Journal of Chemical Ecology, Vol. 15, No. 9, 1989


W.R. LUSBY, l J.E. O L I V E R , 1 J.W. N E A L , JR., 2 and R.R. H E A T H 3 llnsect and Nematode Hormone Laboratory 2Florist and Nursery Crops Laboratory U.S. Department of Agriculture, Agricultural Research Service Beltsville Agricultural Research Center Beltsville, Maryland 20705 3Insect Chemistry Research Laboratory U.S. Department of Agriculture, Agricultural Research Service Gainesville, Florida 32604

(Received October 11, 1988; accepted December 21, 1988) Abstract--The three major components of setal exudate from nymphs of the Hawthorn lace bug, Corythucha cydoniae, were identified as 3,6-dihydroxy2-[ 1-oxo-6(E),8(E)-tetradecadienyl]cyclohex-2-en- 1-one; 3,6-dihydroxy-2[ 1-oxo-dodecanyl]-cyclohex-2-en-1-one; 3,6-dihydroxy-2-[ 1-oxo-8-dodecenyl]cyclohex-2-en-l-one. An additional 10 minor components were partially characterized. Key Words--Hawthorn lace bug, Corythucha cydoniae, Hemiptera, Tingidae, 3,6-dihydroxy-2-[1-oxo-6(E),8(E)-tetradecadienyl]cyclohex-2-en-1-one, 3,6-dihydroxy-2-[ 1-oxo-dodecanyl]-cyclohex-2-en-1-one, 3,6-dihydroxy-2[ 1-oxo-8-dodecenyl]cyclohex-2-en-1-one, 3,6-dihydroxy-2-acyl-cyclohex-2en-l-ones, setal exudate.

INTRODUCTION The nymphs of many species o f lace bugs destructively feed in contiguous aggregations on the abaxial leaf surface o f many trees and ornamental shrubs. In several genera of lace bugs, the nymph has numerous external secretory hairlike structures (setae) over the surface o f the body and antenna that support viscous microdroplets (Livingstone, 1978). W e have noted the unusually low number of reports o f parasites and predators that attack lace bug nymphs, an 2369



obvious food resource (Oliver et al., 1985), and have been examining the chemical composition of the exocrine secretions to determine their function in a suspected defense system. Species were selected from two genera with presocial behavior; one of asiatic origin and one native to North America. To date, we have repotted (Oliver et al., 1985) the occurrence of 1-(2,6-dihydroxyphenyl)1,3 diketones, along with the corresponding 2-alkyl-5-hydroxychromones and chromanones, as well as normal chain aldehydes and ketones in the setal exudate from the azalea bug (Stephanitis pyrioides). From the rhododendron lace bug (S. rhododendri) a more elaborate series of 1-(2,6-dihydroxyphenyl)-l,3diketones and related chromones, and chromones possessing an additional oxygen, have been identified (Oliver et al., 1987). From the sycamore lace bug (Corythucha ciliata), the novel compound 3,6-dihydroxy-2-[1-oxo-10(E)-tetradecenyl]cyclohex-2-en-l-one has been isolated and identified (Lusby et al., 1987). In this continuing examination of the major components of lace bug setal exudates, we now report the isolation and identification of three major components from the hawthorn lace bug (C. cydoniae) and the partial characterization of an additional 10 minor components. METHODS AND MATERIALS Insects were maintained in a greenhouse on either pyracantha Pyracantha coccinea var. Lelandei or Washington Hawthorn Crataegus phaenopyrum (12 m tall) grown in 35.2-liter baskets. As the insects grew to maturity, their cast molt skins, which accumulated on the leaves, were collected by aspiration into Pasteur pipets, transferred to a fritted-disk funnel, and rinsed with methanol.

Isolation of Components By means of methanol rinses (4 x 50 ml), microdroplets of setal exudate were washed from 7.2 g of cast skins and nymphs. After removing methanol under vacuum, the residue was extracted with several portions of warm hexane (total of 35 ml), which were combined and filtered. Removal of the hexane yielded 110 mg of dark brown residue. Flash chromatography of the residue was performed on a 20 % silver nitrate-loaded silica gel column (8 • 2.5 cm) using hexane saturated with formic acid (100 ml) and 10%, then 25%, ethyl acetate in hexane saturated with formic acid (250 and 400 ml, respectively); 25-ml fractions were collected. Fractions 7 and 8 provided 42 mg of a dark brown residue that contained the compounds of interest as determined by gas chromatography (GC) and gas chromatographic-mass spectrometry (GC-MS) analyses. HPLC separation (20% silver nitrate on 20-/zm silica gel) of the above



