Female American Cockroaches Research Articles

Hexamerin and allergen are required for female reproduction in the American cockroach, Periplaneta americana.

Reproduction is of great importance for the continuation of the species. In insects, the fat body is the major tissue for nutrient storage and involved in vitellogenesis, which is essential for female reproduction. Here, 2 proteins, hexamerin and allergen, were separated from the fat bodies of adult female American cockroaches (Periplaneta americana) and identified as storage proteins, encoding for 733 amino acids with molecular weight of 87.88kDa and 686 amino acids with molecular weight of 82.18kDa, respectively. The encoding genes of these 2 storage proteins are mainly expressed in the fat body. RNA interference-mediated knockdown of Hexamerin and Allergen in the early stage of the first reproductive cycle in females suppressed vitellogenesis and ovarian maturation, indicating that these storage proteins are involved in controlling reproduction. Importantly, the expression of Hexamerin and Allergen was repressed by knockdown of the juvenile hormone (JH) receptor gene Met and the primary response gene Kr-h1, and was induced by methoprene, a JH analog, in both in vivo and in vitro experiments. Altogether, we have determined that hexamerin and allergen are identified as storage proteins and play an important role in promoting female reproduction in the American cockroach. The expression of their encoding genes is induced by JH signaling. Our data reveal a novel mechanism by which hexamerin and allergen are necessary for JH-stimulated female reproduction.

A putative direct repeat element plays a dual role in the induction and repression of insect vitellogenin-1 gene expression.

Juvenile hormones (JH) regulate wide-ranging physiological and developmental processes in insects. However, molecular mechanisms underlying JH signaling remain to be determined. Vitellogenin (Vg) is primarily an egg-yolk protein, but recently proposed to serve many functions in insects. In the female American cockroach (Periplaneta americana), vitellogenin (Vg) genes are activated by JH III and suppressed by 20-hydroxyecdysone (20E) via cis-regulatory elements in a dose-dependent manner. In the present study, the upstream promoter region (935 bp) of Vg1 was cloned to elucidate the action of these hormones. A luciferase reporter assay identified an 81 bp region in the promoter region of Vg1 (-120 to -39 bp) that we found to be critical for JH III activation and 20E suppression. This 81 bp region contains a direct repeat separated by a 2-nucleotide spacer-designated Vg1HRE- that is similar to the Drosophila ecdysone response element direct repeat 4. Moreover, nuclear proteins isolated from nymphs, males, females, and Sf9 cells successfully bound to Vg1HRE, while binding was outcompeted by a 100-fold excess of cold probe or dephosphorylated nuclear protein extracts. In addition, binding was outcompeted by other ecdysone and JH response elements with similar half-site sequences (direct repeats) but to varying extents. Ultimately, we postulate that JH III indirectly activates Vg expression by interfering with or inhibiting the phosphorylation of nuclear proteins bound to Vg1HRE. Involvement of JH III in both induction of Vg1 and control of nuclear proteins binding to Vg1HRE suggest the latter to play an important role in JH signaling.

Capsazepine affects thermal preferences of the American cockroach (Blattodea: Blattidae)

Capsazepine is a competitive antagonist of capsaicin, a TRPV1 agonist responsible for the spicy taste of pepper. TRPV1 agonists and antagonists are known to affect mammalian body temperature, but their action on thermoregulation in insects is poorly known. In this study we evaluated the effect of capsazepine on the thermal preference of the American cockroach, Periplaneta americana using a thermal gradient. Our results revealed that capsazepine in submicromolar concentrations induces a preference for higher ambient temperatures when compared to the control insects. To assess whether capsazepine may act also as an antagonist of capsaicin in insects, we determined this insects' thermal behaviour when capsazepine was applied before capsaicin. The hypothermic response to capsaicin was clearly blocked by pre-treatment with capsazepine only in female American cockroaches. Our results indicate the involvement of structures functionally similar to TRPV1 in insect thermosensation.

