bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA probes for species identification of mosquitoes in the Anopheles gambiae complex
Authors: GALE KEVIN R. , CRAMPTON JULIAN M. 
Published: March 2008

Abstract. Identification of species within the Anopheles gambiae Giles species complex is essential for the correct evaluation of malaria vector ecology studies and control programmes. The development of DNA probes to distinguish species of the An.gambiae complex is described.Genomic libraries were prepared for four members of the An.gambiae complex. These were screened using radiolabeled DNA from different species of An. gambiae sensu lato and a number of clones selected on the basis of their species specificity. These clones could be divided into two groups, each containing homologous sequences. Sequences homologous to group 1 inserts are highly reiterated in the genomes of Anopheles arabiensis Patton and Anopheles merus Dönitz, present in low copy number in Anopheles melas Theobald, but were not detected in Anopheles gambiae sensu stricto. Studies on the organization of this sequence in the genome of An.arabiensis show that homologous sequences are male specific and interspersed within the chromatin. Sequences homologous to group 2 inserts are highly repeated in the genomes of An.merus and An.melas, but present in low copy number in An.gambiae s.s. and An.arabiensis. Group 2 homologous sequences are not sex‐specific in the species tested and appear to be tandemly repeated. When used as hybridization probes, these sequences provide a sensitive means for the identification of species within the Anopheles gambiae complex.
Experimental hybridization between members of the Simulium damnosum complex
Authors: MEREDITH S. E. O. , BOAKYE D. A. , RAYBOULD J. N. , CHEKE R. A. 
Published: March 2008

Abstract. Males of the Beffa form of Simulium soubrense Vajime and Dunbar were successfully crossed with female S.squamosum V. & D. and S.sanctipauli V. & D. Fertile eggs from both crosses were reared to larvae and, in the case of the BeifaXsquamosum cross, to adults.Larval chromosomes from the Beffa x sanctipauli cross had normally paired homologues but those of the Beffaxsquamosum cross showed extensive asynapsis and large heterozygous loops. The morphology of the larval and adult hybrids from the BeftaXsquamosum cross were more characteristic of squamosum, but the adult males had scutal patterns typical of the Beffa form and retained this form's laboratory‐mating propensity.
The effect of permethrin‐impregnated bednets on a population ofAnopheles farautiin coastal Papua New Guinea
Authors: CHARLWOOD J. D. , GRAVES P. M. 
Published: March 2008

Abstract.The effect of introducing bednets impregnated with 0.4 g/m2permethrin on local populations of the malaria vector mosquitoesAnopheles farautiLaveran andAn.koliensisOwen was monitored in a coastal village of Papua New Guinea. Whole‐night landing collections were undertaken for 25 consecutive nights before and 21 nights after the introduction of the nets. Capture‐recapture experiments and resting collections were also performed before and after the introduction of the nets.Following the introduction of treated nets, the biting population ofAn.farauti, the predominant vector, dropped from an average of 689 to 483 per man‐night and the oviposition cycle became irregular, although survival rates (determined by time series analysis of the landing catches and log regression of recapture rates) were not significantly affected. The densities ofAn.farautiresting in and around houses and the human blood index of the engorged females also decreased significantly after introduction of the treated bednets.The population ofAn.koliensisdropped prior to the introduction of the nets. However, the number of nulliparous females in the landing catches remained more or less constant which implies that, in this species, survival rates were affected by the nets but that recruitment to the population was not.
The tropical African latrine blowfly, Chrysomya putoria (Wiedemann)
Authors: LAURENCE B. R. 
Published: March 2008

ABSTRACT. The status of the tropical African latrine blowfly Chrysomya putoria (Wiedemann, 1830) is recognized as distinct from the sub‐tropical African blowfly C. chlowpyga (Wiedemann, 1818) (Diptera: Calliphoridae).The biology of C. putoria in laboratory culture is described briefly with emphasis on the differences in development found in three strains of this species from Tanzania, Liberia and Brazil. All three strains were reproductively compatible and there was no evidence of F1 hybrid sterility or hybrid breakdown in subsequent generations. Larval development was significantly faster in the Brazilian strain than in the strain from Tanzania. Sexual maturity was significantly faster in adults of the Liberian and Brazilian strains compared to that found in the strain from Tanzania. This latter strain was affected by the source of protein available as adult food. These differences between strains did not appear to be due to selection in laboratory culture, but rather evidence of the evolution of physiological divergence within a species occupying different geographical regions.
Onchocerciasis transmission levels and Simulium damnosum complex biting activity at riverside and rice field sites in Sierra Leone
Authors: DAVIES J. B. , BEECH‐GARWOOD P. A. , THOMSON M. C. , McMAHON J. E. 
Published: March 2008