residue yielded six fractions. Fractions 4 and 5 were combined and separated further by flash chromatography on 25 g of 20 % silver nitrate on Unisil using 100, 250, and 500 ml, respectively, of 2.5%, 5.0%, and 7.5% ethyl acetate in (1 : 1) hexane-hexane saturated with formic acid. After collecting two initial 50-ml fractions, a series of 5.5-ml fractions was collected and their content monitored by GC. Fractions 70 and 71 contained the major component and were combined and analyzed by GC-MS, [1H]NMR, FT-IR, and UV. An aliquot was subjected to ozonolysis. A portion of the ozonolysis products was analyzed directly by GC-MS, while the remaining portion was reacted with O-benzylhydroxylamine and the resultant O-benzyloximes analyzed by GC-MS.

Instrumentation Mass spectra were obtained from a Finnigan model 4500 quadrupole instrument fitted with an on-column injector (J & W Scientific) and a 30-m x 0.32-mm-ID fused silica column with a 0.25-#m DB-1 film (J & W Scientific) with the temperature held at 170~ for 2 min and then programmed to 260~ at 2~ Ammonia and deuteroammonia chemical ionization (CI) spectra were obtained at an indicated source pressure of 0.6 torr and a source temperature of 80~ A source temperature of 150~ and an ionizing voltage of 70 eV were used to produce electron ionization (EI) spectra. High-resolution mass spectral analyses were performed by the Midwest Center for Mass Spectrometry (Lincoln, Nebraska). Gas-liquid chromatographic trapping was performed on a Varian model 3700 equipped with a thermal conductivity detector and a 15m x 0.58-mm-ID Megabore column with a 1.5-/zm film of DB-1 (J & W Scientific) and operated at 210~ HPLC separations were achieved using a Spectra Physics model SP 8700 fitted with a 1-cm x 22-cm 20% AgNO3 on 20-/xm silica gel column which was eluted with 95 : 3 : 2 (hexane saturated with formic acid-tetrahydrofuran-9:1 hexane-isopropanol) at 4 ml/min and observing at either 220 or 270 nm. [~H]NMR spectra were obtained from a Nicolet NT-300 (300 MHz) Fourier transform spectrometer using either CDC13 and C6D 6 as solvents and TMS as an internal standard. 1H chemical shifts are reported in 6 from TMS and coupling constants are in Hz. UV spectra, 190-400 nm, were obtained with a Perkin-Elmer model 559 using 95 % EtOH as solvent. Infrared spectra were obtained from a Nicolet model 205XC GC-FTIR instrument and processed with a Nicos V3.6 operating system.

Ozonolysis and Preparation of O-Benzyloximes Into a 1-ml conical vial was placed 10 #g (30 nmol in 10 #1 CHIC12) of compound 6. After cooling to - 7 0 ~ (Dry Ice-CH2C12 bath), 600 nmol 03 (24/~1 CH2C12 at - 7 0 ~ saturated with 03) was added and the vial allowed to stand at - 7 0 ~ for 0.5 hr. While still at - 7 0 ~ 41 /zg (600 nmol) dimethyl



sulfide (41 /xl 0.1% in CH2C12) was added, and the vial allowed to come to room temperature. An aliquot of the ozonolysis reaction mixture was analyzed by EI and CI GC-MS. To one half of the ozonolysis reaction mixture (equivalent to 5 #g, 15 nmol starting material) was added 19 txg (150 nmol) O-benzylhydroxylamine (25 txl aq. solution at pH 4.5). After standing, with occasional shaking, at room temperature for 1 hr, 10/zl 2 M HC1 was added and the vial shaken. The CHzCI2 layer was analyzed by EI and CI GC-MS. Compound 1 was examined in a similar manner.

Hydrogenation An aliquot of a fraction from flash chromatography was dissolved in 0.2 ml N,N-dimethylformamide (DMF) saturated with NiC12 9 6H20. While stirring vigorously at ambient temperature, 0.05 ml of 0.5 M NaBH4 in DMF was added and approximately 10 sec later a black precipitate formed. A second 0.05-ml portion of the NaBH4 was added, and after 1 rain the reaction was quenched with aqueous NH4C1, and filtered through a pad of Celite. The filtrate was passed through a C18 extraction cartridge that was subsequently rinsed with water. The products were eluted from the cartridge with tetrahydrofuran, concentrated, and analyzed by GC-MS.