Pheromone Detection by a Pheromone Emitter: A Small Sex Pheromone-Specific Processing System in the Female American Cockroach

Many animals depend on pheromone communication for successful mating. Sex pheromone in insects is usually released by females to attract males. In American cockroaches, the largest glomerulus (B-glomerulus) in the male antennal lobe (first-order olfactory center) processes the major component of sex pheromone. Using intracellular recordings combined with fine neuroanatomical techniques, we provide evidence that the female homolog of the male B-glomerulus also acts as a sex pheromone-specific detector. Whereas ordinary glomeruli that process normal environmental odors are innervated by single projection neurons (PNs), the B-glomerulus in both sexes is innervated by multiple PNs, one of which possesses a thicker axon, termed here B-PN. Both soma size and axon diameter were smaller on B-PNs from females compared with B-PNs from males. The female B-PNs also produce fewer terminal arborizations in the protocerebrum than male B-PNs. Termination fields in the lateral protocerebrum of the female B-PN are mostly segregated from those formed by other uniglomerular PNs innervating ordinary glomeruli. Female B-PN activity was greatest in response to sex pheromone but lower than that in the male B-PN. This specific detection system suggests that sex pheromone affects the behavior and/or endocrine system of female cockroaches.

Responses of cockroach antennal lobe projection neurons to pulsatile olfactory stimuli.

Behavioral evidence indicates that insects preferentially orient toward pulses of odorants as they occur downwind from a point source. Our recent results have shown that cockroach olfactory receptor neurons are able to reliably resolve 10-Hz pulses of the general "green' odorant 1-hexanol, but it is unknown to what extent the central olfactory pathway is able to resolve temporal aspects of a general odor stimulus. In the present study, temporal response characteristics were measured in antennal lobe projection neurons of female American cockroaches, Periplaneta americana in response to series of short odor pulses (2.5-20 Hz). Odor pulses were delivered to olfactory sensilla in a moving airstream controlled by electromagnetic valves and quantified by replacing the odorant with oil smoke and measuring the concentration of smoke passing through a light beam. The responses of projection neurons were recorded with an intracellular microelectrode placed in the projection neuron cell body. A variety of time courses of responses were recorded. Response patterns were consistent among identical stimuli within a neuron and varied among neurons. Some neurons increased spike frequency with stimulus onset while others decreased spike frequency. The latency to the change in spike frequency and the duration of the response also varied among neurons. Regardless of the temporal characteristics of the responses, nearly all projection neurons were able to resolve pulses of 1-hexanol presented at 5 Hz and some could resolve 10-Hz pulses. Thus, responses of antennal lobe projection neurons can reflect fine structures of non-uniform distributions of general odorants in a turbulent odor plume. In addition, the variety of temporal response characteristics to identical stimuli suggests that odor quality is coded by a temporal code expressed across a population of projection neurons.

Evidence for the Site of Female Sex Pheromone Production in Periplaneta americana

We used bioassays to determine the sex pheromone production site in the female American cockroach (Periplaneta americana). Bioassayed extracts from various body parts aroused sexual responses from unmated males. However, the extract of hindgut (including both colon and rectum) induced strong responses. Colon extract stimulated the strongest sexual response. To compare the sex pheromone contents of atrial glands, pygidium, rectum, and colon, we recorded the EAG responses of male antennae to these extracts. Among the four tissues, colon extract caused the strongest EAG response. From gas chromatographic (GC) analysis, the quantities of periplanone-A (PA) and periplanone-B (PB) (the main sex pheromone components in female American cockroach) were 0.34 and 8.31 ng, respectively, in the colon of a virgin female. The ratio of PA to PB was ca. 1:24. The present results are different from those reported in a previous study, in which it was concluded that atrial glands are the sites of sex pheromone production in P. americana, and from GC analysis the quantity of PB was estimated to be 60 ng/female. There was no difference in sexual behaviors induced by colon and atrial glands of calling virgin females. It is unclear whether the colon is the sole sex pheromone source in the female American cockroach.

