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PubMed2004

Stereochemistry of insect kinin tetrazole analogues and their diuretic activity in crickets.

Insect kinin analogues of the sequence Phe-Phe-psi[CN(4)]-Ala-Trp-Gly-NH(2) containing (L-Phe(2),L-Ala(3)) and (L-Phe(2),D-Ala(3)) stereochemical variants of the tetrazole moiety, a mimic of the type VI beta-turn, demonstrate significant agonist and partial antagonist activity, respectively, in a cricket diuretic bioassay. A comparison of the solution conformations of these two stereochemical variants indicates a structural basis for their divergent bioactivities. The (D-Phe(2),D-Ala(3)) stereochemical variant was synthesized and found to demonstrate significant agonist activity. The results further define stereochemical requirements for the diuretic activity of insect kinins in crickets and provide valuable information for the design of biostable analogues capable of disrupting digestive and diuretic processes in pest insects.

Amino Acid Sequence↗
PubMed2006

Hunting for insect-specific protein domains.

Automatically finding new protein domains is a challenge when using the complete collection of known proteins (i.e., UniProt). By limiting the taxonomic range to class insecta, including two full proteomes (A. gambiae and D. melanogaster), we reduced the size of the search space in the hope of finding taxon-specific domains. The MKDOM2 program (http://prodes.toulouse.inra.fr/prodom/xdom/mkdom2.html) was used to cluster the insect proteins into potential domains that were analyzed manually in a second step. We analyzed 219 potential domains, of which 2 were insect-specific. We show that it is possible to find new domains or to extend known domains using a semi-automated method; however the goal to detect class-specific domains was only partially achieved in the sense that the new domains we found were not all insect-specific domains. The files used as input and the resulting output files, as well as extensive descriptions of the domains, are available as supplementary data from http://bioinf.ibun.unal.edu.co/insecta/.

Animals↗
PubMed1991

[Effect of selected compounds from the group of chitin synthesis inhibitors on insects of sanitary importance].

The effect of three aryl and heteroaryl dichlorobenzoylurea compounds as insect chitin inhibitors on sanitary important insects were investigated. These compounds were given insects: larvae and adults flies (Musca domestica) and cockroaches (Blattella germanica) with food. The best results on flies were after exposition to AG-6 and on cockroaches to AG-5. AG-6 complete inhibited metamorphosis after exposition of larvae and after exposition of adults in generation F1. No mature cockroaches from larvae exposed to AG-5, no hatching from cocoons lied by treated adults were observed.

Animals↗
PubMed1991

[Insect stings and visits to emergency departments].

For four representative hospitals, emergency room contacts were registered during 1988, 1989 and 1990. A total of 2,935 of these contacts were due to insect stings, equivalent to approximately 9,000 p.a. in the whole of Denmark. For insect sting allergics and for others with severe reactions to insect stings it is important to realize that stings can occur during whole year and during day as well as at night. However, 59% were stung in July or in August and 46% between 3 and 9 p.m. Stings on head or hands were most common. Only 2% required admission and only 5% were controlled in out-patient clinics or by doctors outside hospitals. This means that surprisingly few patients were referred for allergy testing and possibly immunotherapy.

Adolescent↗
PubMed1985

Disease-bearing insects brought in by international aircraft into Singapore.

Fifty-seven (17.3%) of 330 incoming aircraft landing at Changi International Airport were found to harbour mosquitoes and other insects on board. The frequency of insects detected in aircraft from the Southeast Asian countries varied from 7.1% to 32.2%. Live insects were found in 5 (6.1%) of 82 aircraft disinsectized by the "block away" method. The species of mosquitoes brought in were: Culex quinquefasciatus (96), Culex tritaeniorhynchus (1), Aedes albopictus (2) and Aedes aegypti (1). None of the 51 female Culex quinquefasciatus dissected was found to be infected with microfilariae. They key to the prevention of introduction of exotic vectors and transmission of vector- borne diseases is to continue with the existing system of vector surveillance and control at the international airport, rather than routine disinsecting of aircraft landing in Singapore.

