|
|
|
|||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
First published online July 14, 2008
Journal of Experimental Biology 211, 2486-2491 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.013177
The role of the antennae during courtship behaviour in the parasitic wasp Trichopria drosophilae
1 Dipartimento di Scienze Agrarie e Ambientali, University of Perugia –
Borgo XX Giugno 74, 06121 Perugia, Italy
2 Departimento di Scienze Ambientali e delle Produzioni Vegetali, Politechnic
University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
3 Departimento di Biotecnologie Agrarie, University of Firenze, P. le delle
Cascine 18, 50144 Florence, Italy
* Author for correspondence (e-mail: rromani{at}unipg.it)
Accepted 19 May 2008
| Summary |
|---|
|
|
|---|
Key words: insect, mating behaviour, parasitoids, Drosophila melanogaster, antennal glands, sex pheromone
| INTRODUCTION |
|---|
|
|
|---|
Behavioural experiments were carried out to define the role of male
antennal glands during courtship, as a possible source of a male-produced sex
recognition pheromone. In T. drosophilae, a previous study
(Sacchetti et al., 1999
)
revealed the presence of male antennal glands. Because of the relatively large
body size of individuals and their slow movements during courtship, and also
because of the presence of a single male antennomere (the fourth, A4, counted
from the scape) bearing the glands, T. drosophilae makes an excellent
model for this kind of behavioural study.
| MATERIALS AND METHODS |
|---|
|
|
|---|
T. drosophilae were reared in glass vials containing 1- to 2-day old D. melanogaster puparia, exposed to about 10–15 2-day old mated female parasitoids for about 48 h. The emergence of new parasitoids took place after 23–25 days.
Insect preparation for behavioural observations
Parasitized host puparia were collected 20 days after parasitization and
isolated singly in small glass vials (5 cm length and 15 cm diameter) with a
droplet of honey solution.
Newly emerged virgin parasitoid males and females (24–36h old) were transferred from the incubator to room conditions (temperature 25–28°C, relative humidity 50%) for observation and alterations, i.e. ablation of both male and female antennae and glue applications (Supercolla Saratoga®, Milan, Italy) on the male antennae. In both cases, the parasitoids were anaesthetized in CO2 and put on a cold table (Peltier effect, Labco®, Rome, Italy) kept at about 3°C. For the ablations, the antennae were positioned straight and all the antennomeres, except the scape (A1), were ablated using a scalpel blade under a stereomicroscope. The glue was applied using an insect pin (no. 000), taking care to restrict the glue only to the ventrolateral side of A4 or A5. After the alterations the parasitoids were replaced singly in a vial and used the following day.
The following bioassays were carried out: (a) intact males and females; (b) males with A4 covered with glue and intact females; (c) males with A5 covered with glue and intact females; (d) males and females with the antennae of the same side ablated, i.e. males and females without the right (or left) antenna; and (e) males and females with the antennae of the opposite side ablated, i.e. males without the right antenna and females without the left (or vice versa). The pairs were observed continously for 10 min, starting from the first encounter between male and female. Ten to fourteen replicates for each bioassay were carried out. In the case of successful courtship (i.e. the female exposes its genital aperture to the male and the male moves rearwards to mate) the bioassays were terminated.
In the case of males with one antennomere covered with glue, after the bioassay each individual was isolated and processed for scanning electron microscope (SEM) observation, to check whether the glue was properly applied (Fig. 1E).
|
Statistics
The behavioural parameters, and male antennation frequency and duration,
were analysed using Kruskall–Wallis one-way analysis of variance by
ranks. If the value of H was significant, comparisons were conducted
using the Bonferroni–Dunn method. According to this method the
familywise type I error is controlled under a non-directional hypothesis
(Sheskin, 2004
).
SEM observations
All the T. drosophilae males with glue applied to either A4 or A5
were kept separately and processed for SEM observation to check whether the
glue had been correctly applied. In the case of glued A4 we checked whether
the glue was restricted to the release site of the A4 gland, while in the case
of glued A5 we checked whether the glue was applied only on A5. In all cases,
anaesthetized males were beheaded and air dried, avoiding the use of any
chemical to prevent the removal of the glue. After dehydration, the heads with
antennae were gold coated in a Balzers Union SCD 040 unit (Balzers®,
Vaduz, Luxembourg), and examined with a Philips XL 30 (FEI® Company,
Eindhoven, The Netherlands).
| RESULTS |
|---|
|
|
|---|
Mating behaviour
Observations with intact T. drosophilae individuals were conducted
to define sequential mating steps.