Temporal resolution of general odor pulses by olfactory sensory neurons in American cockroaches

Behavioral and physiological evidence indicates that insect pheromone sensory neurons are able to resolve pulses of pheromone concentration as they occur downwind from a point source, but the abilities of insect sensory neurons that are sensitive to general odors to respond to pulsatile stimuli are unknown. The temporal response characteristics of olfactory sensory neurons of female American cockroaches Periplaneta americana in response to general odors were measured using a series of short odor pulses (20­400 ms). Odor pulses were delivered to olfactory sensilla in a moving airstream controlled by electromagnetic valves. The responses of sensory neurons were recorded using a tungsten electrode placed at the base of the sensillum. The temporal responses of sensory neurons followed the temporal changes in stimulus concentration, which were estimated by replacing the odorant with oil smoke and measuring the concentration of smoke passing through a light beam. Spike frequency varied with odorant concentration with surprisingly fine temporal resolution. Cockroach olfactory sensory neurons were able reliably to follow 25 ms pulses of the pure odorant 1-hexanol and 50 ms pulses of the complex odor blend coconut oil. Lower concentrations of odorants elicited responses with lower peak spike frequencies that still retained the temporal resolution of the stimulus pulses. Thus, responses of olfactory sensory neurons can reflect the fine structures of non-uniform distributions of general odorants in a turbulent odor plume as well as the average odorant concentration.

Coding properties of peak and average response rates in American cockroach olfactory sensory cells

The response of phasic neurons is often measured in terms of average spiking rates over arbitrarily selected time intervals. Averages taken over inappropriate intervals may severely reduce the information content of data, as we show here using response data from female American cockroach peripheral olfactory cells. We demonstrate that a 100-ms period around the peak response contains the best information for discriminating among odors at moderate to high concentrations. Further, the 100-ms post-peak response period contains the best information at low concentrations, as well as in situations where it is important to minimize errors in misidentifying the quality of an odor. Averaging the data over the full 0.5 s stimulus period degrades the odor separation qualities of the data.

Host-location kairomone fromPeriplaneta americana (L.) for parasitoidAprostocetus hagenowii (Ratzeburg)

Chemically mediated host location in the eulophid parasitoidAprostocetus hagenowii (Ratzeburg) was investigated. In Y-tube bioassays 77.6% of female parasitoids responded to aPeriplaneta americana (L.) ootheca; parasitoids did not respond to air with no volatile stimuli. Frass from adult cockroaches was as attractive as an ootheca. Bioassay of one ootheca equivalent of five lipid fractions (eluted with hexane and 1, 5, 10, and 30% ether in hexane) from silica gel column chromatography indicated that the active component was a hydrocarbon. Further separation and bioassay of oothecal hydrocarbons by AgNO3-impregnated silica gel column chromatography indicated that the biological activity was in one fraction. Gas chromatographic (GC) analysis of this fraction revealed a single peak; this peak was identified by researchers in 1963, 1969, and 1972 as (Z,Z)-6,9-heptacosadiene. Qualitative and quantitative GC analyses of total hydrocarbons from oothecae, frass, and adult females were essentially identical; 6,9-heptacosadiene was the dominant hydrocarbon from each source. The alkadiene was 37 times more abundant in frass than on the ootheca. The volatilization of the alkadiene from oothecae was demonstrated by aeration and trapping on Super Q adsorbent. The current study is the first evidence for biological activity of (Z,Z)-6,9-heptacosadiene, a major hydrocarbon component on adult female American cockroaches, on their oothecae, and in their frass.

Endogenously Produced Repellent from American Cockroach (Blattaria: Blattidae): Function in Death Recognition

Ethanol extracts from the bodies of male or female American cockroaches, Periplaneta americana (L.), repel conspecifics of all ages and sexes from shelters during the photophase. Full repellency is obtained above a dosage of 1.6 cockroach equivalents per shelter. The repellent is endogenously produced, is distributed throughout the bodies of individuals of both sexes, and is effective against at least four other species of cockroaches of diverse phylogenetic relationship, including the German cockroach, Blattella germanica (L.). There was no evidence that the repellent is released by living insects as an alarm pheromone. The active materials (identified elsewhere as unsaturated fatty acids) differ from the proteinaceous dispersion-inducing substance produced by living German cockroaches. There was no evidence that the repellent reported here was released from living cockroaches, even at very high population densities. Cockroaches were repelled, however, by intact and ruptured corpses. The repellent may function as a cue for avoiding areas where other cockroaches have died. A literature review suggests that unsaturated fatty acids may elicit avoidance of dead conspecifics across wide phylogenies of invertebrates.

