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PubMed1998

A dose-response relationship between exposure to cockroach allergens and induction of sensitization in an experimental asthma in Hartley guinea pigs.

OBJECTIVE: An indoor allergen, cockroach allergen (CRa) has been partly implicated in the rising prevalence of inner-city asthma. This study investigates a dose-response relationship of exposure to CRa with the degree of sensitization and with airway inflammation through the use of our established guinea pig asthma model. METHODS: Four groups of Hartley guinea pigs were exposed to aerosolized saline (control) and three dose levels of CRa: low-dose, 0.5 mg (LD); medium-dose, 5 mg (MD); or high-dose, 25 mg (HD), nebulized twice a day, 5 days per week, for 4 weeks. The development of anaphylactic antibodies was measured by both allergy skin test and passive cutaneous anaphylaxis assay. Animals were challenged with CRa 5 days after the last sensitization, and specific airway resistance was measured continuously by a double-chamber plethysmograph while animals were in the conscious state. The inflammatory cells in bronchoalveolar lavage fluid (BALF) and the contractile responses of tracheal rings were analyzed in vitro at 24 hours after CRa challenge. RESULTS: The anaphylactic antibodies to CRa were detected in the CRa-sensitized animals by allergy skin test. Passive cutaneous anaphylaxis titers of IgG1a-like antibody were zero in control, 1:2 in LD, 1:40 in MD, and 1:160 in HD. Total leukocytes in BALF were increased by CRa challenge in all three CRa-sensitized groups compared with control (p < 0.0001). The tracheal rings from CRa-sensitized guinea pigs constricted upon addition of incremental doses of CRa challenge in vitro in a dose-responsive manner (p < 0.0001). The leukocytosis in BALF and the anaphylactic contractile responses of the tracheal rings in CRa-sensitized groups were correlated to the levels of CRa to which the groups had been exposed during sensitization (p < 0.001). CRa-provoked increase in SRaw was noted in all three groups of the CRa-sensitized guinea pigs compared with control (p < 0.01). Yet, among CRa-sensitized groups, a greater increase in specific airway resistance was noted in the LD group but not in the HD CRa group. CONCLUSIONS: The development of anaphylactic cockroach sensitivity in guinea pigs was dependent on the levels of CRa exposure during sensitization, and the CRa-sensitized animals showed antigen-specific airway inflammation along with airway smooth muscle contractions. However, the severity of bronchospasm in conscious animals was not in agreement with the degree of CRa sensitivity.

Allergens↗
PubMed1996

Cockroach transferrin closely resembles vertebrate transferrins in its metal ion-binding properties: a spectroscopic study.

The optical and electron paramagnetic resonance (EPR) spectroscopic properties of a transferrin from the cockroach Blaberus discoidalis have been investigated to determine the relation of this protein to vertebrate transferrins. Difference spectrophotometry substantiates the involvement of tyrosyl residues in iron binding, and confirms the specific binding of two equivalents of iron per molecule. The far-UV CD spectrum also indicates a secondary structure with marked similarity to those of vertebrate transferrins. EPR studies show a dependence of iron binding on (bi)carbonate, consistent with the absolute requirement of transferrins for a synergistic anion in binding iron. Continuous wave (CW) and pulsed EPR studies of the cupric complex of the protein implicate a histidyl nitrogen ligand in metal coordination, as in human transferrin. Additional studies establish that the pH-dependent release of iron is similar to that of human serum transferrin. The present data confirm cockroach transferrin as an authentic member of the transferrin superfamily, thereby suggesting an ancestral relationship of insect to vertebrate transferrins.

Animals↗
PubMed1998

An aminoisobutyric acid-containing analogue of the cockroach tachykinin-related peptide, LemTRP-1, with potent bioactivity and resistance to an insect angiotensin-converting enzyme.

