Tergal Gland Secretion Research Articles

The effect of diet on the development of pheromone signals in Apis mellifera scutellata workers

The social organization of honey bee colonies is predominantly controlled by the pheromonal cues produced by the queen, workers and brood. Pheromone composition is dependent on the social environment, context, audience and physiological status of the individual. In the absence of the queen, ontogenic changes and reproductive status modulate pheromone production and composition in workers. In these queenless workers, pheromonal status influences diet with dominant workers consuming less pollen than subordinates as they are fed protein jelly through trophallaxis, which positively correlates with their ovarian activation. However, it is not known to what extent diet affects pheromonal status in queenless workers. To investigate whether diet affects the production of glandular signals, Apis mellifera scutellata workers were fed carbohydrate-only or protein-rich diets for twenty-five days. The mandibular and tergal gland secretions were analyzed using gas chromatography and the ovarian activation statuses were evaluated. A clear link between diet and pheromone profiles was observed with workers fed a protein-rich diet producing mandibular gland chemical profiles more typical of queens. The effect of diet on tergal gland chemical profiles was less distinct, but a shift from fatty acid to n-alkane components was seen in the older workers irrespective of diet, most likely due to ontogeny. Though mandibular gland profiles were queen-like with high proportions of 9-HDA, the levels of 9-ODA remained in the range of non-reproductive workers and the ovaries were not fully activated. This suggests that diet could prime queenless workers to become false queens, but do not trigger the transformation into false queens.

Nutritional condition affects tergal gland secretion and courtship success of male cockroaches.

An integral part of the courtship sequence of the German cockroach (Blattella germanica) involves the male raising his wings to expose tergal glands on his dorsum. When a female cockroach feeds on the secretion of these glands, she is optimally positioned for mating. Core chemical components have been identified, but the effect of male diet on the quality of the tergal gland secretion remains unexplored. After validating the pivotal role of tergal feeding in mating, we starved or fed reproductively mature males for one week. We then paired each male with a sexually receptive female and observed their interactions through an infrared-sensitive camera. While starvation had no effect on male courtship behavior, it did influence the duration of female tergal feeding and mating outcomes. Females fed longer on the gland secretion of fed males, and fed males experienced greater mating success than starved males (73.9% vs. 48.3%, respectively). These results suggest that the quality of the tergal gland secretions, and by association mating success, are dependent on the nutritional condition of the male.

Expression profiles of an inactive aspartic protease (Bla g 2 allergen) in different tissues and developmental stages of the German cockroach (Blattella germanica).

Tergal glands are found in many insect species and contain constituents such as pheromones, sugars, proteins, and so forth. Preliminary studies have revealed that tergal gland secretions in the German cockroach (Blattella germanica L.) contain the human allergen Bla g 2 (B. germanica allergen 2), an inactive aspartic protease. Although Bla g 2 protein expression has been detected previously in various German cockroach body parts, including male tergal glands, studies that link protein expression in various life stages and tissues with mRNA and protein abundance have not been conducted. Therefore, the goal of this study was to measure the relative abundances of Bla g 2 protein and mRNA in different tissues and life stages of B. germanica using immunoblotting, quantitative PCR, and liquid chromatography‐tandem mass spectrometry (LC‐MS/MS)‐based quantitative profiling. We found that Bla g 2 protein was detected in every sampled tissue, including the male tergal glands. Protein abundance was relatively high in adult males and their tergal glands in comparison to nymphs and virgin females. Similarly, Bla g 2 mRNA transcript levels were also comparatively higher in male tergal glands and adult males. In conclusion, this study provides new information on the relative abundance and distribution of Bla g 2 allergen, a medically significant protein, in different tissues and developmental stages of the German cockroach and lays the foundation for future studies that aim to determine the function of this protein in B. germanica development.

Tergal Gland Secretion of the Rove Beetle Aleochara pseudochrysorrhoa (Staphylinidae: Aleocharinae): Chemical Composition and Biological Roles.