Physical Data Compound 1 (3, 6-Dihydroxy-2-[1-oxo-8-dodecenyl]cyclohex-2-en-l-one). EI-MS re~z: 308(100)M +, 290(2)[M-H~O] +, 264(7)[M-C2H40] +, 219(13), 208(33), 183(86), 170(40), 168(52), 155(30), 142(24), 137(30), 126(44), 69(35), 55(72); CI(NH3)-MS m/z: 326(100)[M + NH4] +, 309(19)[M + HI+; CI(ND3)-MS m/z: 332(100)[M + ND4] +, 312(21)[M + D] +.

Ozonolysis Product from Compound 1 [3, 6-Dihydroxy-2-(1,8-dioxooctyl)2-cyclohexen-l-one]. EI-MS m/z: 268(3)M +, 240(63), 196(32), 183(100), 170(23), 153(54), 139(59), 95(68), 69(72), 55(83); CI(NH3)-MS m/z: 303(4)[M + (NH3)2H] +, 286(100)[M + NH4] +, 269(3)[M + HI +.

O-Benzyloximes from Ozonolysis of Compound 1: O-Benzyloxime 1 (nButyraldehyde-O-Benzyloxime). EI-MS re~z: 177(2)M +, 160(5), 147(9), 105(21), 91(100), 77(10), 65(10); CI(NH3)-MS: 212(79)[M + (NH3)zH] +, 195(100)[M + NH4] +, 178(12)[M + H] +

O-Benzyloxime 2 [3,6-dihydroxy-2-(1,8-dioxooctyl)-2-cyclohexene-l-oneO-benzyloxime]. EI-MS re~z: 225(3), 183(4), 108(10), 91(100), 79(12), 77(11), 55(10); CI(NH3)-MS: 391(100)[M + NH4] +, 374(9)[M + HI +.

Compound 2 (3, 6-Dihydroxy-2-[1-oxo-dodecanyl]cyclohex-2-en-l-one). EI-MS re~z: 310(42)M +, 292(3)[M - H20] +, 266(22)[M - C2H40+], 183(100), 170(27), 168(20), 153(21), 140(28), 126(16), 55(23); CI(NH3)-MS:



328(100)[M + NH4]+, 311(52)[M + H]+; CI(ND3)-MS: 334(100)[M + ND4] +, 314(54)[M + D] +. Compound 6 (3,6-Dihydroxy-2-[1-oxo-6(E),8(E)-tetradecadienyl]cyclohex-2-en-I-one). UV (nm, 95 % EtOH); Xmax229(e ca. 45,000), 270(e ca. 15,000). IR (cm-1, gas phase); 3017(w), 2968(m), 2934(s), 2885(m), 1679(s), 1562(s), 1481(s), 1421(m), 1392(m), 1919(m), 984(m); EI-MS re~z: 334(5)M § 316(100)[M - H20] § 290(31)[M - C2H40] § 245(26), 219(29), 205(98), 183(34), 170(69), 155(36), 142(29), 137(32), 126(55), 79(67), 67(75), 55(53); HRMS m/z: 334.2144, M § (C2oH3o04, Calc. 334.2144); 316.2035, [M H 2 0 ] + (C2oH2803, Calc. 316.2038); 290.i885, [M - C 2 H 4 0 ] + (C18H2603, Calc. 290.1882); CI(NH3)-MS m/z: 352(100)[M + NH4] +, 335(32)[M + H] +; CI(ND3)-MS m / z : 358(100)[M + ND4]+, 338(28)[M + D]+; [1H]NMR(CDC13); 0.84 (3H, t, J = 7, CH3), 1.26-1.32 (6H, m, alkane CH2), 1.44 (2H, m, CH2), 1.56-1.69 (2H, m), 1.70-1.85 (H, m), 2.02 (4H, m), 2.33 (H, m), 2.33 (OH), 2.78 (2H, m), 3.01 (2H, m), 4.08 (H, dd, J = 13 and 4Hz), 5.57 (2H, m), 5.98 (2H, m), 18.20 (OH). Ozonolysis Product from Compound 6 [3,6-Dihydroxy-2- (1,6-dioxohexyl)2-cyclohexen-l-one]. EI-MS m/z: 212(39), 194(31), 183(62), 168(57), 153(55), 140(56), 126(28), 85(55), 67(100), 55(95); CI(Ntt3)-MS m/z: 258(100)[M + NH4] +, 241(4)[M + H] +. O-Benzyloximes from Ozonolysis of Compound 6: O-Benzyloxime 3 (Hexanal-O-benzyloxime). EI-MS re~z: 205(1.2)M +, 188(0.7), 175(0.8), 149(8), 91(100), 77(5), 65(5); CI(NH3)-MS: 240(54)[M + (NH3)zH]+, 223(100)[M + NH4] +, 206(19)[M + H] + O-Benzyloxime 4 (Glyoxal-O-benzyloxime). El-MS m/z 268(3)M +, 181 (4), 161(2), 145(1), 105(2), 91(100), 77(8), 65(7); CI(NH3)-MS: 303(2)[M + (NH3)2H] +, 286(100)[M + NH4] +. O-Benzyloxime 5 [3,6-dihydroxy-2-(1,6-dioxohexyl)-2-cyclohexen-2-oneO-benzyloxime]. EI-MS re~z: 345(0.5)M +, 221(1), 193(1), 183(2), 137(2), 108(6), 91(100), 77(8), 69(7), 55(7); CI(NH3)-MS: 363(100)[M + NH4] +, 346(3)[M + HI +.