Nine tachykinin-related peptides (TRPs), designated LemTRP-1-9, were recently isolated from the cockroach, Leucopheae maderae. To obtain a LemTRP resistant to endo- and exoprotease-mediated hydrolysis, we synthesized a peptide with one of the carboxy terminus residues substituted for a sterically hindered aminoisobutyric acid (Aib) and with the amino terminus blocked with a pyroglutamate. The Aib-containing analogue of the nonapeptide LemTRP-1 (Aib-LemTRP-1) thus has the sequence pGlu-Ala-Pro-Ser-Gly-Phe-Leu-Aib-Val-Arg-NH2. This analogue was shown to be resistant to hydrolysis by recombinant angiotensin-converting enzyme (ACE), from Drosophila melanogaster. Endogenous LemTRP-1 on the other hand was rapidly hydrolysed by ACE at the Gly7-Val8 bond, resulting in a single heptapeptide. The Aib-LemTRP-1 has about the same potency as LemTRP-I in inducing contractions of the L. maderae hindgut muscle. It was also tested in intracellular recordings for ability to induce firing of action potentials in dorsal unpaired median (DUM) neurons in the metathoracic ganglion of the locust Locusta migratoria. The Aib-containing analogue was nearly as active as LemTRP-1 and the natural ligand locustatachykinin I. LemTRP-1 and Aib-LemTRP-1 had the same transient time course of action on the cockroach hindgut. This suggests that peptide degradation is not likely to be the cause of the transient action of TRPs.

Amino Acid Sequence↗
PubMed1998

The muscular contractions of the midgut of the cockroach, Diploptera punctata: effects of the insect neuropeptides proctolin and leucomyosuppressin.

We have previously shown differential expression of leucomyosuppressin (LMS) mRNA in apparent endocrine cells in the anterior region of midguts of the cockroach Diploptera punctata, using in situ hybridization. In contrast, other FMRFamide-related peptides, as revealed by immunohistochemistry, have been found most abundantly in the posterior region in both apparent endocrine cells and nerve tracts. Here, we partially purified extracts of anterior and posterior cockroach midguts, using HPLC coupled with radioimmunoassay, and found, among multiple FMRFamide-like immunoreactive fractions, one fraction co-eluting with LMS in both regions. The presence of a co-eluting fraction in the posterior region, in the absence of LMS mRNA positive endocrine cells suggests that LMS might therefore be present in nerve tracts running along the length of the midgut. Using a circular muscle contraction assay from different portions of midgut, we determined the effects of LMS, proctolin and a variety of other midgut peptides on contractions of the midgut of Diploptera. Proctolin caused a sustained tonic contraction in the anterior midgut, the amplitude of which was dose-dependent. In contrast, LMS, and its relative SchistoFLRFamide, reduced the amplitude of these contractions. LMS and SchistoFLRFamide also inhibited spontaneous phasic contractions, which were elicited by proctolin application in only a few preparations. Other postulated midgut peptides did not induce or inhibit contractions, nor augment the proctolin-induced contractions. The C-terminal truncated sequences of LMS, HVFLRFamide and VFLRFamide, were sufficient to reduce the amplitude of the proctolin-induced contractions. This work illustrates a possible physiological role for LMS in Diploptera midguts, in the passage of food along the alimentary canal.

Animals↗
PubMed1997

Seven tachykinin-related peptides isolated from the brain of the Madeira cockroach: evidence for tissue-specific expression of isoforms.

We have isolated seven tachykinin-related peptides (TRPs) from an acidic extract of 1000 brains of the cockroach Leucophaea maderae. Four different reversed-phase high performance liquid chromatography (RP-HPLC) column systems were required to obtain pure peptides. During the purification the fractions were monitored in a radioimmunoassay (RIA) with an antiserum to locust TRP locustatachykinin I (LomTK I) and a cockroach hindgut muscle contraction bioassay. The sequences of the seven isolated LomTK immunoreactive and myostimulatory peptides were determined by Edman degradation. Six of these were confirmed by mass spectrometry and chemical synthesis as: APSGFLGVRamide, APAMGFQGVRamide, APAAGFFGMRamide, VPASGFFGMRamide, GPSMGFHGMRamide, and APSMGFQGMRamide. The seventh peptide, APEESPKRAPSGFLGVRamide, was confirmed only by mass spectrometry. These peptides were designated Leucophaea maderae tachykinin-related peptides 1, 2, 5-9 (LemTRP 1, 2, 5-9). Two more peptides were isolated using the same assays: SGLDSLSGATFGGNR and ALFEESTVSAEPR. The first shares the C-terminus FX1GX2R with the Lem TRPs, whereas the second one is not related to the TRPs (none of these peptides were synthesized and thus putative C-terminal amidation was not confirmed). Three of the brain peptides, LemTRP 1, 2, and 5, have previously been isolated from the midgut of L. maderae, whereas the others appear to be brain specific. Because the LemTRPs 3 and 4 appear to be unique for the midgut, we have indications for tissue-specific expression of TRPs. All seven confirmed LemTRPs of the brain are myotropic and induce increases in the amplitude and frequency of spontaneous contractions and tonus of hindgut muscle in L. maderae.

