Altered hexamerin regulation in prepupal Trichoplusia ni pseudoparasitized by Chelonus sp. near...

Archives of Insect Biochemistry and Physiology 32:537-548 (1 996)

Altered Hexamerin Regulation in Prepupal Trichoplusia ni Pseudoparasitized by Chelonus sp. Near Curvimaculatus D a v y Jones, Helen Turner, and Vikramjit Chhokar Graduate Center for Toxicology, University of Kentucky Medical Center, Lexington

Adult female wasps of species in the subfamily Cheloninae inject an egg, venom, polydnavirus and other materials into the host egg during oviposition. Hosts then exhibit precocious expression of the metamorphic developmental program, but then further development by the precocious prepupa is suppressed. These effects occur in truly parasitized hosts (those that contain a live endoparasite larva) as well as in pseudoparasitized hosts (that do not contain a live endoparasite). We report here that during the precocious prepupal stage, the hexamerins BJHSPl and BJHSP2 persist in the hernolymph of pseudoparasitized hosts, whereas in normal larvae these proteins are cleared from the hemolymph in response to the normal surge in prepupal ecdysteroids. Northern blot analysis of poly(A) RNA showed that the basis for this persistence is not an abnor- mally high abundance of the transcripts on the day following wandering in pseudoparasitized larvae. Nor is the source of the hexamerins the parasite larva, for it is missing from the pseudoparasitized hosts. The hypothesis that the persistence is due to a suppressed titer of ecdysteroids in pseudoparasitired hosts (reported earlier: [Jones et al., Arch Insect Biochem Physiol 21 :I55 (1992)l was tested by use of a large size variant of pseudoparasitized hosts in which the prepupal ecdysteroid titer is partially restored by endogenous ecdysteroid production. In such pseudoparasitized prepupae, the two hexamerins were cleared from the hemolymph on the day following host wandering behavior, as in normal larvae. Thus, the regulatory basis of the persistence of the hexamerins BJHSPl and BJHSPZ in the hemolymph of pseudoparasitized hosts appears to be at the posttranslational level, with suppression of the prepupal ecdysteroid titer causing omission of the normal trigger for fat body uptake of the hexamerins. 0 1996 Wiley-Liss, Inc.

Key words: pseudoparasitized hosts, hexamerin regulation, prepupal stage, parasite

Acknowledgments: This research was supported, in part, by a grant from the National Institutes of Health and by the University of Kentucky program in Research and Graduate Studies.

Received September 15, 1995; accepted February 15, 1996

Address reprint requests to Davy Jones, Gradudte Center for Toxicology, University of Kentucky Medical Center, Lexington, KY 40506.

Vikramjit Chhokar i s a participant in the University of Kentucky Research and Graduate Studies program in undergraduate summer research experience.

0 1996 Wiley-Liss, Inc.

538 jones et al.

INTRODUCTION

Insect parasites have been described to cause a number of interesting effects on the endocrine-driven programs of their insect hosts (Beckage, 1985; Vinson and Iwantsch, 1980). One intriguing phenomenon is the induction of precocious metamorphosis, followed by suppressed development of the precocious prepupae, caused by parasites in the subfamily Cheloninae (Jones, 1985a). Layered on top of these endocrine effects are effects to suppress the immune response of the developmentally redirected host (Taylor and Jones, 1990; Strand and Pech, 1995). A number of causative or potentially causative agents of these effects in chelonine hosts have been identified by various laboratories, such as venom, polydnavirus, teratocytes, or the parasite larva. The proceedings of this conference, JH VI, have provided a further opportunity for assessing the results obtained from the various chelonine systems on mechanisms of host regulation, and have urged productive focussing of discussion on determining the bases for differences in results that might not be so divergent as may first appear to be the case.