Wing fanning. When a male perceived a female, a vigorous and continuous wing fanning was performed, without physical contact. Then the male followed and reached the female, keeping his wings vibrating and the antennae straight and forward.
Encounter. The male touched the female with the antennae.
Mounting. The male mounted the female with the two individuals facing the same way. The female raised the antennae quickly.
Antennation. The male brought his antennae in front of those of the female, which were kept upright and parallel (Fig. 2A). Then the male started to gently stroke the distal region of the female antennae (i.e. the club-shaped portion) with the ventrolateral region of the proximal part of his antennae (i.e. A4). The male often insistently stroked the apical part of the female's antennae (Fig. 2B). The contact lasted 43.71±4.40 s (mean ± s.e.m., N=14; Table 1) without interval. In one case only, the antennation was performed twice (antennation frequency 1.07±0.07, mean ± s.e.m., Table 1). Sexually receptive females reacted by extruding the ovipositor and exposing the genital opening, while their antennae were placed laterally and backwards. This change in the female's antennae position is likely to be the signal that stops the antennation by the male.
|
|
Copulation. The male quickly moved rearward, spread his wings and eventually copulated.
The courtship behaviour of T. drosophilae is available as a video (see Movie 1 in supplementary material).
Bioassays
To understand the role of antennal glands, the following bioassays were
performed with altered pairs. Results and statistical evidence are reported in
Table 1.
Males with A4 covered with glue and intact females
These bioassays were performed to assess the role of the male antennal
gland secretion (Fig. 3B). In
this situation, the behavioural sequence followed the above described scheme
for intact pairs, but no copulation occured (N=12). After several
copulation attempts, the male either gave up or was made to dismount by the
female. The antennal contact lasted 125.55±20.59 s (mean ±
s.e.m.), with an antennation frequency of 2.83±0.66 (mean ±
s.e.m.), both values significantly higher than for the intact pairs.
|
Males and females with antennae of the opposite side ablated
These bioassays were performed to assess whether the gland secretion acts
on contact (Fig. 3D). After
mounting, the male performed the antennation, with no contact with the
female's opposite antenna: no copulation occurred (N=10). The
antennation time lasted 120.89±26.71 s (mean ± s.e.m.,
N=10), with an antennation frequency of 3.90±0.96 (mean
± s.e.m.), both significantly higher than for intact pairs and pairs
with males with glue on A5, but not different from males with glue on A4.
Males tried to copulate unsuccessfully and/or were made to dismount by
females, which did not show the typical signals of receptivity.
Males and females with the antennae of the same side ablated
These bioassays were performed to assess possible side effects of antennal
ablation (Fig. 3C). After
mounting, the male started antennating the female for a longer time, when
compared with intact pairs (56.23±7.42 s, mean ± s.e.m.,
N=10). However, antennal contact was not different from pairs with
males with glue on A5. Copulation occurred in 100% of bioassays.
| DISCUSSION |
|---|
|
|
|---|
This was further demonstrated by selective ablation bioassays. In cross-ablated individuals we were able to prevent mating, while this occurred normally in the case of same-side ablated pairs. These facts support our hypothesis that the courtship pheromone needs to be transferred from male to female antennae through contact, since the short distance between the antennae in cross-ablated individuals could allow the perception of a short-range volatile pheromone. Behavioural experiments also demonstrated that antennal contact is associated with an exact posture between male and female, according to a `lock and key' mechanism allowing the transfer of the pheromone onto female antennal receptors.
Sacchetti and colleagues reported the occurrence of male antennal glands on
the fourth antennomere of T. drosophilae males
(Sacchetti at al., 1999
).
Ultrastructural details of the secretory cells as well as the physical
features of the secretion (i.e. viscous appearance) are consistent with a
possible contact activity of the secretion.