Aircraft↗
PubMed1987

[Decrease in the milk yield in cows casued by dipterous blood-sucking insects and the protection of heifers with Oxamate, a repellent, in the area of Leningrad].

Blood-sucking dipterous insects, milk yield losses caused by these insects to cows in the pasture and the possibilities of cattle protection against these insects were investigated in the Leningrad region of the USSR in 1982-1984. The invasion by horse-flies causes the greatest trouble to grazing cattle. Twenty-five horse-fly species were identified during the study. The nine prevailing species constituted more than 85% of the horse-flies invading the animals. The horse-flies flew for 50-55 days from the beginning of June to the beginning of August; mass flights were observed for two weeks starting in the second decade of June. A twelve-hour repelling action was recorded in the Oxamate repellent applied as 20% emulsion. A new portable motor-powered aerosol sprayer was tested during the study. The losses in milk yields caused by horse-flies in the Leningrad region were computed; in the period of the horse-fly flights the milk yields are reduced by 13%. The economic benefit of the treatment of the animals with the Oxamate repellent was 9.11 roubles per rouble invested. Manitoba-type traps attracting the horse-flies to an optical bait (a black ball or cube) were used as an additional method of reducing the occurrence of horse-flies in the pasture.

Animals↗
PubMed1971

Practical aspects of insect control by juvenile hormone.

The development of juvenile hormone (JH) analogues for insect control, and their laboratory and field testing, are now being carried out on an industrial scale. Studies of the hormone action at the cellular level, and of the many implications of JH applications on various stages of the insect life-cycle, are lagging because such studies require long-term scientific involvement. Although many analogues have little specificity for particular insects, the ultimate effects may be very different. Various considerations that may influence the commercial development of JH are discussed.

Insect Control↗
PubMed1978

Allergy to insect stings. IV. Diagnosis by radioallergosorbent test (R.A.S.T.).

Radioallergosorbent tests (RAST(s)) have been developed and assessed for the diagnosis of insect hypersensitivity by using a purified allergen from honeybee venom, phospholipase A, and crude yellow jacket venom. Sera from 193 patients positive both by history and skin test to one of these insects were compared with various groups of control sera. Eighty percent of sera from skin test-positive patients were RAST positive; positive RAST were found in 16% of sera tested from skin test-negative patients. A highly positive RAST correlates well with a positive skin test and clinical sensitivity, but serum IgE is not measurable in many patients with mast cell or basophil bound antibody. Since biologically important reactions of antigen with IgE require that the antibody be cell bound, skin testing would be preferred to RAST if one were limited to a single test for the diagnosis of insect allergy.

Animals↗
PubMed1980

Mass production of insect cells in suspension.

The production of insect pathogenic viruses for the use in integrated pest control is presently done in vivo in populations of their natural hosts. However, efforts are made in several laboratories to produce some of these baculoviruses in insect cell cultures. The mass production of the viruses in vitro depends on a technology for the mass production of cells. Data are presented for the production of up to 10(10) insect cells per logarithmic growth phase in a continuously running fermenter culture at volumes of 9-10 litres.

Animals↗
PubMedDate not supplied

Central action of insect neuropeptide, periplanetin CC-1, in mice.

The central action of periplanetin CC-1 (Pea-HrTH) (Glp-Val-Asn-Phe-Ser-Pro-Asn-TrpNH2), octapeptide of the insect adipokinetic hormone family (AKH-family), isolated from American cockroach-Periplaneta americana, was studied in Albino Swiss mice (20-25 g). CC-1 was injected intracerebroventricularly (i.c.v.) in the volume of 5 microliters at the dose of 50 ng/mouse. It was found that CC-1 showed strong analgesic activity in "writhing syndrome" test and in "hot plate" test. In addition, periplanetin CC-1 decreased the threshold for tonic seizures and increased mortality in pentetrazole-induced seizures, having no influence on the electric convulsions. CC-1 is known to be a glucagon-like AKH in insects. However, administered i.c.v. to mice, it did not increase the peripheral blood glucose level. The obtained results indicate that periplanetin CC-1 shows a biological action in vertebrates, but its metabolic effects are different than in insects.

