bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of Glossina morsitans centralis originating from Tanzania and Zambia, with respect to vectorial competence for pathogenic Trypanosoma species, genetic variation and inter‐colony fertility
Authors: MOLOO S. K. , GOODING R. H.
Published: March 2008

wo laboratory strains of Glossina morsitans centralis originating from different fly‐belts (one from Singida, in Tanzania, and the other from Mumbwa, in Zambia) were compared with respect to vectorial competence for pathogenic Trypanosoma species, genetic variation and inter‐colony fertility. The vectorial competence of G.m.centralis of Tanzanian origin for Trypanosoma vivax and T.congolense is similar to, whereas for T.brucei brucei it is lower than the colony of Zambian origin. Nevertheless, these two laboratory strains of G.m.centralis showed levels of susceptibility to the three pathogenic Trypanosoma species which were much greater than previously observed in laboratory colonies of other Glossina species. Electrophoresis of fifteen enzymes revealed that the two colonies differ significantly in allele frequencies at only three loci that are relatively close together on one of the autosomes. Hybridization experiments revealed that G.m.centralis from the two fly‐belts are consubspecific.
Comparison of carbon dioxide, octenol and a host‐odour as mosquito attractants in the Upper Rhine Valley, Germany
Authors: BECKER N. , ZGOMBA M. , PETRIC D. , LUDWIG M.
Published: March 2008

ield studies were conducted in the Upper Rhine Valley to determine the responses of mosquitoes to CDC traps baited with either CO2, octenol, light or paired combinations of these. Among eight mosquito species caught, the attractant effect on trap catches was studied in the four most abundant: Aedes vexans, Ae.rossicus, Ae.cinereus and Culex pipiens.

Traps baited only with light or octenol caught few mosquitoes, whereas many were caught by traps baited with CO2 alone or in combination with either of the other candidate attractants. CO2 baited traps, with or without light, caught the most Aedes. The combination of CO2 and octenol attracted most Cx pipiens, but this apparent synergy was not significant.

Using a caged hamster compared to CO2 as bait in a CDC light‐trap with only intermittent fan suction, the hamster attracted less mosquitoes than CO2 emitted at a rate of 225 g/h on days 1 and 2, whereas on days 3 and 4 the smell from the hamster's cage became significantly more attractive than this rate of CO2 for all species of mosquitoes.
Differential lipid reserves influence host‐seeking behaviour in the mosquitoes Aedes cantans and Aedes punctor
Authors: RENSHAW M. , SILVER J. B. , SERVICE M. W.
Published: March 2008

ipid reserves of bait‐caught female Ae.cantans and Ae.punctor mosquitoes (Diptera: Culicidae) were significantly higher than in teneral females. Female Ae.cantans given access to 10% w/v sucrose solution post‐emergence showed an ability to synthesize lipid and, after 192 h, they were willing to take a bloodmeal from a human volunteer. At this point, mean lipid reserves were not significantly different from mean lipid reserves of bait‐caught females. Prior to 192 h, females would not take a bloodmeal and lipid reserves were significantly lower than in bait‐caught females. Female Ae.punctor given access to 10% w/v sucrose solution post‐emergence also showed an ability to synthesize lipid. Females of this species were willing to feed from a human host after only 48 h, at which point lipid content was not significantly different from that in bait‐caught females. The level of lipid reserves in females coming to bait differs significantly between species: Ae.cantans has lipid reserves approximately double those of Ae.punctor. In addition, Ae.punctor is able to synthesize lipid to a level comparable with that found in bait‐caught females after only 24 h, whilst it takes 192 h for Ae.cantans females to synthesize the amount of lipid found in host‐seeking females, when allowed free access to sugar. Physiological differences in lipid synthesis and the level of lipid reserves required may therefore explain the differences observed between the species in the time taken to initiate host seeking.
Faeces feeding by adult Phormia regina (Diptera: Calliphoridae): impact on reproduction
Authors: STOFFOLANO JOHN G. , LI MEI‐FANG , SUTTON JAMES A. , YIN CHIH‐MING
Published: March 2008