The pheromone-based courtship behaviour performed by T. drosophilae males could actually be an integration of different stimuli provided for the female, i.e. contact and visual in combination with chemical. Although we did not investigate the role of visual cues, mechanical stimulations were offered by the male throughout the experiments, except for the ones with cross-ablation of the antennae.
Antennal ablation has proved to be an effective tool in investigating
insect behaviour related to the functional significance of a specific organ,
as already reported for antennae in the cricket Teleogryllus
oceanicus (Le Guillou) (Balakrishnan
and Pollack, 1997
) and the parasitic wasp Leptopilina
heterotoma Meigen (Isidoro et al.,
1999
), and for the mechanosensilla of male genitalia in
Drosophila (Acebes et al.,
2003
).
The presence of antennal glands in males is a common feature, shared by
primitive and evolved hymenopterans. In fact, males of Terebrantia (e.g.
Bin and Vinson, 1986
;
Bin et al., 1999
) and Aculeata
(Felicioli et al., 1998
;
Isidoro et al., 2000
;
Romani et al., 2003
;
Romani et al., 2005
) have
glanded antennomeres.
The role of the secretion in sex recognition has been proved in several
species of Terebrantia (Bin et al.,
1988
; Bin et al.,
1999
; Isidoro et al.,
1999
) and in one species of Aculeata
(Felicioli et al., 1998
).
Besides Hymenoptera, antennal glands have been described in a few other
insect orders (Skilbeck and Anderson,
1994
; Weis et al.,
1999
; Giglio et al.,
2005
; Belcari and
Kozánek, 2006
), as well as the presence of the male
antennal glands associated with courtship behaviour
(Medvedev and Pavlov, 1988
;
Bartlet et al., 1994
).
Male glands involved in the production of courtship pheromones can be
located on body parts other than the antennae, i.e. legs (Wittman and
Blochtein, 1995). In Lepidoptera, male coremata, i.e. eversible scent brushes
present on the abdomen, produce courtship pheromones
(Haynes and Birch, 1985
). The
same function has also been reported for the wings of some butterflies
(Grula et al., 1980
;
Honda, 1980
).
The results we found in T. drosophilae are of great relevance for
studies that attempt to interpret the mating system in Hymenoptera, one of the
largest, biologically diverse and economically important insect orders
(Ayasse et al., 2001
). Large
differences have been found so far in terms of number, distribution and
cytological features of the antennal glands. These differences can be
interpreted as a great diversity in anatomical features of antennal
structures, with a convergent functional significance. The hypothesis of the
lock and key mechanism, i.e. the fact that the morphology of animal genitalia
can be used as a highly species-specific tool
(Shapiro and Porter, 1989
),
could be applied to antennal structures, at least in Hymenoptera Apocrita, the
insect group that seems to rely more than others on the antennae during mating
behaviour.
| Acknowledgments |
|---|
| Footnotes |
|---|
| References |
|---|
|
|
|---|
Acebes, A., Cobb, M. and Ferveur, J. F. (2003).
Species-specific effects of single sensillum ablation on mating position in
Drosophila. J. Exp. Biol.
206,3095
-3100.
Alcock, J. (1981). Notes on the reproductive behaviour of some Australian thynninae wasps (Hymenoptera: Tiphiidae). J. Kans. Entomol. Soc. 54,681 -693.
Ayasse, M., Paxton, R. J. and Tengö, J. (2001). Mating behaviour and chemical communication in the order Hymenoptera. Annu. Rev. Entomol. 46, 31-78.[CrossRef][Medline]
Balakrishnan, R., and Pollack, G. T. S. (1997). The role of antennal sensory cues in female responses to courting males in the cricket Teleogryllus oceanicus. J. Exp. Biol. 200,511 -522.[Abstract]
Barras, R. (1960). The courtship behaviour of Mormoniella vitripennis Walk. (Hymenoptera: Pteromalidae). Behaviour 15,185 -209.[CrossRef]
Bartlet, E., Isidoro, N. and Williams, I. H. (1994). Antennal glands in Psylliodes chrysocephala, and their possible role in reproductive behaviour. Physiol. Entomol. 19,241 -250.[CrossRef]
Belcari, A. and Kozánek, M. (2006). Secretory material from antennal organs and its possible role in mating behaviour of Pipunculidae (Diptera). Can. J. Zool. 84,1727 -1732.[CrossRef]
Bin, F. and Vinson, S. B. (1986). Morphology of the antennal sex-gland in male Trissolcus basalis (Woll.) (Hymenoptera: Scelionidae), an egg parasitoid of the green stink bug, Nezara viridula (Hemiptera: Pentatomidae). Int. J. Insect Morphol. Embryol. 15,129 -138.[CrossRef]
Bin, F., Strand, M. R. and Vinson, S. B. (1988). Antennal structures and mating behavior in Trissolcus basalis (Woll.) (Hym.: Scelionidae), egg parasitoid of the green stink bug. In Trichogramma and Other Egg Parasites (ed. J. Voegele, J. Waage and J. C. van Lenteren), pp.144 -151. Paris: Les Colloques de l'INRA.