In a companion paper in this journal issue, Pfister-Wilhelm and Lanzrein (1996) describe results of studies on the endocrine effect of precocious initia- tion of host metamorphosis, using Chelonus inanfus as the parasite, with em- phasis on detection of any ability of the live endoparasite to also participate in redirection of the host. This present paper will report new findings relat- ing to the second effect, suppression of further development of the precocious prepupa, using Chelonus sp. near curvimaculatus as the parasite. In the Chelonus sp. near curvimaculatus system, suppression of prepupal development in hosts containing a live endoparasite occurs early in the prepupal stage (Jones et al., 1981a). This phenomenon is also observed in "pseudopara- sitism" (Jones, 1985b), in which there is precocious expression of metamorphosis-associated genetic programs [including those regulated independently of the JH* titer such as feeding stage JH esterase (Jones and Sreekrishna, 198411, in the absence of the internal parasite, apparently due to a reduction in the size threshold normally operative for the attainment of the final, metamorphosing instar (Jones et al., 1981b, 1986).

Examination of pseudoparasitized hosts offers the opportunity to assess what effects on the host developmental program are provoked by causative agents other than the live endoparasite. Pseudoparasitized hosts (Trichoplusia ni) of either a natural parasite (Chelonus insularis) or an unnatural parasite (Chelonus sp. near curvimaculatus) exhibit suppressed prepupal development (Jones, 1985b, 1986a). In those two studies it was observed that the pseudoparasitized precocious prepupae stung by C. insularis average a larger size (although they are still below a threshold normal final instar size) than the pseudoparasitized precocious prepupae stung by C. near cuuvimaculatus. It was also observed that the larger size pseudoparasitized prepupae, while not reaching normal pupation, do progress farther through the series of external prepupal

'Abbreviations used: AJHSP1 = acidic JH suppressible protein 1; BJHSPI and BJHSPZ = basic J H suppressible protein 1 and 2; JH = juvenile hormone; PAGE = polyacrylamide gel electrophoresis; SDS = sodium dodecyl sulfate.

Redirection of Prepupal Development 539

developmental markers than do either the smaller pseudoparasitized prepupae, or truly parasitized hosts (those containing a live endoparasite).

In the present study, we have used the differential developmental progression of different size pseudoparasitized prepupae to further assess the status of progression of internal biochemical processes during the precocious prepupal stage.

MATERIALS AND METHODS Insects

Hosts (Tvichoplusia ni) and parasites (C. near curvimaculatus) were reared and staged as described previously (Jones et al., 1981b; Jones, 1986a). No- menclature for staging was patterned as follows: N and P refer to normal and pseudoparasitized larvae, respectively, and the day of the stadium of metamorphosis is indicated by DX, where X is the given day (e.g., D3 means day 3). Under the rearing conditions used, pseudoparasitized wandering larvae weigh typically 50-110 mg, being a mixture of 4th instar hosts and stunted, below metamorphosis-threshold-size 5th instar hosts. There occur more rarely stunted 5th instar wandering larvae of larger size, up to 150-190 mg, which is just short of the smallest size usually attained by normal wandering larvae. Such large pseudoparasitized hosts still have head capsule widths below the size normally associated with attainment of the metamorphosing instar (Jones et al., 1981a, 1986; Jones, 1986b). On the day of wandering, the various size pseudoparasitized hosts were weighed and were either used then for experiments, or held for a given number of subsequent days before experimental use. These pseudoparasitized hosts remain as prepupae for up to a week before finally dying (becoming shriveled and unresponsive to prod- ding). Rarely, the very largest pseudoparasitized prepupae may attempt to ecdyse, but only even more rarely are successful, more usually arresting at the stage of tracheal withdrawal and eventually showing tanning coloration.

Protein Electrophoresis and Immunoblotting Proteins extracted from pooled fat body samples, or in 0.5 p1 of pooled

hemolymph from stung, pseudoparasitized insects, or from normal insects, were subjected to SDS-10% PAGE and either the gels silver stained or subjected to immunoblotting with antisera generated against the four hexamerin storage proteins reported from T. ni (Jones et al., 1993). Preliminary immunoblots verified that the number of washes of the fat body were suffi- cient to eliminate the vast majority of hemolymph proteins from the surface of the tissue. In experiments on fat body content of hexamerins, the amount of fat body protein loaded (typically between 2-5 mg) for electrophoretic analysis was normalized to the arylphorin concentration, such that detected changes in concentration of the other hexamerins were relative to a constant amount of arylphorin detected immunologically.