ABSTRACT. Biting densities of the Simulium damnosum Theobald complex of blackflies and their levels of parasitism by Onchocerca volvulus (Leuckart) were compared at two ecologically contrasted sites in the Southern Province of Sierre Leone, West Africa: by the Tabe riverside close to Gbaiima village where onchocerciasis is hyperendemic (63.1% positive skin‐snips) and in open rice fields 2 km from the mesoendemic (54.9%) village of Senehun.Using a combination of morphometric and enzyme electrophoresis techniques, the primary vector was found to belong to the S. sanctipauli sub‐complex and was most probably S. soubrense‘B’ (sensu Post, 1986). In the wet season biting activity took place throughout the day at the village, but had morning and evening peaks in the rice fields.Transmission of O. volvulus was detected at the village in all months except February‐April, while in the rice fields it was detected only during September‐November and May at one tenth the level of the village. There was a significant difference between the two sites in the proportion of parous flies carrying third stage larvae in the head, but not of other larval stages.
Uptake and persistence of ingested antibody in the mosquito Anopheles stephensi
Authors: LACKIE A. M. , GAVIN S. 
Published: March 2008

ABSTRACT. A sensitive ELISA was developed to monitor the persistence of a specific antibody, rabbit anti‐BSA, in the bloodmeal, haemolymph and tissues of the mosquito Anopheles stephensi Liston. Different concentrations of anti‐BSA were fed to female mosquitoes in sheep blood, via a membrane‐feeder, and it was found that antibody persisted in the gut as the bloodmeal was digested: concentrations present at 24 h were directly related to those fed.Homogenates of mosquito bodies, from which the intact guts had been removed, were always antibody‐positive up to 9 days post‐feeding, indicating that undigested antibody had passed through the gut wall into the haemocoele. Haemolymph was extracted from mosquitoes at different times post‐feeding, using a microcapillary and manipulator, and antibody was detected in several of the assays. The level of antibodies in the haemolymph 24 h post‐feeding was less than half of the level in mosquito heads, indicating removal of antibodies from the haemolymph, perhaps by binding onto haemocoelic tissues.The relevance of these results to the ingestion, survival and fate of antibody against malaria sporozoites is discussed.
Chrysops silacea and C.dimidiata seasonality and loiasis prevalence in the Chaillu mountains, Congo
Authors: NOIREAU F. , NZOULANI A. , SINDA D. , CAUBÈRE P. 
Published: March 2008

Abstract. Seasonal activity of the loiasis vectors Chrysops dimidiata Wulp and Chrysops silacea Austen (Diptera: Tabanidae) was studied during 1987–89 in villages and surrounding forest of the Chaillu Mountains, Congo. Chrysops were captured mainly in the hot rainy season (November ‐May) and densities of both species were higher in the forest than in villages. C.silacea predominated at all sites and C.dimidiata was rarely found in villages.In the rain forest, between 07.00 and 18.00 hours, 12 times more C.silacea and 3 times more C.dimidiata were collected with hand‐nets (range 15–81 per man‐day) than were caught in landing/biting collections on human bait. Chrysops man‐biting rates were higher in villages closer to the forest, but variations in loiasis prevalence among villagers (microfilaraemia rates 16–37%) were not proportional to the intensity of contact between people and vectors in the villages, indicating that the majority of loiasis transmission probably occurs when people go into the forest.
Probing behaviour and sporozoite delivery by Anopheles stephensi infected with Plasmodium berghei
Authors: LI XIAOHONG , SINA BARBARA , ROSSIGNOL PHILIPPE A. 
Published: March 2008

