bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of Brugia pahangi infection on survival of susceptible and refractory species of the Aedes scutellaris complex
Authors: IBRAHIM M. S. , TRPIS M. 
Published: March 2008

Abstract. . Life table statistics were used to examine the survival functions of filarial susceptible and refractory species of the Aedes scutellaris (Walker) group of mosquitoes, following infection with high and moderate doses of Brugia pahangi (Buckley & Edeson). Survivorship curves and hazard function curves were generated, and the median survival times and the proportions of mosquitoes surviving beyond the extrinsic incubation period of the parasite were determined.In the susceptible populations of Aedes polynesiensis Marks, Ae.pseudo‐scutellaris (Theobald) and Ae. tabu Ramalingam & Belkin a dose‐response relationship was detected between parasite load and mortality. This relationship was characterized by a significant reduction in the proportions of infected female mosquitoes surviving at days 1 and 9 postinfection, reduction in the median survival times and an increase in the hazard rates as the infectious dose increased.The survival of the refractory species, Ae.alcasidi Huang and Ae.katherinensis Woodhill was not significantly affected by the infection. A positive correlation between microfilaraemia in the vertebrate host and parasite load in the susceptible mosquito populations was also observed.Regression analysis of the number of parasites recovered from susceptible mosquitoes at the time of death showed that mosquitoes at highest risk of dying harboured from 11.6 to 19.4 infective larvae when fed on a gerbil with sixty‐five microfilariae per 20,μl blood; this resulted in 34.4–40.2% mortality by day 9 postinfection. A mean number of 32.6–46.9 infective larvae was observed when these populations were exposed to a gerbil with a microfilaraemia of 150 mf/20 μl and resulted in 72.8% to 80% mortality in these populations. Viable infective larvae were recovered from infected mosquitoes up to 50 days postinfection.
An experimental assessment of the tampan tick Ornithodoros moubata as vector of hepatitis B virus
Authors: JUPP P. G. , JOUBERT J. J. , CORNEL A. J. , SWANEVELDER C. , PROZESKY O. W. 
Published: March 2008

Abstract. Wild‐caught and colonized tampan ticks, Ornithodoros moubata (Murray), were fed on hepatitis B virus (HBV)‐positive blood‐means in a series of four experiments.Hepatitis B surface antigen (HBsAg) persisted in nymphal and adult ticks for up to 779 days, while the epsmark antigen (HBeAg) persisted in mature nymphs up to 13 days, in adult males up to 11 days and in adult females up to 16 days. HBsAg was transmitted trans‐stadially through two moults during the life cycle but transovarial transmission did not occur. The surface antigen was transmitted by two out of fifteen single ticks into 0.4 ml aliquots of HBV‐negative blood, although six groups of ticks failed to transmit into 5.5 ml aliquots of blood: this antigen was not transmitted to hamsters. HBsAg was detected in samples of the ticks' coxal and rectal fluid secretions always at the infecting feed and usually at the second feed. HBeAg was only detected in one of two samples of coxal fluid collected at the infecting feed.The results as a whole indicate that no biological multiplication of virus occurs in O.moubata but that mechanical transmission from ticks to man could occur by: (i) contamination of a person when crushing infected ticks; (ii) infection by bite; (iii) contamination with coxal fluid, especially by scratching bites. This is thought to take place among the Kavango tribe in their village huts in north‐eastern Namibia where infestations of infected O.moubata occur.
Selective attractiveness of rodent‐baited traps for female blowflies
Authors: AVANCINI RITA M. P. , LINHARES ARíCIO X. 
Published: March 2008

Abstract. Five species of Calliphoridae, mostly females, were collected using fly‐traps baited with freshly killed rodent carcasses. Female blowflies were examined to determine the stages of ovarian development.The traps were selective for certain ovarian stages which varied according to the species. Phoenicia eximia (Wiedemann) was attracted to the traps mainly to oviposit, whereas females of Chrysornya albiceps (Wiedemann), C.putoria (Wiedemann) and C.megacephala (Fabricius) were captured in intermediate stages of oogenesis but seldom with eggs mature for oviposition.It is concluded that this kind of baited trap is unsuitable for the collection of male blowflies and that samples of female blowflies are specifically biased in favour of certain ovarian conditions.
Effects of 'closed' houses on the Aedes aegypti eradication programme in Trinidad
Authors: CHADEE DAVE D. 
Published: March 2008

