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Function of the neuroendocrine complex in diapausing Pyrrhocoris apterus females
J. insect Physiol.. 1977. Vol. 23, pp. 23 to 28. Pergamon Press. Printed in Great Britain.
FUNCTION OF THE NEUROENDOCRINE COMPLEX DIAPAUSING PYRRHOCORIS APTERUS FEMALES
IN
MAGDALENA HODKOVA* Department of Insect Physiology, Entomological Institute, Czechoslovak Academy of Science, Na Folimance 5, 120 00 Praha, Czechoslovakia (Received 9 July 1976)
Abstract-The
role of the brain in inhibiting the action of corpora allata in diapausing short-day females was investigated by transplantation experiments. The function of the transplanted glands was evaluated by oviposition, Active glands from long-day females remained active for a long period of time after transplantation into short-day females, although in situ corpora allata were inhibited shortly after the transfer of females from long to short day. Moreover, inactive glands from short-day females became active after transplantation into other short-day females. In contrast. corpora allata remained inhibited when transplanted together with the brain in the neuroendocrine complex (brainxorpora cardiacs-corpus allatum) where the nervous connections between the brain and corpus allatum remained intact. It is therefore suggested that short-day conditions inhibit corpora allata via nervous connections with the brain.
obtain diapausing females (SD-females). Reproducing females were kept under long-day (18L:6D) condiThe lack of the activity of the corpora allata (CA) tions (LD-females). Three to five days after the surgiis a cause of reproductive arrest in diapausing cal treatment experimental females were isolated into females. This is proved by the fact that after implanPetri dishes with males from the same breeding tation of the active complex consisting of corpora car- group. diaca-corpora allata (CC-CA) or CA alone into diaThe donor glands were dissected under insect pausing females the reproductive activity is resumed saline. They were implanted into recipients (narco(DE WILDE and DE BOER, 1969; BROZA and F%NEX, tized in water) through a small incision in the 1969; GIRARDIE and GRANIER, 1973; ENGELMANN, abdomen. CC-CA or CC were implanted together 1970; DE WILDE and DE LOOF, 1974). Also in Pyrrhowith a piece of aorta. Brain-CC-CA was implanted cork upterus the implantation of CC-CA from active together with suboesophageal ganglion. In shamfemales induced oviposition in diapausing females operated females the same procedure was followed, (Z~%REK, 1968). It is believed that the inactivity of except that nothing was implanted. In most experCA in diapausing females is due to a lack of the actiiments post-treatment mortality was about 20%. vation hormone from the brain (DE WILDE and DE To evaluate the action of implanted glands several BOER,1969; GIRARDIEand GRANW, 1973). parametres of reproductive activity were used: (1) inThis paper describes a part of the study devoted cidence of ovipositing females; (2) duration of the to regulation of CA activity by the brain in females preoviposition period (preovipos.); (3) oviposition of Pyrrhocoris apterus. We have investigated here the period = period between the first and the last batch role of diapausing brain in inhibition of CA by transin experiment (ovipos.); (4) postoviposition period plantations of different parts of the neuroendocrine throughout duration of the experiment (postovipos.); complex (brain-CCCA) between active and diapausand (5) number of eggs and number of batches laid ing females. during experiment. INTRODUCTION
MATERIALS
RESULTS
AND METHODS Transplantation
Pyrrhocoris apterus adults were collected in Southern Bohemia and the first generations (F,) of laboratory cultures were used in all experiments. The insects were fed on linden-seed and kept at 26 + 2°C. Shortday photoperiod (12L: 12D) was used in order to *This paper is dedicated to Prof. Jan occasion of his 60th birthday.
DE WILDE
of active glands into SD-females
The implantation
of CC-CA or CA from active LD-females into diapausing SD-females induced oviposition in most individuals. Implantation of CC alone had no effect (Table 1). This suggests that in situ CA of diapausing females are not sufficiently active to ensure effective amounts of juvenile hor-
at the
mone for reproduction. 23
24
MAGDALENA HODKOV~.
Table 1. Transplantation
Operation 1 CA implanted
1 CCCA implanted
2-4 CC implanted Sham-oper.
