The composition of the defensive secretions of Thaumastella namaquensis and T. elizabethae with notes on the higher classification of the thaumastellidae (insecta: heteroptera)

Comp. Biochem. Physiol. Vol. 93B, No. 2, pp. 459-463, 1989 Printed in Great Britain

0305-0491/89 $3.00+ 0.00 © 1989 Pergamon Press plc

THE COMPOSITION OF THE DEFENSIVE SECRETIONS OF THA UMASTELLA NAMAQUENSIS A N D T. ELIZABETHAE WITH NOTES ON THE HIGHER CLASSIFICATION OF THE THAUMASTELLIDAE (INSECTA: HETEROPTERA) D. H. JACOBS,* P. J. APPSt and H. W . VILJOEN~" *Department of Genetics and tInstitute for Chromatography, University of Pretoria, Pretoria, 0002, South Africa (Tel: 012 4209111) (Received 3 October 1988) Abstract--l. The defensive secretion of two species of Thaumastella, a primitive group in the Pentatomoidea, were analysed by dynamic solvent effect sampling, gas-liquid chromatography and mass spectrometry. 2. Twenty-one components were recognized in the secretion of T. namaquensis and nineteen in that of T. elizabethae. 3. Sixteen components were identified and mass spectra of the five unknowns are given. The major components of both species are 2-decenal, tridecane, pentadecane and one of the unidentified components. 4. Five of the identified components have not previously been reported from the Heteroptera.

INTRODUCTION

The Thaumastellidae is a small family with only two described species, T. aradoides Horvath from Algeria and Iran and T. namaquensis Schaefer and Wilcox from N a m a q u a l a n d in South Africa. A third species has also been collected in N a m a q u a l a n d and will be described as T. elizabethae by Jacobs (in prep). The family is o f great interest because it appears to be very primitive in the Pentatomoidea (Stys, 1964; Schaefer and Wilcox, 1971). The higher classification of Thaumastella has a history of uncertainty; it was placed originally in the Lygaeidae (superfamily Lygaeoidea or Coreoidea sensu Stys and Kerzhner, 1975) but later removed to form the Thaumastellidae, very primitive in the Pentatomoidea, near the Cydnidae (refer to Schaefer and Wilcox (1971) for a summary of this confusion). This latter placement is probably correct although Dolling (1981) sinks the Thaumastellidae to a subfamily of the Cydnidae. Jacobs (unpublished) recently found that the Thaumastellidae are cytogenetically unique in the Pentatomoidea since m-chromosomes are present in both species from Namaqualand. While m-chromosomes are c o m m o n in the Lygaeoidea and Coreoidea they have not yet been reported from the Pentatomoidea except for a doubtful case in a Scotinophara sp. (Jande, 1960). Furthermore the primitive chromosome n u m b e r in the Pentatomoidea is considered to be 2n = 12 XY or 2n = 14 XY; more than 90% of the species thus far examined having one of these numbers. The chromosome n u m b e r of T. namaquensis is 18XY ( 1 7 X l X2Y in one population) and that of T. elizabethae is 20 XY. Both these chromosome numbers are very u n c o m m o n in the Pentatomoidea. F r o m comparative tables of the scent compositions of different species and higher taxa of the Heteroptera (e.g. Baggini et al., 1966; Calam and

Youdeowei, 1968; Prestwich, 1976) it is evident that there are significant differences between taxa which can possibly be used as an aid in classification. In order to elucidate the relationships of Thaumastella the scents of both species from N a m aqualand have been analyzed by means of gas chromatography-mass spectrometry and the results compared to the existing information in the literature.

