Insects Of Medical Importance Research Articles

Genetic diversity of Brazilian Bacillus thuringiensis isolates with toxicity against Aedes aegypti (Diptera: Culicidae)

Bacillus thuringiensis (Bt) isolates native to Maranhão (BtMA) that are highly toxic to Aedes aegypti larvae and seven standard subspecies of Bt were analyzed for genetic diversity using the rep-PRC technique with BOX, ERIC, REP, MB1, and GTG5 markers. The rep-PCR technique is considered an extremely reliable, reproducible, fast and highly discriminatory technique that may be used even among populations of the same species. These five markers revealed a total of 38 polymorphic DNA fragments for 30 BtMA isolates. Eight groups were obtained with the dendrogram generated through Pearson's correlation analysis, with four groups formed only with BtMA isolates and four comprised of isolates of BtMA and the standard subspecies toxic to dipterans and lepidopterans. Despite the high genetic diversity of BtMA, a low correlation between the collection site, gene content and mortality against A. aegypti larvae was evidenced. The clustering of the standard subspecies of Bt that were toxic against dipterans with BtMA isolates confirm the mosquitocidal action of the native isolates from Maranhão, and they can be used as an alternative for A. aegypti control and other insects of medical importance and for the control of agricultural pests.

Ultrastructural comparison and distribution of sensilla on male and female antennae of the sand fly Phlebotomus papatasi (Diptera: Psychodidae): the vector of cutaneous leishmaniasis in Egypt

BackgroundSince sand flies are insects of medical importance and most of its sensilla were found on the antennae, the present investigation was designed to characterize the ultrastructure of the antennae of males and females and the sensilla distribution using scanning electron microscopy (SEM).ResultsThe filiform antenna of males and females consisted of a scape, pedicel, and flagellum. Male antennae appeared longer than those of females and exhibited obvious sexual dimorphism. In addition to the microtrichiae, six cuticular sensillary types, namely trichoid, coeloconic (subtype the common grooved coeloconic), chaetic, campaniform, squamiform, and the basiconic, were identified. The trichoid sensilla occurred in five subtypes, namely long blunt-tipped trichoid, short sharp-tipped trichoid, short blunt-tipped trichoid, medium pointed-tipped trichoid, and apical trichoid. Little changes in the number and distribution pattern of same sensillar types between males and females were revealed. Trichoid sensilla were the most abundant of all sensillar types. The short sharp-tipped trichoid sensilla were observed on the pedicel of males, while in females they were found on both scape and pedicel. The position of the apical trichoid sensilla on the last flagellomere differs in males than in females.ConclusionsThe current study is the first to describe differences in the last three flagellomeres between males and females. Our results could provide a foundation for further research on sensory organs and approaches for the control of sand flies and enable for the use of new taxonomic characters to differentiate among species.

Morphological Keys for Identification of Sandflies from Morocco (Diptera: Psychodidae: Phlebotominae)

The Moroccan phlebotomine fauna is composed of 24 species whose morphological determination may be difficult for non-taxonomists. The identification keys, presented here, allow the identification of sandflies genera and species in Morocco and will facilitate future studies on these insects of medical importance, Leishmaniasis vectors.

Sand fly fauna (Diptera: Psychodidae) from Serra da Mocidade Nacional Park: report of vectors and putative vectors of American cutaneous leishmaniasis and new records for the state of Roraima, Brazil.

Phlebotomine sand flies are insects of medical importance, as they are vectors of viruses, bacteria and trypanosomatids of the genus Leishmania Ross, the causative agent of leishmaniasis (Forattini 1973). During the past 20 years approximately 500,000 cases of leishmaniasis have been reported in Brazil. Most of these cases were reported in the North and Northeast regions. In the State of Roraima, almost 2,000 cases, including both cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL), have been reported during the past three years (SINAN 2017). Usually the transmission by infected female sand flies occurs in wild or rural areas, but there have also been recorded cases and vector captures in urban environments. Some sand fly species are known to enter houses in search of resting places and blood meal sources; as a result of this behavior, they are remarkably adaptable to new environments (Carvalhoet al. 2010).

Insecticidal Activity of Moringa oleifera Synthesized Silver and Zinc Nanoparticles against the House Fly, Musca domestica L.