Initially, samples of setal exudate material were obtained by wicking the microdroplets onto small triangular pieces of absorbent filter paper. Samples obtained in this manner will be referred to as "wicked" samples. Examination by GC-MS of a dichloromethane extract of the filter paper revealed a remarkably clean sample consisting of a band of peaks (Figure 1) containing 13 components of retention times from 14 to 33 min and ranging in molecular weight




















FIO. 1. Reconstructed total ion chromatogram of setal exudate compounds from C.


from 308 to 378 (Table 1). By comparing the value for the ammonium adduct ion using first ammonia then deuteroammonia CI-MS, it was determined that all of the components possessed two exchangeable hydrogens except compound 7, which had one. Electron ionization mass spectra, while being distinct from one another, were sufficiently similar to suggest the components of the mixture were structurally related. Examination of cast skins revealed retention of setal microdroplets; therefore, in order to secure sufficient material for additional spectroscopic characterization, lace bugs were mass reared and cast skins collected. Extracts of cast skins yielded material that contained fewer spurious compounds than material obtained from extraction of intact nymphs, but the cast skin extract was not as clean as wicked samples. Gas chromatographic and mass spectral analyses of exudate wicked from insects reared on either hawthorn or pyracantha were indistinguishable, and therefore cast skins from both sources were pooled. The isolation procedure yielded a sufficient amount of compound 6 to permit both [1H]NMR analysis and ozonolysis followed by preparation of O-benzyloxime derivatives. However, only enough compound 1 was obtained to permit ozonolysis and subsequent formation of O-benzyloximes. No other components were individually isolated.




Compound number

Percent ~

Ret time a

Molecular weight



Ring moiety e

1 2 3 4 5 6 7 8 9 10 1t 12 13

14.4 6.0 4.6 3.0 3.2 28.1 3.6 9.8 11.2 2.3 5.l 5.2 3.5

14.2 14.6 19.6 20.5 20.8 23.7 23.9 25.8 26.4 26.6 27.6 29.9 32.9

308 310 334 336 336 334 346 350 362 362 364 362 378

2 2 2 2 2 2 1 2 2 2 2 2 2

12/1 12/0 14/2 14/l 14/1 14/2 16/2


16/2 16/2 16/1 16/2

I ] I I

~'Percentage composition based on the 13 most abundant components as measured by reconstructed ion chromatogram of electron ionization mass spectral analysis. b30-m DB-1 fused silica column (see Methods and Materials for details). c Number of exchangeable hydrogens. dLength of side chain/number of double bonds in side chain. eSee Figure 2 for structure of ring moiety.







FIG. 2. Structures o f setal e x u d a t e c o m p o u n d s f r o m T a b l e 1).