Extraction and Analysis of Poly(A) RNA The extraction of poly(A) RNA from normal and pseudoparasitized larvae

was performed as described previously (Jones et al., 1988). The cloned cDNA

540 Jones et al.

for yeast RP49 was used as a template for the random primer radiolabelling method of Feinberg and Vogelstein (1983), and the products of the reaction were used to probe a preliminary northern blot. On the basis of the result, the mRNA samples were loaded onto a second gel in a way calculated to provide equal amounts of RP49 mRNA to each lane. Cloned cDNA for the respective hexamerin was used as a template for the random primer radiolabelling, as above, and the reaction products were used to probe the second northern blot. Samples of poly(A) RNA were taken from two independent pools of normal larvae on each of Day 3 (day of wandering) and Day 4 (prepupa) of the final larval stadium. Probes used were radiolabelled cDNA for the hexamerins AJHSPl, BJHSPl, and BJHSP2 (Jones et al., 1990, 19931, and hybridization and washing conditions at 65°C were similar to the proce- dure described previously (Jones et al., 1993). Two independent samples were analyzed for the first day of the precocious prepupal stage of pseudoparasitized hosts of smaller, typical size, and two other independent samples were analyzed for rarer, large pseudoparasitized larvae that were just short of the normal threshold size (Jones et al., 1981a). The RP49 standard used as a probe is that described by OConnell and Rosbash (1984).

RESULTS AND DISCUSSION Hemolymph Protein Concentrations of Hexamerins in 4th Instar, Pseudoparasitized Larvae

During normal metamorphic development, the AJHSPl protein remains abundant in the hemolymph in both the wandering and prepupal stage, and in the pupal stage, while BJHSPl and BJHSP2 are present on the day of wandering but are quantitatively removed from the hemolymph by the following day (Jones et al., 1993). In comparison, we noted that all three proteins are typically present in the hemolymph of pseudoparasitized 4th instar hosts on the day of wandering, are present on the following day, and remain present for a number of subsequent days (Fig. 1). Hemolymph Protein Concentrations of Hexamerins in 5th Instar, Pseudoparasitized Larvae

In typical 5th instar pseudoparasitized hosts, AJHSPl, BJHSPl, and BJHSP2 are present on the day of wandering, on the following day, and for subsequent days of the arrested prepupal stage (Fig. 2).

Hexamerin Concentration as a Function of Size of Pseudoparasitized Prepupa We sought a way to manipulate the concentration of the hexamerins in the

hemolymph, which could then be exploited as a means of probing the basis of the persistence of the hexamerins in the hemolymph of pseudoparasitized hosts. In view of our earlier observation that the larger size classes of pseudoparasitized hosts overtly progressed farther in prepupal development before ceasing development (Jones et al., 1986,1992), we considered that there may be a difference between the typical, smaller pseudoparasitized prepupae and rarer, larger pseudoparasitized prepupae that could be used as an experimental tool. Analysis of the hemolymph of each size class of 4th instar pseudoparasitized prepupa showed that all three hexamerins were present


for all size classes (Fig. 3). However, similar analysis of 5th instar pseudoparasitized prepupae showed that BJHSPZ and BJHSP2 were at a much lower abundance in the hemolymph of the largest size classes (Fig. 4). This clearance from the hemolymph was specific for BJHSPl and BJHSP2, since the abundance of AJHSPl in the hemolymph was essentially the same for all size classes (Figs. 3 and 4).