It is known that females transferred from long- to short-day conditions (LD/SD-females) stop oviposition within about 1-2 weeks (HODEK, 1968), apparently as a result of CA inhibition by short daylengths. The reproductive activity of SD-females with implanted active CC-CA was, therefore, compared with that of LD/SD-females (Table 2, Fig. 1). The oviposition period was seven times longer and fecundity was three times higher in the females with implanted glands. This indicates that implanted active CC-CA cannot be properly inhibited by short daylengths. Implanted glands differ from those in situ by lack of nervous connections with the brain. It seems, therefore, that short-day conditions inhibit active CC-CA via nervous connections with the brain.
of active glands into SD-females Ovipos. females (rr)
n 1I”’
9
, S2)
I1
5”’
4
12’2’
12
6’”
0
23”’ 14’2’
0 0
Preovipos. period (days) 11.2 (93t;) (8-13) 10.8 (9-l 3) 10.9 (9-14)
-
Transplantation of inactioe glands into SD-females
Photoperiod during experiment: short day 12L: 12D. Donor: (1) LD-females 1 to 2 days after adult ecdysis (2) LD-females 2 to 3 days after adult ecdysis. Recipient: (1) SD-females 1 to 2 days after adult ecdysis, one day fasting. (2) SD-females 4 to 5 weeks after adult ecdysis. Duration of experiment: 25 days. CA = corpus allatum, CC = 2 corpora cardiaca, CCCA = corpora cardiacs-corpus allaturn.
The foregoing experiments indicated that disconnection of the CC-CA from the brain prevents inhibition of the active glands by short daylengths. Further experiments investigated whether the glands which had been inactive before the disconnection from the brain would become activated after transplantation. Implantation of CC-CA or CA from SD-females into other SD-females induced oviposition in most indivi-
Table 2. Transfer of females from long to short day and transplantation
Treatment Transfer from LD to SD”’ 1 CC-CA implantedt2’
n
Fecundity
Ovipos. females (n)
eggs/female
14
14
(419:82)
10
10
313 (150-441)
batches/female 1.6 (l-3) 5.6 (3-8)
of active glands into SD-females Preovipos. period (days) 7.9 (7-10) 11.0 (9-14)
Ovipos. period (days) 4.0 (O-12) 30.2 (10-38)
Postovipos period (days) 38.1 (23336) 8.8 (O-31)
Photoperiod during experiment: short day 12L: 12D. (1) Females transferred from long (18L:6D) to short day (12L: 12D) 2 to 3 days after adult ecdysis. (2) Donor: LD-females 2 to 3 days after adult ecdysis; Recipient: SD-females 4 to 5 weeks after adult ecdysis. Duration of experiment: 50 days.
0
LHl5 0
a
EGG
4 0 * HATCHES
Fig. 1. The variation in reproductive activity for females transferred from long to short day and SDfemales with implanted active glands. Open-organs of LD-females. shaded+rgans of SD-females. Left-in situ organs of recipient, right-implanted organs. Broken line-preoviposition period, solid line-preoviposition + oviposition period. Other explanations see Table 2. Symbols explained in Fig. 2.
Function of the neuroendocrine Table 3. Transplantation
n
Ovipos. females (n)
1 CA implanted 1 CC-CA implanted CA extirp. and 1 CCCA implanted”’ 1 cc implanted
11
9
13
11
7
6
13
1
Sham-oper. Unoperated
32 12
0 0
Operation
25
complex
of inactive glands into SD-females Fecundity
eggs/female
batches/female
127 (6221) 158 (6G335) 205 (49-373)
2.6 (l-4) &
Preovipos. period (days)
Ovipos. period
(days)
(days)
12.7 (917) 13.5 (8-20) 16.3 (l&21)
13.4 (o-37) 17.3 (C-36) 23.4 (G37)
23.9 (3336) 19.0 (o-39) 6.3 (@29)
10
7
33
4.0 (l-7)
128
2
Postovipos. period
Photoperiod during experiment: short day 12L: 12D. Donor and recipient: SD-females 4 to 5 weeks. after adult ecdysis. (1) Donor: SD-females 3 to 4 weeks after adult ecdysis; Recipient: SD-females 3 to 4 weeks after adult ecdysis,
3 weeks after allatectomy. Duration of experiment: 50 days. duals (Table 3, Fig. 2). The presence of the host’s own CA was not essential for the effect because the implantation of the same CC-CA into allatectomized females induced oviposition as well. Implantation of the CC alone had small effect on the reproductive
024 EGG
5 BATCHES
activity. These results suggest that short daylengths maintain the inhibition of CC-CA or CA via the nervous connections with brain. The denervated glands become spontaneously activated without regard to the photoperiodic conditions.
0
10
20
20
.O
50 DAYS
......,.,...,.,.. .,..... ......... BRAIN-CC-CA
CC-CA
Fig. 2. The variation in reproductive activity for SD-females with implanted inactive glands. Explanations see Table 3 and Fig. 1.
26
MAGDALENA
Table 4. Transplantation Ovipos. females 01)
Operation 1 brain-CC-CA implanted 1 CC-CA implanted Sham-oper.