459

MATERIAL AND METHODS

Specimens of T. elizabethae collected at CJifberg in Namaquaiand (31° 44' S, 18° 46'E) were maintained on a diet of water and seeds of their host plant Pharnaceum aurantium (DC) Druce. Specimens of T. namaquens/s collected near Springbok in Namaqualand (29° 42' S, 17° 42' E) were maintained on a diet of water and seeds of various plants from the vicinity where they were collected as their host plant could not be established. Volatiles from the defensive secretion were sampled by dynamic solvent effect (Apps et al., 1987) as follows. Individual insects were gently aspirated into small sampling chambers made by necking down one end of a 1 cm piece of 1.4 mm i.d., 2 mm o.d. borosilicate glass tube. Activecharcoal-filtered air was passed through the chamber and into a dynamic solvent effect concentrator at a flow of 20cm 3 rain -I (Fig. I). N-hexane was used as solvent. After I rain a stream of hot air was passed momentarily over the sampling chamber. This induced the insect to release its defensive secretion and quickly killed it by thermal shock. Sampling was continued for a further 5 min to ensure transport of the volatiles out of the sampling chamber into the concentrator. Gas chromatography-flame ionization detector (GC-FID) analyses of the defensive secretion volatiles were carried out on a Varian 3700 gas chromatograph fitted with a dynamic solvent effect inlet (Apps et al., 1987) with a 25 m x 0.3 m m x 0.4 #m methyl silicone capillary column. The carrier gas was hydrogen with a linear velocity of

D. H. JACOBSet al.

460

21%; 66 21%; 40 19%; 94 17%; 77 15%; 55 15%; 65 14%; 109 14%; 67 9%; 51 9%; 54 8%; 42 8%; 92 7%; 120 7%; 95 6%; 82 4%; 107 4%; 136 1%. Unknown 2:69 100%; 70 83%; 55 72%; 41 57%; 29 23%; 67 21%; 81 17%; 111 17%; 43 16%; 39 16%; 27 13%; 54 12%;40 12%; 57 11%; 110 11%;68 10%; 79 8%; 53 7%; 42 6%; 83 5%; 91 4%; 82 4%; 80 4%; 56 4%; 109 4%; 77 3%; 123 2%; 136 1%.

lmm I---J

Unknown 3:43 100%; 54 32%; 41 22%; 55 21%; 67 20%; 68 15%; 40 12%; 29 12%; 81 11%; 82 10%; 39 10%; 57 9%; 27 8%; 96 7%; 95 6%; 83 6%; 71 6%; 69 6%; 110 6%; 42 5%; 138 3%; 109 3%; 156 2%. Unknown 4:43 100%; 69 51%; 54 45%; 55 43%; 41 31%; 79 30%; 110 23%; 80 19%; 81 18%; 67 17%; 29 15%; 68 12%; 39 10%; 94 8%; 93 8%; 27 8%; 82 7%; 70 7%; 66 7%; 78 6%; 57 6%; 40 6%; 95 5%; 91 5%; 42 5%; 164 5%; 113 5%; 107 5%; 77 4%; 71 4%; 53 4%; 135 3%; 122 3%; 121 3%; 123 2%.

Fig. 1. Micro-chamber used for sampling volatiles from thaumastellid bugs. 1: outlet of activated charcoal filter; 2: polytetrafluoroethylene sleeve connector; 3: 2ram o.d., 1.4 mm i.d. borosilicate glass tube; 4: bug; 5: top end of dynamic solvent effect concentrator. 55 cm/s. The starting temperature of both inlet and column was 40°C, the inlet was heated ballistically to 220°C after 2.2 rain, and the column temperature was programmed at 5°C/rain after 7 rain. The detector sensitivity was 4 x 10-H A/mV full scale deflection. Gas chromatography-mass spectrometry (GC-MS) analyses were carried out under equivalent conditions on a modified Varian 1400, using helium as carrier gas, with an open split interface to a VG Micromass 16F spectrometer operating in the electron impact mode. The source temperature was 220°C and the electron energy was 70 eV. Where possible compounds were identified by comparison of their mass spectra with those in the libraries or in the literature. Where necessary identities were confirmed by retention indices. Seven (two ~ and five ~ ) T. namaquens/s and five (one and four ~<~) T. elizabethae were examined individually by GC-FID. Four individual T. namaquens/s and four, pooled T. elizabethae were examined by GC-MS. Quantitativecomparisons were based on the GC-FID analyses. RESULTS Individuals of both species proved very reluctant to emit their defensive secretion except under extreme stress. The secretion was sometimes emitted as a fine spray in sufficient quantities to wet the walls of the sampling chamber; it was a colourless liquid which evaporated within 10-20 see. The secretion's odour closely resembled that of green coriander. The defensive secretion of both species contained a complex mixture of volatiles (Fig. 2). Identities were assigned to sixteen compounds, another five remain unidentified. The mass spectra of the unidentified compounds are: Unknown 1:41 100%; 70 65%; 39 58%; 69 39%; 81 37%; 68 35%; 27 29%; 29 27%; 91 22%; 53 22%; 79