resh beef liver, sugar, and five different types of faeces were evaluated as supportive diets for egg development in the blowfly Phormia regina. Females on a sugar diet were unable to develop follicles beyond stage 3, whereas liver proved to be the best diet for complete egg maturation. Some faecal diets were unable to support egg maturation when fed upon for a short period of time; however, longer periods of feeding produced complete egg maturation. The necessity to feed for longer periods of time in order to produce eggs on most of these diets was attributed to their low protein content. Males, in a shorter period of time than females, obtained enough protein from faeces to activate the neuroendocrine system involved in mating.
Effect of host packed cell volume on the bloodmeal size of male tsetse flies, Glossina pallidipes
Authors: BAYLIS MATTHEW , MBWABI ALBERT L.
Published: March 2008

aematin contents of engorged, male tsetse flies, Glossina pallidipes Austen, were compared with the packed cell volumes of oxen on which they had fed. Haematin contents icnreased with packed cell volume up to packed cell volumes of approximately 30%. Haematin contents appeared to level off or decline with further increase in packed cell volume. These results support a model of blood‐feeding in tsetse flies in which the rate of blood consumption decreases as packed cell volume increases, because of increase in blood viscosity, and tsetse are unable to compensate for the decrease in consumption rate by feeding for a longer time. After allowing for the effects of packed cell volume, bloodmeal sizes of tsetse increased with ox body temperature.
Brindley's gland exocrine products of Triatoma infestans
Authors: LOPEZ LEOPOLDO CRUZ , MORGAN E. DAVID , ONDARZA RAUL N.
Published: March 2008

olatile exocrine products of the metathoracic Brindley's glands in Triatoma infestans (Hemiptera: Reduviidae) were obtained by dissection and by sampling the air passed over agitated live adults. Isobutyric acid was the main component in the glands, together with isobutyl, isoamyl and amyl alcohols, 2‐phenylethanol and other carboxylic acids and esters. Isobutyric acid, isobutyl, isoamyl and amyl alcohols and esters were also found to be emitted into the air, apparently for defence. No volatile products were detected in the metasternal glands.
Evaluation of non‐conventional treatments for control of the biting louse (Bovicola ovis) on sheep
Authors: HEATH A. C. G. , LAMPKIN N. , JOWETT J. H.
Published: March 2008

variety of non‐conventional treatments was applied to biting louse (Bovicola ovis) infested sheep in order to evaluate ways in which farmers could control the louse infestations and still maintain Organic Production Standards.

In one trial, louse scores of sheep shorn but kept dry or wetted by water alone or with water plus detergent were compared with unshorn sheep treated similarly. Shearing alone accounted for a 35.7–66.3% reduction in mean louse scores. Wetting alone either with water or with water and added detergent accounted for a 26.9–35.3% reduction in mean louse scores. The combined effects on mean louse scores of shearing and wetting, as opposed to shearing alone, were statistically significant on two of the three farms at 32–35 days post‐treatment. The effects persisted for the duration of the trial (between 48 and 52 days), at which point shearing and wetting with detergent provided 95.3–99.6% control of lice. In a second trial, a range of insecticidal substances considered acceptable by Organic Production Standards, azadirachtin (neem), pyrethrum, soap, was applied to louse‐infested sheep and their efficacy compared with that of a commercial formulation of cypermethrin. The sheep treated with azadirachtin and pyrethrum had significantly fewer lice than either the control or soap treated sheep over the 48 days of the trial. Neither azadirachtin nor pyrethrum were significantly less effective than cypermethrin. Control (reduction in louse score) of 85.0–100% was achieved over the period of the trial.

It is concluded that most of the non‐conventional treatments evaluated had a useful and cost‐effective role to play in reducing louse numbers on sheep for at least 40–50 days. The lack of persistence compared with that obtained with conventional insecticides was the only apparent drawback.
Movement of Anopheles gambiae s.l. malaria vectors between villages in The Gambia
Authors: THOMSON MADELEINE C. , CONNOR STEPHEN J. , QUIÑONES MARTHA L. , JAWARA MUSA , TODD JAMES , GREENWOOD BRIAN M.
Published: March 2008

ovement of mosquitoes belonging to the Anopheles gambiae complex (mixed wild populations of An.arabiensis, An.gambiae and An.melas) between three neighbouring rural villages in The Gambia was investigated by mark‐release‐recapture. A total of 12,872 mosquitoes were collected in bednets, marked with a magenta fluorescent powder and released over a 15‐day period in one of the villages. A further 15,507 mosquitoes were collected in exit traps, marked with a yellow powder and released over the same period. Mosquitoes were captured daily in all three villages using pyrethrum spray catches, as well as bednet and exit trap catches. The catching period extended for 6 days after the last day of release.

