Lepidopteran species sexes

Number of lepidopteran species whose sex pheromones were found to be the indicated component... 

Sexual communication between sexes in Lepidopteran species is mediated mainly by sex pheromones, which are volatile compounds used by the female to attract potential mates from a distance [18]. In moths, sex pheromones play an important role in the elicitation of mating behaviour, and are, therefore, crucial for successful mating. They are synthesised by females in a specialised gland, which is a modification of the inter-segmental membrane located between the eighth and ninth abdominal segments [19, 20]. The pheromone is produced within the epithelial cells, transported through the cuticle via special porous cuticular spines and disseminated from the surface [19, 20]. 

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 mori [89], Lymantria dispar [90], Helicoverpa assuita [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]. 

Contrary to the structure similarity of the pheromones secreted by taxonomical related moths, some differences are necessary for their sexual communication systems to play an important role in their reproductive isolation. In addition to further modifications of the various structures, diversity of the lepidopteran sex pheromones is generated by blending multiple components. Innumerable pheromone blends are based not only on combinations of different components but also on variations in the mixing ratio. A pioneer study with Adoxophyes spp. (Tortricidae Tortricinae) had already proposed this concept in the early 1970s. While the smaller tea tortrix (A. honmai) and the Japanese summerfruit tortrix (A. oranafasciata) had been considered to be variant strains with different host preferences in the same species, Tamaki et al. found that females of the former pest insect in the tea garden secreted Z9-14 OAc and Zll-14 OAc in a ratio of 7 4 but females of the latter defoliator of apple trees secreted them in a ratio of 13 4 [127,128]. Furthermore, two other components (Ell-14 OAc and MelO-12 OAc) were subsequently identified from the former species [129]. 

A sex pheromone component was identified for three North American moth species of the lepidopteran genus Satumia. EA, Z 9)-tetradecadienal was identified as a component for S. walterorum, S. Mendocino and S. albofasciata ... 

Even more extraordinary, the authors presented evidence that the attractant mixture produced may vary with time both within and between individuals, suggesting that the spiders have some degree of control over the composition of the blend. This would explain why at least 19 different moth species are captured by M. cornigera, even when compounds that attract one species are known to be inhibitory to a second prey species. For example, the noctuid moth Peridroma saucia is attracted to blends of 16 and 18, but attraction is inhibited by 17. This type of situation is well documented with lepidopteran sex pheromones and is one of the mechanisms that allows related species to share some pheromone components while still maintaining species-specific attractant blends (Roelofs, 1995). Thus, M. cornigera must... 

P americana is one of just a few species of insects in which both peripheral and central olfactory processing have been studied. In contrast to many short-lived lepidopterans, in which the male antenna is highly specialized for sex pheromone reception, the antennae of male cockroaches contain numerous food-responsive sensilla. In addition to olfactory sensilla, the antennae also house mechano-, hygro-and thermoreceptors, as well as contact chemoreceptors (Schaller, 1978 review Boeckh et al., 1984). Extensive ultrastructural and electrophysiological evidence has demonstrated that morphologically defined sensillum types house receptor cells of specific functional types (Sass, 1976, 1978, 1983 Schaller, 1978 Selzer, 1981, 1984 review Boeckh and Ernst, 1987). Boeckh and Ernst (1987) defined 25 types of cell according to their odor spectra, but of the 65 500 chemo- and mechanosensory sensilla on the antenna of adult male P. americana, an estimated 37 000 house cells that respond to periplanone-A and periplanone-B. 

The taxonomic distribution of Type II pheromones has been previously reviewed in some detail (Millar, 2000 Ando et al., 2004), and so I will focus only on the main patterns and trends, along with a discussion of more recent findings. The reader is also cautioned that these patterns and trends are heavily biased by the fact that the identification of lepidopteran pheromones has not been conducted methodically. Rather, species that are of economic importance have been most intensively studied for example, pheromones or sex attractants are known for hundreds of tortricid species, whereas few or no pheromones at all have been identified for members of other families (Ando et al., 2004). 

Watanabe, H., Tabunoki, H., Miura, N., Sato, R. and Ando, T. (2007). Analysis of odorant-binding proteins in antennae of a geometrid species, Ascotis selenaria cretacea, which produces lepidopteran Type II sex pheromone components. Invert. Neuroscience, 7, 109-118. 

Reproductive Behavior. Male accessory glands contain peptides which affect female reproductive behavior. Female sexual receptivity is diminished after mating (22) and oviposition is stimulated (22). Peptides responsible for these behaviors have been isolated from Drosophila species (22,23) and sequenced. In addition, a peptide with similar behavioral influences in a lepidopteran has been isolated from Helicoverpa zea (24). Miller (this volume) discusses the potential of these "sex peptides" in the development of unique insect control strategies. While males influence female reproductive behavior via the action of "sex peptides", females, especially in the Lepidop-tera, influence male behavior through the release of pheromone. The production of pheromone, in turn, is controlled by the pheromone biosynthesis activating neuropeptide (PBAN for a comprehensive review see 25). PBAN-like activity has been observed in more than 20 insect species (25) and offers another avenue for exploitation of neuropeptides in insect control. 

The s pheromones of Lq>idoptera are usually produced toale moths and attract males. The pha omme is a main factor for reproductive isolati(Hi, so it must be species-specific. Lepidopto-a is one of the biggest insect groups v ich has been established for over 100 million years since die Mesozoic era. To date, lepidopteran sex pheromones have been identified fi om nearly 540 specie. Additionally, sex attractants of another 1,240 q>ecies have been found 1 field tests with synth ic phertmumes and their related compounds (/, 2). 

Z)-9-tetradecenyl acetate, which is used in the blends of 223 lepi-dopteran species and (Z)-ll-tetradecenyl acetate (Figure 3.23) used by 214 species. Some further examples of lepidopteran pheromones are shown in Figure 3.23. Bombykol, the sex pheromone of the silkworm moth Bombyx mori (Plate 2) was the first pheromone isolated and identified, in an effort that took many years of work (Butenandt, Beckmann, Stamm and Hecfcer, Zeitschrift fur Naturforschung, 1959,14b, 283). It is not easy to see how bombykol could be biosynthesized by use of a A11-desaturase. Indeed it is made in the insect from palmitic acid, which is converted to (Z)-ll-hexadecenoic acid, and then an unusual 10,12-desaturase converts that into (10 , 12Z)-10,12-hexadecadienoic acid. 

J. A. Tilman, S. J. Seybold, R. A. Jurenka and G. J. Blomquist, Insect pheromones - an overview of biosynthesis and endocrine regulation. Insect Biochemistry and Molecular Biology, 1999, 29,481-514. www-pherolist.slu.se for a comprehensive list of lepidopteran sex pheromones, species and pictures. 

Klun et al. 267), in studies at Ankeny, Iowa, on the European corn borer, found that males were only weakly attracted to highly purified (Z)-l 1-tetradecenyl acetate while the red-banded leafroller was not attracted at all to this compound. However, if small amounts of the E-isomer were added to the Z-isomer, both species were strongly attracted, yet neither species showed any response to the E-isomer alone. It was primarily after this study that it was realized that many lepidopteran sex pheromones are specific blends of the E- and Z-isomers of long chain acetate esters. The results on the Iowa European corn borer have recently been confirmed by more sophisticated separation techniques for chemically complex mixtures 268) and a number of specific ratios of the nonpheromone, (Z)- and ( )-ll-tridecenyl acetate, have been studied in field trials on the red-banded leafroller 269). 

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