Unknown 5:41 100%; 55 60%; 70 33%; 39 30%; 81 30%; 67 29%; 83 28%; 27 27%; 29 23%; 123 22%; 69 20%; 68 17%; 95 13%; 43 13%; 53 12%; 82 11%; 84 11%; 79 10%; 108 10%; 40 10%; 1099%; 947%; 152 1%. All 21 of these compounds were found in T. namaquensis, nineteen of them occurred in T. elizabethae (Table 1). In both species there was substantial quantitative variation among individuals (Tables 1 and 2), which extended to variable presence or absence of some components (Table 1). Of the 21 components of the secretion of T. namaquensis, four (2-decenal, tridecane, pentadecane and unknown 1) constitute about 94% (by peak areas) of the secretion while only two other components (heptadecane and unknown 2) are present in quantities of more than 1% (Tables 1 and 2). The same four major components constitute more than 97% of the secretion of T. elizabethae while the other 15 are present in quantities of less than 1%. DISCUSSION To our knowledge only eleven of the identified components of the secretion of Thaumastella have previously been reported in the Heteroptera. Tridecene, pentadecene, heptadecadiene, heptadecene and methoxyphenylethanone are reported here for the firsttime. The reason why they have not been found previously m a y be a consequence of the high sensitivity of the analytical technique compared to conventional chromatographic methods. For none of the five was the mean peak area equivalent to more than approximately 1.5 ng, although in some individuals quantities were larger; up to approximately 5 ng for the most abundant of the seven, pentadecene. It is also possible that some of these components originated from glands, other than the metathoracic scent glands. In comparing Thaumastella with other taxa of the Pentatomorpha we shall limit our discussion to the eleven identified components that have been reported from the Heteroptera (dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, 2-octenal, 2-nonenal, 2-decenal, hexyl acetate and

Defensive secretions of Thaumastella

7

A

1

461

14 12

ti

6

21

2

8 18

r

B

.2 Fig. 2. Chromatograms of volatiles from defensive secretions of (A) Thaumastella namaquensis and (B) T. elizabethae. Secretion was sampled from single insects by the dynamic solvent effect and separated on a 20 m x 0.3 mm x 4/am methylsilicone column with a temperature programme of 5°C/rain. Detection was by FID at a sensitivity of 4 x 10-" A/mV. Peak numbers correspond to identities in Table 1. (E, E)-2,4-hexadienyl acetate). We follow the classification of the Heteroptera as presented by Schuh (1986). There is little agreement between Thaumastella and the Coreoidea as all the families belonging to this superfamily lack the hydrocarbons. The major component in Thaumastella, 2-decenal has only once been reported from the Coreoidea in extracts of whole species (Baggini et al., 1966). The composition of the secretion from adults of only two species belonging to the Pyrrhocoroidea, both of the genus Dysdercus, are reported in the literature (Calam and Youdowei, 1968; Everton et al., 1979; Daroogheh and Olagbemiro, 1982). Although tridecane and pentadecane have been found (the latter in a nymph) 2-decenal has not yet been reported from them. 2'Hexenal and 2-octenal seem to be the major components of the metathoracic scent

gland secretion in both species. In the secretion of Thaumastella 2-hexenal is absent and 2-octenal is only a minor component. The compositions of the secretion of only four species of the Lygaeoidea, all from the Lygaeidae, have been reported. They are Oxycarenus hyalinipennis (Olagbemiro and Staddon, 1983; Knight et al., 1984; Staddon and Olagbemiro, 1984), Oncopeltusfasciatus (Games and Staddon, 1973; Everton and Staddon, 1979; Staddon and Daroogheh, 1981), Spilostethus rivularis (Staddon et al., 1985) and Geocoris varius (Yamashita and Kanehisa, 1979). From this scant data the Lygaeidae seem to be a diverse group as the four species differ markedly in the composition of their scents. Only four (hexadecane, heptadecane, 2-nonenal and hexyl acetate) of the eleven components under discussion have not yet been found in them. 2-Decenal (the major component

462

D.H. JACOBSet al.