Animals↗
PubMed1998

Pharmacokinetics, formulation, and safety of insect repellent N,N-diethyl-3-methylbenzamide (deet): a review.

This review is intended to provide the reader with an overview of the all-purpose topical insect repellent N,N-diethyl-3-methylbenzamide (deet), with emphasis on its pharmacokinetics, formulation, and safety aspects. N,N-diethyl-3-methylbenzamide is effective against a variety of mosquitoes, flies, fleas, and ticks, and its protection efficacy depends on factors such as type of formulation, application pattern, physical activity of the user, environment, and species and feeding behavior of the insects. It offers an inexpensive and practical means of preventing the attack of biting insects and, more importantly, the transmission of vector-borne diseases. In both humans and animals, deet skin penetration and biodistribution are rapid and extensive, and metabolism and elimination appear to be complete. As evidenced by over 4 decades of human experience and rigorous animal testing, deet is generally safe for topical use if applied as recommended, although it has occasionally been related to side effects such as toxic encephalopathy, seizure, acute manic psychosis, cardiovascular toxicity, and dermatitis, along with a few cases of death due to extensive skin absorption. N,N-diethyl-3-methylbenzamide may compete in metabolism with and alter the biodistribution properties of other compounds to which a subject is simultaneously exposed, resulting in an added risk of side effects. The appropriate use of formulation techniques and new formulation excipients not only offers a way to extend the duration of protection, but also reduces deet skin penetration. In addition to extended repellency, minimal skin penetration of deet should be an important consideration in the evaluation of a deet formulation during new product development.

Animals↗
PubMed2000

Epidemiology and optimal foraging: modelling the ideal free distribution of insect vectors.

Existing models of the basic case reproduction number (R0) for vector-borne diseases assume (i) that the distribution of vectors over the susceptible host species is homogeneous and (ii) that the biting preference for the susceptible host species rather than other potential hosts is a constant. Empirical evidence contradicts both assumptions, with important consequences for disease transmission. In this paper we develop an Ideal Free Distribution (IFD) model of host choice by blood-sucking insects, predicated on the argument that vectors must have evolved to choose the least defensive hosts in order to maximize their feeding success. From a re-analysis of existing data, we demonstrate that the interference constant, m, of the IFD can vary between host species. As a result, the predicted distribution of insects over hosts has 2 desirable and intuitively plausible behaviours: that it is heterogeneous both within and between host species; and that the intensity of heterogeneity varies with host and vector density. When the IFD model is incorporated into R0, the relationship with the vector:host ratio becomes non-linear. If correct, the IFD could add considerable realism to models which seek to predict the effect of these ecological parameters on disease transmission as they vary naturally (e.g. through seasonality in vector density or host population movement) or as a consequence of artificial manipulation (e.g. zooprophylaxis, vector control). It raises the possibility of targeting transmission hot spots with greater accuracy and concomitant reduction in control effort. The robustness of the model to simplifying assumptions is discussed.

Animals↗
PubMed2002

Comparative efficacy of insect repellents against mosquito bites.