Expression of the Hexamerin Genes in Normal and Pseudoparasitized Hosts The report by Shelby and Webb (1994) of apparent inhibition of translation

of an otherwise abundant hexamerin transcript, in a model system using a nonchelonine wasp, caused us to consider the possibility that the opposite effect might explain the results shown in Figures 1 and 2, i.e., persistence of BJHSPl and BJHSP2 transcript into the prepupal stage and its continued translation at that time. Therefore, northern analysis was performed on the abundance of the hexamerin transcripts in normal and pseudoparasitized hosts during the day of wandering and on the following day that is normally the l-day-long prepupal stage. The results show that the transcript is normally highly abundant on the day of wandering, and then declines on the following day (Fig. 5). Interestingly, in both the typical, smaller pseudoparasitized hosts and in the rarer, larger pseudoparasitized hosts the abundance of the hexamerin transcripts on the day following wandering was similar to that observed in normal larvae (Fig. 5). Thus, the persistence of BJHSPl and BJHSP2 in the hemolymph of smaller pseudoparasitized prepupae and their clearance from the hemolymph of larger pseudoparasitized prepupae is not due to a differential persistence of their mRNAs in the two size classes of pseudoparasitized hosts.

Basis of Persistence of BJHSPl and B JHSP2 in Hemolymph of Pseudoparasitized Larvae

The overt parasite effect on pseudoparasitized hosts is to suppress the developmental progression of the prepupae through the physiological and mor- phological markers associated with normal prepupal development (Jones et al., 1981b). In the development of normal T. ni prepupae, a surge of prepupal ecdysteroid production occurs (Jones et al., 1986) that is necessary in most Lepidoptera to cause ecdysis and attainment of the pupal stage. A series of studies by various laboratories on chelonine species appear to have estab- lished the endocrine basis for suppressed development of pseudoparasitized prepupae. In pseudoparasitized hosts of both C. near curvimaculatus and C. insularis, the prepupal ecdysteroid titer is suppressed (Jones, 1985b, 1986a; Jones et al., 1986). The titer is more strongly suppressed in prepupae pseudoparasitized by the former parasite, which correlates well with more strongly suppressed development of those prepupae than hosts pseudoparasitized by the latter parasite. A more complicated situation exists in truly parasitized hosts that contain a live endoparasite, since a delayed but high ecdysteroid peak is seen in truly parasitized prepupae (Grossniklaus-Burgin et al., 1989,1990). Brown and Kainoh (1992) also reported the basal condition of a suppressed ecdysteroid titer in hosts pseudoparasitized by Ascogaster reticulatus, and an elevated titer in truly parasitized host. However, it ap-

542 Jones et al.

1 2

Fig. 1. Concentration of three hexamerin proteins (Jones et al., 1993) as detected by irnrnunob- lotting in the hemolymph of normal larvae on the 3rd and 4th days (day of wandering and day of prepupa, respectively) of the final larval stadium. Also shown are the concentrations of the proteins in the hemolymph of 4th instar pseudoparasitized (PL4) hosts on the indicated day of the stadium in which precocious metamorphosis and suppressed prepupal development are exhibited (day 3 = D3, and is the day of precocious wandering behavior). In normal larvae, the two basic proteins are cleared from the hernolymph by day 4 (day of prepupa). However, the proteins persist for a number of days in the hemolymph of the pseudoparasitized prepupae.

Fig. 2. Concentration of three hexarnerin proteins (Jones et al., 1993) as detected by imrnunob- lotting in the hemolymph of normal larvae on the 3rd and 4th days (day of wandering and day of prepupa, respectively) of the final larval instar. Also shown are the concentrations of the proteins in the hemolyrnph of stunted, subthreshold size 5th instar pseudoparasitized (PL5) hosts on the indicated day of the stadium in which precocious metamorphosis and suppressed prepupal development are exhibited (day 3 = D3, and i s the day of precocious wandering behavior). In normal larvae, the two basic proteins are cleared from the hemolyrnph by day 4 (day of prepupa). However, the proteins persist for a number of days in the hemolyrnph of the pseudoparasit i zed p repu pae.

pears that chelonine parasite larvae release into the host prepupal hemolymph the ecdysteroids that are detected in hemolymph at that stage (Brown and Reed-Larsen, 1992; Brown and Kainoh, 1992), and when the parasite is removed from the host prior to that stage, the large increase in ecdysteroids in the host prepupal hemolymph is prevented (Jones et al., 1992).