Aleochara pseudochrysorrhoa has a glandular complex known as the tergal gland. Generally, the tergal gland secretion (TGS) has been described to have defensive function, but some reports point to a possible secondary function of this complex. For example, the TGS of the related species A. curtula has been demonstrated to possess an important role in intraspecies communication. In this work, we describe the chemical composition of the TGS of A. pseudochrysorrhoa males and females. Eleven compounds were identified based on GC/MS and GC-FT-IR analyses, retention indexes and derivatization products. Furthermore, a brief study regarding the biological function of the TGS in mating behavior is provided, in which the stimulation of male grasping response reaction by female TGS proved to be dependent on concentration.

Glandular sources of pheromones used to control host workers (Apis mellifera scutellata) by socially parasitic workers of Apis mellifera capensis

Pheromonal control by the honey bee queen is achieved through the use of secretions from diverse glandular sources, but the use of pheromones from a variety of glandular sources by reproductively dominant workers, has not previously been explored. Using the social parasite, Apis mellifera capensis clonal worker we studied the diversity of glandular sources used for pheromonal control of reproductively subordinate A. m. scutellata workers. To determine whether pheromones from different glandular sources are used by reproductively active workers to achieve dominance and evaluate the degree of pheromonal competition between workers of the two sub-species, we housed groups of workers of the two sub-species together in cages and analysed mandibular and tergal gland secretions as well as, ovarian activation status of each worker after 21days. The results showed that A. m. capensis invasive clones used both mandibular and tergal gland secretions to achieve reproductive dominance and suppress ovarian activation in their A. m. scutellata host workers. The reproductively dominant workers (false queens) produced more queen-like pheromones and inhibited ovarian activation in subordinate A. m. scutellata workers. These results show that tergal gland pheromones working in synergy with pheromones from other glands allow individual workers (false queens) to establish reproductive dominance within these social groups and to act in a manner similar to that of queens. Thus suggesting that, the evolution of reproductively dominant individuals (queens or false queens) and subordinate individuals (workers) in social insects like the honey bee is the result of a complex interplay of pheromonal signals from different exocrine glands.

Effects of age and Reproductive Status on Tergal Gland Secretions in Queenless Honey bee Workers, Apis mellifera scutellata and A. m. capensis

Secretions from tergal glands are part of a queen's pheromonal control of worker reproduction in honey bees. However, in queenless honey bee colonies, workers compete to gain pheromonal, and hence reproductive dominance, over nestmates with ontogenetic changes in their glandular secretions that affect the behavioral or physiological responses of other individuals. Using gas chromatography/mass spectrometry, we investigated for the first time the age-dependent changes in tergal gland secretions of queenless workers of the clonal lineage of Apis mellifera capensis and workers of A. m. scutellata. The reproductive status of honey bee workers was determined by recording the presence of spermathecae and the level of ovarian activation. The tergal gland chemicals identified in both A. m. scutellata workers and A. m. capensis clone workers were oleic acid, n-tricosene, n-pentacosene, and n-heptacosene, with three additional compounds, palmitic acid, n-heneicosene, and n-nonacosene, in A. m. capensis clones. We report ethyl esters as new compounds from honey bee worker tergal gland profiles; these compounds increased in amount with age. All A. m. capensis clone workers dissected had spermathecae and showed ovarian activation from day 4, while ovarian activation only started on day 7 for A. m. scutellata workers that had no spermathecae. Tergal gland secretions were present in higher quantities in bees with activated, rather than inactive ovaries. This suggests that tergal gland secretions from reproductive workers could act as releaser and primer pheromones in synergy with other glandular compounds to achieve pheromonal and reproductive dominance.

The Tergal Gland Secretion of the Two Rare Myrmecophilous SpeciesZyras collarisandZ. haworthi(Coleoptera: Staphylinidae) and the Effect onLasius fuliginosus

The beetle speciesZyras collarisandZ. haworthibelong to the rove beetle tribe Myrmedoniini (Staphylinidae: Aleocharinae), which comprises many myrmecophilous species. Due to their rareness, it is unknown how the two species interact with their host ants. GC-MS analyses revealed that both species releaseα-pinene,β-pinene, myrcene and limonene from their defensive tergal glands. This composition of tergal gland secretion is unique within the subfamily Aleocharinae. In biotests,Lasius fuliginosusants showed increased antennation towards filter paper balls treated with mixtures of these substances in natural concentrations. Because these monoterpenes are also present in some aphid species which are attended by ants, we hypothesize thatZyrasbeetles mimic the presence of aphids and thereby achieve acceptance by their host ants.