C. cydoniae (R defined in



Compound 6 Examination of compound 6, the most abundant component, by [~H]NMR yielded a spectrum nearly identical to that reported for 3,6-dihydroxy-2-[1-oxo10(E)-tetradecenyl]-cyclohex-2-en-l-one that had been isolated from Corythuca cilata (Lusby et al., 1987). The near identity of the [~H]NMR spectra together with both HRMS and CI-MS established that compound 6 contains the ring moiety shown in Figure 1 and possessed a side chain of 14 carbons containing two olefinic bonds. In order to locate the position of the olefinic bonds within the side chain, a portion of compound 6 was subjected to ozonolysis. Ozonolysis of Compound 6. Mass spectral analyses of the ozonolysis products from component 6 indicated the formation of 3,6-dihydroxy-2-(1,6-dioxohexyl)-2-cyclohexen-l-one, thereby locating one of the olefinic bonds of 6 between carbons 6' and 7' of the side chain. Further examination of the mass spectral data of the ozonolysis reaction did not provide the identity of other products, which would locate the position of the second olefinic bond. Reaction of the ozonolysis products with O-benzylhydroxylamine yielded three oximes, one of which corresponded to the above-identified aldehyde. A second oxime compound was derived from hexanal, indicating cleavage of a six-carbon fragment from the end of the side chain. The third oxime, a dioxime, yielded a multiplicity of gas chromatographic peaks due to combination of syn and anti configurations. Their mass spectra and a gas chromatographic comparison to an authentic sample established that they were derived from glyoxal. These data indicate the presence of a conjugated diene system with olefinic bonds located at carbons 6' and 8' of the side chain. Among the [1H]NMR signals were two in the olefinic region: a multiplet at 5.98 6 and a multiplet at 5.57 6. Irradiation at 5.57 5 collapsed the signal at 5.98 to a singlet, and irradiation at 5.98 6 yielded a triplet at 5.57 5. These data confirm the presence of a conjugated diene system. In order to establish isomeric configuration of the side-chain olefinic bonds, GC-FTIR analyses were performed on compound 6 and, as models, the four isomers of hexadeca-5,7-dienyl acetate. A band at 984 cm- 1, corresponding to C - - H out-of-plane stretching, was present in both compound 6 and the E,E isomer of hexadeca-5,7-dienyl acetate but was absent in the remaining three isomers. A like band has been previously reported in the spectrum of the E,E isomer during the comparison of the four isomers of hexadeca-10,12-dien-l-ol (Butenandt et al., 1962). The UV spectrum exhibited maxima at 229 nm (e ca. 45,000) and 270 nm (e ca. 15,000), with slight inflections at 216 and 235 nm (determined by inspection of the first derivative), and a shoulder at 226 nm. By comparison to a similar compound (Lusby et al., 1987) possessing a single olefinic bond in the side chain, it is seen that the conjugated diolefinic system in compound 6 produces both a greater extinction coefficient at the 229 nm maximum and a shift



of that maximum to slightly shorter wavelength. The above data establish compound 6 as 3,6-dihydroxy-2-[1-oxo-6(E),8(E)-tetradecadienyl]cyclohex-2-en1-one. The configuration of the chiral center at C-6 was not determined.

Compound 2 Compound 2, which has a molecular weight of 310 and two exchangeable hydrogens, was identical in both GC retention time and mass spectrum to 3,6dihydroxy-2-(1-oxododecanyl)-cyclohex-2-en-l-one, whose structure was recently confirmed by synthesis (Oliver and Lusby, 1988).

Compound 1 Compound 1 possesses a molecular weight of 308, thereby indicating a side-chain length of 12 carbons with a single olefinic bond. Hydrogenation of compound 1 yielded compound 2, thereby establishing the structure of the ring moiety. In order to determine the location of the olefinic bond in the side chain, compound 1 was subjected to ozonolysis and, under the gas chromatographic conditions used, a single reaction product was observed. Ammonia C1 mass spectral analysis yielded a molecular weight of 238. EI analysis indicated the product to be 3,6-dihydroxy-2-(1,8-dioxooctyl)-2-cyclohexen-1-one. This indicated the presence of an olefinic bond between carbons 8' and 9' of compound 1. The ozonolysis products were converted to O-benzyloximes by reaction with O-benzylhydroxylamine. CI and E1 mass spectral analysis of the O-benzyloxime reaction mixture revealed the presence of the O-benzyloxime of n-butyraldehyde, thus demonstrating the presence of n-butyraldehyde in the original ozonolysis product, and thereby confirmed the location of the olefinic bond. Insufficient material was available to determine the geometry of the double bond.

