels in the hemolymph of parasitizedHeliothisindicates that each parasitoid species exerts a different effect onHeliothis. A number of parasitoid genera still remain to be evaluated relative to their effects on host growth before a relationship can be established between parasitoid taxon and effects of their parasitism on hosts.

ISSN:0739-4462    

DOI:10.1002/arch.940130107

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

年代:1990

数据来源: WILEY

摘要:

AbstractParasitism byEuplectrus plathypenaeinhibits larval–larval ecdysis inTrichoplusia niby injecting nonparalytic factor(s) into the host during the stinging process via the parasitoid's ovipositor. The parasitized host moves freely, feeds, and gains weight prior to the time of the normal ecdysis but does not molt. Parasitoid development is not required for the expression of molt arrest in the host. Parasitism during the first three fourths of the larval stadium results in molt arrest. Arrestment of molting is independent of 20‐hydroxyecdysone and juvenile hormone. The arrestment factor(s) affect the epidermal tissue of the thorax and abdomen in ligated hosts without apparent interaction from other areas of the body. Cuticle and epidermal tissue of parasitized insects do not show signs of apolysis or ecdy

ISSN:0739-4462    

DOI:10.1002/arch.940130108

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe venom apparatus ofChelonusnearcurvimaculatus(Braconidae) has a simple (type 2) morphology. Most of the venom is accumulated in a thin‐walled venom reservoir at the distal end of the gland filament as a 10–17% protein solution. The best results for isolation of the proteins were obtained using 7.5% sucrose in phosphate buffer, pH 7.4. There are four major proteins, with respective Mrvalues of 32,500, 47,000, 53,000, and 131,000. Of these, those of Mr32,500, 53,000, and 131,000 contain carbohydrate. Most of the venom proteins are acidic with pI values between 4.9 and 6.9. The venom does not show proteolytic activity corresponding to serine or thiol proteinases, nor does it show antitrypsin or antichymotrypsin activity. Using immunoblotting techniques, it was established that during parasitization of a single host egg (Trichoplusia ni) about 1/200 of a venom reservoir equivalent is injected. All major venom proteins have been found in stungT.nieggs; thus, no detectable changes in their molecular weight occur during injection or shortly after injection into the h

ISSN:0739-4462    

DOI:10.1002/arch.940130109

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

年代:1990

数据来源: WILEY

摘要:

AbstractInsect endoparasitoids are able to circumvent the defense reactions of their habitual hosts. In the ichneumonid waspVenturia canescens, viruslike particles found on the egg surface are responsible for the protection of the parasitoid against the encapsulation reaction of the host. Some of the particle proteins are structurally and probably functionally related to a protein in the host caterpillarEphestia kühniella. The host protein is synthesized in hemocytes and fat body in low amounts and can be induced together with other proteins to higher levels of protein synthesis after bacterial infection. Hemocytes that show an increased expression of protein(s) are less likely to attach to a glass surface and are not involved in spreading

ISSN:0739-4462    

DOI:10.1002/arch.940130110

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

年代:1990

数据来源: WILEY

摘要:

AbstractArlyphorin (Ap) is the principal protein of the last larval instar hemolymph ofTrichoplusia ni. It was shown to be homologous with the Aps ofManduca sextaandLymantria disparby Western blot and quantitative immunoelectrophoresis. Another hemolymph storage protein inT.niof lesser titer was shown to be homologous with larval hemolymph protein (LSP) ofM.sexta. Ap titer increased dramatically in the last larval instar ofT.ni, as in other holometabolous insects studied. Parasitization byChelonus sp. caused the Ap titer to rise prematurely in the penultimate larval instar ofT.ni. This rise in Ap in the fourth instar is one of the earliest diagnostic signs of parasitization. Among the suite of behaviors of theChelonuslarva on exiting the host is depletion of the host cadaver of most remaining protein. TheT.niAp titer in the alimentary tract ofChelonuspeaks at that time and declines to zero in the first 24 h after parasitoid emergence, prior to its pupation. Aps are a source of phenolic storage compounds. Hence, premature induction ofT.niis advantageous for the parasitoid's own pupation and adult development.

ISSN:0739-4462    

DOI:10.1002/arch.940130111

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

年代:1990

数据来源: WILEY