Bin, F., Waeckers, F. L., Romani, R. and Isidoro, N. (1999). Tyloids in Pimpla turionellae are release structures of male antennal glands involved in courtship behaviour (Hymenoptera: Ichneumonidae). Int. J. Insect Morphol. Embryol. 28,61 -68.[CrossRef]
Cade, W. H. (1985). Insect mating and courtship behaviour. In Comprehensive Insect Physiology, Biochemistry and Pharmacology. Vol. 9 (ed. G. A. Kerkut and L. I. Gilbert), pp. 591-619. Oxford: Pergamon Press.
Dahms, E. C. (1973). The courtship behaviour of Melittobia australica Girault, 1912; (Hymenoptera: Eulophidae). Mem. Queensl. Mus. 16,411 -414.
Dahms, E. C. (1984). An interpretation of the structure and function of the antennal sense organs of Mellittobia australica (Hymenoptera: Eulophidae) with the discovery of a large dermal gland in the male scape. Mem. Queensl. Mus. 21(2),361 -377.
Eller, F. J., Bartlet, R. J., Jones, R. L. and Kulman, H. M. (1984). Ethyl (Z)-9-hexadecenoate, a sex pheromone of Syndipnus rubiginosus, a sawfly parasitoid. J. Chem. Ecol. 10,291 -300.[CrossRef]
Fauvergue, X., Hopper, K. R. and Antolin, M. F.
(1995). Mate finding via a trail sex pheromone by a parasitoid
wasp. Proc. Natl. Acad. Sci. USA
92,900
-904.
Felicioli, A., Isidoro, N., Romani, R., Bin, F. and Pinzauti, M. (1998). Ethological and morphological analysis of mating behaviour in Osmia cornuta Latr. (Hymenoptera, Megachilidae). Int. J. Insect Morphol. Embryol. 2, 137-144.
Field, S. A., and Keller, M. A. (1994). Localization of the female sex pheromone gland in Cotesia rubecola Marshall (Hymenoptera: Braconidae). J. Hymenopt. Res. 3, 151-156.
Giglio, A., Ferrero, E. A. and Zetto Brandmayr, T. (2005). Ultrastructural identification of the antennal gland complement in Siagona europaea Dejean 1826, a myrmecophagous carabid beetle. Acta Zool. 86,195 -203.[CrossRef]
Goodpasture, C. (1975). Comparative courtship behaviour and karyology in Monodontomerus (Hymenoptera: Torymidae). Ann. Entomol. Soc. Am. 68,391 -397.
Gordh, G. and DeBach, P. (1978). Courtship behaviour in the Aphytis lingnanensis group, its potential usefulness in taxonomy, and a review of sexual behavior in the parasitic Hymenoptera (Chalcidoidea: Aphelinidae). Hilgardia 46, 37-75.
Grula, J. W., McChesney, J. D. and Taylor, O. R. (1980). Aphrodisiac pheromones of the sulfur butterflies Colias eurytheme and C. phillodice (Lepidoptera, Pieridae). J. Chem. Ecol. 6,241 -256.[CrossRef]
Guerrieri, E., Pedata, P. A., Romani, R., Isidoro, N. and Bin, F. (2001). Functional anatomy of male antennal glands in three species of Encyrtidae (Hymenoptera: Chalcidoidea). J. Nat. Hist. 35,41 -54.[CrossRef]
Haynes, K. F., and Birch, M. C. (1985). The role of other pheromones, allomones and kairomones in the behavioural responses of insects. In Comprehensive insect Physiology, Biochemistry and Pharmacology. Vol 9 (ed. G. A. Kerkut and L. I. Gilbert), pp. 225-255. Oxford: Pergamon Press.