Table 1. Compounds from the defensive secretion of Thaumoatella nanmquensis and T. elizabethae and their occurrenoe in each sampled individual. -Absent; 0 less than 0.5 ng present; + more than 0.5 ng present. The pereentag¢ of each component in relation to the total secretion of the individual3, i f 0 . 1 % o r more, is shown. Compound

Sp~: n1~

n2£

n12£

7".nwrlquenl/8 flSo~ fl1OdP

0

+ 0.3

0 0.1

+ 0.4

1. Hexyl Ilcetl,to

T, n3£

n7£

+ 0.4

+ 0.2

od~

eg£

+

+ 0.2

+ 0,2

0

0

eo~

ee~

0

2. 2-(x,tei~ll

0 0.1

+ 0.4

3. (E,E)-2,4-htx~llenyl ~oetste -

e~d°

+ 4.4

0

+ 0.4 O 0.1

4. 2-noneNd

0

+ 0.4

0 0.1

+ 0.2

0

+ 0.2

+ 0.1

0

+ 0.1

0

0

5. dodec~e

0

+ 0.4

0 0.1

+ 0.7

0 0.1

+ 0.3

+ 0.3

O

+ 0.1

+ 0.2

0

0

6, unknown3

0

+ 0.2

0 0,1

0

+ 0.3

0

0

0

0

+ 2.0

0

0

7. 2-de,enid

+484

+80.1

+62.4

+49.3

+47.4

+41.7

+3@"2

+474

+46.3

+38.1

+12`3

+44.7

8. methoxypheny~othsnor~e

+ 0.1

+ 0.1

0 0.1

0

+ 0.g

+ 0.2

0

9. unknown 1

+ 6.4

+ 1.5

0 0.1

+ 1.9

+ 7.8

+ 8.9

+ S.7

+ 7.6

+ ~7

+ 8.4

+32.2

10. tf~i~¢erle

0

+ 0.1

0

+ 0.1

0

0

0

0

0

0

11,ffide~arm

+19.8

+28.0

+11.3

+38.9

+17,2

+14.1

+13.4

+ 3.3

+16.5

+10.9

+ 2,1

+114

12. unknown 3

+ 0.3

0

0 0.1

+ 0.g

+ 1.3

+ 2,1

+ 0.8

0

0

+ 0.8

0

0

13. t~'~ecane

+ 0.5

+ 0.6

0 0.1

+ 0.4

+ 0.3

+ 04

+ 1.0

+ 0.7

+ 0.g

+ 1.2

+ 0.6

+ 0.7

14. unknown2

+ 2.1

+ 0.6

0 0.3

+ 0.6

+ 1.1

+ 1.7

+ 1.1

+ 0.5

+ 0.4

+ 0.8

0

0

15. plmtadqmene

0

+ 0.1

0 0.1

0

0 0.1

+ 0,2

+ 0.4

0

0

0

O

16. pe~tade~me

+ 18.3

+ 7.5

+24.7

+ 3.1

+1~4

+00.6

+00.9

+31.6

+30.4

+40.4

+314

17. unknown 4

+ 1.1

0

0 0.1

0

0

0

0

+ 3.0

0

+ 0.2

0

18. hex~ocane

0

0

0 0.1

19, heptadeolu;llene

0

0

20. heptsdecene

0

0

21.heptadocane

+ 1.8

+ 0.1

0 0,3

0

0

+ 0.2

+ 0.3

0

0

0

0

0

+

+ 0.2

0

0 0.1

0

0 0,4

0

0

+ 0.1

+ 0.2

+ 0,2

+ 2.4

+ 2.4

+ 3.3

0

0

0

0

~

1. Hexyl Ilcetato

T, namaquene/,I

T

28±78

0.00~ ± 0.0104

100±223

0.01m ~ 0.0~0)