Three beetles—three concepts. Different defensive strategies of congeneric myrmecophilous beetles

Myrmecophiles, i.e., organisms associated with ants live in a variety of ecological niches in the vicinity or inside ant colonies and employ different strategies to survive ant encounters. Because different niches are characterized by different encounter rates with host ants, strategies used to avoid ant aggressions should depend on these niches. This hypothesis was studied with three rove beetle species of the genus Pella, which are myrmecophiles of the ant Lasius fuliginosus and the non-myrmecophilous relative Drusilla canaliculata. Behavioral tests in the field revealed that Pella species are better adapted to interactions with ants than D. canaliculata, but that they use species-specific strategies in ant interactions. Pella cognata and Pella funesta avoid encounters with ants by swift movements. Chemical analyses of the defensive tergal gland secretions showed that P. cognata has replaced the aggression inducing undecane by the behaviorally neutral tridecane. P. funesta repels the ants by releasing the panic alarm pheromone sulcatone from its tergal gland resulting in an “ant free space” around the beetles. Finally, Pella laticollis uses a specific and unique appeasing behavior. Behavioral and chemical data did not reveal any indication for the mimicry of the ants' cuticular hydrocarbon profiles by any of the beetle species. It is discussed that the employed strategies correlate with the ecological niches of the beetles. P. cognata and P. funesta are living along ant trails with ample space to escape and the employed strategies are probably sufficient to escape from dangerous conflicts. In contrast, P. laticollis lives in refuse areas of ant nests with frequent ant encounters, and its appeasement strategy allows it to stay at the encounter site.

Could male tergal secretions be considered as a nuptial gift in the Madeira cockroach?

Many male insects provide somatic nuptial gifts that may strongly influence reproductive fitness, ensuring effective copulation or mediating paternal resource benefits in offspring. Although the courtship feeding behaviour on tergal gland secretions has been described in numerous cockroaches, studies on the function of these so-called nuptial gifts are lacking in this group. In this study, we examined, in the Madeira cockroach, Leucophaea maderae, the functional significance of tergal secretions by manipulating their availability on the back of males. We tested whether male tergal secretions function as a form of mating effort, and/or as a form of paternal investment. In a first experiment, we gave females the choice between two males, one with and one without tergal secretions. In a second experiment, we gave females the opportunity to copulate with a male of these two male types. Our results showed that the difference in male mating success was significant only when females could choose between the two male types. Contrary to all past expectations, females preferred to copulate with males whose tergal secretions were experimentally removed. Additionally, we showed that females did not gain any fitness benefit from copulating with a male with tergal secretions, but it even seems to be the contrary in terms of longevity. Consequently, neither the mating effort hypothesis nor the paternal investment hypothesis has been confirmed in this species. Our results are discussed with regard to the chase-away sexual selection model.

Characterization of BGTG‐1, a tergal gland‐secreted alpha‐amylase, from the German cockroach, Blattella germanica (L.)