11
3
I2
10
14
0
HODKOVA
of inactive neuroendocrine
complexes into SD-females
Fecundity eggs/female 143 (124-157) 164 (48-317)
batches/female 2.7 (2-3) 3.0 (l-6)
Preovipos. period (days)
Ovipos. period (days)
Postovipos period (days)
54.7 (42-71) 15.8 (10-25)
18.3 (9-27) 28.1 ((f-59)
7.0 (O-19) 33.0 (9-61)
Photoperiod during experiment: short day 12L: 12D. Donor and recipient: SD-females 3 to 4 weeks after adult ecdysis Duration of experiment: 80 days. Brain-CC-CA = neuroendocrine complex. Although SD-females oviposited well after the implantation of the CCXJA from both active and diapausing females, reproductive activity was much higher in the first case, as shown in Tables 2 and 3. It seems, therefore, that the implanted CC-CA from diapausing females cannot reach the same degree of gonadotropic activity as the CC-CA from previously active females. Transplantation into SD-females
of inactive neuroendocrine
complexes
The foregoing experiments suggested that short-day conditions inhibit CC-CA or CA via nervous connections with the brain. But it is still possible that the transplanted glands were activated by other factors in addition to the disconnection from the brain. In order to exclude this possibility we transplanted brain-CC-CA from SD-females into other SDfemales. As shown in Table 4 and Fig. 3 the implantation of brain-CC-CA. in which the glands remained attached to the brain, is much less effective in stimulation of oviposition than the implantation of CC-CA without the brain. Thus, the CGCA remained inactive when transplanted with the brain. This strongly supports the above mentioned conclusion that CCCA is activated by its disconnection from the brain.
Transplantation of inactive neuroendocrine into allatectomiaed LD-females
complexes
It has been already shown (Table 3) that the transplantation of CC-CA from SD-females into the allatectomized SD-females was followed by oviposition. However, the same operation performed with the allactectomized LD-females was considerably more effective inducing higher reproductive activity (Table 5). This difference suggests that long-day conditions favour in some way (probably by causing the release of the activation hormone from the brain) the reproductive activity induced by the implanted CC-CA. In this respect there arises the question of whether these favourable physiological conditions could also influence the secretory activity of the implanted inactive brain-CC-CA in which the nervous connections between the brain and glands remain intact. The results presented in Table 5 and Fig. 4 show that, like the former experiments with diapausing females (Table 4), the implanted brain-CC-CA taken from the diapausing females and implanted into the LDallatectomized ones was much less effective in stimulation of reproduction than the CC-CA without the brain. Therefore. inhibition which was induced in the donor brainXX_CA by short daylengths has
-Ll
g
.j
?
0
1 poo
,.:...: ....,:.:.,
::‘:::::::~;c:::
~~
if ./
.:
“.‘.‘::.:::::
:.:.: ::,
75
11
30 25-
t-l
Fig. 3. The variation in reproductive activity for SD-females with implanted inactive neuroendocrine complex. Explanations see Table 4 and Figs. 1 and 2.
Function of the neuroendocrine Table 5. Transplantation
of inactive neuroendocrine
Operation 1 brain-CC-CA implanted 1 CC-CA implanted Allatectomized
II
females (n)
9
2
7
I
17
0
complexes into allatectomized LD-females
Fecundity
Ovipos.
21
complex
Preovipos.
Ovipos.
Postovipos.
period (days)
period (days)
17.0 (O-34) 30.7 (1441) -
2.5 (l-4) 7.0 (o-19)
eggs/female
batches/female
period (days)
284 (34-535) 361 (139-619)
5.0
30.5
(I;--) (3-l 1) -
(%? (8-13)
Photoperiod during experiment: long day 18L:6D. Donor: SD-females 4 to 5 weeks after adult ecdysis. Recipient: LD-females 11 days after adult ecdysis, 10 days after allatectomy. Duration of experiment: 50 days.