Purification and characterization of vitellogenin from the American cockroach, Periplaneta americana

Abstract 1. 1. Vitellogenin (VG) was isolated and purified from the hemolymph of female American cockroaches. 2. 2. The purification method used in this study comprises two steps: the first step is based on the method originally developed for purifying lipophorin from hemolymph, and the second step is the separation of VG from lipophorin by a KBr density gradient ultracentrifugation. 3. 3. The purified VG was characterized according to molecular weight, substructure, shape and size, and lipid composition. 4. 4. The VG molecule is almost globular in shape with the diameter of about 15.5 nm and is indistinguishable from lipophorin in shape and size. 5. 5. The native molecular weight determined by light scattering method was 560 kDa. 6. 6. The VG consists of four subunits with molecular weights of approximately 102, 81, 49 and 40 kDa, respectively. 7. 7. VG is a lipoprotein and comprises 92% protein and 8% lipid. 8. 8. Major lipid components were found to be diacylglycerol (25%) and phospholipids (71%).

Structure-function studies on neurohormone D: activity of naturally-occurring hormone analogues

The relative potencies of 11 naturally-occurring peptides of the adipokinetic hormone/red pigment-concentrating hormone family (AKH/RPCH-family) have been assessed with respect to increase in heart rate in adult, female American cockroaches, Periplaneta americana, in in vitro and in vivo bioassays. In addition, analogues that lacked the N-terminal pyroglutamate residue or had a free threonine acid at the C-terminus were also investigated. In both bioassays the N- or C-terminal-modified analogues give no or little response suggesting that blocked termini are essential for receptor-binding. In both bioassays the naturally-occurring peptide from the cockroach corpus cardiacum Pea-CAH-I (neurohormone D) is more potent than the second endogenous peptide, Pea-CAH-II. On the basis of this result and previous data it is proposed that neurohormone D is the only physiologically important "true" cardioactive peptide. The dose-response curves of the other peptides indicate that in octapeptides, amino acid residues at positions 2, 6, and 7 are important for receptor-recognition, and that decapeptides are not as effective as octapeptides (exception: the peptide Rom-CC-I isolated from the grasshopper Romalea microptera).

Periplanon D1 und periplanon D2-zwei neue biologisch aktive germacranoide sesquiterpene aus periplaneta americana

Two novel bioactive sesquiterpenes 3 and 4a have been isolated from the faeces of female American cockroaches and identified on the basis of spectroscopic data and comparison with synthetic material.

Identifizierung und synthese von periplanon A

The pheromone periplanone-A has been isolated from fecal material of the female American cockroach (Periplaneta americana). The structure of periplanone-A was deduced spectroscopically and proved by its synthesis.

Effect of gender on the inducible humoral immune response to honeybee venom in the american cockroach ( [formula omitted][formula omitted

It is well known that in higher animals, the female of the species usually possesses a superior immune response to that of the male. We investigated the possibility that this rule of nature might also be true amongst the invertebrates. Adult female American cockroaches ( Periplaneta americana ) were immunized with Honeybee venom, and their responses were compared to that of the adult male. The female primary response was found not only to be enhanced, but prolonged as compared to the male. The response was also specific and demonstrated long-term immunological memory. Thus, the humoral immune response of this advanced invertebrate shares yet another characteristic common to higher vertebrates, since the female of the species demonstrated much better immune responsiveness than the male.

On the function of sex pheromone components in Periplaneta americana: improved odour source localization with periplanone‐A

ABSTRACT. The female American cockroach, Periplaneta americana L., produces two sex pheromone components: periplanone‐A (PA) and periplanone‐B (PB). PB induces male locomotion and upwind orientation. PA, when presented alone, has the same effect but with a higher threshold concentration. When added to PB in the natural ratio, however, PA reduces rather than increases locomotory activity. To examine whether PA affects male orientation in the natural blend, a pheromone source was suspended above the centre of a circular arena. Efforts were made to exclude air movements so that pheromone concentration declined centrifugally. Males walking in a PB gradient spent more time near the source than in the peripheral areas when low doses were presented. At emission rates approximately equivalent to those of a female, however, they were not able to locate the pheromone source as precisely as at lower rates. In contrast, males walking in a PA gradient spent more time in the centre of the arena when the pheromone dosage was increased. When PA was added to natural levels of PB, males walked more slowly and stopped more frequently near the source than with PB alone. Thus PA improves chemo‐orientation of males when presented in a natural ratio with PB. A reduction of linear velocity near the pheromone source (an orthokinetic effect) is involved in this process.