Abstract. The effects of closed (i.e. locked) houses on the efficiency of control measures against Aedes aegypti (L.) were monitored weekly for 1 year (March 1981 to February 1982) using ovitraps in the towns of Felicity and Trincity, Trinidad. Regular anti‐aegypti activities comprised source reduction, focal treatment with larvicidal 1% temephos sand granules and perifocal treatment with 40% wp fenthion.In Felicity, only 6% of houses were closed and after each treatment cycle ovitrap indices showed 100% control. In Trincity, 32% of houses were closed and after each treatment cycle reductions in ovitrap indices were less than 50%. Ae.aegypti eggs sampled in ovitraps totalled 493 (1–70 per positive paddle) in Felicity and 2310 (1–75 per positive paddle) in Trincity; twenty‐three ovitraps were found to be positive in Felicity and 247 in Trincity. Ae.aegypti was successfully eliminated from Felicity during weeks 40–52 using focal/perifocal treatment monitored by ovitraps. Control failure in Trincity was attributed to the survival of untreated Ae.aegypti populations in closed houses.Recommendations to improve gaining access for inspection and treatment of closed houses include having control/surveillance workers commence activities at 06.00 hours on weekdays, to work at weekends or during school holidays, or as a last resort to invoke court orders against householders harbouring Ae.aegypti.
ELISA absorbance cut‐off method affects malaria sporozoite rate determination in wild Afrotropical Anopheles
Authors: BEIER JOHN C. , ASIAGO CHARLES M. , ONYANGO FRED K. , KOROS JOSEPH K. 
Published: March 2008

ABSTRACT. Malaria sporozoite infection rates in a mixed species group of 244 Anopheles gambiae Giles sensu lato and 115 An. funestus Giles wild female mosquitoes were compared using three methods to determine cutoff absorbance values for positivity of a Plasmodium falciparum Welch enzyme‐linked immunosorbent assay (ELISA). Positive controls were based on P. falciparum circumsporozoite protein. As negative controls, four wild male Anopheles were included on each microtitre plate; tests were repeated on four consecutive days for each plate.Infection rates were estimated at 13.1–22.8% using the mean absorbance value of negative controls plus three standard deviations, 11.7–12.8% using double the mean and 12.5–13.6% using the fixed cut‐off value of 0.20 (allowing for 20% variation in negative control absorbance values).Observed agreement for positivity or negativity among samples tested four times was 98.6% for the 2× mean method, 97.2% for the fixed cut‐off 0.20 value, but only 82.7% for the mean +3 SD method. It was concluded that the 2× mean cut‐off method is most reliable for field studies. P. falciparum sporozoite rates of 12.2% in An. funestus and 11.9% in An. gambiae s. l. were thus determined on the basis of the 2× mean cut‐off method.This comparative evaluation demonstrates that vector infectivity rates can be seriously over‐estimated from sporozoite ELISA tests, by as much as 87% in one case considered here, depending on the absorbance cut‐off method applied for negative controls.
Effects of screen materials on droplet size frequency distribution of aerosols entering sentinel mosquito exposure tubes*
Authors: BOOBAR L. R. , DOBSON S. E. , PERICH M. J. , DARBY W. M. , NELSON J. H. 
Published: March 2008

ABSTRACT. Aerosol filtration effects of three types of mesh screen used for mosquito cages were evaluated with aerosolized water, mineral oil and chlorpyrifos. The screen materials were two nylon tulles (3times4 and 8times11 repeats per cm2) and corrosion‐resistant steel (7times7 repeats per cm2). Open areas of these three mesh materials were, respectively, 94%, 79% and 88%.Aerosol droplet size frequency distributions were altered when passed through test screens of these materials fitted to standard tubes from World Health Organization test‐kits for exposure of adult mosquitoes. The alterations included reductions in total droplets and volume median diameter (VmD). Nylon screen with fewer repeats of the mesh altered droplet VmD and frequency distribution the least, allowing the greatest number of droplets to enter sentinel mosquito cages for bioassays of mortality‐rates.The greater filtration effect of screens with less open area, giving rise to selective deposition of particular droplet sizes on the screen material, could result in anomalous exposures of test mosquitoes to contact with insecticide filtrate on the screen substrate. This might help to explain the poor correlation often observed between insecticide aerosol impact on wild target mosquito populations as compared with sentinel caged mosquitoes. In addition to other standard test procedures, the need for standardization of materials used for construction of sentinel cages employed for aerosol bioassays is emphasized.
A laboratory investigation of mosquito larval predation by Toxorhynchites moctezuma on Aedes aegypti
Authors: SHERRATT THOMAS N. , TIKASINGH ELISHA S. 
Published: March 2008

