Studies on the biting habits and medical importance of East African mosquitos in the genus Aëdes. II.—Subgenera Mucidus, Diceromyia, Finlaya and Stegomyia

1961 ◽  
Vol 52 (2) ◽  
pp. 317-351 ◽  
Author(s):  
A. J. Haddow
Keyword(s):  
Forest Canopy ◽  
Ground Level ◽  
Maximum Intensity ◽  
East African ◽  
Productive Area ◽  
Medical Importance ◽  
Different Levels ◽  
Diurnal Species ◽  
Biting Behaviour ◽  
Made In

The cyclic biting activities of East African mosquitos of the genus Aëdes, belonging to the subgenera Mucidus, Diceromyia, Finlaya and Stegomyia are discussed. The total number of 24-hour catches involved was 448, all in East Africa, of which 401 were made in forest in Uganda.It is pointed out that many species in the subgenera of Aëdes dealt with show arboreal tendencies of varying degree and, while a species may show a preference for some particular level, many of them appear to make daily vertical migrations. Consequently, biting may reach its maximum intensity at different times at different levels. It is also pointed out that the habits of a species may vary from one area to another, and therefore it is often best to discuss a representative series of catches from a productive area, noting such differences as may have been observed elsewhere. It has been found further that, under certain circumstances, a species may fail to show a clear pattern of biting behaviour and the possible reasons for this are discussed.All members of the subgenus Mucidus so far adequately studied are arboreal and nocturnal. In the subgenus Finlaya, A. ingrami Edw. is a mosquito of the forest understorey which bites most freely in the hour before sunset. It makes vertical migrations, however, and the biting cycle at ground-level differs from that in the trees. A. longipalpis (Grünb.) is a diurnal species of the forest canopy. A view formerly put forward by the writer, that the form of the biting cycle in this species could be attributed to different physiological groups biting at different times, can no longer be supported.In the subgenus Stegomyia, A. dendrophilus Edw. and A. apicoargenteus (Theo.) are diurnal species with rather irregular biting cycles, A. dendrophilus

Studies on the Biting Habits and Medical Importance of East African Mosquitos in the Genus Aëdes. I.—Subgenera Aëdimorphus, Banksinella and Dunnius

1960 ◽  
Vol 50 (4) ◽  
pp. 759-779 ◽  
Author(s):  
A. J. Haddow
Keyword(s):  
Rift Valley Fever Virus ◽  
Ground Level ◽  
East African ◽  
African Species ◽  
Valley Fever ◽  
Single Exception ◽  
Fourth Species ◽  
Medical Importance ◽  
Group Pattern ◽  
Biting Behaviour

The biting behaviour of East African species of Aëdes in the subgenera Aëdimorphus, Banksinella and Dunnius, as shown in numerous series of 24-hr, catches made predominantly in Uganda, is discussed. It is shown that with the single exception of A. (A.) natronius Edw., which is arboreal, all the species encountered have been most prevalent at ground level. They bite mostly by day, but A. cumminsi (Theo.) shows a marked peak of activity from just before to just after sunset, and A. natronius is crepuscular. When, however, samples were obtained in environments less favoured than the forest floor, and in which the mosquito concerned was less abundant, the biting cycle might be altered. Thus various species which were essentially diurnal at ground level in forest might be nocturnal in the canopy or in banana plantations.In some cases there seemed to be a tendency towards a group pattern of behaviour. For example, in the abnormalis (Theo.) and tarsalis (Newst.) groups of Edwards it was found that at least three species showed very similar biting cycles. A fourth species, A. nigricephalus (Theo.), which occurs in Nigeria, is reported there to differ in its biting habits, and is also strikingly different in appearance and in the structure of the terminalia.Members of all three subgenera have been involved in various isolations of virus, but it is not possible to prove that they, rather than other species of Aëdes included in the infected lots, were the vector mosquitos, except in the case of the A. tarsalis group, from which there have been two definite isolations of Rift Valley fever virus, and in that of A. circumluteolus (Theo.), which has been shown by recent work in South and East Africa to be of major importance, well over 20 isolations of virus having been made from this species. So far as is known at present, seven separate viruses and one distinct variant have been isolated from A. circumluteolus, and other members of the subgenus Banksinella also appear to be involved in transmission.