Abstract. We observed that Plasmodium berghei sporozoite‐infected Anopheles stephensi was not impaired in its ability to locate blood on a host. When probing rats, infected mosquitoes took as long as non‐infected mosquitoes to locate blood.Contrary to previous suggestions, infective mosquitoes delivered sporozoites into mineral oil even after extensively probing a vertebrate host. We observed that, in mosquitoes having probed a host, both the mean number of sporozoites ejected over 3min into oil (35.9 v. 31.7 sporozoites) and the proportion of mosquitoes delivering sporozoites (60% v. 50%) were similar to mosquitoes not having probed.We then developed a model of sporozoite delivery, taking into account observations that sporozoites are clumped in the lumen of the glands as well as upon delivery, and that output is uneven and inconsistent. We conclude that clumping optimizes transmission, if a threshold of infection exists and the mean number of sporozoites per clump is greater than the threshold.
Impact of permethrin‐impregnated mosquito nets compared with DDT house‐spraying against malaria transmission by Anopheles farauti and An.punctulatus in the Solomon Islands
Authors: HII JEFFREY L. K. , KANAI L. , FOLIGELA A. , KAN S. K. P. , BURKOT T. R. , WIRTZ R. A. 
Published: March 2008

Abstract. In villages of northern Guadalcanal in the Solomon Islands, where the predominant malaria vector is An.farauti No. 1 and An. puctulatus is also involved, malaria transmission rates were compared for three zones: (1) non‐intervention: 438 people in seventeen villages; (2) residual DDT house‐spraying two cycles per year: 644 people in thirty villages; (3) bednets impregnated with permethrin 0.5 g/m2 twice per year, used by 580 people in sixteen villages. Regular DDT spraying in zones 1 and 3 had been withdrawn 18 months previously.Malariological blood smear surveys of children aged 1‐9 years in August 1986 to January 1987 showed a mean‐baseline malaria parasite rate of 38% (32/84). By February 1988, 18 months after introduction of impregnated bednets, the Plasmodium falciparum infection rate in children was lowest in the zone using impregnated bednets (21% of 29), intermediate in the untreated zone (29% of 34) and highest in the DDT zone (46% of 53), but these differences were not statistically significant. P.vivax infection rates were 9–14%.Using ELISA tests for malaria circumsporozoite antigen in the vectors, overall positivity rates were 0.7% of 49,902 An.farauti and 2.54% of 118 An.punctulatus, comprising 228 P.falciparum and 124 P. vivax infections. In the study zones, vector positivity rates were 0.93% of 31,615 An.farauti in the untreated zone; 0.32% of 16, 883 An.farauti in the DDT zone; 0.07% of 1404 An.farauti and 2.54% of 118 An.puctulatus in the impregnated bednet zone. There was no significant correlation between malaria parasite rates in the vectors and the children.Entomological inoculation rates were consistently highest in the untreated zone (1.6–2.8 infective bites/night), intermediate in the DDT zone (0.8– 1.1/night) and significantly lowest in the bednet zone (0.03‐0.23/night). Geometric mean densities of P.falciparum sporozoites were also significantly higher in the DDT zone (50% > 10,000 sporozoites/mosquito compared with 20% in untreated zone). The highest individual infection density was an estimated 52,080 sporozoites of P.falciparum in a specimen of An.punctulatus from the bednet zone. P.vivax sporozoite densities were not significantly different between zones, and both species of vector had similar mean sporozoite loads for both species of malaria.It is concluded that permethrin‐impregnated mosquito nets exerted significantly more impact on vector infectivity and the inoculation rate than resulted from DDT spraying. Even so, the inoculation rate for people in the bednet zone remained at one infective bite every 4–32 days, an insufficient reduction to control malaria without additional countermeasures. Ineffectiveness of house‐spraying and the limited impact of impregnated bednets are attributed to exophily and other behavioural aspects of An. farauti.
Reduced susceptibility of Anopheles gambiae to permethrin associated with the use of permethrin‐impregnated bednets and curtains in Kenya
Authors: VULULE J. M. , BEACH R. F. , ATIELI F. K. , ROBERTS J. M. , MOUNT D. L. , MWANGI R. W. 
Published: March 2008