With respect to the hexamerins in the prepupal hemolymph, during normal development, T. ni prepupae clear BJHSPZ and BJHSP2, but not AJHSPl, from the hernolymph, with at least part of the pool of the two basic proteins being taken up by the fat body (Jones et al., 1993). There is considerable evi-

3 Redirection of Prepupal Development 543

4

Fig. 3. Concentration of three hexamerin proteins (Jones et al., 1993) as detected by immunoblotting in the hemolymph of normal larvae on the 3rd and 4th days (day of wandering and day of prepupa, respectively) of the final larval instar. Also shown are the concentrations of the proteins in the hemolymph of 4th instar pseudoparasitized (PL4) hosts of the various indicated size classes (weights measured on day 3, the day of wandering), on the first day of the precocious prepupal stage. In normal larvae, the two basic proteins are cleared from the hemolymph by day 4 (day of normal prepupa). However, the proteins are present on the corresponding day in the hemolymph of the various size classes of fourth instar pseudoparasitized prepupae.

Fig. 4. Concentration of three hexarnerin proteins (Jones et al., 1993) as detected by immunoblotting in the hemolymph of normal larvae on the 3rd and 4th days (day of wandering and day of prepupa, respectively) of the final larval instar. Also shown are the concentrations of the proteins in the hemolymph of subthreshold size 5th instar pseudoparasitized (PL51 hosts of the various indicated size classes (weights measured on day 3, the day of wandering), on the first day of the precocious prepupal stage. In normal larvae, the two basic proteins are cleared from the hernolymph by day 4 (day of normal prepupa). However, the proteins are present in the hemolymph of the various size classes of fifth instar pseudoparasitized prepupar, except that they have been cleared from the hemolymph of the largest size class of pseudoparasitized prepupae.

dence that the uptake is stimulated by the large increase in prepupal ecdysteroids that also stimulates the eventual ecdysis to the pupa (Webb and Riddiford, 1988). Our present results show that a higher than normal persistence of the transcripts of BJHSPl and BJHSP2 does not occur in pseudoparasitized larvae, and thus continued translation of a higher than normal abundance of BJHSPl and BJHSP2 transcripts is not a basis for a higher than normal abundance of the proteins in pseudoparasitized hosts. Since we are dealing with pseudoparasitized hosts that contain no endoparasite, the parasite larva is not the source of persistent BJHSPl and BJHSP2 in the pseudoparasitized hosts. Given these results, it is reasonable to postulate that the suppressed

544 Jones et al.

Fig. 5. Northern analysis of expression of mRNAs for the hexarnerins AJHSP1, BJHSP1, and BJHSPZ, on the indicated day of the final larval stadium. For normal larval 3 = day of wandering, 4 = day of prepupa. The results presented for two independent sample5 for each day show that relative to the control of RP49 (which encodes a ribosomal protein) the transcripts are in high abundance on the day of wandering, and then decline on day 4. Also shown are the transcript abundance for first day pseudoparasitized precocious prcpupac from a size class (60- 70 mg) within the typical range and in rarer, larger size (greater than 170 mg) hosts. The results show that each transcript in both groups of pseudoparasitized prepupae is not more abundant than that occurring in normal prepupae.

ecdysteroid titer in pseudoparasitized prepupae constitutes the absence of the normal endocrine trigger for fat body uptake of the proteins.