2, 2-octlml

6437 ± (1~2

0"2400 ± 0,16'/8

0008 z 31~I

0.1t~0 ± 0.1643)

3. ( E , E ) - 2 , 4 - h e x ~ k m . ~ m

4 ~ a ± 12070

0.3~0 :i: 1 . 1 ~

120 ± 214

0.01'r6 = O.OMO)

4. 2-rmnenol

4417 ± 4886

0 . 1 ~ z 0.1270

1177 ± 21(16

ao3,w ± 0.0,106)

3. dode~me

3310 ± 10719

0.2840 ± 0.2000

1851 ± 2324

o.om4 2 o D ; , q )

6. unknow~ 3

1283 ± 1804

0.~67:1: 0.1lEa

7323 ± 16438

7.

3-dermal

8. methoxyp~c/le~81,Xlfle 9. unknown 1 10. Mdecqme

2 @ 7 ~ z 833~68

( 43.¢¢21 ± 3.84Sl

3004 ± 3100

( 0.31/7 ± 0.42"/0

88176 ± 71797

( 4,~041 ± 3.41(10

1100 ±

o.
( 37.1943 ± 14.4743) 0 1ffoo79 Z 110710

( 11"2946 ~: 11~34

( 0,03m±0.04~

g0¢74

( 21.0342 ± 0.4N5

243002 tt 317817 3137 ± 0678

0.170~ ± 0,38~ 0~127 = 0.2101

12. unkflown 3

18~3 ± 20~4

( 0.neae ± 0.82~

13. t e t m d e ( l ~

13124 ¢ 1¢ ~

( o.w.n~ ± o"200e

13M~ ± 15477

14. unknowTi2

10~4 :i: 134112

( 1.0e~/' ± 0.¢,~00

819D4 ± 8431

1~ pentadecene

2138 ± 3 ~ 4

( 0,1~0 ± 0 , 1 ~

70¢45

13. pentade~ne

94770¢

64M2

0,34.12=: 00041 ± 0 . 0 ~ i

310751 ± 2Tr4~2

( 18.1003 ¢ 9.0012

672186 ± 4~2100

17. unknow~ 4

1388 ± 3133

( 0.18~ = 0.4147

9 3 4 4 ± 13m6

18. hexa~uo~e

1797 ± a~67

( 0~32",' ± 0.1075

100 ± 84

0.0~0 ± 0.0087

1313 ¢ 1747

0.f006 .¢ 0.111414

19. heptsdc~ldMne 00. heptsde~ene 21. hept~m~mme

TOtal

864 ± 1 1

( 0.0~0 ¢ 0.0e~

I12~± I ~ 0

( 00601 ± 0.0/110

26738 ± 31877.

( 1.8015 ± 1.2824

2043137 ± 1571743

+004

To our knowledge only six of the eleven components under discussion have been reported from the Pentatomoidea (2-octenal, dodecane, 2-deccnal, tridecanc, pentadecane, hexadecane). Those that have not been reported include three of the four which have also not been reported from the Lygaeidae (2-nonenal, hexyl acetate and hcptadecane) as well as tetradccane and (E,E)-2,4-hexadienyl acetate. 2-Decenal and tridecane have been rcporte~I from about 5 0 % of the species while pentadecane has been reported from three pentatomid and five cydnid species. Surprisingly, 2-hexenal which has been reported from more than 8 0 % of the species was not found in Thaumastella. The defensive secretion of at least nine species of Cydnidae belonging to the genera Macroscytus,

Table 2. Mean ± standarddeviationof peak areasforvolatilecomponents of defensivesecretion of ThaumasteIIa namaqueruis and T. eliz~bed~e. Mean pcrcentag,'+ standarddeviationam given in brackets. Compound

+ 2.0 0

0

of Thaumastella) has however only been reported from Geocoris varius and the nymphs of O. hyalinipennis (Staddon and Olagbemiro, 1984). It is interesting to note that (E,E)-2,4-hexadienyl acetate for which there is a sex dimorphism in S. rivularis (Staddon et al., 1985) was found in one (of two) males in T. namaquensis and in the only male and, in lesser quantities, in two (of four) females in T. elizabethae. Hexyl acetate, on the other hand, was only observed in the males of both Thaumastella species. The secretion of more than 45 species of the Pentatomoidea, the superfamily to which Thaumastella belongs, have been analysed. Most of them (about 30 species) belong to the Pentatomidae but at least nine species of the Cydnidae, the family closest to the Thaumastellidae, have been analysed.