Amino Acid Sequence↗
PubMedDate not supplied

Rate code input produces temporal code output from cockroach antennal lobes.

The experiments presented here were designed to determine the origin of the temporally complex activity of antennal lobe projection neurons in the cockroach olfactory system. We determined this through the use of complex chemical stimuli that evoked neural activity recorded extracellularly from olfactory sensory neurons and intracellularly from antennal lobe projection neurons in the cockroach Periplaneta americana. Olfactory information was represented by a simple, short time-scale rate code in the olfactory sensory neurons. This rate code input from the sensory neurons was processed by the antennal lobe and transformed into a longer time-scale, temporally encoded output expressed across a smaller population of antennal lobe projection neurons. The projection neuron responses comprised temporal patterns of increases and decreases in spike frequency that differed among projection neurons and were consistent among repeated presentations of the same stimulus. Presentation of simple and complex chemical stimuli showed that the complexity of projection neuron activity was a product of the antennal lobes and was not associated with the chemical complexity of the stimulus. To characterize the encoding schemes used by each class of neurons, the responses were decomposed into their principal components. The stimulus was correlated with only the first principal component of the activity of sensory neurons, which is consistent with a rate encoding scheme. The stimulus was correlated with higher order principal components of the activity of projection neurons, which is consistent with a temporal encoding scheme.

Action Potentials↗
PubMed1989

Analysis of biogenic amines in the brain of the American cockroach (Periplaneta americana) by gas chromatography-negative ion chemical ionisation mass spectrometry.

Biogenic amines in the brain of the American cockroach have been identified and quantified by an extraction-derivatisation procedure involving their reaction with ditrifluoromethylbenzoyl chloride (DTFMB) in the aqueous phase followed by extraction into an organic solvent, hydrolysis of phenolic esters and conversion of free hydroxyl groups to trimethylsilyl (TMS) ethers and subsequent analysis by gas chromatography-negative ion chemical ionisation mass spectrometry. The molecular ion of these DTFMB-TMS derivatives carried most of the ion current which made the method highly specific and gave a potential limit of detection below the picogram level. This method establishes unequivocally that the principal amines in cockroach brain are tyramine, p-octopamine, dopamine, 5-hydroxytryptamine and noradrenaline. In contrast to mammalian nervous tissue, the other positional isomers of octopamine, together with the isomeric synephrines, are absent.

Animals↗
PubMed2000

Substrate-stereoselectivity of a high-affinity glutamate transporter cloned from the CNS of the cockroach Diploptera punctata.

A cDNA encoding a Na(+)-dependent glutamate transporter has been cloned from the brain of the cockroach Diploptera punctata. The cDNA encodes a transporter protein of 481 amino acids, designated DipEAAT1, which when expressed in baculovirus infected insect cells, resulted in a 40-50 fold increase in [(3)H]L-glutamate uptake. DipEAAT1 mRNA is expressed in the brain, as is the RNA encoding TrnEAAT1, a related transporter recently isolated from the caterpillar Trichoplusia ni. The affinity of these transporters for L-glutamate and several structural analogues was compared. Both have a high affinity for L-glutamate, their presumed primary substrate, but quite different affinities for D-aspartate. TrnEAAT1 was found to be similar to other glutamate transporters in that its ability to transport [(3)H]L-glutamate into cells was inhibited strongly by D- and L- isomers of aspartate and its analogues. DipEAAT1, by contrast, was inhibited weakly by all D- isomers tested. The affinity of DipEAAT1 for [(3)H]D-aspartate was found to be an order of magnitude lower than that of TrnEAAT1, revealing an unusual stereoselectivity for aspartate substrates by the cockroach transporter. The activity of DipEAAT1 was also unaffected by the presence of Zn(++) in the bathing solution, despite the presence of a putative Zn(++)-binding motif conferring Zn(++)-sensitivity on some mammalian glutamate transporters.

ATP-Binding Cassette Transporters↗
PubMedDate not supplied

Nadph-diaphorase activity in corpus allatum cells of the cockroach, Diploptera punctata.