Green synthesizednanoparticles have been studied as newand more effective biopesticides against insects of medical importance and thisfor their eco-friendly aspects. In the current study Moringa oleiferaleaf extract (Mo-LE) was used to synthesis silver nanoparticles (Mo-AgNPs) andzinc oxide nanoparticles (Mo-ZnONPs). Low concentrations of Mo-LE, Mo-AgNPs andMo-ZnONPs showed the larvicidal and pupicidal toxicityagainst Musca domestica. In larvicidal bioassay, the values of LC50were 16.50, 2.03 and 6.41 mg/ml for Mo-LE, Mo-AgNPs andMo-ZnONPs,respectively. In addition, the LC50 was determined against pupae,which were129.77, 9.604 and 17.10 mg/ml for Mo-LE, Mo-AgNPs andMo-ZnONPs,respectively. Moreover, treatment larvae with LC50's of Mo-LE, Mo-AgNPs andMo-ZnONPsproduced a significant reduction (P<0.05) in the fecundity of femaleand a highly significant reduction (P<0.01) in the egg hatchability.The total protein content and activities of nonspecific esterases, acetylcholine esterase, and glutathione S-transferase enzymes were significantly declined afterlarvae had fed on LC50 Mo-AgNPs andMo-ZnONPstreated diets as compared with the control. This study indicates that it isfeasible to use M. oleifera synthesized nanoparticles as effective candidates to develop newer and cheapcontrol tools for immature stages of M. domestica.

Ecology, feeding and natural infection by Leishmania spp. of phlebotomine sand flies in an area of high incidence of American tegumentary leishmaniasis in the municipality of Rio Branco, Acre, Brazil

BackgroundPhlebotomine sand flies (Diptera: Psychodidae) are insects of medical importance due to their involvement in the zoonotic transmission of Leishmania spp. to vertebrates. The aim of this work was to study the ecology of the sand fly fauna of two types of environments, a rural environment (the Transacreana Road) and an urban park (Horto Florestal Park), both located in the municipality of Rio Branco in the state of Acre, Brazil. Additionally, this study intended to investigate Leishmania infection and blood meal sources of these sand flies using molecular techniques.MethodsThe sand fly fauna was studied in different environments (i.e. forest and peridomestic environments in a rural area, and an urban forest) using Shannon traps and HP light traps to collect sand fly specimens over 13 consecutive months (December 2014 to January 2016). For investigating natural infection by Leishmania and the source of sand fly blood meals, DNA samples were extracted from female sand flies and subjected to polymerase chain reaction targeting ITS1 and cytb genes. DNA sequencing was subsequently used to identify species of Leishmania and the source of blood meals.ResultsA total of 2515 individual sand flies of 43 species were collected and identified, Trichophoromyia auraensis (839; 33.35%), Trichophoromyia spp. (537; 21.35%) and Evandromyia saulensis (187; 7.43%) were more abundant in the rural area (S = 41 species) than in the urban forest. No significant differences were found in species richness between forest and peridomestic environments in the rural area (H = 0.04; P > 0.05), but a larger number of species was found in the forest. Leishmania DNA was sequenced in 13 samples, confirming the presence of L. (V.) braziliensis in Th. auraensis (n = 1), Ev. saulensis (n = 2), Ev. walkeri (n = 1), Ps. llanosmartinsi (n = 1), Pi. nevesi (n = 2), Ps. davisi (n = 1), Ps. ayrozai (n = 1), Pa. aragaoi (n = 1), Ny. antunesi (n = 1) and Ev. infraspinosa (n = 1). Only Ps. ayrozai possessed a sequence similar to that of L. (V.) guyanensis (99%). Through microscopic analysis, five specimens of Ev. saulensis were found to possess flagellate forms in the hindgut, with an infection rate of 2.4%. Samples from 33 fed females were submitted to cytb gene amplification, for which sequencing determined that all were similar to the sequence deposited on GenBank for Gallus gallus (domestic chicken).ConclusionsThe high abundance of Trichophoromyia auraensis and Ev. saulensis, and the detection of L. (V.) braziliensis DNA, suggests that both species may be vectors of American tegumentary leishmaniasis. Psychodopygus ayrozai was found to be infected by L. (V) braziliesnsis and L. (V.) guyanensis, and although collected in low abundance, it may be a potential vector in the region. The sand fly fauna was found to be rich and diverse with predominance of the genus Psychodopygus. Identification of food sources of fed females showed that 100% amplified a gene region compatible with the domestic chicken, which although considered refractory in the disease transmission cycle, may have an influence on the population dynamics of sand flies.