scholarly journals Molecular Modelling of Oligomeric States of DmOR83b, an Olfactory Receptor in D. Melanogaster

2012 ◽  
Vol 6 ◽  
pp. BBI.S8990 ◽  
Author(s):  
K. Harini ◽  
R. Sowdhamini
Keyword(s):  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Insect Species ◽  
Agricultural Pests ◽  
Negative Effects ◽  
C Terminus ◽  
Receptor Neurons ◽  
Medical Importance ◽  
G Protein Coupled ◽  
Made In

After the discovery of the complete repertoire of D. melanogaster Olfactory Receptors (ORs), candidate ORs have been identified from at least 12 insect species from four orders (Coleoptera, Lepidoptera, Diptera, and Hymenoptera), including species of economic or medical importance. Although all ORs share the same G-protein coupled receptor structure with seven transmembrane domains, they share poor sequence identity within and between species, and have been identified mainly through genomic data analyses. To date, D. melanogaster remains the only insect species where ORs have been extensively studied, from expression pattern establishment to functional investigations. These studies have confirmed several observations made in vertebrates: one OR type is selectively expressed in a subtype of olfactory receptor neurons, and one olfactory neuron expresses only one type of OR. The olfactory mechanism, further, appears to be conserved between insects and vertebrates. Understanding the function of insect ORs will greatly contribute to the understanding of insect chemical communication mechanisms, particularly with agricultural pests and disease vectors, and could result in future strategies to reduce their negative effects. In this study, we propose molecular models for insect olfactory receptor co-receptor OR83b and its possible functional oligomeric states. The functional similarity of OR83b to GPCRs and ion channels has been exploited for understanding the structure of OR83b. We could observe that C-terminal region (TM4-7) of OR83b is involved in homodimer amd heterodimer formation (with OR22a) which suggests why C-terminus of insect ORs are highly conserved across different species. We also propose two possible ion channel pathways in OR83b: one formed by TM4-5 region with intracellular pore-forming domain and the other formed by TM5-6 with extracellular pore forming domain using analysis of the electrostatics distribution of the pore forming domain.

scholarly journals Retrospective analysis of GLEs and estimates of radiation risks

2018 ◽  
Vol 8 ◽  
pp. A52 ◽  
Author(s):  
Leonty I. Miroshnichenko
Keyword(s):  
Solar Activity ◽  
Ground Level ◽  
Radiation Hazard ◽  
Occurrence Rate ◽  
Solar Cosmic Rays ◽  
Dose Rates ◽  
Recent Debate ◽  
Unique Distribution ◽  
Different Levels ◽  
Ground Level Enhancements

28 February 2017 marked 75 years since the first confident registration of solar cosmic rays (SCRs), i.e., accelerated solar particles with energies from about 106 to ~1010 ÷ 1011 eV. Modern state of the problems related to the studies of Ground Level Enhancements (GLEs) of relativistic SCRs is critically analyzed based on available direct and proxy data. We are also taking into account extremely large fluxes of non-relativistic solar energetic particles (SEPs). Both kinds of SCR events are of great astrophysical and geo-scientific (geophysical) interests. A number of the GLE properties (total statistics, occurrence rate, longitude distribution, ranking of GLEs, a number of specific GLEs – so-called “rogue” SEP events etc.) are discussed in some detail. We note also the problems of GLE identification (definition) by ground-based observations, the difficulties in the studies of weak (“hidden”, or sub-) GLEs etc. One of serious challenges to the problem of radiation hazard in space is a lack of a clear, unambiguous relation between the fluxes (fluences) of relativistic SCR and non-relativistic SEPs. Special attention is paid to the recent debate on the validity, origin and properties of the “ancient” events AD775, AD994, AD1859 (Carrington event) and BC3372. We demonstrate that, in spite of existing uncertainties in proton fluences above 30 MeV, all of them are fitted well by a unique distribution function, at least, with the present level of solar activity. Extremely large SEP events are shown to obey a probabilistic distribution on their fluences with a sharp break in the range of large fluences (or low probabilities). The studies of this kind may be extended for periods with different levels of solar activity in the past and/or in the future. Dose rates at aircraft altitudes are also demonstrated during some GLEs. Several examples of using the SCR data and GLE properties in radiation prediction schemes are considered.