ABSTRACT. 1. Functional responses of predatory Toxorhynchites moctezuma (Dyar & Knab) larvae feeding on Aedes aegypti (L.) larvae (Diptera: Culicidae) were found to be type II of Holling (1959) and Rogers (1972).2. Estimates of searching rate were generally higher for later instar predators. The search rate of second instar predators declined as prey instar increased, but fourth instar Tx. moctezuma had the highest search rate for second instar Ae. aegypti.3. Prey handling times were higher for early instar predators and late instar prey.4. When presented with mixtures of two instars of Ae. aegypti, second instar Tx. moctezuma showed frequency independent selectivity for the early instars, whereas fourth instar predators showed frequency independent selectivity for the late instars of Ae. aegypti. There was no evidence of frequency dependent predation. Preferences appeared to be transitive.5. Extended random predator equations, using parameters derived from the functional responses, did not adequately describe the outcome of predation in the prey mixture experiment, even when the possibility of optimal switching behaviour was accounted for.
Seasonal patterns of rodents, fleas and plague status in the Western Usambara Mountains, Tanzania
Authors: NJUNWA K. J. , MWAIKO G. L. , KILONZO B. S. , MHINA J. I. K. 
Published: March 2008

ABSTRACT. Field and commensal rodents were live‐trapped at three villages in an active focus of plague (Yersinia pseudotuberculosis pestis) in Lushoto District, Western Usambara Mountains, Tanga Region, Tanzania, from December 1983 to November 1984. Their flea ectoparasites were collected, identified and counted. The rodent carcasses were serologically examined for specific plague antibodies and antigens, and bacteriologically examined for bipolar staining bacilli.A total of 1758 traps were set during the 12‐month period and 924 animals were caught. From these, 1037 fleas were collected. Rattus rattus (L.), Praomys natalensis (Smith) and Lophuromys flavopunctatus Thomas comprised the largest proportions of the rodent population, while Dino‐psyllus lypusus Jordan & Rothschild, Ctenophthalmus calceatus Waterston and Xenopsylla brasiliensis (Baker) were the dominant flea species.Rodents were most abundantly trapped during December and January. Flea indices were highest from December to May. Human plague was most active from November to March. Rodents contained plague antibodies every month except May and July, with a peak in September. Plague antigens and bipolar bacilli were detected in rodent organs during January‐April. From the product of abundance and infection rate, the most prevalent rodent hosts of plague appeared to be R. rattus, Otomys ango‐niensis Wroughton, P.natalensis and Pelomys fallax (Peters).Continuous integrated control of rodents and fleas was recommended, reinforced by quarantine and maintenance of a surveillance service for clinical detection, diagnosis and treatment of patients in the plague endemic area.
Selection of Anopheles stephensi for refractoriness and susceptibility to Plasmodium falciparum
Authors: FELDMANN A. M. , PONNUDURAI T. 
Published: March 2008

ABSTRACT. Variation in susceptibility of the vector Anopheles stephensi Liston to the human malaria parasite Plasmodium falciparum (Welch) was demonstrated using twelve strains of mosquitoes and one strain of parasites cultured in vitro.The Beech strain of An. stephensi exhibited greatest natural refractoriness, but with high intrapopulation variability. By selection for the required characteristic, two refractory lines of the Punjab strain and one highly susceptible line of the Sind strain were obtained. The median number of oocysts in the two refractory lines was less than 4% of that in the unselected line, whilst the highly susceptible line yielded about twice as many oocysts as the unselected line.Selection progressed more by keeping the descendants of individual females separate and selecting between them (individual selection) rather than pooling the progeny of all selected mosquitoes (mass selection). Using the former procedure many lines were lost due to inbreeding depression, but the outcome was more successful.
Estimation of rates of predation on tsetse
Authors: ROGERS DAVID J. , RANDOLPH SARAH E. 
Published: March 2008