The protein fraction of the German cockroach, Blattella germanica (L.), tergal gland secretion was examined. SDS-PAGE separation of proteins present in B. germanica tergal gland secretion revealed a tergal gland-secreted protein, BGTG-1, at approximately 63 kDa. BGTG-1 first appeared in tergal gland secretion at 2 days postimaginal moult and the amount of protein observed increased through day 5. A 2051 bp cDNA sequence, bgtg-1, was obtained by RACE polymerase chain reaction and contains a 1494 bp ORF encoding a predicted protein of 498 amino acids. In a Northern hybridization experiment using total RNA from B. germanica tergal gland tissue, a (32)P-labelled bgtg-1 probe hybridized to an RNA approximately 2000 bp and confirmed the 2051 bp cDNA size obtained by RACE PCR. Using the BLASTx sequence similarity search tool, the top match to the bgtg-1 ORF was found to be an alpha-amylase from Drosophila kikkawai (e-value = 1 x 10(-178)). Alignment of the bgtg-1 deduced protein sequence with alpha-amylases from fruit fly, Drosophila melanogaster, honey bee, Apis mellifera (L.) and yellow mealworm, Tenebrio molitor (L.), revealed conserved residues throughout the ORF and sequence identities ranging from 58.4 to 58.2%. Using a gel-based assay, degradation of starch by native BGTG-1 was demonstrated in vitro and we propose that BGTG-1 may be involved in processing phagostimulatory sugars present in B. germanica tergal gland secretion.

Effects of the juvenile hormone analog pyriproxyfen on German cockroach,Blattella germanica (L.), tergal gland development and production of tergal gland secretion proteins

Male German cockroaches possess secretory glands that secrete fluid into a pair of transverse depressions on the seventh and eighth abdominal tergites. We investigated the effects of altered juvenoid titer during the first part of the last instar on tergal gland secretory tissue development and the production of tergal gland secretion proteins. Male fifth (last) instar nymphs (1-3 days post-emergent) were topically treated with the JH analog pyriproxyfen. Light and transmission electron microscopy demonstrated that treatment with pyriproxyfen produced a visible decrease in the amount of tergal gland tissue present, a deformation of the overall shape of the gland located on tergite seven, and a less orderly arrangement of the secretory cells in the tissue. The protein fraction of tergal gland secretion was examined in pyriproxyfen-treated and control insects 1, 5, and 15 days after the insects molted to the adult stage. Amounts of all tergal secretion proteins were reduced in treated insects.

NMR structure determination of (11 E)-trinervita-1(14),2,11-triene, a new diterpene from sexual glands of termites

Female alates of Nasutitermes ephratae termites from Guadeloupe and Nasutitermes sp. from Brazil produce a diterpene hydrocarbon of the molecular formula C 20H 30 as the main component of their tergal gland secretion. Analysis of NMR, IR, and mass spectra of the diterpene led to a structure of (11 E)-trinervita-1(14),2,11-triene. Based on a comparison with the published oxygenated trinervitane skeleton from termites we prefer the enantiomer with absolute configurations (4 R,7 S,8 R,15 S,16 S). The suggested structure is supported by ab initio quantum chemical calculation of 1H and 13C chemical shifts for the optimized geometry of the molecule.

Oligosaccharide composition and pheromonal activity of male tergal gland secretions of the German cockroach, Blattella gennanica (L.).

In the sequential courtship behavior of the German cockroach, Blattella germanica (Dictyoptera: Blattellidae), females feed on the tergal gland secretions from the male tergites. The phagostimulative components in the male secretions were composed of a complex mixture of oligosaccharides and phospholipids. Besides seven oligosaccharides previously identified, two new trisaccharides, O-alpha-D-glucopyranosyl-(1 --> 6)-alpha-D-glucopyranosyl alpha-D-glucopyranoside and O-alpha-glucopyranosyl-(1 --> 4)-O-alpha-glucopyranosyl-(1 --> 1)-myo-inositol, were characterized as the sugar components of the secretions. The activity of the sugar components was compared in combination with the lipid fraction. Individual oligosaccharides exhibited the activity either alone or synergistically with the phospholipids. A complex mixture of these primary substances in the tergal gland secretions, thus, serves as a pheromonal phagostimulant in the precopulatory behavior, strongly eliciting feeding response in the female cockroach.