scholarly journals Amblyomma tapirellum  (Acari: Ixodidae) collected from tropical forest canopy

F1000Research ◽  
2014 ◽  
Vol 2 ◽  
pp. 194
Author(s):  
Jose R Loaiza ◽  
Matthew J Miller ◽  
Eldredge Bermingham ◽  
Oris I Sanjur ◽  
Patrick A Jansen ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Forest Canopy ◽  
Ground Level ◽  
Barro Colorado Island ◽  
Light Traps ◽  
Ecological Relationship ◽  
Questing Ticks ◽  
Free Ranging ◽  
Central Panama ◽  
Tropical Forest Canopy

Free-ranging ticks are widely known to be restricted to the ground level of vegetation. Here, we document the capture of the tick species Amblyomma tapirellum in light traps placed in the forest canopy of Barro Colorado Island, central Panama. A total of forty eight adults and three nymphs were removed from carbon dioxide–octenol baited CDC light traps suspended 20 meters above the ground during surveys for forest canopy mosquitoes. To our knowledge, this represents the first report of questing ticks from the canopy of tropical forests. Our finding suggests a novel ecological relationship between A. tapirellum and arboreal mammals, perhaps monkeys that come to the ground to drink or to feed on fallen fruits.

Studies of the Biting-habits of African Mosquitos. An Appraisal of Methods employed, with special Reference to the twenty-four-hour Catch

1954 ◽  
Vol 45 (1) ◽  
pp. 199-242 ◽  
Author(s):  
A. J. Haddow
Keyword(s):  
Vertical Distribution ◽  
Special Reference ◽  
Geometric Mean ◽  
Seasonal Abundance ◽  
Central Tendency ◽  
Valuable Method ◽  
Different Seasons ◽  
Working Out ◽  
Different Levels ◽  
Biting Behaviour

It is felt that the 24-hour catch presents a valuable method of studying the biting-behaviour of mosquitos in the field, and further that conclusions concerning seasonal abundance, vertical distribution and times of biting-activity must be based on catches of this type if serious errors of interpretation are to be avoided.The time-divisions of the catch should not exceed one hour, and even shorter intervals may be desirable. Timing should be related to the actual times of sunrise and sunset. Where possible, a series of consecutive catches should be carried out, and a shift system must be carefully considered in relation to the particular series projected.Usually the results from different levels above ground should be treated separately in working out biting-cycles, and this may also apply to results from different seasons or different localities. Further, while in some instances the summation of long series of catches seems permissible, in others it is not, and in these detailed analysis of the figures may be necessary before consistent behaviour-patterns become apparent.In cases where a measure of the central tendency is to be employed, the geometric mean as modified by C. B. Williams appears to be the most suitable.