Of the mosquitoes released, 372 (1.3%) were recaptured 2–21 days later. Of these recaptures, 272 were caught in the release village, and 98 were caught in other villages situated 1–1.4 km away. The ‘movement index’ between villages was calculated as 17.2% (12.2–22.4% confidence limits) for mosquitoes released after feeding and 20.1% (14.7–25.3%) for those released unfed.

These results suggest that movement of mosquitoes between neighbouring villages in The Gambia seriously affects the entomological evaluation of pyrethroid‐impregnated bednet programmes in areas where treated and untreated villages are interspersed.
Age determination in the blackfly Simulium woodi, a vector of onchocerciasis in Tanzania
Authors: HOC T. Q. , WILKES T. J.
Published: March 2008

Abstract. Age‐dependent changes in the ovarioles of Simulium woodi (Diptera: Simuliidae) and the age structure of a wild population of this species in the Amani hills of north‐eastern Tanzania were studied using the ovarian oil injection technique. Contrary to previous theories, egg sacs degenerate completely and do not form dilatations. The physiological age of the females could be determined only by gonotrophic dilatations formed from degenerating follicles during gonotrophic cycles. In individual females, the proportions of ovarioles with degenerating follicles were 3–54% (mean 22%) in the first cycle and 8–61% (mean 36%) in the second gonotrophic cycle. Agonotrophic degenerating follicles occurred in 2% of ovarioles in 12% of females. Additional information with regard to the degree of parity is given by the level of granulation in the basal body of each ovariole, a group of six to eight cells in the calyx wall enclosed by the end of the ovariolar sheath. Their granulation progressively increased in intensity following each subsequent ovulation.
Proportions of eggs laid by Aedes aegypti on different substrates within an ovitrap in Trinidad, West Indies
Authors: CHADEE DAVE D. , CORBET PHILIP S. , TALBOT HELEN
Published: March 2008

Abstract. Ovitraps were exposed outdoors during wet and dry seasons in Trinidad to determine the proportions of eggs laid on three substrates: the widely‐used hardboard ‘paddle’ (P), the water surface (W) and the inside surface of the ovitrap wall (S) in three types of blackened ovitrap: round, glass (RG), round, plastic (RP) and rectangular, plastic (SP). Of the 3556 eggs obtained, most (86.4%) were laid during the wet season when statistically significant differences were detected between substrates but not between ovitrap types. Most eggs (>80%) were laid on P, significantly fewer (P < 0.005) on W, on S and on W + S, thus confirming the superiority of the paddle as a device for monitoring oviposition activity. Implications of these findings for the interpretation of Aedes studies using ovitraps are discussed.
Orientation of agents of wound myiasis to hosts and artificial stimuli in Hungary
Authors: HALL MARTIN J. R. , FARKAS ROBERT , KELEMEN FERENC , HOSIER MATTHEW J. , EL‐KHOGA JAMAL M.
Published: March 2008

Abstract. The orientation of adults of the myiasis species Wohlfahrtia magnified and Lucilia sericata to artificial visual stimuli (cloth targets) and olfactory stimuli (‘swormlure‐4’, a potent screwworm attractant), was studied in sheep pastures near to Sarbogard in Hungary. Experiments with odour‐baited cloth targets, enclosed in electrocuting grids, demonstrated that colour was an important factor influencing catches on targets: a black target caught most flies of both species, with other colours in the following order of effectiveness, blue > white > yellow. Wohlfahrtia magnified did not respond to swormlure‐4 in the strong manner that L. sericata did. The sex ratios of W. magnifica caught on targets (67.2% males) and hand‐netted from fence posts (68.8% males) were similar and biased towards males, whereas that of L. sericata on targets was strongly biased towards females (15.6% males), indicating a fundamental difference in the response of these two myiasis species towards the swormlure‐baited targets. The orientation of these two species towards hosts was also recorded together with that of a third species, Phormia regina. Electric nets placed beside infested sheep caught significantly more flies of all three species than those placed beside uninfested sheep or in the absence of sheep. The sex ratio of W. magnified caught around infested sheep was the reverse of that on targets, with 68.5% females. Wohlfahrtia magnifica responded more strongly to healthy, uninfested sheep than did L. sericata and P. regina. The potential for use of targets both for population monitoring and control is discussed.
Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis and Oestrus ovis
Authors: COLWELL DOUGLAS D. , SCHOLL PHILIP J.
Published: March 2008