Abstract. Susceptibility of the malaria vector Anopheles gambiae to permethrin decreased following the installation of mosquito nets impregnated with 0.5 g permethrin per square metre in four villages near Kisumu, Kenya. During the first year that permethrin‐impregnated bednets and curtains were in place, the exposure time to 50% mortality (LT50) increased 2.5‐fold from 13 to 33min, while the LT5() for An.gambiae was unchanged in two other villages where no intervention measures were used. Two years after permethrin‐impregnated mosquito nets were distributed the LT50s for An.gambiae were 28, 28 and 16min, respectively, in the villages with bednets, curtains and with no such intervention.Using a colony of An.gambiae derived from females collected in the villages using permethrin‐impregnated moquito nets, we lengthened the LT5n from 28 to 41 min in two generations by exposing all females to permethrin‐treated papers for 60 min and rearing offspring of the survivors.Permethrin‐impregnated bednets and curtains are intended to reduce vectorial capacity. Reduced susceptibility to permethrin could counter this beneficial effect.
Pyrethroid‐sprayed tents for malaria control
Authors: HEWITT SEAN , ROWLAND MARK , MUHAMMAD NASIR , KAMAL MUHAMMAD , KEMP ELIZABETH 
Published: March 2008

Abstract>Field trials were undertaken in the North West Frontier Province of Pakistan to determine the effects of pyrethroid‐sprayed tents on feeding success, mortality and biting‐rates of wild mosquitoes attracted to bait cows confined within the tents. Under natural conditions, endophagic mosquitoes rested only briefly in untreated tents during the night, followed by complete exodus at dawn.In tents sprayed on the interior surface with permethrin 0.5 mg/m2 or with deltamethrin 0.03 g/m2 the biting rate of Anopheles stephensi was reduced by about 40%; detergency against culicines and other anophelines was much less. Mortality‐rates of bloodfed mosquitoes from the treated tents were 75%An.stephensi, 65%An. subpictus but only 10% of culicines.Outer fly‐sheets prolonged the effective life of the treatment; bioassays on the sprayed inner‐sheets showed that insecticidal efficacy remained high for over a year, whereas on tents without fly‐sheets permethrin residual efficacy declined rapidly 20–40 weeks post‐treatment. It is concluded that tent‐spraying with fast‐acting photostable residual pyrethroid insecticide would probably provide effective protection against malaria transmission for the inhabitants of tents in any part of the world where the vector mosquitoes are endophilic and susceptible to pyrethroids.
A simple, sterile food source for rearing the larvae of Lucilia sericata (Diptera: Calliphoridae)
Authors: SHERMAN RONALD A. , TRAN JULIE MY‐TIEN 
Published: March 2008

Abstractarvae of the sheep blowfly Lucilia sericata (Meigen) were reared on various mixtures of puréed liver, agar, brewer's yeast and trypsin, in order to develop a simple, sterile, tissue‐based diet. Growth and survival rates of larvae reared on a sterile 1:1 mixture of puréed liver with 3% Bacto agar equalled or exceeded those of larvae reared on raw liver. The addition of yeast and/or trypsin to the medium was of no additional benefit. This sterile, homogenous, tissue‐based substrate offers a simple, convenient, inexpensive growth medium for rearing larvae for maggot therapy, and for testing the effects of various chemicals and dietary constituents on necrophagous insect larvae. It may be useful, therefore, in studies of myiasis, forensic entomology, and toxicology. This rearing medium also has the advantage that it can be stored for many months at room temperature without progressive decomposition or offensive odour.
Permethrin resistance in the head louse Pediculus capitis from Israel
Authors: MUMCUOGLU KOSTA Y. , HEMINGWAY JANET , MILLER JACQUELINE , IOFFE‐USPENSKY INNA , KLAUS SIDNEY , BEN‐ISHAI FIAMETA , GALUN RACHEL 
Published: March 2008