Origin and distribution of the polyatomic molecules in the atmosphere

1956 ◽  
Vol 236 (1205) ◽  
pp. 187-193 ◽  
Keyword(s):  
Water Vapour ◽  
Ultra Violet ◽  
Ground Level ◽  
Absorption Bands ◽  
Ultra Violet Radiation ◽  
Low Concentrations ◽  
Vertical Distributions ◽  
Similar Accuracy ◽  
Lapse Rates ◽  
Made In

Of those gases which occur in the upper atmosphere and have strong absorption bands in the infra-red part of the spectrum and which must, therefore, be con­sidered when calculating the absorption and radiation of heat in the atmosphere, only carbon dioxide is uniformly mixed with the air at all heights which we are likely to be dealing with; it will not be considered further here. The vertical distributions of water vapour and ozone are of great interest, particularly when considered together. Water vapour, originating at ground level, usually decreases rather rapidly with increasing height, particularly in the lower stratosphere. This leads to extremely low concentrations at a height of about 15 km. On the other hand, ozone, being formed by the action of solar ultra-violet radiation at a height of 30 km or more, decreases in concentration downwards. We find, therefore, ozone diffusing downwards and water vapour diffusing upwards through the same region of the atmosphere, but, as we shall see, with very different lapse rates. Water vapour The standard hygrometers which are used to measure the humidity from free balloons are only satisfactory at temperatures above about 235°K, and our knowledge of the humidity at high levels in the atmosphere is almost entirely dependent on measurements made with frost-point hygrometers carried on air­craft. The work of the Meteorological Research Flight of the British Meteorological Office is notable for the very large number of measurements made from Mosquito aircraft to a height of about 12 km and more recently from Canberra aircraft to 15 km. Most unfortunately, hardly any measurements having similar accuracy have been made in other parts of the world. However, at the present time Dr A. W. Brewer is in north Norway making such measurements with the kind co-operation of the Norwegian Air Force and I had hoped that some results might have been available in time to report them at this Discussion (see note at end of paper).

The biting habits of Aedes (Skusea) pembaensis Theo. and some other mosquitos of Faza, Pate Island, East Africa

1964 ◽  
Vol 55 (1) ◽  
pp. 97-124 ◽  
Author(s):  
E. C. C. van Someren ◽  
M. Furlong
Keyword(s):  
East Africa ◽  
East Coast ◽  
The Other ◽  
Moon Phase ◽  
Moon Phases ◽  
Biphasic Pattern ◽  
North East ◽  
The North ◽  
Biting Behaviour ◽  
Made In

Descriptions are given of 24-hour biting catches, made in and around Faza, a village on Pate Island, off the north-east coast of Kenya, East Africa.Aedes pembaensis Theo. was the predominant mosquito in these catches but fair numbers of Aedes mombasaensis Mattingly were also taken; the biting cycles of these two are discussed. Six other species were taken in small numbers.For Ae. pembaensis, biting cycles calculated on catches grouped for site, moon phases, neap tides and spring tides show that both moon and tide and light intensity influence the biting behaviour. Different but recurring patterns occur with various combinations of these factors.For Ae. mombasaensis, the cycles have a very constant biphasic pattern. Catches grouped for moon phases, tides and catch sites, as for Ae. pembaensis, show that more biting females are taken at neap tides than at spring tides. Two patterns of behaviour occur, one associated with spring tides and the other with neap tides. An even level of biting activity occurs during the night with intense and prolonged moonlight; otherwise moon-phase cycles have little effect on biting behaviour.It is felt that 24-hour biting catches can give useful information on behaviour patterns but it is desirable to have a long series of catches to analyse. For the purpose of calculating biting cycles, the results of catches showing similar modifications in behaviour should be treated separately.

Observations on the Biting-habits of some Tabanidae in Uganda, with special Reference to arboreal and nocturnal Activity

1950 ◽  
Vol 41 (1) ◽  
pp. 209-221 ◽  
Author(s):  
A. J. Haddow ◽  
J. D. Gillett ◽  
A. F. Mahaffy ◽  
R. B. Highton
Keyword(s):  
Special Reference ◽  
Yellow Fever ◽  
Forest Canopy ◽  
Dry Season ◽  
Forest Trees ◽  
Close Correspondence ◽  
Nocturnal Activity ◽  
Wet Season ◽  
Natural Hosts ◽  
Biting Behaviour