Regulatory Basis of Suppressed Ecdysteroid Titer in Pseudoparasitized Hosts The large size pseudoparasitized prepupae provide a means of testing this

proposition, since they possess an ecdysteroid titer intermediate between that of normal prepupae and of smaller, typical pseudoparasitized hosts (Jones et al., 1992). The results presented here in Figure 6 show that the two basic hexamerins clear from the hemolymph on the first day of the precocious prepupal stage, in parallel with the timing of the clearance that occurs on that day in normal prepupae. In further support of this thesis the abundance of the two basic proteins in the fat body of the very large pseudoparasitized prepupae is intermediate between that of the smaller pseudoparasitized hosts and of normal prepupae (Fig. 6).

These endocrine effects on prepupal ecdysteroids and their biochemical consequences are especially interesting in view of the biology of the intro-


Fig. 6. lmmunoblot analysis of the relative abundance of three hexamerin proteins in the fat body of normal prepupae (ND4), and first day pseudoparasitized prepupae in a size class (70- 11 0 mg) within the typical size range and in the rarer, larger pseudoparasitized prepupae (> 150 mg). The results show an amount in the fat body of > 150 mg pseudoparasitized hosts that i s intermediate between the normal prepupae and the smaller, typical pseudoparasitized hosts. This same trend was observed in multiple independent samples.

duction into the host of the causative agents by these egg-larval parasites. Various researchers have tackled this question using several approaches. Ferran and colleagues made early reports of the cold sensitivity of the parasite, and that when the newly parasitized hosts were held at 5°C for several days it selectively killed the parasite egg, and the hosts still showed disrupted prepupal development (Ferran and Daumal, 1973; Ferran and Laforge, 1974). Those authors also observed that dislodging the female during oviposition before entry of the parasite egg resulted in suppressed prepupal development, as with the pseudoparasitized host of the present study.

The first such tests with wasps in the genus Chelonus were reported by Ables and Vinson (1981), who tested (for C. insulavis) for a role of the calyx fluid from the female oviduct by injecting the material, with and without venom, into host eggs. The hosts showed slower development than normal, but nevertheless still initiated metamorphosis at the correct instar and pu- pated. Those authors, though, were also dealing with the difficulty in inter- preting the negative results with such injections when a clear positive control is not available for the contingency that a crucial molecule or agent in the injection mixture necessary for the given effect has been denatured or made ineffective. Buhler et al. (1985) used C. near curvirnaculatus as the parasite, and performed transplantations of parasite larvae, with a negative outcome for both metamorphic effects. They also tried dislodging the females during oviposition, which can be difficult due to variation between and within wasps in the oviposition time (varying from 15-30 s in their study), and again received negative results, and were left with their proposition that teratocytes, liberated at egg hatching, were responsible for both metamorphic effects.

Jones (1987) avoided the obstacle of a lack of a positive control for inter- preting negative results for each endocrine effect by revisiting the approach

546 Jones et al.

of Ferran and colleagues. He used the cold-sensitivity of the parasite (C. near curvimaculatus) and careful dissections to show that when stung host eggs were held at 4°C for several days, the parasite egg would fail to hatch, yet the hosts still precociously initiated metamorphosis and then became developmentally arrested as precocious prepupae. This result suggested that the presence of the parasite larva was not necessary for the endocrine effects to become manifest, and that another factor(s) introduced into the host can cause the effects. (This conclusion does not rule out the possibility that the parasite larva, when present, might also introduce agents, such as parasitization proteins (Soldevila and Jones, 19931, that could cause either metamorphic effect). Leluk and Jones (1989) minimized the effect of the large variation from one female to the next in oviposition time by selecting females calibrated for a standard oviposition time to be within 2-3 s of 20 s, and then he dislodged the ovipositing female just prior to entry of the egg (the timing determined in preliminary tests). He obtained hosts that contained no detected parasite egg, yet these hosts that were injected by the wild type, unmutagenized female with her natural sources and amounts of venom and calyx fluid compo- nents, still showed the metamorphic disruptions of precocious metamorphosis and suppressed prepupal development. These results were independently supported by the results using a different approach in which Soldevila and Jones (19931, Jones (19871, and Buhler et al. (1985) dissected the parasite larva from hosts as young as the 2nd and 3rd instar, and the hosts still invariably showed suppressed prepupal development following their precocious initia- tion of pupation.

