Pheromones production in insects

The three hormones that regulate pheromone production in insects are shown in Figure 1.1. PBAN alters enzyme activity through second messengers at one or more steps during or subsequent to fatty acid synthesis during pheromone production (Rafaeli and Jurenka, Chapter 5). In contrast, 20-hydroxyecdysone and JH induce or repress the synthesis of specific enzymes at the transcription level (Tittiger, Chapter 7 Blomquist, Chapter 9). 

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.

Percy J. and Weatherston J. (1974) Gland structure and pheromone production in insects. In Pheromones, Frontier of Biology, ed. M. Birch. North Holland, Amsterdam. 

The application of the powerful tools of molecular biology to work on pheromone production in insects, including the housefly, will undoubtedly allow us to obtain a much better understanding of how pheromone biosynthesis is regulated by hormones, and should allow advances in pheromone-based insect control techniques. 

The three hormones that regulate pheromone production in insects are juvenile hormone 111 (JH), 20-hydroxyecdysone and PBAN (pheromone biosynthesis activating neuropeptide). 

Abstract Pheromones are utilized by many insects in a complex chemical communication system. This review will look at the biosynthesis of sex and aggregation pheromones in the model insects, moths, flies, cockroaches, and beetles. The biosynthetic pathways involve altered pathways of normal metabolism of fatty acids and isoprenoids. Endocrine regulation of the biosynthetic pathways will also be reviewed for the model insects. A neuropeptide named pheromone biosynthesis activating neuropeptide regulates sex pheromone biosynthesis in moths. Juvenile hormone regulates pheromone production in the beetles and cockroaches, while 20-hydroxyecdysone regulates pheromone production in the flies. 

Another aspect of the sex pheromone communication system concerns the endogenous signals that control pheromone production and release from the emitting insect. A number of hormones have been found to be involved in the control of pheromone production in various insect species (18). Juvenile hormone was found to induce vitellogenesis and sex pheromone production in some cockroach and beetle species. However, ecdysteroids were found to be involved in regulating reproductive processes, including vitellogenin synthesis, in dipteran species. 

The biosynthesis and endocrine regulation of pheromone production in beetles has been reviewed [33, 34]. Nevertheless, some more general pathways will be briefly discussed here. As corresponding structures are widespread among insects [2], the examples shown here are selected mostly from taxa other than beetles. Structures representing beetle pheromones will be shown in the context of the discussion of the corresponding species. 

Schal, C., Burns, E. L., Gadot, M., Chase, J. and Blomquist, G. J. (1991). Biochemistry and regulation of pheromone production in Blattella germanica (L.) (Dictyoptera, Blattellidae). Insect Biochemistry 21 73-79. 

Resh, V. H. and Wood, J. R. (1985). The site of pheromone production in three species of Trichoptera. Aquatic Insects 7 65-71. 

In no model pheromone biosynthetic system is the molecular mechanism of hormonal regulation completely understood. The mechanism of action of JH and the nature of its receptor remain one of the mysteries of insect science, and the clear-cut action of JH by itself in inducing specific genes in pheromone production in bark beetles offers an excellent model for study. A better understanding of the PBAN receptor and the second messenger system it triggers as well as the steps regulated in pheromone biosynthesis is also needed. The next several years should see some of the key questions answered in model insects. 

Byers J. A., Wood D. L., Browne L. E., Fish R. H., Piatek B. and Hendry L. B. (1979) Relationship between a host plant compound, myrcene, and pheromone production in the bark beetle, Ips paraconfusus. J. Insect Physiol. 25, All-Ail. 

Vanderwel D. (1994) Factors affecting pheromone production in beetles. Arch. Insect Biochem. Physiol. 25, 347-362. 

Clearwater J. R. and Sarafis V. (1973) The secretory cycle of a gland involved in pheromone production in the Noctuid moth, Pseudaletia separata. J. Insect Physiol. 19, 19-28. 