In a search for the forest vector of yellow fever, catches of biting Diptera have been made by various methods in forest trees in Bwamba County, Uganda. The work here reported concerns Tabanids taken in catches made during the period 1944–45.Three species of Tabanids have been taken in trees during these catches, and one of these, Chrysops centurionis, has proved to be mainly arboreal.Observations on C. centurionis have shown that its main biting-activity begins just before sunset and reaches a peak during the hour after sunset. Thereafter the numbers taken diminish rapidly, but some activity continues throughout the night.In the wet-season catches, this species was most prevalent in the forest canopy at heights of 50 to 60 feet above ground. In the dry season the most favourable level was lower, at 20 to 30 feet above ground.It is suggested that monkeys are the natural hosts of C. centurionis, and that C. centurionis may be the vector of filarial infections among wild monkeys.It is shown that there is a very close correspondence between the biting-behaviour of C. centurionis and that of the mosquito, A ëdes africanus.Evidence of nocturnal activity has now been obtained in the case of one species of Tdbanus, three species of Haematopota and two species of Chrysops. It is suggested that there may be some connection between the remarkable eye colours of Tabanids and crepuscular or nocturnal activity.Records of other Bwamba Tabanids are given.

scholarly journals Considerations on the Necessity of Modernization of Engineer Forces from NATO Members Countries

2017 ◽  
Vol 23 (1) ◽  
pp. 344-347
Author(s):  
Mircea Vladu ◽  
Ioan-Dan Popa
Keyword(s):  
Armed Forces ◽  
Historical Evolution ◽  
Social Activities ◽  
Member States ◽  
Joint Forces ◽  
The Common ◽  
Different Levels ◽  
Over Time ◽  
Made In ◽  
Structural Perspective

Abstract The engineer branch has been established at a certain stage of historical evolution of the armed forces to provide engineer support to the combat forces, as well as to support civil societies to achieve, develop and maintain the necessary infrastructure elements in order to conduct of economic and social activities. Having in mind all these elements and taking into account the structural perspective and the endowment, the evolution of engineer forces should have been made in accordance with the evolution of the common combat joint forces, keeping the same rhythm of development. Unfortunately, the engineer forces within the armies of the NATO member states did not evolve under the aforementioned aspects, even if some commitments have been made at the various summits held over time at different levels. As a result of these realities, in this paper we present some considerations about what should be the way ahead in the evolution of the engineer forces until the horizon of 2050.

Growth characteristics of rough fescue (Festuca scabrella var. campestris) after three years of repeated harvesting at scheduled frequencies and heights

1992 ◽  
Vol 70 (11) ◽  
pp. 2125-2129 ◽  
Author(s):  
Walter D. Willms ◽  
Joanna Fraser
Keyword(s):  
Growth Response ◽  
Ground Level ◽  
Forage Yield ◽  
Repeated Treatment ◽  
Dormant Season ◽  
Cutting Height ◽  
Optimum Management ◽  
Rough Fescue ◽  
Forage Yields ◽  
Made In

A study was made in the rough fescue grasslands of southwestern Alberta to determine the growth response of rough fescue (Festuca scabrella var. campestris Rydb.) to five cutting frequencies and three cutting heights after 3 years of repeated treatments. The same plants were cut either 1, 2, 4, 8, or 16 times over a 16-week period beginning in mid-May, at 16-, 8-, 4-, 2-, or 1-week intervals, respectively, and at heights of either 5, 10, or 15 cm above ground level. After 3 years of repeated treatment, dry matter yields, etiolated growth, tiller height, tiller number, and growth rate decreased with increased cutting frequency and decreased cutting height. A single harvest at the end of August, cut at a height of 15 cm, produced yields that were similar to previously undisturbed plants. This treatment also produced the maximum sustainable forage yields. The study confirms the high susceptibility of rough fescue to grazing during the growing season and indicates that optimum management should include dormant-season grazing. Key words: defoliation, forage yield, regrowth, etiolated growth, tillers.

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