Using the fixation insensitive NADPH-diaphorase reaction as a histochemical marker for the enzyme nitric oxide synthase (NOS), we investigated the possible sites of putatively NOS-related NADPH-diaphorase in the brain and retrocerebral complex of the cockroach, Diploptera punctata. In the cerebral ganglion, NADPH-diaphorase expression was localized in antennal lobes, optic lobes, mushroom bodies and neurosecretory cells. The highest NADPH activity was detected in the corpora allata (CA). Spectrophotometric quantitation indicated that NADPH-diaphorase activity first increased and then decreased (cycled) in the CA of mated females. In addition, during the first ovarian cycle, NADPH-diaphorase activity fluctuated concurrently with cyclic changes in the size of corpus allatum cells. In virgin females, NADPH-diaphorase activity remained at a low level, but it increased if the neural connectives between CA and brain were severed, indicating that the brain inhibited NADPH-diaphorase expression in the CA. Although nerve terminals were abundant in the CA, NADPH-diaphorase was clearly endogenous and synthesized by glandular cells, as was shown by histochemical staining of the cytosol in all dissociated cells of the CA. We have also demonstrated NADPH-diaphorase activity in the CA of the American cockroach Periplaneta americana, the house cricket Acheta domesticus, the lepidopteran Leucania loreyi, and the fruit fly Drosophila melanogaster, suggesting that NOS occurs in the CA of most, if not all insects. It is therefore possible that corpus allatum cells release NO, along with juvenile hormone, which presumably can function as a messenger molecule.

Animals↗
PubMedDate not supplied

The interactions between juvenile hormone (JH), lipophorin, vitellogenin, and JH esterases in two cockroach species.

For the cockroach species Leucophaea maderae and Periplaneta americana two major juvenile hormone (JH)-binding proteins have been identified: lipophorin (Lp) and vitellogenin (Vg). Each of these macromolecules binds JH with an approximate affinity of K(d) of 10 nM. In Leucophaea the concentration of Lp is augmented by JH during vitellogenesis at the same time when Vg is induced de novo. The circulating levels of each of Lp and Vg at mid-vitellogenesis are in the 10 microM range. Similar values have been determined for Periplaneta. Total JH concentrations (bound and free) can be as high as micromolar in Leucophaea. However, because of the large quantities of the two major JH-binding proteins and their high affinity for JH, we can assume that the amount of free (unbound) JH in circulation is extremely low (the actual values are not know). The JH esterases (JHEs) of the hemolymph in both cockroach species have been isolated by anion exchange chromatography. The JHEs of Leucophaea bound to the anion exchange resin more tightly than the JHE of Periplaneta. The V(max) of the Leucophaea esterases fluctuated by a factor of 2 to 3 during vitellogenesis. The K(m) values for the two distinct esterases of Leucophaea were similar (about 0.15x10(-6) M). On the other hand, k(cat) of the JHEs for Leucophaea at ovulation time was two to three times higher than earlier during vitellogenesis, i.e. 23.30 min(-l) compared to 6.20 min(-1). The JHE of Leucophaea is shown to bind JH III with high affinity: K(d)=3x10(-9) M. However, since there are only very small amounts of JH available for degradation (due to the binding to Lp and Vg), the quantitative removal of JH from circulation, and this includes the release of bound JH, is indeed slow, with a measured half-life of 6-8 h. Classical kinetic assumptions are not met in conditions where the enzyme concentrations exceed by far that of the available substrate. Nonetheless, we attempted to determine the initial velocity of JH hydrolysis under natural conditions, i.e. for undiluted hemolymph, by measuring the initial velocities of JH hydrolysis in serially diluted hemolymph and extrapolating to zero dilution. For in vivo conditions we estimated an initial velocity of JH hydrolysis of <0.1 fmol microl hemolymph(-1) min(-1), i.e. four to five orders of magnitude lower than that measured at substrate saturation in vitro.

Animals↗
PubMed2002

Synergistic interaction between two cockroach sodium channel mutations and a tobacco budworm sodium channel mutation in reducing channel sensitivity to a pyrethroid insecticide.