Limited genomic divergence between intraspecific forms of Culex pipiens under different ecological pressures

BackgroundDivergent selection can be a major driver of ecological speciation. In insects of medical importance, understanding the speciation process is both of academic interest and public health importance. In the West Nile virus vector Culex pipiens, intraspecific pipiens and molestus forms vary in ecological and physiological traits. Populations of each form appear to share recent common ancestry but patterns of genetic differentiation across the genome remain unknown. Here, we undertook an AFLP genome scan on samples collected from both sympatric and allopatric populations from Europe and the USA to quantify the extent of genomic differentiation between the two forms.ResultsThe forms were clearly differentiated but each exhibited major population sub-structuring between continents. Divergence between pipiens and molestus forms from USA was higher than in both inter- and intra-continental comparisons with European samples. The proportion of outlier loci between pipiens and molestus (≈3 %) was low but consistent in both continents, and similar to those observed between sibling species of other mosquito species which exhibit contemporary gene flow. Only two of the outlier loci were shared between inter-form comparisons made within Europe and USA.ConclusionThis study supports the molestus and pipiens status as distinct evolutionary entities with low genomic divergence. The low number of shared divergent loci between continents suggests a relatively limited number of genomic regions determining key typological traits likely to be driving incipient speciation and/or adaptation of molestus to anthropogenic habitats.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0477-z) contains supplementary material, which is available to authorized users.

The genital atrium armature of some Brazilian sand fly females (Diptera: Phlebotominae)

Phlebotomine sand flies are insects of medical importance. Species in the Neotropical region are highly diverse. Some of these species are considered cryptic species because of their morphological similarity between adult females of different species make identification especially difficult. The aim of this study was to analyze and describe the armature in the genital atrium (AGA) of some adult female sand flies, in order to discover new taxonomic characters that make it possible to distinguish between species that would otherwise be treated as cryptic by analysis of the AGA. The AGA of 16 Phlebotomine sand fly species are described. Distinct differences were found in relation to the shape and size of the armature, the presence or absence of spines on the armature, and the shape, size, and grouping patterns of the spines. These characters made it possible to distinguish between the species studied.

Probing insect odorant receptors with their cognate ligands: Insights into structural features

Odorant receptors (ORs) are essential for insect survival in the environment and thus are ideal molecular targets for the design of insect-inspired modern green chemicals to control populations of agricultural pests and insects of medical importance. Although insect ORs are known for more than a decade, their structural biology is still in its infancy. Here, we unravel the first structural features of ORs from the malaria mosquito, the Southern house mosquito and the silkworm moth. The second extracellular loops (ECL-2s) of their predicted structures are much longer than ECL-1s and ECL-3s. The 27 amino-acid-residue-long of the ECL-2s in mosquito and the 43 amino-acid-residue-long ECL2s in moth ORs are well-conserved. About one-third of the residues are identical, including 3–4 Pro residues. Thorough examination of well-conserved residues in these structures, by point mutation and functional assay with the Xenopus oocyte recording system, strongly suggest that these “loops” include three β-turns and some degree of folding. In the Southern house mosquito three Pro residues in ECL-2 are essential for full activation of the receptor, which is finely tuned to the oviposition attractant 3-methylindole. Additionally, the “corner residues” of prolines, including Gly, Tyr, and Leu are functionally important thus suggesting that turns are stabilized not only by backbone hydrogen bonds, but also by side–chain interactions. Examination of ECL-2s from a distant taxonomical group suggests these ECL-2 loops might be functionally important in all insect ORs. Two of the four Pro residues in the predicted ECL-2 of the bombykol receptor in the silkworm moth, BmorOR1, are essential for function. Experimental evidence indicates that these loops may not be specificity determinants, but they may form a cover to the yet-to-be-identified membrane embedded binding cavities of insect ORs.

Optimization of the Gal4-UAS system in an Anopheles gambiae cell line

The development of the bipartite Gal4-UAS system in Anopheles gambiae would improve the functional characterization of genes in this important malaria vector. Towards this aim, we used Gal4 driver plasmids to successfully activate expression of the reporter gene, luciferase, from UAS responder plasmids when cotransfected into an An. gambiae cell line. To optimize Gal4-regulated gene expression in mosquitoes, we compared the efficiency of a series of alternative Gal4 transactivators to drive reporter gene expression from responder plasmids incorporating different numbers of tandemly arrayed Gal4 binding sites or upstream activation sequences (UAS). The results indicated that the native Gal4 is only weakly active in these cells. Modified forms of Gal4, including those carrying minimal VP16 activation domains, as well as a deleted form of Gal4, give up to 20-fold greater activity than the native protein, when used in conjunction with a responder plasmid having 14 UAS repeats. The identification of Gal4-UAS vectors that are efficiently expressed in a mosquito cell line should facilitate the transfer of this versatile expression system to An. gambiae, and potentially to other insects of medical importance.