Honda, K. (1980). Odor of a papilionid butterfly odoriferous substances emitted by Atrophaneura alcinous alcinous (Lepidoptera: Papilionidae). J. Chem. Ecol. 6,867 -873.[CrossRef]
Isidoro, N. and Bin, F. (1995). Male antennal gland of Amitus spiniferus (Brethes) (Hymenoptera: Platygastridae), likely involved in courtship behaviour. Int. J. Insect Morphol. Embryol. 24,365 -373.[CrossRef]
Isidoro, N., Bin, F., Colazza, S. and Vinson, S. B. (1996). Morphology of antennal gustatory sensilla and glands in some parasitoid Hymenoptera with hypothesis on their role in sex and host recognition. J. Hymenopt. Res. 5, 206-239.
Isidoro, N., Bin, F., Romani, R., Pujade-Villar, J. and Ros-Farré, P. (1999). Diversity and function of male antennal glands in Cynipoidea (Hymenoptera). Zool. Scr. 28 (1-2),165 -174.[CrossRef]
Isidoro, N., Romani, R., Velasquez, D., Renthal, R., Bin, F. and Vinson, S. B. (2000). Antennal glands in queen and worker of the fire ant, Solenopsis invicta Buren: first report in female social Aculeata (Hymenoptera: Formicidae). Insectes. Soc. 47,236 -240.[CrossRef]
Kainoh, Y. (1999). Parasitoids. In Pheromones of Non-Lepidopteran Insects Associated With Agricultural Plants (ed. J. Hardie and A.K Minks), pp.384 -404. Wallingford, UK: CABI Publishing.
Lewis, W. J., Snow, J. W. and Jones, R. L. (1971). A pheromone trap for studying populations of Cardiochiles nigriceps, a parasite of Heliothis virescens.J. Econ. Entomol. 64,1417 -1421.
Medvedev, L. N. and Pavlov, S. I. (1988). Mating behaviour of the Chrysomelidae (Coleoptera). Annu. Rev. Entomol. 67,100 -109.
Ridsdill Smith, T. J. (1970). The behaviour of Hemithynnus hyalinatus (Hymenoptera: Tiphiidae), with notes on some other Thynninae. J. Aust. Entomol. Soc. 9, 196-208.[CrossRef]
Robacker, D. C. and Hendry, L. B. (1977). Neral and geranial: components of the sex pheromone of the parasitic wasp Itoplectis conquisitor. J. Chem. Ecol. 3, 563-577.[CrossRef]
Robacker, D. C., Weaver, K. M. and Hendry, L. B. (1976). Sexual communication and associative learning in the parasitic wasp Itoplectis conquisitor. J. Chem. Ecol. 2, 39-48.[Medline]
Romani, R., Isidoro, N. and Bin, F. (1999). Further evidence of male antennal glands in Aphelinidae: the case of Aphytis melinus DeBach (Hymenoptera: Aphelinidae). J. Hymenopt. Res. 8 (1),109 -155.
Romani, R., Isidoro, N., Riolo, P. and Bin. F. (2003). Antennal glands in male bees: structures for sexual communication by pheromones? Apidologie 34,603 -610.[CrossRef]
Romani, R., Isidoro, N., Riolo, P., Bin. F., Fortunato, A., Turillazzi, S. and Beani, L. (2005). A new role for antennation in paper wasps (Hymenoptera, Vespidae): antennal courtship and sex dimorphic glands in antennomeres. Insectes. Soc. 52, 96-102.[CrossRef]
Sacchetti, P., Belcari, A., Romani, R., Isidoro, N. and Bin, F. (1999). External morphology and ultrastructure of male antennal glands in two diapriids (Hymenoptera: Diapriidae). Entomol. Problems 30(1), 63-71.
Shapiro, A. M. and Porter, A. H. (1989). The lock-and-key hypothesis: evolutionary and biosystematic interpretation of insect genitalia. Annu. Rev. Entomol. 34,231 -245.[CrossRef]
Sheskin, D. J. (2004). Parametric and nonparametric statistical procedure. 3rd edn. Boca Raton, FL: Chapman & Hall/CRC.