tinuously stimulated by the activation hormone from the brain in order to induce oviposition. The lack of the activation hormone in diapausing L. decemlineata and A. aegyptium is probably the reason that DISCUSSION several active CA have to be implanted for resumpWe confirmed that the arrest of reproduction in tion of reproduction and that implantation of CC-CA diapausing Pyrrhocoris_ apterus females is a result of is more effective than implantation of CA alone (DE the inactivity of CA (Z&~REK, 1968). Moreover, our WILDE and DE BOER, 1969; GIRARDIEand GRANIER, 1973). We received indications that some stimulatory results indicate that the glands are inhibited by the factor (probably the activation hormone) is lacking brain via nerves. Nervous inhibition of CA has been also in diapausing P. apterus females. It confirms the proposed also for pregnant females of Leucophueu suggestion of SLAMA (1964) that ‘diapause in P. muderae (ENGELMANNand LYJSCHER,1957), fasting females of Oncopeltus fasciatus (JOHANSSON,1958), apterus females results as a consequence of both the activation and the corpora allata insufficiency’. But females of Rhodnius prolixus (BAMR, 1973), virgin in contrast to the above mentioned species the imfemales of Dyndimus oersicolor (FRIEDEL,1974) or diapausing females of Locusta migratoriu @ARIO, 1976). plantation of only one gland taken from diapausing individuals stimulates diapausing P. upterus females This mechanism, however, cannot underlie the phototo oviposit and CA alone has the same stimulatory periodic arrest of reproduction in other species. Thus, effect as CC-CA. It seems therefore, that it is the in Anacridium aegyptium implantation of the CA from inhibition of CA via nervi allati and not the lack of diapausing into other diapausing specimens was without effect on reproduction (GIRARDIEand GRANIER, the activation hormone which ensures perfection of the reproductive arrest. The inhibition of the CA 1973). DE WILDEand DE BOER(1969) found that transwithin the implanted brain-CC
$00 75
50 i
i OJ i’ too p
z
75 50
as r__________-----
0~
024080
i
EGG SATCHES
0
(0
20
20
40
50 DAYS
Fig. 4. The variation in reproductive activity for allatectomized LD-females with implanted inactive neuroendocrine complex. Explanations see Table 5 and Figs. 1 and 2.
28
MAGDALENA HODKOV~
contradict the fact that diapausing females transferred from short- to long-day conditions are readily activated (HODEK, 1968). Probably long-day conditions activate the brain-CC-CA in situ only through the head receptors and they cannot act on the implanted neuroendocrine complex. This study does not exclude that the function of the implanted glands is influenced by interactions with the glands of the host. In order to confirm our conclusion about the inhibition of CA, we pursued this problem further using the method of transsection of the nervi allati or nervi corporis cardiaci (HODKOVA.1974, 1975, 1976). We have found that these operations stimulated LD/SD-females or SD-females similarly as transplantations.
FRIEDELT. (1974) Endocrine control of vitellogenesis in the harlequin bug, Dindymus uersicolor. J. Insect Physiol. 20. 717-733.
G~RARDIEA. and GRANIERS. (1973) Systeme endocrine et physiologie de la diapause imaginale chez le criquet kgyptien, Anacridium aegyptium. J. Znsect Physiol. 19, 2341-2358. HODEKI. (1968) Diapause in females of Pyrrhocoris apterus L. (Heteroptera). Acta ent. bohemoslou. 65, 422435. HODKOV~~ M. (1974) Neuroendocrine regulation of reproduction in Pyrrhocoris apterus. Regulation of insect reproduction, Symp. Liblice 1974, unpubl. HODKOVAM. (1975) Regulation of the activity of corpora allata in Pyrrhocoris apterus (Heteroptera). CSc. Thesis, Czechoslovak Academy of Sciences, Praha. HODKOVAM. (1976) Nervous pathways in photoperiodic regulation of reproduction in females of Pyrrhocoris apterus. In preparation. Acknowledgements-I would like to thank Dr. SLAMA, JOHANS~~N A. S. (1958) Relation of nutrition to endocrineDr. SEHNAL.and Dr. %&K for critically reading the reproductive functions in the milkweed bug Oncopeltus manuscript. fasciatus (Dallas) (Heteroptera: Lygeidae). Nytt. Mag. Zool. 7, 3-132. REFERENCES SLAMAK. (1964) Hormonal control of respiratory metaboBAEHRJ. C. (1973) Controle neuroendocrine du fonctionnelism during growth, reproduction. and diapause in ment du corpus allatum chez Rhodnius prolixus. J. Insect female adults of Pyrrhocoris apterus L. (Hemiptera). J. Physiol. 19, 1041~1055. Insect Physiol. 10, 283-303. BROZAM. and PENERM. P. (1969) Hormonal control of DE WILDE J. and DE BOER S. A. (1969) Humoral and nerthe reproductive diapause in the grasshopper. Oedipoda vous pathways in photoperiodic induction of diapause miniata. Experientia 25. 414415. in Leptinotarsa decemlineata. J. Insect Physiol. 15. DARJO A. (1976) Activitt des corpora allata et controle 66lii75. photoperiodique de la maturation ovarienne chez DE WILDE J. and DE Loon A. (1973) Reproduction-endoLocusta migratoria. J. Insect Physiol. 22. 347-355. crine control. In The Physiology of Insecta (Ed. by ENGELMANN F. (1970) The Physiology of Insect ReproducR~CKSTEINM.) 2nd ed. 1.97-157. Academic Press, New tion. Pergamon Press, Oxford. York. ENGELMANNF. and L~~XHERM. (1957) Die hemmende ~GREK J. (1968) Le comportement d’accouplement g la Wirkung des Gehims auf die Corpora allata bei Leucofin de la diapause imaginale et son controle hormonal phaea maderae (Orthoptera). Verh. deutsch. Zoo/. Ges. dans le cas de la punaise Pyrrhocoris apterus L. (Pyrrho1956. 2 15-220. coridae, Heteroptera). Ann. Endocr. 29. 703-707.