Pyrethroid insecticide resistance due to reduced nerve sensitivity, known as knockdown resistance (kdr or kdr-type), is linked to multiple point mutations in the para-homologous sodium channel genes. Previously we demonstrated that two mutations (E434K and C764R) in the German cockroach sodium channel greatly enhanced the ability of the L993F mutation (a known kdr -type mutation) to reduce sodium channel sensitivity to deltamethrin, a pyrethroid insecticide. Neither E434K nor C764R alone, however, altered sodium channel sensitivity. To examine whether E434K and C764R also enhance the effect of pyrethroid resistance-associated sodium channel mutations identified in other insects, we introduced a V to M mutation (V409M) into the cockroach sodium channel protein at the position that corresponds to the V421M mutation in the Heliothis virescens sodium channel protein. We found that the V409M mutation alone modified the gating properties of the sodium channel and reduced channel sensitivity to deltamethrin by 10-fold. Combining the V409M mutation with either the E434K or C764K alone did not reduce the V409M channel sensitivity to deltamethrin further. However, the triple mutation combination (V409M, E434K and C764R) dramatically reduced channel sensitivity by 100-fold compared with the wild-type channel. These results suggest that the E434K and C764R mutations are important modifiers of sodium channel sensitivity to pyrethroid insecticides.

Animals↗
PubMed2002

Vitellogenin of the cockroach, Leucophaea maderae: nucleotide sequence, structure and analysis of processing in the fat body and oocytes.

A cDNA encoding vitellogenin (Vg) of the cockroach, Leucophaea maderae was cloned and sequenced. The deduced amino acid sequence consisting of 1913 residues (including 15 residues for a putative signal peptide) was obtained. Amino-terminal sequence analysis demonstrated that the pro-Vg was cleaved into four polypeptide 'subunits' following the three consensus RXXR cleavage site sequences, which were secreted as four Vg polypeptides (apparent molecular weights = 112-, 100-, 92- and 55-kD), sequestered, and deposited in the egg as four respective vitellin (Vn) polypeptides. There was, however, an additional 90-kD Vn polypeptide existed in the egg. We show that this polypeptide is a processed product from 92-kD Vn polypeptide. Northern blot analysis of poly (A)+ RNA reveals that mRNA coding for Vg is present only in the female fat body cells but neither in the ovary nor in the male fat body cells. The deduced amino acid sequence contained a serine-rich stretch at the C-terminal region. This stretch occurred also in Vgs of Periplaneta americana (Vg1 and Vg2) and Blattella germanica. The Vg of L. maderae had 26% and 31% homology with those of P. americana (Vg1 and Vg2) and B. germanica, respectively. Phylogenetic analysis (neighbour-joining) was made using four cockroach Vgs and the tree was compared with other molecular and conventional phylogenetic trees.

Adipose Tissue↗
PubMed1996

Characterization of the gene for leucomyosuppressin and its expression in the brain of the cockroach Diploptera punctata.

Using HPLC separation, radioimmunoassay, and subsequent bioassay, we have detected the presence of an active peptide, which co-elutes with the insect myoinhibitory peptide leuco-myosuppressin, in the brain of the cockroach Diploptera punctata. We have isolated a cDNA encoding the precursor for this peptide from cDNA libraries representing D. punctata brain RNA. The cDNA sequence contains an open reading frame that upon translation would result in a prepropolypeptide of 96 amino acids. Proteolytic cleavage of the predicted precursor could result in several peptides, including a 10 amino acid C-terminal peptide that would, upon modification of the NH2 and COOH-terminal amino acids, be identical to the insect FLRFamide, leucomyosuppressin. No other RFamide products are predicted to be processed from the precursor. Southern blot analysis indicates that the gene is present in the D. punctata genome in a single copy. Northern blot analysis shows that the gene is predominantly expressed as a 3.8 kb mRNA in cockroach brain. Study of the expression of the leucomyosuppressin gene in D. punctata brain, using in situ hybridization, indicates that expression occurs primarily in the pars intercerebralis of the protocerebrum, a region showing abundant FMRFamide-like immunoreactive neurosecretory cells. Immunohistochemistry and HPLC coupled to radioimmunoassay indicates that leucomyosuppressin represents a significant proportion of FMRFamide-related peptide production in the brain. However, HPLC analysis also indicates the presence of significant levels of other related peptides, demonstrating the presence of more than one FMRFamide-related gene in this insect.

Amino Acid Sequence↗
PubMed1998

Cytochrome P450 purification and immunological detection in an insecticide resistant strain of German cockroach (Blattella germanica, L.).