ABSTRACT. The levels of natural predation of puparial and adult tsetse flies, Glossina pallidipes Austen, were investigated at Nguruman, Kenya, during January 1989. Puparial experiments involved the production, by individually tubed female flies, of naturally deposited, unhandled puparia in soil cores; handled puparia were obtained from groups of caged flies kept in the normal way. Equal numbers of handled and unhandled puparia were planted out at different densities (1, 2, 4 or 8 per linear metre) in fifty‐one natural puparial sites in four major vegetation types. After 10 days puparia were recovered using a soil corer and sieving system. Average predation rates (adjusted for the displacement of puparia by vertebrate activity at the puparial sites) were 9.4% and 7.8% for the two types of puparia during the experiment, equivalent to an average loss of 23.7% of all puparia during a normal 30‐day developmental period.Maximum potential predation rates of adult flies were investigated by pinning freshly killed adults at densities of1, 2, 4 or 8 per m3 to natural vegetation and scoring the results after 24 h. 70% of flies were attacked during this time, by a variety of predators, thought to include both vertebrates and invertebrates.No density dependence was detected in the experiments, either because natural puparial densities were too low for it to occur at this stage of the life cycle or because adult predation levels were too high for it to be detected.Present results are compared and contrasted with previous results for this and another species of tsetse. Calculations of the life‐time fertilities of female tsetse suggest that the levels of puparial predation revealed by the present experiments are entirely realistic. Behaviour of the adult flies allows them to escape most of the considerable predation pressure under which they live. How they do so remains a mystery.
Testing Anopheles albimanus for genetic linkage of insecticide resistance genes by combining insecticide bioassay and biochemical methods
Authors: LINES J. D. , FfRENCH‐CONSTANT R. H. , KASIM S. H. 
Published: March 2008

Abstract. A microtitre‐plate assay which distinguishes propoxur‐resistant from susceptible Anopheles albimanus Weidemann was used to test for linkage between the genes for propoxur‐ and dieldrin‐resistance. The adult progeny of a backcross between a doubly‐resistant colony and a fully susceptible colony were exposed in conventional test kits to the standard discriminating dose of dieldrin, and kept in the insectary overnight. Both live and dead insects were then assayed individually for propoxur‐resistance.The results showed that heterozygotes for propoxur‐resistance could be reliably distinguished from susceptibles whether or not they had been killed up to 24 h previously by dieldrin treatment. In this way all the backcross progeny could be scored at both resistance loci, and all four genotypic classes identified. Resistant and susceptible alleles at the two loci were inherited independently, demonstrating the absence of linkage.The usual method of testing for linkage between resistance genes is inefficient and open to bias, because insects have to be exposed to each insecticide in turn, and only half of them can be scored at both loci. The method shown here avoids these drawbacks.
Intraspecific variation in the cuticular hydrocarbons of the sandfly Phlebotomus perfiliewi from Italy
Authors: PHILLIPS A. , MILLIGAN P. J. M. , MAROLI M. , LANE R. P. , KAMHAWI S. , BROOMFIELD G. , MOLYNEUX D. H. 
Published: March 2008

Abstract. The cuticular hydrocarbons of Phlebotomus perfiliewi Parrot from representative localities on both sides of Italy show contrasts which support the view of Ward et al. (1981) that there are distinguishable populations of this sandfly on the Adriatic and Tyrrhenian coasts. It is suggested that the Appennine mountains form a barrier between the Adriatic and Tyrrhenian populations.A third distinct hydrocarbon type of P.perfiliewi was detected in Calabria, southern Italy, where contact between the Adriatic and Tyrrhenian types of flies is most likely to occur. P.perfiliewi from a trans‐Appennine pass were also of the Calabrian hydrocarbon type.These hydrocarbon contrasts between allopatric populations of P.perfiliewi may result from clinal variation across the Appennines, associated with different host preferences, or they may represent apomictic populations with differential mate recognition systems.
Automatic recording of flea activity
Authors: GREENWOOD M. T. , CLARK F. , SMITH J. S. 
Published: March 2008