FUNCTION OF THE NEUROENDOCRINE COMPLEX DIAPAUSING PYRRHOCORIS APTERUS FEMALES
IN
MAGDALENA HODKOVA* Department of Insect Physiology, Entomological Institute, Czechoslovak Academy of Science, Na Folimance 5, 120 00 Praha, Czechoslovakia (Received 9 July 1976)
Abstract-The
role of the brain in inhibiting the action of corpora allata in diapausing short-day females was investigated by transplantation experiments. The function of the transplanted glands was evaluated by oviposition, Active glands from long-day females remained active for a long period of time after transplantation into short-day females, although in situ corpora allata were inhibited shortly after the transfer of females from long to short day. Moreover, inactive glands from short-day females became active after transplantation into other short-day females. In contrast. corpora allata remained inhibited when transplanted together with the brain in the neuroendocrine complex (brainxorpora cardiacs-corpus allatum) where the nervous connections between the brain and corpus allatum remained intact. It is therefore suggested that short-day conditions inhibit corpora allata via nervous connections with the brain.
obtain diapausing females (SD-females). Reproducing females were kept under long-day (18L:6D) condiThe lack of the activity of the corpora allata (CA) tions (LD-females). Three to five days after the surgiis a cause of reproductive arrest in diapausing cal treatment experimental females were isolated into females. This is proved by the fact that after implanPetri dishes with males from the same breeding tation of the active complex consisting of corpora car- group. diaca-corpora allata (CC-CA) or CA alone into diaThe donor glands were dissected under insect pausing females the reproductive activity is resumed saline. They were implanted into recipients (narco(DE WILDE and DE BOER, 1969; BROZA and F%NEX, tized in water) through a small incision in the 1969; GIRARDIE and GRANIER, 1973; ENGELMANN, abdomen. CC-CA or CC were implanted together 1970; DE WILDE and DE LOOF, 1974). Also in Pyrrhowith a piece of aorta. Brain-CC-CA was implanted cork upterus the implantation of CC-CA from active together with suboesophageal ganglion. In shamfemales induced oviposition in diapausing females operated females the same procedure was followed, (Z~%REK, 1968). It is believed that the inactivity of except that nothing was implanted. In most experCA in diapausing females is due to a lack of the actiiments post-treatment mortality was about 20%. vation hormone from the brain (DE WILDE and DE To evaluate the action of implanted glands several BOER,1969; GIRARDIEand GRANW, 1973). parametres of reproductive activity were used: (1) inThis paper describes a part of the study devoted cidence of ovipositing females; (2) duration of the to regulation of CA activity by the brain in females preoviposition period (preovipos.); (3) oviposition of Pyrrhocoris apterus. We have investigated here the period = period between the first and the last batch role of diapausing brain in inhibition of CA by transin experiment (ovipos.); (4) postoviposition period plantations of different parts of the neuroendocrine throughout duration of the experiment (postovipos.); complex (brain-CCCA) between active and diapausand (5) number of eggs and number of batches laid ing females. during experiment. INTRODUCTION
MATERIALS
RESULTS
AND METHODS Transplantation
Pyrrhocoris apterus adults were collected in Southern Bohemia and the first generations (F,) of laboratory cultures were used in all experiments. The insects were fed on linden-seed and kept at 26 + 2°C. Shortday photoperiod (12L: 12D) was used in order to *This paper is dedicated to Prof. Jan occasion of his 60th birthday.
DE WILDE
of active glands into SD-females
The implantation
of CC-CA or CA from active LD-females into diapausing SD-females induced oviposition in most individuals. Implantation of CC alone had no effect (Table 1). This suggests that in situ CA of diapausing females are not sufficiently active to ensure effective amounts of juvenile hor-
at the
mone for reproduction. 23
24
MAGDALENA HODKOV~.
Table 1. Transplantation
Operation 1 CA implanted
1 CCCA implanted
2-4 CC implanted Sham-oper.
