Helicoverpa assulta

The next example is used to demonstrate how different pathways could produce the same pheromone component. Helicoverpa zea and Helicoverpa assulta are closely related species that use aldehydes as the major pheromone. Helicoverpa zea uses a blend of components with Z11-16 Aid as the major component, and minor components include 16 Ald, Z9-16 Aid, and Z7-16 Aid (Klun et al., 1980). H. assulta uses Z9-16 Ald as the major component and Z11-16 Aid as a minor component (Cork et al., 1992 Sugie et al., 1991). The biosynthesis of Zll-16 Aid occurs by Al 1 desaturation of 16 CoA to produce Z1 l-16 CoA, which is reduced to the aldehyde. This probably occurs in both species, but Z9-16 Ald could be produced by the action of a A9 desaturase using 16 CoA as a substrate or by the Al 1 desaturation of 18 CoA to produce Zll-18 CoA that is then chain shortened to Z9-16 CoA. To determine between these two pathways, deuterium-labeled precursors were applied topically to the glands in dimethyl sulfoxide and females injected with PBAN 1 h later the glands were extracted and analyzed for incorporation using GC/MS (Choi et al., 2002). Figure 3.4 shows the data and biosynthetic pathways. 

Figure 3.4 Biosynthetic pathways for producing the sex pheromone components of Helicoverpa zea and Helicoverpa assulta. The CoA derivatives indicated with an arrow are reduced to aldehydes. The unlabeled and labeled aldehyde amounts for each pheromone component are shown in the graphs on the right. The y-axis indicates ng/gland for each aldehyde indicated in the biosynthetic pathway. The graphs indicate unlabeled and labeled aldehyde amounts after application of D3-16 acid (left bars) and D3-18 acid (right bars). No label was found in Z7-16 Ald when D3-16 acid was applied to glands of H. zea. No label was found in either Z9-16 Ald or Z11-16 Ald when D3-18 acid was applied to glands of H. assulta.

Cork A., Boo K. S., Dunkelblum E., Hall D. R., Jee-Rajunga K., KehatM., Jie E. K., Park K. C., Tepgidagam P. and Xun L. (1992) Female sex pheromone of Oriental tobacco budworm, Helicoverpa assulta (Guenee) (Lepidoptera Noctuidae) identification and field testing. J. Chem. Ecol. 18, 403-418. 

Helicoverpa assulta T TMNFSPRLamideb Choi etal. (1998a)... 

Choi M. Y., Tanaka M., Kataoka H., Boo K. S. and Tatsuki S. (1998a) Isolation and identification of the cDNA encoding the pheromone biosynthesis activating neuropeptide and additional neuropeptides in the oriental tobacco budworm, Helicoverpa assulta (Lepidoptera Noctuidae). Insect Biochem. Mol. Biol. 28, 759-766. 

Berg B. G., Galizia C. G., Brandt R. and Mustaparta H. (2002) Digital atlases of the antennal lobe in two species of tobacco budworm moths, the Oriental Helicoverpa assulta (male) and the American Heliothis virescens (male and female). J. Comp. 

PBAN has been reported to control sex pheromone biosynthesis in many other moth species, and the peptide itself has been found in many Lepidopteran species as well as in other insect orders. Since 1989 the primary sequence of PBAN has been determined in numerous other moth species (Bombyx rnori [89], Lymantria dispar [90], Helicoverpa assulta [91], Agrotis ipsilon [92], Mamestra brassicae [93] and Spodoptera littoralis [94] either by sequencing of the purified neuropeptide or from cloned cDNA or gene sequence [95-97]. 

Table 10.1 Primary and secondary odorants of five receptor neuron types identified by GC-SCR and GC-MS in four species of moth Heliothis virescens, Helicoverpa armigera, Helicoverpa assulta, and Mamestra brassica) (Ulland et al...

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