Simser, D. H. and Coppel, H. C. (1980). Female-produced sex pheromone in Brachymeria lasus and B. intermedia (Hym.: Chalcididae). Entomophaga 25 (4),373 -380.[CrossRef]
Skilbeck, C. A. and Anderson, M. (1994). The fine structure of glandular units on the antennae of two species of the parasitoid Aleochara (Coleoptera: Staphylinidae). Int. J. Insect Morphol. Embryol. 23,319 -328.[CrossRef]
Speith, H. T. (1974). Courtship behaviour in Drosophila. Annu. Rev. Entomol. 19,385 -405.[CrossRef][Medline]
Syvertsen, T. C., Jackson, L. L., Blomquist, G. J. and Vinson, S. B. (1995). Alkadienes mediating courtship in the parasitoid Cardiochiles nigriceps (Hymenoptera: Braconidae). J. Chem. Ecol. 21,1971 -1989.[CrossRef]
Tagawa, J. (1977). Localization and histology of the sex pheromone-producing gland in the parasitic wasp, Apanteles glomeratus. J. Insect Physiol. 23, 49-56.[CrossRef][Medline]
Tagawa, J. (1983). Female sex pheromone glands in the parasitic wasps, genus Apanteles. Appl. Entomol. Zool. (Jpn.) 18,416 -427.
Takahashi, S. and Sugai, T. (1982). Mating behaviour of the parasitoid wasp Tetrastichus hagenowii (Hymenoptera: Eulophidae). Entomol. Gen. 7(4), 287-293.
van den Assem, J. (1969). Reproductive behaviour of Pseudeucoila bochei (Hymenoptera: Cynipidae). I. A description of courtship behaviour. Neth. J. Zool. 19,641 -648.[CrossRef]
van den Assem, J. and Jachmann, F. (1982). The coevolution of receptivity signalling and body size in the Chalcidoidea. Behaviour 80,96 -105.[CrossRef]
van den Assem, J. and Putters, F. A. (1980). Patterns of sounds produced by courting chalcidoid males and its biological significance. Entomol. Exp. Appl. 27,293 -302.[CrossRef]
Viggiani, G. (1985). Additional notes and illustrations on some species of aphelinids described by A. A. Girault and A. P. Dodd in the genera Coccophagus Westw., Encarsia Foerst. and Prospaltella Ashm. (Hym.: Chalcidoidea). Boll. Lab. Entomol. Agr. `Filippo Silvestri' 42,233 -255.
Vinson, S. B. (1972). Courtship behaviour and evidence for a sex pheromone in the parasitoid Campoletis sonorensis (Hymenoptera: Ichneumonidae). Environ. Entomol. 1, 409-414.
Vinson, S. B. (1978). Courtship behaviour and source of a sexual pheromone from Cardiochiles nigriceps. Ann. Entomol. Soc. Am. 71,832 -837.
Virant-Doberlet, M. and Cokl, A. (2004). Vibrational communication in insects. Neotrop. Entomol. 33 (2),121 -134.
Weis, A., Schonitzer, K. and Melzer, R. R. (1999). Exocrine glands in the antennae of the carabid beetle, Platynus assimilis (Paykull) 11790 (Coleoptera, Carabidae, Pterostichinae). I. Int. J. Insect Morphol. Embryol. 28,311 -335.
Weseloh, R. M. (1980). Sex pheromone gland of the gypsy moth parasitoid, Apanteles melanoscelus: revaluation and ultrastructural survey. Ann. Entomol. Soc. Am. 73,576 -580.
Wittmann, D. and Blochtein, B. (1995). Why males of leafcutter bees hold the females' antennae with their front legs during mating. Apidologie 26,181 -195.[CrossRef]
![]()
CiteULike
Complore
Connotea
Del.icio.us
Digg
Reddit
Technorati
Twitter What's this?
Related articles in JEB:
This article has been cited by other articles:
![]() |
K. Phillips ANTENNAE ARE KEY FOR COURTING FRUITFLIES J. Exp. Biol., August 1, 2008; 211(15): ii - ii. [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||