With respect to the present study, Jones’ results from prevention of egg entry by disruption of oviposition, or removal of either the parasite egg by cold treatment or of the young parasite larva by dissection, and Buhler’s result on removal of the young parasite larva by dissection, all establish that material(s) injected by the female are capable of causing the ecdysteroid-based arrest of development in the precocious prepupae, in the absence of either a parasite egg or parasite larva. Recently, Lanzrein and colleagues identified these female factors as the venom and calyx fluid, when they demonstrated that injection of both the venom and calyx fluid from adult females (of C. inanitus) into host eggs can cause arrested development of prepupa (Lanzrein, personal communication). We have identified a specific polydnavirus transcript, the presence of which appears correlated with the suppression of the ecdysteroid titer in prepupae (Jones et al., unpublished data). Of key impor- tance in the future will be the identification of the target sites of polydnaviral gene products, or of venom proteins that can act to induce these metamorphic effects.

LITERATURE CITED

Ables R, Vinson SB (1981): Regulation of host larval development by the egg-larval endoparasitoid CheIonus insularis (Hym.: Braconidae). Entomophaga 25453456.

Beckage, NE (1985): Endocrine interactions between endoparasitic insects and their hosts. Ann Rev Entomol30:371-413.


Brown JJ, Kainoh Y (1992): In vitro release of ecdysteroids by an endoparasitoid, Ascogaster reticulafus Watanabe. J Insect Physiol39:229-234.

Brown JJ, Reed-Larsen D (1992): Ecdysteroids and insect host/parasitoid interactions. Biol Contr 1:136-143.

Buhler A, Hanzlik TN, Hammock BD (1985) Effects of parasitization of Trichoplusia ni by Che- lonus sp. Physiol Entomol10:383-394.

Feinberg AP, Vogelstein B (1983): A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Anal Biochem 132:6-13.

Ferran A, Daumal J (1973): Consequences sur les larves d’Anagasta kuhniella Zeller (Lep. Phycitidae) de l’elimination precoce par le froid de son endoparasite Phanerotoma flavifestacea Fischer (Hym. Braconidae). C R Acad Sci Paris 277D:869-871.

Ferran A, Laforge JP (1974): Mise en evidence d’une action toxique des secretions ovariennes des femmelles d‘un insecte entomophage [Phanerotoma flavitestacea Fischer (Hym. Bra- conidae)] sur les Ieves de son hote, Anagasta kuphniella Zeller (Lep. Phycitidae). CR Acad Sci Paris 279D:134-7344.

Grossniklaus-Burgin C, Lanzrein B (1990) Endocrine interrelationships between the parasitoid Chelonus sp. and its host Trichoplusia ni. Arch Insect Biochem Physiol 14:201-216.

Grossniklaus-Burgin C, Connat JL, Lanzrein B (1989): Ecdysone metabolism in the host-parasitoid system Trichoplusia nilchelanus sp. Arch Insect Biochem Physiol11:79-92.

Jones D (1985a): Endocrine interaction between host (Lepidoptera) and parasite (Cheloninae, Hymenoptera): Is the host or the parasite in control? Ann Entomol SOC Am 78:141-148.

Jones D (198510): The endocrine basis for developmentally stationary prepupae in larvae of Trichoplusia ni pseudoparasitized by Chelonus insularis. J Comp Physiol IBI 155:235-240.

Jones D (1986a): Suppression of host ecdysteroids and developmentally stationary pseudoparasitized prepupae. Exp Parasitol61:lO-17.

Jones D (1986b): Parasite redirection of neurohormonally driven developmental pathways that are associated with size thresholds. In Borkovec AB, Gelman D (eds): Advances in Insect Neurochemistry and Neurophysiology. New York: Plenum Press, pp 397-300.