BACKGROUND: The worldwide threat of arthropod-transmitted diseases, with their associated morbidity and mortality, underscores the need for effective insect repellents. Multiple chemical, botanical, and "alternative" repellent products are marketed to consumers. We sought to determine which products available in the United States provide reliable and prolonged complete protection from mosquito bites. METHODS: We conducted studies involving 15 volunteers to test the relative efficacy of seven botanical insect repellents; four products containing N,N-diethyl-m-toluamide, now called N,N-diethyl-3-methylbenzamide (DEET); a repellent containing IR3535 (ethyl butylacetylaminopropionate); three repellent-impregnated wristbands; and a moisturizer that is commonly claimed to have repellent effects. These products were tested in a controlled laboratory environment in which the species of the mosquitoes, their age, their degree of hunger, the humidity, the temperature, and the light-dark cycle were all kept constant. RESULTS: DEET-based products provided complete protection for the longest duration. Higher concentrations of DEET provided longer-lasting protection. A formulation containing 23.8 percent DEET had a mean complete-protection time of 301.5 minutes. A soybean-oil-based repellent protected against mosquito bites for an average of 94.6 minutes. The IR3535-based repellent protected for an average of 22.9 minutes. All other botanical repellents we tested provided protection for a mean duration of less than 20 minutes. Repellent-impregnated wristbands offered no protection. CONCLUSIONS: Currently available non-DEET repellents do not provide protection for durations similar to those of DEET-based repellents and cannot be relied on to provide prolonged protection in environments where mosquito-borne diseases are a substantial threat.

Animals↗
PubMed2006

Rhythmic expression of the cycle gene in a hematophagous insect vector.

BACKGROUND: A large number of organisms have internal circadian clocks that enable them to adapt to the cyclic changes of the external environment. In the model organism Drosophila melanogaster, feedback loops of transcription and translation are believed to be crucial for the maintenance of the central pacemaker. In this mechanism the cycle (or bmal1) gene, which is constitutively expressed, plays a critical role activating the expression of genes that will later inhibit their own activity, thereby closing the loop. Unlike Drosophila, the molecular clock of insect vectors is poorly understood, despite the importance of circadian behavior in the dynamic of disease transmission. RESULTS: Here we describe the sequence, genomic organization and circadian expression of cycle in the crepuscular/nocturnal hematophagous sandfly Lutzomyia longipalpis, the main vector of visceral leishmaniasis in the Americas. Deduced amino acid sequence revealed that sandfly cycle has a C-terminal transactivation domain highly conserved among eukaryotes but absent in D. melanogaster. Moreover, an alternative form of the transcript was also identified. Interestingly, while cycle expression in Drosophila and other Diptera is constitutive, in sandflies it is rhythmic in males and female heads but constitutive in the female body. Blood-feeding, which causes down-regulation of period and timeless in this species, does not affect cycle expression. CONCLUSION: Sequence and expression analysis of cycle in L. longipalpis show interesting differences compared to Drosophila suggesting that hematophagous vector species might present interesting new models to study the molecular control of insect circadian clocks.

Amino Acid Sequence↗
PubMedDate not supplied

Causes and effective management of insect bites in the UK.

Insects play an important role in maintaining the world's ecosystem (Zhu and Stiller, 2002) but many of them feed on other animals. Humans are relatively hairless and provide an easy target, especially when partly clothed (Cohn, 2003). Biting insects common to the UK include midges, gnats, mosquitoes, flies, fleas, lice, mites, ticks, and bedbugs (Fig 1).

Animals↗
PubMed1996

Neuroanatomy of a crayfish thoracic ganglion: sensory and motor roots of the walking-leg nerves and possible homologies with insects.

The internal organization of the third and fourth thoracic ganglia of the crayfish, Pacifastacus leniusculus, was studied in serial sections stained with osmium ethyl gallate. The aims were 1) to provide an anatomical framework for studies of sensorimotor integration in the walking system and 2) to explore possible homologies with abdominal ganglia in crayfish and with the thoracic ganglia of insects. Crayfish thoracic ganglia show several intersegmental homologies with the unfused ganglia of the abdominal nervous system: 1) Longitudinal tracts and dorsal commissures are arranged similarly, allowing use of the same nomenclature. 2) Paired lateral neuropils are located dorsolaterally and contain many large neurites including those of leg motor neurons and of nonspiking, proprioceptive afferents from the basal limb joints. They resemble the lateral neuropils of abdominal ganglia. 3) Neuropil lying more ventrally is fine textured and receives projections from other leg afferents. This ventral neuropil resembles the "horseshoe neuropil" of abdominal ganglia. The functional implications of this organization are discussed. Compared to the abdominal ganglia, however, thoracic ganglia also show specific intersegmental differences: 1) They have more ventral commissures; 2) the ventral neuropil undergoes a large bilateral extension; 3) distinct anteromedial regions of the ventral neuropil receive specific afferent projections; and 4) recognizable dorsoventral "T-tracts" occur. Moreover, these "thoracic" features show a striking resemblance to structures found in thoracic ganglia of orthopteran insects. These correspondences provide further indications that the neuropil of segmental ganglia may be organized in homologous ways in crustaceans and in insects.

