Helicoverpa

Akhunov et al. (2008) purified chitin-specific PO with fungicidal activity from cotton and observed the increase of its activity in plants, penetrated by Verticillium dahliae. Golubenco et al. (2007) showed the presence of the chitin-binding PO isozyme in Hibiscus trionum, which activated dramatically after inoculation by V, dahliae. The plants of Nicotiana tabacum overexpressing the anionic PO (chitin-specific according to our data) were more resistant to Helicoverpa zea and Lasioderma serricorne as compared with the wild-type (Dowd et al., 2006). 

Fig. 5 Proposed signal transduction mechanisms that stimulate the pheromone biosynthetic pathway in Helicoverpa zea and Bombyx mori. It is proposed that PBAN binds to a G protein-coupled receptor present in the cell membrane that upon PBAN binding will induce a receptor-activated calcium channel to open causing an influx of extracellular calcium. This calcium binds to calmodulin and in the case of B. mori will directly stimulate a phosphatase that will dephosphorylate and activate a reductase in the biosynthetic pathway. In H. zea the calcium-calmodulin will activate adenylate cyclase to produce cAMP that will then act through kinases and/or phosphatases to stimulate acetyl-CoA carboxylase in the biosynthetic pathway...

Fig. 6 Sequence alignment of the deduced amino acid sequence from the identified cDNA encoding PBAN and related peptides from Helicoverpa zea and Bombyx mori. The putatively expressed peptides are shown in boxes. The conserved amino acids are underlined in the B. mori sequence. Putative proteolytic posttranslational processing sites are shown in bold with glycine contributing the C-terminal amide. Sequences of PBAN-like peptides are also shown in Table 1. GenBank accession numbers H. zea - PI 1159 and B. mori - BAA05971...

Barbour, J.D., Farrar Jr., R.R. and Kennedy, G.G. (1993). Interaction of Manduca sexta resistance in tomato with insect predators of Helicoverpa zea. Entomologia Experimentalis Et Appilcata 68 143-155. 

Com earworm moth, Helicoverpa zea, females emit a blend of hexade-canal and (Z)-7-, (Z)-9-, and (Z)-ll-hexadecenal (16) that is a highly... 

In moths, it was discovered in Helicoverpa zea that a peptide produced in the subesophageal ganglion portion of the brain complex regulates pheromone production in female moths (19). This factor has been purified and characterized in three species, Helicoverpa zea (20), Bombyx mori (21, 22), and Lymantria dispar (23). They are all a 33- or 34-amino acid peptide (named pheromone biosynthesis activating neuropeptide, PBAN) and have in common an amidated C-terminal 5-amino acid sequence (FXPRL-amide), which is the minimum peptide fragment required for pheromon-tropic activity. In the redbanded leafroller moth, it was shown that PBAN from the brain stimulates the release of a different peptide from the bursae copulatrix that is used to stimulate pheromone production in the pheromone gland found at the posterior tip of the abdomen (24). 

Interaction with cell membranes is also supported by recent experimental data from Barbeta et al In feeding trials using artificial diets and larvae from Helicoverpa armigera it was shown that kalata B1 has a... 

Zea mays Maysin (C-glycosyl flavone) Corn earworm, Helicoverpa zea 369... 

The development of natural resistance in corn (Zea mays) to the corn earworm (CEW) Helicoverpa zea) received many contributions. The CEW is a major insect pest of maize and other crops (cotton, soybeans, etc.) the eggs are laid on the silks, and the larvae access the ear by feeding through the silk channel. 

Snook, M.E. et al.. New flavones from corn Zea mays L.) silk including a novel biflavone that contribute resistance to the corn earworm Helicoverpa Zea (Boddie)), Abs. 222nd ACS Nat. Meeting, Chicago, 26, 2001. 

Bayes, A., de la Vega, M. R., Vendrell, J., Aviles, F. X., Jongsma, M. A., Beekwilder, J. (2006). Response of the digestive system of Helicoverpa zea to ingestion of potato carboxypeptidase inhibitor and characterization of an uninhibited carboxypeptidase B. Insect Biochem. Mol. Biol., 36,654-664. 

Insecticides Vetch aphid (Megoura viciae) bollworm (Helicoverpa zea) army worm (Spodoptera littoralis) diamondback moth (Plutella xylostella) mustard beetle (Phaedon cochleariae) corn rootworm (Diabrotica undecimpunctata) whitefly Bemisia tabaci) red spider mite (Tetranychus urticae). 

Microplitis croceipes Helicoverpa and Heliothis spp. Cotton, cowpea, + McCall et al., 1993 Turlings et al.,... 

Maysin (2 -0-a-l-rhamnosyl-6-C-(6-deoxyxv/o-hexos-4-ulosyl)-lutcolin 6.17a), apimaysin (6.17b) and methoxymaysin (6.17c) are C-glycosyl flavones that confer resistance against the com earworm (Helicoverpa zea (Boddie)), a major silk- and kernel-feeding insect pest in the United States. 

Figure 1.1 The three major types of hormones that regulate pheromone production in insects. A Juvenile Hormone III (C16 JH), B 20-Hydroxyecdysone and C PBANs from the corn earworm, Helicoverpa zea (Raina et al., 1989), the silkworm moth Bombyx mori (Kitamura et al., 1989) and the gypsy moth, Lymantira dispar (Master et al., 1994). The minimum sequence (pentapeptide) required for activity is indicated.

Raina A. K., Wergin W. P., Murphy A. C. and Erbe E. F. (2000) Structural organization of the sex pheromone gland in Helicoverpa zea in relation to pheromone production and release. Arthropod Struct. Develop. 29, 343-353. 

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.

---