Sreng L., Leoncini I. and Clement J. L. (1999) Regulation of sex pheromone production in the male Nauphoeta cinerea cockroach role of brain extracts, corpora allata (CA), and juvenile hormone (JH). Arch. Insect Biochem. Physiol. 40, 165-172. 

Ando T., Kasuga K., Yajima Y., Kataoka H. and Suzuki A. (1996) Termination of sex pheromone production in mated females of the silkworm moth. Arch. Insect Biochem. Physiol. 31, 207-218. 

Delisle J. and Simard J. (2002) Factors involved in the post-copulatory neural inhibition of pheromone production in Choristoneura fumiferana and C. rosaceana females. J. Insect Physiol. 48, 181-188. 

Fan Y., Rafaeli A., Gileadi C., Kubli E. and Applebaum S. W. (1999b) Drosophilia melanogaster sex peptide stimulates juvenile hormone synthesis and depresses sex pheromone production in Helicoverpa armigera. J. Insect Physiol. 45, 127-133. 

Foster S. P. (1993) Neural inactivation of sex pheromone production in mated lightbrown apple moths, Epiphyas postvittana (Walker). J. Insect Physiol. 39, 267-273. 

Matsumoto S., Ozawa R., Uchiumi K., Kurihara M. and Mitsui T. (1995a) Intracellular signal transduction of PBAN action in the common cutworm, Spodoptera litura effects of pharmacological agents on sex pheromone production in vitro. Insect Biochem. Mol. Biol. 25, 1055-1059. 

Raina A. K. (1997) Control of pheromone production in moths. In Insect Pheromone Research New Directions, eds R. T. Carde and A. K. Minks, pp. 21-30. Chapman Hall, New York. 

Raina A. K., Kempe, T. G. and Jaffe H. (1991) Pheromone biosynthesis-activating neuropeptide Regulation of pheromone production in moths. In Insect Neuropeptides Chemistry, Biology and Action, eds J. J. Menn, T. J. Kelly and E. P. Masler, pp. 100-109. American Chemical Society, Washington, DC. 

Tang J. D., Charlton R. E., Carde R. T. and Yin C.-M. (1987) Effect of allatectomy and ventral nerve cord transection on calling, pheromone emission and pheromone production in Lymantria dispar. J. Insect Physiol. 33, 469-476. 

Thyagaraja B. S. and Raina, A. K. (1994) Regulation of pheromone production in the gypsy moth, Lymantria dispar, and development of an in vitro bioassay. J. Insect Physiol. 40, 969-974. 

H. D. Pierce, Jr, J. H. Borden, and G. J. Blomquist for their roles as teachers, mentors, and sounding boards R. Bacala for many interesting discussions on insect pheromone biochemistry and the Natural Sciences and Engineering Research Council (NSERC) for the continuous funding of the work on the biochemistry of pheromone production in beetles from 1992 to the present. 

Figure 7.5 Tissue localization of HMG-R expression. Exposed whole mounts show that HMG-R mRNA is observed in the midgut of JH Ill-treated male D. jeffreyi (A) and I. pini (C), but not in untreated insects (B, D). Panels E through H show whole mount hybridizations of isolated I. pini alimentary canals. HMG-R expression in the anterior midgut (AMG, marked by brackets) correlates with pheromone production in starved, JH Ill-treated males (E) and fed males (G), while starved and untreated males (F, G), which do not produce monoterpenoid pheromone components, do not strongly express HMG-R. Asterisks mark non-specific signal in the hindguts. PV, pro-ventriculus HG, hindgut. Scale bars = 0.5 mm. Figure modified from Hall et al. (2002a, 2002b) with permission.

Juvenile hormone (JH) regulates both vitellogenesis and pheromone production in some insect species (Tillman et al., 1999). In some Diptera, including the housefly, ovarian-produced ecdysteroids are involved in regulating vitellogenesis (Hagedom, 1985 Adams et al., 1997) at the transcriptional level (Martin et al., 2001). Because ovariectomy abolished sex pheromone production while alletectomy (which abolishes JH production) had no effect on pheromone production (Blomquist et al., 1992), it was therefore hypothesized that an ecdysteroid, and not JH,... 

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