Sampling High-Altitude and Stratified Mating Flights of Red Imported Fire Ant

With the exception of an airplane equipped with nets, no method has been developed that successfully samples red imported fire ant, Solenopsis invicta Buren, sexuals in mating/dispersal flights throughout their potential altitudinal trajectories. We developed and tested a method for sampling queens and males during mating flights at altitudinal intervals reaching as high as "140 m. Our trapping system uses an electric winch and a 1.2-m spindle bolted to a swiveling platform. The winch dispenses up to 183 m of Kevlar-core, nylon rope and the spindle stores 10 panels (0.9 by 4.6 m each) of nylon tulle impregnated with Tangle-Trap. The panels can be attached to the rope at various intervals and hoisted into the air by using a 3-m-diameter, helium-filled balloon. Raising or lowering all 10 panels takes approximately 15-20 min. This trap also should be useful for altitudinal sampling of other insects of medical importance.

P.5.094 Drug-based design of biologicallyactive dipeptides

Odorant receptors (ORs) are essential for insect survival in the environment and thus are ideal molecular targets for the design of insect-inspired modern green chemicals to control populations of agricultural pests and insects of medical importance. Although insect ORs are known for more than a decade, their structural biology is still in its infancy. Here, we unravel the first structural features of ORs from the malaria mosquito, the Southern house mosquito and the silkworm moth. The second extracellular loops (ECL-2s) of their predicted structures are much longer than ECL-1s and ECL-3s. The 27 amino-acid-residue-long of the ECL-2s in mosquito and the 43 amino-acid-residue-long ECL2s in moth ORs are well-conserved. About one-third of the residues are identical, including 3–4 Pro residues. Thorough examination of well-conserved residues in these structures, by point mutation and functional assay with the Xenopus oocyte recording system, strongly suggest that these “loops” include three β-turns and some degree of folding. In the Southern house mosquito three Pro residues in ECL-2 are essential for full activation of the receptor, which is finely tuned to the oviposition attractant 3-methylindole. Additionally, the “corner residues” of prolines, including Gly, Tyr, and Leu are functionally important thus suggesting that turns are stabilized not only by backbone hydrogen bonds, but also by side–chain interactions. Examination of ECL-2s from a distant taxonomical group suggests these ECL-2 loops might be functionally important in all insect ORs. Two of the four Pro residues in the predicted ECL-2 of the bombykol receptor in the silkworm moth, BmorOR1, are essential for function. Experimental evidence indicates that these loops may not be specificity determinants, but they may form a cover to the yet-to-be-identified membrane embedded binding cavities of insect ORs.

THE HISTORICAL AND CURRENT STATE OF MEDICAL ENTOMOLOGY SYSTEMATICS IN SOUTH AFRICA

SUMMARY Systematic studies on South African insects of medical importance have been mainly the preserve of the departments of Medical Entomology at the South African Institute for Medical Research (SAIMR) and the National Institute for Virology (NIV) in Johannesburg. Very few such studies have emanated from universities or museums. From 1927–1960, these systematic studies resulted in the production of the definitive standard works on the Anophelinae, Simuliidae and Siphonaptera of Africa that are still in use today. After 1960, further books were produced on mites, myiasis and biting flies, lice and sandflies. Revisions of some of these works have been undertaken by SAIMR and NIV staff in recent times, in particular on the Siphonaptera and Culicinae of southern Africa and the Anophelinae of the Afrotropical Region. Because of the presence of species complexes, current systematic studies of the Anophelinae are obliged to use genetical data. Despite their importance for the health of the people of southern Africa, systematic studies on insects of medical importance have decreased over the years, mainly due to diminished resources and a lack of support for this field of endeavour.

The Black Fly Simulium vittatum Trypsin Gene: Characterization of the 5′-Upstream Region and Induction by the Blood Meal

The events leading to blood digestion in hematophagous insects are nor well understood at the molecular level. Here we report on the characterization of a trypsin gene from the black fly Simulium vittatum. Southern blot analysis indicated that the S. vittatum genome contains at least two trypsin genes. Primer extension experiments identified two closely spaced transcription initiation sites, 3 bp apart. A genomic clone containing the trypsin gene was restriction mapped and the nucleotide sequence of the 5′-upstream region was determined. Several sequence elements were identified, including a consensus TATA box 35 nucleotides upstream from the transcription initiation sire, a consensus arthropod initiator site at position −7, and two conserved sequence elements, 5′GGATTAA (position −77) and 5′TGTTTCCT (position −148). The latter two elements are present at comparable distances from the transcription initiation sites in black fly and mosquito trypsin genes. Significant amounts of trypsin mRNA were detected in guts of sugar-fed flies. Upon blood feeding, trypsin mRNA levels gradually increased to reach twice the initial abundance at 8 hr after blood ingestion. In contrast to other hematophagous insects, the induced mRNA level persists for a prolonged period of time (at least 48 hr) after blood ingestion. The results of this study provide information that may be useful for the expression of transgenes in insects of medical importance.