Jones D (1987): Material from adult Chelonus sp. directs expression of altered developmental programme of host Lepidoptera. J Insect Physiol33:129-134.

Jones D, Sreekrishna S (1984): Precocious pupation in Chelonus parasitized Trichoplusia ni: En- docrine basis for this anti-juvenile hormone effect: In Borkovec AB, Thoman TJ (eds) Insect Neurochemistry and Neurophysiology. New York: Plenum Press, pp 389-391.

Jones D, Jones G, Hammock BD (1981a): Developmental and behavioral responses of larval Trichoplusia ni to parasitization by an imported braconid parasite Chelonus sp. Physiol Ento- mol6:387-394.

Jones D, Jones G, Hammock BD (1981b): Growth parameters associated with endocrine events in larval Trichoplusia ni (Hubner) and timing of these events with developmental markers. J Insect Physiol27:771-788.

Jones D, Jones G, Rudnicka M, Click A, Reck-Mallezewen V, Iwaya H (1986): Pseudoparasit- ism of host Trichoptusia ni and Chelonus spp.: A new model system for parasite regulation of host physiology. J Insect Physiol32:315-328.

548 Jones et al.

Jones D, Gelman D, Loeb M (1992): Hemolymph concentrations of host ecdysteroids are strongly suppressed in precocious prepupae of Trichoplusia ni parasitized and pseudoparasitized by Chelonus near curuimaculatus. Arch Insect Biochem Physiol21:115-165.

Jones G, Hiremath S, Hellman GM, Rhoads RE (1988): Juvenile hormone regulation of mRNA levels for a highly abundant hemolymph protein in larval TrichopIusia ni . J Biol Chem 26:1089-1092.

Jones G, Brown N, Manczak M, Hiremath S, Kafatos FC (1990): Molecular cloning regulation, and complete sequence of a hemocyanin-related, juvenile hormone-suppressible protein from insect hemolymph. J Biol Chem 265:8596-8602.

Jones G, Manczak M, Horn M (1993): Hormonal regulation and properties of a new group of basic hemolymph proteins expressed during insect metamorphosis. J Biol Chem 268:12&2-1291.

Leluk J, Jones D (1989): Chelonus sp. near cuwimaculatus venom proteins: Analysis of their potential role and processing during development of host Trichoplusia ni. Arch Insect Bio- chem Physiol 1O:l-12.

OConnell P, Rosbash M (1984) Sequence, structure and codon preference of the Drosophila ribosomal protein 49 gene. Nucleic Acids Res 12:5495-5513.

Pfister-Wilhelm R, Lanzrein B (1996): Precocious induction of metamorphosis in Spodoptera littaralis (Noctuidae) by the parasitic wasp Chelonus inarzitus (Braconidae): Identification of the parasitoid larva as the key regulatory element and the host corpora allata a s the main targets. Arch Insect Biochem Physiol32:511-525.

Shelby KS, Webb BA (1994): Polydnavirus infection inhibits synthesis of an insect plasma protein, arylphorin. J Gen Virol75:2285-2292.

Soldevila A, Jones D (1993): Expression of a parasitism-specific protein in lepidopteran hosts of Ckelonlrs sp. Arch Insect Biochem Physiol24:149-169.

Strand M, Pech LL (1995): Immunological basis for compatibility in parasitoid-host relation- ships. Ann Rev Entomol40:31-56.

Taylor T, Jones D (1990): Isolation and characterization of the 32.5 kDa protein from the venom of an endoparasitic wasp. Biochem Biophys Acta 1035:3743.

Vinson SB, Iwantsch GF (1980): Host regulation by insect parasitoids. Q Rev Biol55:143-165.

Webb RA, Riddiford LM (1988): Synthesis of two storage proteins during larval development of the tobacco hornworm, Manduca sexta. Dev Biol130:671-681.

Altered hexamerin regulation in prepupal Trichoplusia ni pseudoparasitized by Chelonus sp. near...

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