It is known that females transferred from long- to short-day conditions (LD/SD-females) stop oviposition within about 1-2 weeks (HODEK, 1968), apparently as a result of CA inhibition by short daylengths. The reproductive activity of SD-females with implanted active CC-CA was, therefore, compared with that of LD/SD-females (Table 2, Fig. 1). The oviposition period was seven times longer and fecundity was three times higher in the females with implanted glands. This indicates that implanted active CC-CA cannot be properly inhibited by short daylengths. Implanted glands differ from those in situ by lack of nervous connections with the brain. It seems, therefore, that short-day conditions inhibit active CC-CA via nervous connections with the brain.
of active glands into SD-females Ovipos. females (rr)
n 1I”’
9
, S2)
I1
5”’
4
12’2’
12
6’”
0
23”’ 14’2’
0 0
Preovipos. period (days) 11.2 (93t;) (8-13) 10.8 (9-l 3) 10.9 (9-14)
-
Transplantation of inactioe glands into SD-females
Photoperiod during experiment: short day 12L: 12D. Donor: (1) LD-females 1 to 2 days after adult ecdysis (2) LD-females 2 to 3 days after adult ecdysis. Recipient: (1) SD-females 1 to 2 days after adult ecdysis, one day fasting. (2) SD-females 4 to 5 weeks after adult ecdysis. Duration of experiment: 25 days. CA = corpus allatum, CC = 2 corpora cardiaca, CCCA = corpora cardiacs-corpus allaturn.
The foregoing experiments indicated that disconnection of the CC-CA from the brain prevents inhibition of the active glands by short daylengths. Further experiments investigated whether the glands which had been inactive before the disconnection from the brain would become activated after transplantation. Implantation of CC-CA or CA from SD-females into other SD-females induced oviposition in most indivi-
Table 2. Transfer of females from long to short day and transplantation
Treatment Transfer from LD to SD”’ 1 CC-CA implantedt2’
n
Fecundity
Ovipos. females (n)
eggs/female
14
14
(419:82)
10
10
313 (150-441)
batches/female 1.6 (l-3) 5.6 (3-8)
of active glands into SD-females Preovipos. period (days) 7.9 (7-10) 11.0 (9-14)
Ovipos. period (days) 4.0 (O-12) 30.2 (10-38)
Postovipos period (days) 38.1 (23336) 8.8 (O-31)
Photoperiod during experiment: short day 12L: 12D. (1) Females transferred from long (18L:6D) to short day (12L: 12D) 2 to 3 days after adult ecdysis. (2) Donor: LD-females 2 to 3 days after adult ecdysis; Recipient: SD-females 4 to 5 weeks after adult ecdysis. Duration of experiment: 50 days.
0
LHl5 0
a
EGG
4 0 * HATCHES
Fig. 1. The variation in reproductive activity for females transferred from long to short day and SDfemales with implanted active glands. Open-organs of LD-females. shaded+rgans of SD-females. Left-in situ organs of recipient, right-implanted organs. Broken line-preoviposition period, solid line-preoviposition + oviposition period. Other explanations see Table 2. Symbols explained in Fig. 2.
Function of the neuroendocrine Table 3. Transplantation
n
Ovipos. females (n)
1 CA implanted 1 CC-CA implanted CA extirp. and 1 CCCA implanted”’ 1 cc implanted
11
9
13
11
7
6
13
1
Sham-oper. Unoperated
32 12
0 0
Operation
25
complex
of inactive glands into SD-females Fecundity
eggs/female
batches/female
127 (6221) 158 (6G335) 205 (49-373)
2.6 (l-4) &
Preovipos. period (days)
Ovipos. period
(days)
(days)
12.7 (917) 13.5 (8-20) 16.3 (l&21)
13.4 (o-37) 17.3 (C-36) 23.4 (G37)
23.9 (3336) 19.0 (o-39) 6.3 (@29)
10
7
33
4.0 (l-7)
128
2
Postovipos. period
Photoperiod during experiment: short day 12L: 12D. Donor and recipient: SD-females 4 to 5 weeks. after adult ecdysis. (1) Donor: SD-females 3 to 4 weeks after adult ecdysis; Recipient: SD-females 3 to 4 weeks after adult ecdysis,
3 weeks after allatectomy. Duration of experiment: 50 days. duals (Table 3, Fig. 2). The presence of the host’s own CA was not essential for the effect because the implantation of the same CC-CA into allatectomized females induced oviposition as well. Implantation of the CC alone had small effect on the reproductive
024 EGG
5 BATCHES
activity. These results suggest that short daylengths maintain the inhibition of CC-CA or CA via the nervous connections with brain. The denervated glands become spontaneously activated without regard to the photoperiodic conditions.
0
10
20
20
.O
50 DAYS
......,.,...,.,.. .,..... ......... BRAIN-CC-CA
CC-CA
Fig. 2. The variation in reproductive activity for SD-females with implanted inactive glands. Explanations see Table 3 and Fig. 1.
26
MAGDALENA
Table 4. Transplantation Ovipos. females 01)
Operation 1 brain-CC-CA implanted 1 CC-CA implanted Sham-oper.