小笠原諸島の衛生害虫とくにカおよびゴキブリ類について

小笠原諸島の衛生害虫とくにカおよびゴキブリ類について

Gas-propelled aerosols and micronized dusts for control of insects in aircraft. 6. Insects of medical importance.

In 2 types of exposure in truck trailers, micronized insecticidal dusts (2 g/1000 ft3) of chlorpylifos, fenitrothion, Mobam® (benzo[b]thien-4-yl-methylcarbamate), and propoxur were the most effective of the singletoxicant formulations against normal specimens of Blattella germanica (L.), Cimex lectularius L., Periplaneta Americana (L.), and Xenopsylla cheopis (Rothschild). The most effective multiple-toxicant formulations, at doses of 2 g/1000 ft3, contained chlorpyrifos, Gardona® (2-chloro-I-(2,4,5-trichlorophenyl)vinyl dimethylphosphate), propoxur, or resmethrin, and those con taining chlorpyrifos, Mobam, propoxur, or resmethrin were also effective against these species at doses of g/1000 ft3. When the more effective dust formulations in the truck trailers were tested in passenger aircraft, the distribution of the dust particles was not satisfactory, and the insects, representative of insects of medical importance that might be introduced via air transport, were not controlled; therefore, the present technique for application of micronized dusts in aircraft must be revised. The most effective insecticidal aerosols (30 or 10 g/1000 ft3) in the truck trailers were resmethrin and trans - (+)-allethrin; however, when these formulations were used at a rate of 10 g/1000 ft3 in aircraft, they were less effective. Aerosols of resmethrin had residual activity against the test species.

New Records and a New Species of Mesonyssus (Mesostigmata: Rhinonyssidae) from Pigeons and Doves (Columbiformes: Columbidae)

Mesonyssus hirtus sp. n. is described from Chalcophaps indica indica from Negros Island, Philippines. New records of M. columbae, M. geopeliae, M. melloi, and M. ptilinopi are given for Malaya, New Guinea, Philippines, Taiwan, and United States. The nasal mites reported herein have been collected largely by Bishop Museum staff members or field associates in conjunction with the Museum's program on insects of medical importance in southeast Asia. A small number of records were obtained from material supplied by Dr. H. E. McClure of the Migratory Animal Pathological Survey. All specimens are deposited in the Bernice P. Bishop Museum. Host nomenclature follows Peters (1937) and Delacour and Mayr (1946). Mesonyssus hirtus sp. n. (Figs. 1-8)

Entomology: A Handbook for the Identification of Insects of Medical Importance . By John Smart, with chapters by Karl Jordan and R. J. Whittick. British Museum (Natural History), London, ed. 4, 1965. 340 pp., £3.

Entomology: <i>A Handbook for the Identification of Insects of Medical Importance</i> . By John Smart, with chapters by Karl Jordan and R. J. Whittick. British Museum (Natural History), London, ed. 4, 1965. 340 pp., £3.

Tactics of Insect Control, Particularly in Medical Entomology

AbstractChlorinated hydrocarbon insecticides and notably DDT have provided means of effectively controlling mosquitoes, blackflies and insects of medical importance not only in Canada but elsewhere, and of eradicating the transmission of malaria by anophelines, the world programme for which is already successfully half completed. However resistance has developed to these insecticides in 80 species of public-health importance, including 3 in Canada. Basic studies on the physiological mechanism and mode of inheritance of resistance in Culicine mosquitoes are being performed in Canada. Among insects and mites of agricultural importance, 14 species have developed resistance in Canada, and a world total of 77. Basic studies on the mode of inheritance of cyclodiene-resistance in root maggots are being undertaken in Canada. Countermeasures against resistance include the use of synergists, non-detoxicatable analogues, and negatively-correlated compounds. Resistance usually dictates a shift from the chlorinated-hydrocarbon to the organophosphorus insectices, thus reducing the residue problem, particularly for wildlife. Alternative methods of control include the sterile-male technique, with 2 successful examples but no success yet with mosquitoes, and the use of chemosterilants, with an example of imminent success against houseflies on islands. Chemosterilants however, like bacterial toxins, are not free from the possible development of resistance by detoxication.

コロモジラミ及びイエバエの殺虫剤抵抗性に関する研究

Since 1950 the author has been engaged in the research of insecticide resistance developed in the insects of medical importance in Japan. This report dealt with the main points of the author's observations and findings.