AbstractHead lice, Pediculus capitis, were collected from children aged 3–12 years in Maale Adumin, a town near Jerusalem, after reports of control failure with the pyrethroid insecticide permethrin. A total of 1516 children were examined: living lice and eggs were found on 12.1% of the children; or another 22.8% of the children only nits were found. Twice as many girls as boys (8.1% v 4%) were infested with lice and or nits. Head lice collected from infested children were exposed to permethrin impregnated filter‐papers. Log time probit mortality (ltp) regression lines were calculated for mortality data and compared to ltp lines for a similar collection of head lice made in 1989. The regression lines for the two years were significantly different, with a 4‐fold decrease in susceptibility at the LT50 level between 1989 and 1994. The slopes of the lines also suggested that the 1994 population was more heterogenous in its response to permethrin than the 1989 population. In contrast, a laboratory population of body lice (Pediculus humanus) tested with the same batch of permethrin‐impregnated papers showed a slight but non‐significant increase in susceptibility between 1989 and 1994. The results suggest that resistance to pyrethroids has developed rapidly among head lice since permethrin was introduced in 1991 as a pediculicide in Israel.
Village trial of bednets impregnated with wash‐resistant permethrin compared with other pyrethroid formulations
Authors: MILLER J. E. , LINDSAY S. W. , ARMSTRONG J. R. M. , SCHELLENBERG  , ADIAMAH J. , JAWARA M. , CURTIS C. F. 
Published: March 2008

Abstract. A village‐scale field trial of pyrethroid‐impregnated mosquito nets was undertaken in The Gambia, West Africa, in the Mandinka village of Saruja (13o13'N, 14o55'W) during July‐November 1989. Nearly all the villagers possessed and used their own bednets. Anopheles gambiae is the main vector of human malaria in the area.An experimental wash‐resistant formulation of permethrin was compared with standard emulsifiable concentrate (EC) formulations of permethrin and lambda‐cyhalothrin, versus placebo‐treated bednets. Target concentrations of pyrethroids on bednets were permethrin 500mg/m2 and lambda‐cyhalothrin 25 mg/m2. The experimental design involved random allocation of a treatment to one net per family. Whereas 68% of people questioned said they washed their nets fortnightly, observations during the 16‐week trial period showed that only 4/130 (3%) of nets involved in the trial had been washed as frequently as once per month.Early morning searches for mosquitoes under bednets (1 day/week for 16 weeks) found significantly more mosquitoes (60%An. gambiae) in placebo‐treated nets than in pyrethroid‐treated nets. The numbers found with each of the three pyrethroid treatments did not differ significantly from each other. Insecticidal efficacy of the treatments was tested by bioassays using wild‐caught unfed mosquitoes exposed to netting for 3min. Linear regression analysis of bioassay mortality against number of times that a net had been washed by villagers showed that nets impregnated with the wash‐resistant permethrin retained their insecticidal properties better than nets impregnated with lambda‐cyhalothrin or with the standard permethrin formulation.
Low‐volume application by mist‐blower compared with conventional compression sprayer treatment of houses with residual pyrethroid to control the malaria vector Anopheles albimanus in Mexico
Authors: VILLARREAL C. , RODRIGUEZ M. H. , BOWN D. N. , ARREDONDO‐JIMÉNEZ J. I. 
Published: March 2008

Abstract. Village‐scale trials were carried out in southern Mexico to compare the efficacy of indoor‐spraying of the pyrethroid insecticide lambda‐cyhalothrin applied either as low‐volume (LV) aqueous emulsion or as wettable‐powder (WP) aqueous suspension for residual control of the principal coastal malaria vector Anopheles albimanus. Three indoor spray rounds were conducted at 3‐month intervals using back‐pack mist‐blowers to apply lambda‐cyhalothrin 12.5 mg a.i./m2 by LV, whereas the WP was applied by conventional compression sprayer at a mean rate of 26.5 mg a.i./m2.Both treatments caused mosquito mortality indoors and outdoors (collected inside house curtains) as a result of contact with treated surfaces before and after feeding, but had no significant impact on overall population density of An. albimanus resting indoors or assessed by human bait collections. Contact bioassays showed that WP and LV treatments with lambda‐cyhalothrin were effective for 12–20 weeks (>75% mortality) without causing excito‐repellency.Compared to the WP treatment (8 houses/man/day), LV treatment (25 houses/man/day) was more than 3 times quicker per house, potentially saving 68% of labour costs. This is offset, however, by the much lower unit price of a compression sprayer (e.g. Hudson ‘X‐pert’ at US120) than a mist‐blower (e.g. ‘Super Jolly’ at US350), and higher running costs for LV applications. It was calculated, therefore, that LV becomes more economical than WP after 18.8 treatments/100 houses/10 men at equivalent rates of application, or after 7.6 spray rounds with half‐rate LV applications.