CDNA cloning of an adult male putative lipocalin specific to tergal gland aphrodisiac secretion in an insect ( Leucophaea maderae)

Lma-P22 is a cuticular surface protein specific to the tergal gland secretion of Leucophaea maderae adult males which is ingested by females just before copulation. The complete Lma-P22 cDNA sequence was determined by RT-PCR using primers based on Edman degradation fragments. The recombinant protein expressed in Escherichia coli was recognized by an anti-Lma-P22 antibody. Northern blot analysis indicates that the corresponding mRNA is transcribed only in the epidermis of male tergites. Sequence analysis indicated that Lma-P22 deduced protein belongs to the lipocalin family. Lipocalins are extracellular proteins which carry hydrophobic compounds and some of them can bind sexual pheromone in vertebrates. Lma-P22 is the first example of a lipocalin-like protein involved in insect sexual behavior.

Mass spectral identification of the tergal gland secretions of female castes of two African honey bee races (Apis mellifera)

SUMMARYThe tergal gland secretions in queens, workers and pseudoqueens of Apis mellifera capensis and Apis mellifera scutellata are composed of long-chain fatty acids, long-chain esters and a linear series of unsaturated hydrocarbons. The cuticular extracts, on the other hand, consisted of a linear series (C23-C31) of saturated hydrocarbons and were shown to be identical for both A. m. capensis and A. m. scutellata queens and workers. The major compound in the tergal gland secretion for all test groups, was (Z)-9- octadecenoic acid. Virgin queens are distinguishable from mated queens (P = 0.0001) and workers (P = 0.0001) in that they secrete a series of long-chain esters, the predominant ester being decyl decanoate. A. m. capensis workers differed significantly (P = 0.0001) from A. m. capensis mated queens, as did pseudoqueens (P = 0.001), in their tergal gland secretion profiles. Significant inter-racial differences were found between the tergal gland secretions of mated queens (P = 0.0001) and workers (P = 0.001) from the two contiguous African races, but not between the virgin queens (P = 0.39). Consequently, mated queens and workers of these two African races can be separated on their tergal gland secretion profiles.

The Releaser Effects of the Tergal Gland Secretion of Queen Honeybees ( Apis mellifera )

Queen honeybees are attractive to their workers, due partially to the pheromonal bouquet they secrete. Queen mandibular gland pheromone is a powerful attractant to worker honeybees but it is not solely responsible for eliciting retinue behavior. The attractiveness of virgin queen tergal gland secretions and queen mandibular pheromone to worker honeybees was tested using a retinue bioassay. The number of workers attending the treated pseudoqueen lures was videorecorded in order to allow for the quantification of attractiveness. Queen mandibular gland secretions were more attractive than tergal gland secretions (P ≤ 0.008), and both queen tergal gland secretions (P ≤ 0.0002) and mandibular gland secretions (P ≤ 0.0001) were significantly more attractive than the control treatment. This laboratory bioassay indicates that queen tergal gland secretions have a releaser effect that evokes retinue behavior from worker honeybees.

Honeybee queen tergal gland secretion affects ovarian development in caged workers

Les ovaires des ouvrieres d'abeille (Apis mellifera L.) sont partiellement inhibes par les secretions de la glande mandibulaire de la reine. On a etudie au laboratoire, par un test biologique, les effets inhibiteurs de la secretion des glandes tergales de la reine sur le developpement ovarien des ouvrieres chez les races capensis et scutellata. Des leurres de reine en verre, realises a partir de pipettes Pasteur, ont ete traites quotidiennement et presentes a des groupes d'ouvrieres orphelines encagees. Les cagettes ont ete placees a l'obscurite dans des pieces a temperature controlee (27 °C). Les groupes experimentaux (n = 15) ont ete exposes a des extraits de glandes tergales de reines vierges correspondant a 0,05 equivalent reine. L'extrait a ete depose sur le leurre a l'aide d'une microseringue et on a laisse le solvant, du dichloromethane, s'evaporer avant d'introduire le leurre dans les cagettes. Les groupes temoins (n = 15) n'ont ete exposes qu'au solvant. On a finalement tue par le froid toutes les ouvrieres pour examiner leurs ovaires. Le degre de developpement ovarien a ete evalue et classe de 1 a 4. L'âge des ouvrieres des groupes temoins et des groupes traites n'etait pas significativement different (tableau I), que ce soit chez A. m. capensis ou A. m. scutellata (test de la mediane : p≥0,116). L'analyse par des modeles logarithmiques lineaires (tableau II) n'a pas montre d'interactions significatives (race × traitement × cage; race × traitement; race × cage; traitement × cage). Les principaux effets cage (p = 0,225) et race (p = 0,665) n'etaient pas statistiquement significatifs et le modele final qui convient le mieux comprenait l'effet traitement seul qui, lui, etait hautement significatif (X 2 = 8,28; df = 1; p = 0,004; tableau II, figure 1). Ces resultats montrent que la secretion des glandes tergales peut agir comme pheromone modificatrice mais qu'elle fonctionne vraisemblablement en synergie avec les secretions des autres glandes. Le maintien de la sterilite des ouvrieres est regule par de multiples facteurs et la reproduction est finalement regie par des facteurs physiologiques propres a l'ouvrieres consideree individuellement. Ce travail a montre que la secretion des glandes tergales de la reine peut influencer le developpement ovarien des ouvrieres qui y sont exposees.