A German cockroach strain, Munsyana (MA) had 80-fold resistance to the pyrethroid insecticide cypermethrin, 4.5-fold greater total cytochrome P450 content and 2.5-fold greater cytochrome P450-mediated N-demethylation of 4-chloro-N-methylaniline compared to the susceptible Johnson Wax (JWax) strain. Immobilized artificial membrane high performance liquid chromatography (IAM-HPLC) of microsomal proteins from the MA strain enriched cytochrome P450 greater than 70-fold. Following purification, a single protein band of M(r) = 49,000 (P450 MA), was detected by silver-staining SDS PAGE gels. Antiserum to the purified protein from the MA strain (anti-P450 MA) was produced in mice. Anti-P450 MA inhibited cytochrome P450-mediated N-demethylation by 4-fold in both MA and JWax strains. In Western blots of microsomal proteins, anti-P450 MA differentiated single MA and JWax individuals by recognizing and M(r) 49,000 protein band in only the MA strain. In JWax cockroaches, the M(r) 49,000 band was only detectable in Western analysis following induction with pentamethylbenzene (PMB). PMB induction also increases N-demethylation 2.6 and 8.0-fold in the MA and JWax strains, respectively. These results are consistent with the hypothesis that insecticide resistance in the MA strain is due to over-expression of a cytochrome P450.

Animals↗
PubMed2002

Structure-activity relationships of benzylidene anabaseines in nicotinic acetylcholine receptors of cockroach nerve cords.

Ten analogues of 6'-chloro-3-benzylideneanabaseine (CBA) bearing substituents at the ortho- and the para-positions of the phenyl group were synthesized, together with two related compounds. The affinity of the synthesized compounds for nicotinic acetylcholine receptors (nAChRs) in the nerve cord of the American cockroach (Periplaneta americana L.) was examined by the radioligand binding assay using [(3)H]epibatidine (EPI), a nAChR agonist. All 12 tested compounds inhibited [(3)H]EPI binding, showing K(i) values ranging from 14.6 to 6830nM. The potency variation of para-substituted CBA analogues was explained by the steric (Delta B(1)) and electronic (sigma(p)) parameters of the para-substituents, or by the steric parameter and the charge of the N1 nitrogen atom (qN(1)). Among the CBA analogues, only two compounds containing a dimethylamino group and a methoxy group at the para-position showed high insecticidal activity against the German cockroach (Blattella germanica) when injected after pretreatment with metabolic inhibitors. High-affinity analogues of CBA might be suitable probes for use in classifying and characterizing insect nAChR subtypes.

Anabasine↗
PubMed2001

Inositol trisphosphate mediates the action of hypertrehalosemic hormone on fat body of the American cockroach, Periplaneta americana.

The rate of synthesis of inositol trisphosphate (InsP(3)) in trophocytes derived from disaggregated cockroach (Periplaneta americana) fat body increases following treatment of the cells with hypertrehalosemic hormone I or II (HTH-I, -II) in vitro. Trophocytes preloaded with [3H]inositol display a significant increase in InsP(3) synthesis as early as 15 s after addition of the hormone. When the trophocytes are pre-incubated with LiCl and subsequently incubated with HTH the [3H] content of the InsP(3) fraction is greater than that found with HTH alone. This is taken as evidence that inositol monophosphate phosphatase is part of the mechanism for clearing InsP(3) from the cytosol. In contrast to HTH, octopamine, which is also capable of exerting a hypertrehalosemic effect in the cockroach, does not increase the synthesis of InsP(3). 1-Octadecyl-2-methyl-rac-glycero-3-phosphocholine (ET-18-OCH(3)), a potent and selective inhibitor of phosphatidylinositol phospholipase C, blocks the activation of phosphorylase by HTH-I as well as the hypertrehalosemic effect induced by the hormone.

Animals↗
PubMed2003

La Réunion and Mayotte cockroaches: impact of altitude and human activity.

Competitive displacement is the outcome of interspecific competition between invading and native species. Alien insect species invade not only cultivated areas but also natural habitats. We prospected the cockroach fauna on two oceanic islands (Mayotte and La Réunion) to investigate the impact of altitude and anthropic disturbance on the distribution of these species. Most invading cockroach species seem to benefit from cultivation of land whereas endemic species occupy more specific and reduced habitats that are threatened by human impact.

Animals↗
PubMed1978

Observations of the effects of formaldehyde on cockroaches and their flora: III. The effect of formaldehyde in eliminating the normal gut flora.

The normal flora of cockroaches (Periplaneta americana) was determined over a period of 24 days prior to substituting water with 1% Formalin for drinking water. During the first 4 days of treatment the normal flora was significantly reduced and by the fifth day, when the cockroaches became diarrhoeic, no bacteria, fungi, or viruses could be detected by the methods used.

Animals↗