11
3
I2
10
14
0
HODKOVA
of inactive neuroendocrine
complexes into SD-females
Fecundity eggs/female 143 (124-157) 164 (48-317)
batches/female 2.7 (2-3) 3.0 (l-6)
Preovipos. period (days)
Ovipos. period (days)
Postovipos period (days)
54.7 (42-71) 15.8 (10-25)
18.3 (9-27) 28.1 ((f-59)
7.0 (O-19) 33.0 (9-61)
Photoperiod during experiment: short day 12L: 12D. Donor and recipient: SD-females 3 to 4 weeks after adult ecdysis Duration of experiment: 80 days. Brain-CC-CA = neuroendocrine complex. Although SD-females oviposited well after the implantation of the CCXJA from both active and diapausing females, reproductive activity was much higher in the first case, as shown in Tables 2 and 3. It seems, therefore, that the implanted CC-CA from diapausing females cannot reach the same degree of gonadotropic activity as the CC-CA from previously active females. Transplantation into SD-females
of inactive neuroendocrine
complexes
The foregoing experiments suggested that short-day conditions inhibit CC-CA or CA via nervous connections with the brain. But it is still possible that the transplanted glands were activated by other factors in addition to the disconnection from the brain. In order to exclude this possibility we transplanted brain-CC-CA from SD-females into other SDfemales. As shown in Table 4 and Fig. 3 the implantation of brain-CC-CA. in which the glands remained attached to the brain, is much less effective in stimulation of oviposition than the implantation of CC-CA without the brain. Thus, the CGCA remained inactive when transplanted with the brain. This strongly supports the above mentioned conclusion that CCCA is activated by its disconnection from the brain.
Transplantation of inactive neuroendocrine into allatectomiaed LD-females
complexes
It has been already shown (Table 3) that the transplantation of CC-CA from SD-females into the allatectomized SD-females was followed by oviposition. However, the same operation performed with the allactectomized LD-females was considerably more effective inducing higher reproductive activity (Table 5). This difference suggests that long-day conditions favour in some way (probably by causing the release of the activation hormone from the brain) the reproductive activity induced by the implanted CC-CA. In this respect there arises the question of whether these favourable physiological conditions could also influence the secretory activity of the implanted inactive brain-CC-CA in which the nervous connections between the brain and glands remain intact. The results presented in Table 5 and Fig. 4 show that, like the former experiments with diapausing females (Table 4), the implanted brain-CC-CA taken from the diapausing females and implanted into the LDallatectomized ones was much less effective in stimulation of reproduction than the CC-CA without the brain. Therefore. inhibition which was induced in the donor brainXX_CA by short daylengths has
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.:
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75
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Fig. 3. The variation in reproductive activity for SD-females with implanted inactive neuroendocrine complex. Explanations see Table 4 and Figs. 1 and 2.
Function of the neuroendocrine Table 5. Transplantation
of inactive neuroendocrine
Operation 1 brain-CC-CA implanted 1 CC-CA implanted Allatectomized
II
females (n)
9
2
7
I
17
0
complexes into allatectomized LD-females
Fecundity
Ovipos.
21
complex
Preovipos.
Ovipos.
Postovipos.
period (days)
period (days)
17.0 (O-34) 30.7 (1441) -
2.5 (l-4) 7.0 (o-19)
eggs/female
batches/female
period (days)
284 (34-535) 361 (139-619)
5.0
30.5
(I;--) (3-l 1) -
(%? (8-13)
Photoperiod during experiment: long day 18L:6D. Donor: SD-females 4 to 5 weeks after adult ecdysis. Recipient: LD-females 11 days after adult ecdysis, 10 days after allatectomy. Duration of experiment: 50 days.
tinuously stimulated by the activation hormone from the brain in order to induce oviposition. The lack of the activation hormone in diapausing L. decemlineata and A. aegyptium is probably the reason that DISCUSSION several active CA have to be implanted for resumpWe confirmed that the arrest of reproduction in tion of reproduction and that implantation of CC-CA diapausing Pyrrhocoris_ apterus females is a result of is more effective than implantation of CA alone (DE the inactivity of CA (Z&~REK, 1968). Moreover, our WILDE and DE BOER, 1969; GIRARDIEand GRANIER, 1973). We received indications that some stimulatory results indicate that the glands are inhibited by the factor (probably the activation hormone) is lacking brain via nerves. Nervous inhibition of CA has been also in diapausing P. apterus females. It confirms the proposed also for pregnant females of Leucophueu suggestion of SLAMA (1964) that ‘diapause in P. muderae (ENGELMANNand LYJSCHER,1957), fasting females of Oncopeltus fasciatus (JOHANSSON,1958), apterus females results as a consequence of both the activation and the corpora allata insufficiency’. But females of Rhodnius prolixus (BAMR, 1973), virgin in contrast to the above mentioned species the imfemales of Dyndimus oersicolor (FRIEDEL,1974) or diapausing females of Locusta migratoriu @ARIO, 1976). plantation of only one gland taken from diapausing individuals stimulates diapausing P. upterus females This mechanism, however, cannot underlie the phototo oviposit and CA alone has the same stimulatory periodic arrest of reproduction in other species. Thus, effect as CC-CA. It seems therefore, that it is the in Anacridium aegyptium implantation of the CA from inhibition of CA via nervi allati and not the lack of diapausing into other diapausing specimens was without effect on reproduction (GIRARDIEand GRANIER, the activation hormone which ensures perfection of the reproductive arrest. The inhibition of the CA 1973). DE WILDEand DE BOER(1969) found that transwithin the implanted brain-CC
$00 75
50 i
i OJ i’ too p
z
75 50
as r__________-----
0~
024080
i
EGG SATCHES
0
(0
20
20
40
50 DAYS
Fig. 4. The variation in reproductive activity for allatectomized LD-females with implanted inactive neuroendocrine complex. Explanations see Table 5 and Figs. 1 and 2.