0

( 80.'r317 ± 3 4 1 1 O.S~e3 ± 130~'

0 100 ¢ 71 lglgES4 ± i ~ r O r

0,0076 ± 0.00~)

Defensive secretions of Thaumastella

Scaptocoris, Adrisa, Aethus, Rhytidoporus, Pangaeus and Cyrtomenus have been analysed (Roth, 1961; Baggini et al., 1966; Hayashi et al., 1976; Smith, 1978; Olagbemiro et al., 1984; Scheffrahn et al., 1987). 2-Octenal and tridecane are major components in most species. Tridecane is also a major component of Thaumastella but 2-octenal makes up less than 0.3% of the secretion in both species. The other major components of the thaumastellids, 2-decenal and pentadecane, have been reported in three and five cydnid species respectively. The other two superfamilies of the Pentatomorpha (Aradoidea and Idiostoloidea) are not considered here as no data exist on their scent composition. There is however no reason to believe that they are closely related to the Thaumastellidae. It is evident that the composition of the secretion of Thaumastella shows differences from that of all superfamilies in the Pentatomorpha. Although Thaumastella belongs to the Pentatomoidea its secretion also includes elements from the Lygaeoidea. It actually shares more components with four species of the Lygaeidae than with more than 45 species belonging to the Pentatomoidea. This may serve as additional evidence that it branched off from the pentatomid line very early when it still possessed many lygaeid properties, as proposed by Stys (1964). Many of its minor components have not been reported from either of these superfamilies or from the Heteroptera as a whole. This may, however, be due to improvements in analytical techniques. It is concluded that the Thaumastellidae branched off very early from the pentatomid line and combine morphological, cytogenetical and chemical characters from both the Pentatomoidea and Lygaeoidea. It is most probably the sistergroup of the rest of the Cydnidae as Dolling (1981) proposed. It is however, unique and very different from the rest of the Cydnidae and to our mind it should be treated as a separate family near the Cydnidae in the Pentatomoidea. Acknowledgements--We would like to thank Prof V. Pretorius, Institute for Chromatography, for funding and facilities, Mrs J. van der Wateren and H. Neethling for typing the manuscript, and the University of Pretoria for financial assistance.

REFERENCES

Apps P. J., Pretorius V., Lawson K. H., Rohwer E. R., Centner M. R., Viljoen H. W. and Hulse G. (1987) Trace analysis of complex organic mixtures using capillary gas-liquid chromatography and the dynamic solvent effect. J. high resolut. Chromatogr. Chromatogr. Commun. 10, 122-127. Baggini A., Bernardi R., Casnati G., Pavan M. and Ricca A. (1966) Ricerche sulle secrezioni defensive di Insetti Emitteri Eterotteri. EOS (Madrid) 42, 7-26. Calam D. H. and Youdeowi A. (1968) Identification and functions of secretion from the posterior scent gland of fifth instar larva of the bug Dysdercus intermedius. J. Insect. Physiol. 14, 1147-1158. Daroogheh H. and Olagbemiro T. O. (1982) Linalooi from the cotton stainer Dysdercus superstitiosus (F.) (Heteroptera: Pyrrhocoridae). Experientia 38, 421-423.