Characterization of two male-specific polypeptides in the tergal glands secretions of the cockroach Leucophaea maderae (Dictyoptera, blaberidae)

During the sexual behavior of cockroaches, the female mounts the courting male to feed on the proteinaceous secretion of the tergal glands. Polyacrylamide gel electrophoresis of male and female protein extracts after cuticle wiping revealed three major bands. Two of 18 and 22 kDa, named Lma-P18 and Lma-P22, are specific to the male tergal extracts. Moreover, Lma-P22 is only found in the male second tergite extracts. The third one of 54 kDa, named Lma-P54, is common to male and female extracts and could be considered as an ubiquitous surface protein. Several other minor proteins are also present on the body surface of adults of both sexes. Quantitation of the total protein amount of the male tergal gland secretion shows a progressive accumulation from adult ecdysis to sexual maturity. Western blot analysis using antibodies raised against Lma-P22 and Lma-P54 confirms that Lma-P22 is only secreted by the male second tergite glands. Immunohistolocalization demonstrates that these three major proteins are produced by class 3 glandular cells.

The use of the tergal gland defensive secretion in male intrasexual aggression of the rove beetle,Aleochara curtula (Coleoptera: Staphylinidae), measured by closed-loop-stripping-analyses and tandem bioassay ? mass fragmentography

2-methyl-1,4-benzoquinone as a target compound of the tergal gland secretion of the rove beetle,Aleochara curtula, was quantified from the reservoirs of individual beetles. Males store less secretion than females, and they evaporate more of the secretion as measured by adsorption from the air (closed-loop-stripping-analysis). The amount of emitted quinone is increased during aggressive interactions of rival males. The pulsed emission of the secretion during aggression is demonstrated by a novel technique combining observation of behavior with the on-line measurement of target fragment ions by mass-spectrometry (tandem bioassay — mass fragmentography). The emission of the secretion is used as a weapon in combats between males and may result in the repulsion of subordinate males from the mating site, but may also serve to mimic females chemically in order to avoid aggressive encounters.

Seducin, male sex pheromone of the cockroachNauphoeta cinerea: Isolation, identification, and bioassay

The male sex pheromone of the cockroachNauphoeta cinerea was isolated from adult sternal glands and identified by gas chromatography-mass spectrometry. This pheromone, which attracts females from a distance, is a multicomponent blend. It is composed principally of three compounds: 3-hydroxy-2-butanone (acetoin), 2-methylthiazolidine, and 4-ethyl-2-meth-oxyphenol. A mixture of synthetic compounds in a ratio of 4∶4∶1 (2700 ng) elicits maximal response and short latency of response by receptive females, similar to that induced by male sternal gland extracts. Tested separately, each compound induces a positive response, but the moving times spent by females are generally longer than with the mixture or extracts. These three volatile compounds also are found in small amounts (about 1/40 of sternal glands) in tergal gland secretions licked by females. Acetoin also is found in the sternal and tergal glands of two closely related speciesLeucophaea maderae andHenschoutedenia flexivitta. The biological relationship of each compound and pheromone blend to behavioral response is discussed.