Behavioural responses to female sex pheromone components in Periplaneta americana

Female American cockroaches, Periplaneta americana, release two sex pheromones, periplanone-A and periplanone-B, each of which is perceived by a specialized receptor type on the male antennae. This study investigates whether male behavioural responses to both components may differ qualitatively or quantitatively. Running, upwind orientation and wing-raising were evoked by stimulation with either component. The intensity of running increased with stimulus concentration in much the same way for both substances. However, the relative effectiveness of periplanone-A was 30 times lower in behavioural assays than in the electroantennogram. Behavioural responses to periplanone-B declined faster and were more easily adapted by repeated stimulation than those to periplanone-A. It is hypothesized that periplanone-B is responsible for long distance attraction while periplanone-A influences male behaviour near the female.

Diacylglycerol-carrying lipoprotein of hemolymph of the American cockroach: purification, characterization, and function

A diacylglycerol-carrying lipoprotein (DGLP) was isolated from the hemolymph of adult male and female American cockroaches, Periplaneta americana. The purification procedure involved dialysis against distilled water, precipitation at low ionic concentration at pH 6.6, and separation by column chromatography on DEAE-cellulose. The final preparation was homogeneous as judged by polyacrylamide gel electrophoresis and electron microscopy. The lipoprotein comprised over 50% of the total hemolymph protein. The DGLP molecule was almost globular in shape with a diameter of approximately 160 A. The molecular weight, determined by a sedimentation-equilibrium method, was approximately 600,000. Apoprotein of DGLP consisted of two subunits, heavy chain (mol wt 250,000) and light chain (mol wt 85,000). The total lipid content of DGLP amounted to about 50%. The lipids comprised diacylglycerol (15% of total lipid), hydrocarbons (28%), cholesterol (5%), and phospholipids (43%). n-Pentacosane, 3-methylpentacosane, and 6,9-heptacosadiene were identified as major hydrocarbons. Mannose(0.9%) and glucosamine (0.3%) were associated with apoprotein of DGLP. The capacity of the purified DGLP to accept diacylglycerol from both fat body and midgut was demonstrated in vitro; thus it was suggested that the same carrier molecule served to transport this lipid from storage site and absorption site. The possible multiple role of cockroach DGLP in transporting such lipids as diacylglycerol, cholesterol, and hydrocarbon from the site of storage, absorption, or synthesis is discussed.

The role of vertical and horizontal object orientation in mate-finding and predator-avoidance by the American cockroach

Air currents with and without sex pheromone were presented perpendicularly to the dorsum of individual male and female American cockroaches, Periplaneta americana, on horizontal and vertical surfaces. Males and females on the horizontal surface turned in small angles (0 ° to 90 °) in response to air currents with and without sex pheromone (horizontal object orientation). On the vertical surface, tethered males and females consistently moved upward in response to air currents without sex pheromone (predator-avoidance), whereas males moved downward in response to air currents with sex pheromone (mate-finding). Male and female vertical distributions in a semi-natural situation revealed that most males were found above some females.

Electroantennogram Responses from Parts of Antennae of the American Cockroach

Electroantennograms (EAG) were recorded from the distal, middle and basal parts of the antennae of adult male and female American cockroach. Stimulating chemicals employed were three sex pheromone mimics [(-)-bornyl acetate, (+)-trans-verbenyl acetate and germacrene-D] and a general odor (nerol). EAG responses produced from the male antennae were greater than those from females at any part of the antenna in all compounds. Among the antennal regions, the middle region was stimulated with the strongest EAG response in the male, whereas the distal region was most strongly stimulated in the female with any stimulus. From the above EAG results, the distribution of olfactory sensilla on the antennae is discussed along with the observations of morphologists.