Animals↗
PubMed1996

Neurogenesis in adult insect mushroom bodies.

The occurrence of neurogenesis in mushroom bodies of adult insects belonging to several orthopteroid and coleopteran families is described. Using injections of 5-bromo, T2'-deoxyuridine, we showed that neuroblasts, which are progenitors of Kenyon cells during preimaginal instars, continue to divide in adult Acheta domesticus. Their progeny constitute a central column in mushroom body cortices of 3-week-old females. Other Gryllidae, Gryllus bimaculatus and Gryllomorpha dalmatina, show the same pattern of neuroblast activity and migration of their progeny. Immunocytochemical staining of glial cells failed to reveal any immunoreactivity, either in proliferating regions or in the resulting cells. In another orthopteran, Locusta migratoria, discrete clusters of cells, located dorsolateral to the Kenyon cells, incorporated 5-bromo, 2'-deoxyuridine, but we could not detect any neuronal progeny migrating to the mushroom body cortices. These cells were strongly labeled with an antiglial antibody, indicating that the replicating cells are glioblasts rather than neuroblasts. In Periplaneta americana (Dictyoptera), cells replicating their DNA were similarly shown to immunoreact with glial antibodies. In contrast, three coleopterans (Tenebrio molitor, Zophobas species, Harmonia axyridis) have two large neuroblasts located in the middle of the mushroom body cortices. These produce cells which migrate within the group of Kenyon cells, their nuclei having the same shape and size as those of surrounding Kenyon cells. In adult insects, neurogenesis in mushroom bodies occurs in Gryllidae and several coleopteran families, but could not be demonstrated in Dictyoptera and Acrididae. Its occurrence and distribution raise the issue of unexpected plasticity in the adult insect brain.

Animals↗
PubMed2000

Distribution of ryanodine receptor Ca(2+) channels in insect photoreceptor cells.

Physiological studies have provided evidence for the existence of ryanodine receptor (RyR) Ca(2+) channels in compound eyes of insects. The present study identifies and localizes RyR in insect photoreceptors by use of an affinity-purified antibody against lobster muscle RyR. Western blotting and indirect immunofluorescence staining confirm cross-reactivity of the antibody with insect muscle RyR. In both honeybee and fly eyes, the antibody identifies a single protein that comigrates with muscle RyR on sodium dodecylsulfate (SDS) polyacrylamide gels demonstrating that RyR is present in this tissue. By confocal immunofluorescence microscopy on honeybee eyes, RyR is detected within the photoreceptors and shows a nonhomogeneous distribution over the endoplasmic reticulum (ER). Double labeling studies have demonstrated further that RyR is localized at distinct ER elements close to the light-sensitive microvilli and juxtaposed to adherens junctions. RyR has also been observed within the remaining soma of honeybee photoreceptors, being concentrated on ER cisternae close to mitochondria and the nonreceptive plasma membrane. For comparative purposes, the distribution of RyR has also been assayed in compound eyes of flies. In both Calliphora and Drosophila photoreceptors, the anti-RyR antibody provides punctate labeling throughout the cell body. The submicrovillar ER cisternae associated with the base of the microvilli, however, are only lightly labeled for RyR. These results suggest that RyR is involved with Ca(2+) regulation in the nonreceptive cell area of both fly and honeybee photoreceptors, but that it may contribute to Ca(2+) regulation close to the phototransduction compartment only in the latter cell.

Animals↗