28
MAGDALENA HODKOV~
contradict the fact that diapausing females transferred from short- to long-day conditions are readily activated (HODEK, 1968). Probably long-day conditions activate the brain-CC-CA in situ only through the head receptors and they cannot act on the implanted neuroendocrine complex. This study does not exclude that the function of the implanted glands is influenced by interactions with the glands of the host. In order to confirm our conclusion about the inhibition of CA, we pursued this problem further using the method of transsection of the nervi allati or nervi corporis cardiaci (HODKOVA.1974, 1975, 1976). We have found that these operations stimulated LD/SD-females or SD-females similarly as transplantations.
FRIEDELT. (1974) Endocrine control of vitellogenesis in the harlequin bug, Dindymus uersicolor. J. Insect Physiol. 20. 717-733.
G~RARDIEA. and GRANIERS. (1973) Systeme endocrine et physiologie de la diapause imaginale chez le criquet kgyptien, Anacridium aegyptium. J. Znsect Physiol. 19, 2341-2358. HODEKI. (1968) Diapause in females of Pyrrhocoris apterus L. (Heteroptera). Acta ent. bohemoslou. 65, 422435. HODKOV~~ M. (1974) Neuroendocrine regulation of reproduction in Pyrrhocoris apterus. Regulation of insect reproduction, Symp. Liblice 1974, unpubl. HODKOVAM. (1975) Regulation of the activity of corpora allata in Pyrrhocoris apterus (Heteroptera). CSc. Thesis, Czechoslovak Academy of Sciences, Praha. HODKOVAM. (1976) Nervous pathways in photoperiodic regulation of reproduction in females of Pyrrhocoris apterus. In preparation. Acknowledgements-I would like to thank Dr. SLAMA, JOHANS~~N A. S. (1958) Relation of nutrition to endocrineDr. SEHNAL.and Dr. %&K for critically reading the reproductive functions in the milkweed bug Oncopeltus manuscript. fasciatus (Dallas) (Heteroptera: Lygeidae). Nytt. Mag. Zool. 7, 3-132. REFERENCES SLAMAK. (1964) Hormonal control of respiratory metaboBAEHRJ. C. (1973) Controle neuroendocrine du fonctionnelism during growth, reproduction. and diapause in ment du corpus allatum chez Rhodnius prolixus. J. Insect female adults of Pyrrhocoris apterus L. (Hemiptera). J. Physiol. 19, 1041~1055. Insect Physiol. 10, 283-303. BROZAM. and PENERM. P. (1969) Hormonal control of DE WILDE J. and DE BOER S. A. (1969) Humoral and nerthe reproductive diapause in the grasshopper. Oedipoda vous pathways in photoperiodic induction of diapause miniata. Experientia 25. 414415. in Leptinotarsa decemlineata. J. Insect Physiol. 15. DARJO A. (1976) Activitt des corpora allata et controle 66lii75. photoperiodique de la maturation ovarienne chez DE WILDE J. and DE Loon A. (1973) Reproduction-endoLocusta migratoria. J. Insect Physiol. 22. 347-355. crine control. In The Physiology of Insecta (Ed. by ENGELMANN F. (1970) The Physiology of Insect ReproducR~CKSTEINM.) 2nd ed. 1.97-157. Academic Press, New tion. Pergamon Press, Oxford. York. ENGELMANNF. and L~~XHERM. (1957) Die hemmende ~GREK J. (1968) Le comportement d’accouplement g la Wirkung des Gehims auf die Corpora allata bei Leucofin de la diapause imaginale et son controle hormonal phaea maderae (Orthoptera). Verh. deutsch. Zoo/. Ges. dans le cas de la punaise Pyrrhocoris apterus L. (Pyrrho1956. 2 15-220. coridae, Heteroptera). Ann. Endocr. 29. 703-707.