463

Dolling W. R. (1981) A rationalized classification of the Burrower Bugs (Cydnidae). Syst. Ent. 6, 61-76. Everton I. J. and Staddun B. W. (1979) The accessory gland and metathora~c scent gland function in Oncopeltus fasciatus. J. Insect Physiol. 25, 133-141. Everton I. J., Knight D. W. and Staddon B. W. (1979) Linalool from the metathoracic scent gland of the cotton stainer Dysdercus intermedius Distant (Heteroptera: Pyrrhocoridae). Comp. Biochem. Physiol. 63B, 157-161. Games D. E. and Staddon B. W. (1973) Chemical expression of a sexual dimorphism in the tubular scent glands of the milkweed bug Oncopeltus fasciatus (Dallas) (Heteroptera: Lygaeidae). Experientia 29, 532-533. Hayashi N., Yamamura Y., Obama S,, Yokoch6 K., Komae H. and Kuwahara Y. (1976) Defensivesubstances from stink bugs of Cydnidae. Experientia 32, 418-419. Jande S. S. (1960) m-Chromosomes in a pentatomid bug, Scotinophara sp. Curr. Sci. I1, 436--437. Knight D. W., Rossiter M. and Staddon B. W. (1984) (Z,E)-~-famesene: Major component of secretion from metathoracic scent gland of cotton seed bug, Oxycarenus hyalinipennis (Costa) (Heteroptera; Lygaeidae). J. chem. Ecol. 10, 641~:~49. Olagbemiro T. O. and Staddon B. W. (1983) Isoprenoids from metathoracic scent glands of cotton seed bug, Oxycarenus hyalinipennis (Costa) (Heteroptera: Lygaeidae). J. chem. Ecol. 9, 1397-1413. Olagbemiro T. O., Khan M. N. and Mohammed A. (1984) ~-butyrolactone from the black stink bug: Aethus indicus Westwood (Hemiptera: Pentatomidae). Z. Naturforsch. 39(2, 313-314. Roth L. M. (1961) A study of the odoriferous glands of Scaptocoris divergens (Hemiptera: Cydnidae). Ann. ent. Soc. Am. 54, 900-911. Prestwich G. D. (1976) Composition of the scent of eight East African hemipterans. Nymph-adult chemical polymorphism in coreids. Ann. ent. Soc. Am. 69, 812-814. Schaefer C. W. and Wilcox D. B. (1971) A new species of Thaumastellidae (Hemiptera: Pentatomoidea) from southern Africa. J. Ent. Soc. sth. Afr. 34, 207-214. Scheffralm R. H., Hsu R-C., Su N-Y. and Toth J. P. (1987) Composition of adult exocrine gland secretions from three species of burrower bugs (Hemiptera: Cydnidae) in Florida. J. entomol. Sci. 22, 367-370. Schuh R. T. (1986) The influence of cladistics on Heteropreran classification. Ann. Rev. EntomoL 31, 67-93. Smith R. M. (1978) The defensive secretion of the bugs Lamprophara bifasciata, Andrisa numeensis and Tectocoris diophthalmus from Fiji. N. Z. J. Zool. 5, 821-822. Staddon B. W. and Daroogheh H. (1981) Allometry of C6 and Cs alk-2-enals and alka-2,4-dienals in the metathoracic scent gland of Oncopeltus fasciatus. Comp. Biochem, Physiol. 68B, 593-598. Staddon B. W. and Olagbemiro T. O. (1984) Composition and novel pattern of emission of defensivescent oils in the larva of the cotton seed bug Oxycarenus hyalinipennis (Costa) (Heteroptera: Lygaeidae). Experientia 40, 114-116. Staddon B. W., Gough A. J. E., Olagbemiro T. O. and Games D. E. (1985) Sex dimorphism for ester production in the metathoracic scent gland of the lygaeid bug Spilostethus rivularis (Germar) (Heteroptera). Comp. Biochem. Physiol. 80B, 235-239. Stys P. (1964) Thaumastellidae--a new family of pentatomid Heteroptera. Acta Soc. ent. Cech. 61, 238-253. Stys P. and Kerzhner I. (1975) The rank and nomenclature of higher taxa in recent Heteroptera. Acta ent. bohemoslov. 72, 65-79. Yamashita T. and Kanehisa K, (1979) Studies on the odour components of stink and squash bugs. Nogaku Kenhyu 58, 13-18.