Abstract. An Insect Activity Monitor was created to measure the behavioural responses of fleas (Siphonaptera). The apparatus allows for a range of visual, chemo‐ and mechanoreceptor cues to be presented. The jumping response is detected by counting amplified pulses produced as the fleas land on a stretched membrane held over a microphone. Horizontal movements are detected using a system of infra‐red beams and phototransistors which, when broken, are counted as a measure of activity.The apparatus was tested using Ceratophyllus hirundinis (Curtis), Ceratophyllusfarreni (Rothschild) and Ceratophyllus rusticus (Wagner), co‐inhabiting species from the nests of the house martin (Delichon u.urbica L.). No unaided emigration or immigration has been demonstrated in these species (Clark, 1988) and much of their time is spent confined to the darkness of the nest. In addition to species contrasts, females were more active than males and fleas were more active at 25oC than at 18oC.The more active bird flea Ceratophyllus garei (Rothschild) from the nest of pheasant (Phasianus colchicus L), was tested for responses to light of varying intensity. Activity was stimulated by white light, but not proportional to light intensity.
Glossina fusca group tsetse as vectors of cattle trypanosomiasis in Gabon and Zaire
Authors: LEAK S. G. A. , COLARDELLE C. , D'IETEREN G. , DUMONT P. , FERON A. , JEANNIN P. , MINENGU M. , MULUNGU M. , NGAMUNA S. , ORDNER G. , SAUVEROCHE B. , TRAIL J. C. M. , YANGARI G. 
Published: March 2008

Abstract.

he significance of Glossina fusca group tsetse flies as vectors of cattle trypanosomiasis was examined using biconical traps to survey tsetse populations at one site in Gabon and two sites in Zaire.
Mean trypanosome infection rates in G.tabaniformis Westwood over the study period ranged from a minimum of 8.9% at one site to a maximum of 17.7% at another. The mean infection rate in G.nashi Potts was 6.0%.
Up to 49% of bloodmeals of G.tabaniformis were from cattle. Trypanosome prevalence in cattle where G.tabaniformis appeared to be the main vector was 9.5% and 5.4% at the Mushie and OGAPROV ranches, respectively.
A highly significant positive correlation was found between tsetse challenge and trypanosome prevalence in N'Dama cattle across sites. Tsetse challenge was defined as the product of tsetse relative densities, trypanosome infection rates in the flies and the proportion of feeds taken by them from cattle. Thus, G.tabaniformis can be an important vector of pathogenic Trypanosoma species in cattle.
Induction of dominant lethal mutations for control of the facefly, Musca autumnalis DeGeer
Authors: MANSOUR Y. M. , KRAFSUR E. S. 
Published: March 2008

Abstract.

Application of the sterile insect technique (SIT) to the facefly, Musca autumnalis DeGeer, is considered.
Six‐day‐old pupae were exposed to ionizing irradiation at doses in the range 100–1600 rads, each treatment being replicated six times.
Eclosion was unaffected but fecundity and fertility was inversely proportional to the radiation dose.
1600 rads gave 97% dominant lethality of sperm in treated males and suppressed ovarian development in females. Irradiated flies did not recover fertility.
Irradiation of males and females did not affect insemination rates.
Sterile males showed a decline in longevity and reduced mating competitiveness.
Local eradication of M. autumnalis is considered to be feasible if sufficient diapausing sterile flies are stockpiled and released in early spring, followed by additional releases of non‐diapausing flies in late spring and early summer, with further releases of diapausing sterile flies in late summer and autumn.
Malathion and pyrethroid resistance in Culex quinquefasciatus from Cuba: efficacy of pirimiphos‐methyl in the presence of at least three resistance mechanisms
Authors: BISSET J. A. , RODRIGUEZ M. M. , HEMINGWAY J. , DIAZ C. , SMALL G. J. , ORTIZ E. 
Published: March 2008

Abstract. Use of malathion for mosquito control in Cuba for 7 years up to 1986 has selected for elevated non‐specific esterase and altered acetylcholinesterase (AChE) resistance mechanisms in populations of the pest mosquito Culex quinquefasciatus Say. These mechanisms are still present in relatively high frequencies in the Havana area, despite the replacement of malathion by pyrethroid insecticides for the last 3 years in the mosquito control programme.Samples of Culex quinquefasciatus populations from within a 100 km radius of Havana had high levels of resistance to malathion and lower levels of resistance to propoxur, but there was little or no cross‐resistance to the organophosphorus insecticide pirimiphos‐methyl.Selection with malathion for twenty‐two consecutive generations in the laboratory increased the level of malathion resistance to 1208‐fold and propoxur level to 1002‐fold, but the maximum level of pirimiphos‐methyl resistance was only 11‐fold.Pirimiphos‐methyl is still operationally effective, despite the resistance mechanisms segregating, so this insecticide if used for control is unlikely to select either of the known resistance factors directly in the field population.Since 1986, pyrethroids have been used extensively, and low levels of pyrethroid resistance were detected in two of five field population samples tested.Malathion selection did not increase the level of pyrethroid resistance, which indicates that one or more distinct pyrethroid resistance factors are now being selected in the field populations of Culex quinquefasciatus.