Compounds 3-5, 7-12 A fraction containing all components of the wicked sample except compounds 8 and 13 was hydrogenated using NaBH4/NiC12/DMF. Catalytic hydrogenation with Pd or Pt catalysts provided results that were difficult to reproduce as well as to interpret. In contrast, the presumed in situ generation of both hydrogen and catalyst achieved by adding NaBH4 to DMF containing NiC12 afforded clean reduction of olefinic side chains without affecting the enolic C = C or other functional groups. Interestingly, this same medium had been used recently to selectively reduce an isoxazole N - - O bond in the presence of a side chain C = C (Oliver and Lusby, 1988). Slight modification of the reaction conditions (Methods and Materials) allowed, in this case, clean reduction of the side-chain double bonds while preserving the ring functionalities. Compounds 3, 4, 5, and 6, with molecular weights of 334, 336, 336, and 334 respectively, were hydrogenated to a single product with a molecular weight of 338 and



having a mass spectrum virtually identical to that of compound 2 except for the molecular ion and ions derived by simple losses from the molecular ion. In a like manner, compounds 9, 10, 11, and 12 yielded a single product with a molecular weight of 366 and a saturated side chain. These data indicate that compounds 1-6 and 9-12 all possess the same ring moiety but differ by length of the side chain (12, 14, or 16 carbons) and/or degree and position of unsaturation in the side chain. These results demonstrate the presence of exudate compounds in C. cydoniae that are very similar to those isolated from C. ciliata (Lusby et al., 1987) and quite distinct from those isolated from S. pyrioides (Oliver et al., 1985) and S. rhododendri (Oliver et al., 1987). Compounds from the two genera are distinct in that those from Corythucha are nonaromatic vs. the aromatics from Stephanitis; however, the gross structures and oxygenation patterns suggest related biosynthetic pathways. Acknowledgments--The authors are grateful for the skilled technical assistance provided by: Dawn Harrison, Janet Genovese, and Jennifer Wagner (Insect and Nematode Hormone Laboratory) and Robert Murphy (Insect Chemical Research Laboratory). The authors acknowledge the Midwest Center for Mass Spectrometry, University of Nebraska (NSF grant CHE 8211164) for high-reso~ lution mass measurements.

REFERENCES BUTENANDT, A., HECKER, E., HOPP, M., and KOCH, W. 1962. Die Synthese des Bombykols und der cis trans-isomeren Hexadecadien-(10,12)-ole-(1). Annalen 658:39-64. LIVNGSTONE, D. 1978. On the body outgrowths and the phenomenon of "sweating" in the nymphal instars of Tingidae (Hemiptera: Heteroptera). J. Nat. Hist. 12:377-394. LUSBY, W.R., OLIVER, J.E., NEAL, J.W., JR., and HEATH, R.R. 1987. Isolation and identification of the major component of setal exudate from Corythucha ciliata. J. Nat. Prod. 50:11261130. OLIVER, J.E,, and LUSBY, W.R. 1988. Synthesis of 2-acyl-3,6-dihydroxy-2-cyclohexen-l-ones. Tetrahedron 44:1591-1596. OLIVER, J.E., NEAL, J.W., JR., LUSBY, W.R., ALDRICH, J.R., and KOCHANSKY,J.P. 1985. Novel components from secretory hairs of azalea lace bug, Stephanitis pyrioides (Hemiptera: Tingidae). J. Chem. Ecol. 11:1223-1228. OLIVER, J.E,, NEAL, J.W., JR,, and LUSBY, W.R. 1987. Phenolic acetogenins secreted by rhododendron lace bug, Stephanitis rhododendri Howarth (Hemiptera: Tingidae). J. Chem. Ecol. 13:763-769. TALLAMY, D.W. 1982. Age specific maternal defense in Gargaphia solani (Hemiptera: Tingidae). Behav. Ecol. Sociobiol. 11:7-11. TALLAMY, D.W. 1984. Insect parental care. Bioscience 34:20-24. TALLAMY, I).W., and DENNO, R.F. 1981. Maternal role in Gargaphia solani (Hemiptera: Tingidae). Anim. Behav. 29:771-778. TALLAMY, D.W., and DINGLE, H. 1986. Genetic variation in the maternal defensive behavior of the lace bug (Gargaphia solani), pp. 135-143, in M.H. Heuttle (ed.). Evolutionary Genetics of Invertebrate Behavior: Progress and Prospects. Plenum Press, New York.

Acyclohexanediones from setal exudate of Hawthorn lace bug nymphCorythucha cydoniae (Hemiptera: Tingidae).

The three major components of setal exudate from nymphs of the Hawthorn lace bug,Corythucha cydoniae, were identified as 3,6-dihydroxy-2-[1-oxo-6(E),8...
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