Examination of the interior of sand fly (Diptera: Psychodidae) abdomen reveals novel cuticular structures involved in pheromone release: Discovering the manifold

The males of many species of New World Phlebotomines produce volatile terpenoid chemicals, shown in Lutzomyia longipalpis s.l. to be sex/aggregation pheromones. Pheromone is produced by secretory cells which surround a cuticular reservoir which collects the pheromone and passes it through a cuticular duct to the surface of the insect. The pheromone then passes through specialised cuticular structures on the abdominal surface prior to evaporation. The shape and distribution of the specialised structures are highly diverse and differ according to species. In this study we used SEM to examine the interior cuticular pheromone collection and transport structures of 3 members of the Lu. longipalpis s.l. species complex and Migonemyia migonei. We found a new structure which we have called the manifold which appears to be a substantial extension of the interior tergal cuticle connected in-line with the cuticular duct and reservoir. The manifold of the Campo Grande member of the complex is longer and wider than the Jacobina member whereas the manifold of the Sobral member was shorter than both other members of the complex. Overall, the secretory apparatus of the Sobral member was smaller than the other two. The manifold of M. migonei was very different to those found in Lu. longipalpis s.l. and was positioned in a pit-like structure within the tergal cuticle. The secretory reservoir was connected by a short duct to the manifold. Differences in the size and shape of the manifold may be related to the chemical structure of the pheromone and may have taxonomic value. Examination of the interior cuticle by SEM may help to locate the secretory apparatus of vector species where pheromonal activity has been inferred from behavioural studies but the external secretory structures or pheromones have not yet been found.

Interior of sand fly (Diptera: Psychodidae) abdomen reveals novel structures involved in pheromone release: discovering the Manifold.

The males of many species of New World Phlebotomines produce volatile terpenoid chemicals which have been shown in Lutzomyia longipalpis s.l. and L. cruciata to be sex/aggregation pheromones which attract female and male conspecifics. Pheromone is produced in secretory cells surrounding a cuticular reservoir which collects the pheromone and passes it through a cuticular duct to the surface of the insect. On the surface the pheromone passes through a specialised structure prior to evaporation. The shape and distribution of the structures are highly diverse and differ according to species. They range in appearance from slightly raised domes (papules) to almost spherical apple shaped structures to slight depressions with central spikes and all with a central pore. They can occur either singly or in many hundreds distributed on most abdominal tergites or grouped on one. The pheromone secreting apparatus in sand flies and other insects have historically been examined from the exterior using scanning electron microscopy (SEM) and from the interior using transmission electron microscopy. In this study we used SEM to examine the interior cuticular structure of 3 members of the Lutzomyia longipalpis s.l. species complex and Migonemyia migonei and found a new structure associated with pheromone release which we have called the Manifold. The Manifold is a substantial structure siting in-line between the cuticular duct and the underside of the tergite. Differences in the size and shape of the Manifold may be related to the chemical structure of the pheromone. In addition to the importance of this hitherto unknown structure in the production, dissemination and ecology of the pheromone, as well as its potential taxonomic value, examination of the interior cuticle by SEM may help locate the secretory apparatus in important vector species where pheromonal activity has been inferred from behavioural studies but the external secretory structures or potential pheromones have not been found.

Enantioselective synthesis and determination of the absolute configuration of the male sex pheromone of the parasitoid wasp Urolepis rufipes

The parasitoid wasp Urolepis rufipes uses terminally oxidized dihydrolinalool as a sex pheromone. The absolute configuration of the active enantiomer was established as 2S,6S by synthesis and its pheromonal activity was proven in a bioassay.

Transfer of [3H]estradiol-17β and [3H]progesterone from conspecifics to cohabiting female mice

Estradiol-17β (E2) and progesterone (P4) play critical roles in female reproductive physiology and behavior. Given the sensitivity of females to exogenous sources of these steroids, we examined the presence of E2 and P4 in conspecifics' excretions and the transfer of excreted steroids between conspecifics. We paired individual adult female mice with a stimulus male or female conspecific given daily injections of [3H]E2 or [3H]P4. Following 48 h of direct interaction with the stimulus animal, we measured radioactivity in the uterus, ovaries, muscle, olfactory bulbs, mesencephalon and diencephalon (MC+DC), and cerebral cortex of the untreated female cohabitant. Radioactivity was significantly present in all tissues of female subjects after individual exposure to a stimulus male or female given [3H]E2. In females exposed to males given [3H]P4, radioactivity was significantly present in the uterus, ovaries, and muscle, but not in other tissues. In females exposed to stimulus females given [3H]P4, radioactivity was significantly present in all tissues except the MC+DC. In mice directly administered [3H]steroids, greater radioactivity was found in the urine of females than of males. Among females directly administered [3H]steroids, greater radioactivity was found in urine of those given [3H]P4 than of those given [3H]E2. When females were administered unlabeled E2 before exposure to [3H]E2-treated females, less radioactivity was detected in most tissues than was detected in the tissues of untreated females exposed to [3H]E2-treated females. We suggest that steroid transfer among individuals has implications for the understanding of various forms of pheromonal activity.

Effect of prostaglandin on reproduction in relation to pituitary gonadal axis in the fish, Cyprinus carpio (L.)

Prostaglandins are a class of fatty acids which are “traditionally” associated with a variety of autocrine and paracrine functions in the vertebrate body. In many fishes, however, F prostaglandins also function as a hormone that stimulates sexual behavior. In the present study, F prostaglandin was used to assess the efficacy on reproductive behavior and spawning in relation to pituitary gonadal axis in the fish, Cyprinus carpio by administering different doses. Early maturity was observed in fish leading to courtship and spawning. The histological study of olfactory lobe, pituitary gland and gonads showed that the prostaglandin is also functioning as potent olfactory stimulants with sex pheromonal activity of the fish. F prostaglandin was metabolized and released into the water where it functions as a sex pheromone, stimulating male and female sexual behavior resulting into spawning. It was concluded that F prostaglandin acts as an inducer for successful breeding in the fish, C. carpio.

Sex pheromones in amphibians: a review

Amphibians are interesting animals, very often kept by aquarists and vivarists. Their ability of intraspecific chemical signalization belongs to very interesting biological features. The skin glands of anurans secrete various biologically active compounds. The pheromones are peptides consisting of various numbers of amino acid residues and their synthesis is regulated by hormones (e.g. prolactin and androgens). Similarly, the responsiveness of the vomeronasal epithelium to some of these compounds is enhanced by some hormonal substances (prolactin and oestrogen). Hypophyseal hormones, arginine vasotocin and gonadotropin-releasing hormone are involved in the humoral regulation of pheromone discharge. The storage of some compounds with pheromonal activity in a biologically inactive form was also proved. The pheromones have an important role in sexual relationships. These chemosignals increase female receptivity and are probably involved in the mate choice. The courtship pheromone signals may be conserved across related species. Chemosignals play an important role in female attraction and/or territorial announcement. In addition to sex pheromones, various neuropeptides, antimicrobial and other biologically active peptides were found in skin glands of these amphibians. The infochemical system can be disturbed by a chemical influence in the environment.