Abstract.Cuticular sensilla on newly hatched larvae ofGasterophilus intestinalisDe Geer (Diptera: Gasterophilidae) andOestrus ovis(L.) were studied by scanning electron microscopy. Two types of trichoid sensilla, two types of coeloconic sensilla and a pit sensillum were present on the thoracic and abdominal segments ofG. intestinalislarvae. Sensilla on larvae ofO. oviswere similar although only one type of trichoid sensillum was present. Total number of sensilla were higher forO. ovisthan forG. intestinalis(248v. 214). Variation in numbers of sensilla is consistent with the concept that increasing numbers of sensilla are associated with increasingly complex searching behaviour required to locate suitable habitats for development.
Analysis of gene flow in North American face fly (Musca autumnalis) populations
Authors: KRAFSUR E. S.
Published: March 2008

Abstract. Vertical polyacrylamide gel electrophoresis was used to resolve enzymes at ten putative loci in face flies Musca autumnalis De Geer, a colonizing, Palaearctic species established in North America for at least 210 generations. Flies were sampled in 1991 from six locations in Iowa, two in Maryland, two in Minnesota, two in Tennessee, three in New York, and three in Missouri. Nondirectional temporal variation in gene frequencies over a 4‐year interval was detected at farms in central Iowa. Heterogeneity in allele frequencies was detected among farms in Iowa, Maryland, New York and Minnesota but not in Tennessee and Missouri. There were no consistent departures from random mating. Partitioning variances in gene frequencies showed that 58% of the variation occurred in populations among states and 43% between populations within states. Mean reproducing immigrants per population per generation was estimated to be eighteen flies. No regional genetic differentiation was detected, and there were no barriers to gene flow within or among diverse populations in the six states. Earlier data bearing on gene flow among and between Nearctic and Palearctic face fly samples were analysed and significant differentiation was not detected.
Effects of fenoxycarb on development and reproduction of the Oriental cockroach, Blatta orientalis
Authors: EVANS R. G. , SUNLEY A. , BRADFORD C. , PATMORE R. I.
Published: March 2008

Abstract. In a laboratory study, groups of third‐instar Blatta orientalis nymphs were reared to adulthood in arenas containing fenoxycarb (48 mg a.i./m2) treated ceramic or plywood tiles. The reproductive capacity of the emergent adults was assessed by pairing each individual with two untreated individuals of the opposite sex. Oothecal production, oothecal hatch and the numbers of nymphs emergent from each hatched ootheca were monitored. Exposure to 1‐day‐old deposits of fenoxycarb reduced adult emergence by 45–75% in comparison with an untreated control treatment. Substantial (>40%) mortality also resulted when nymphs were exposed to deposits up to 3 months old on plywood and up to 6 months old on ceramic. Exposure to fenoxycarb significantly extended the time taken to reach adulthood of males contacting 6‐month‐old deposits on both surfaces, and of females contacting 1‐year‐old deposits on ceramic. Adult females exposed as nymphs to fenoxycarb were unable to produce oothecae, except one female laid a non‐viable ootheca. Untreated females paired with treated males produced large numbers of oothecae of normal appearance but very low viability, with only 0–7.1% hatching. With marked effects on both development and reproduction in B. orientalis, fenoxycarb is a promising agent for control of this species.
The relationship between CDC light‐trap and human‐bait catches of endophagic sandflies (Diptera: Psychodidae) in the Peruvian Andes
Authors: DAVIES C. R. , LANE R. R. , VILLASECA P. , PYKE S. , CAMPOS P. , LLANOS‐CUENTAS A.
Published: March 2008

Abstract. A study was carried out in the Peruvian Andes to test the suitability of CDC light traps for monitoring changes in the human‐landing rate of endophagic phlebotomine sandflies, following house‐spraying with pyrethroid insecticide. On four pairs of consecutive nights, sandflies were caught inside eight sprayed and eight unsprayed houses, either by human bait or by CDC light traps. The sandflies collected were Lutzomyia verrucarum (97%) and Lu. peruensis (3%), both probable vectors of Leishmania peruviana, and the species composition was unaffected by house‐spraying. A non‐linear relationship was detected between light‐trap and human‐bait catches, but the relationship did not diverge significantly from linearity within the range of sandfly abundance found in most houses in the endemic area (i.e. between 3 and 200 sandflies/house‐night), and did not differ significantly between sprayed and unsprayed houses. However, light trap catches had a significantly lower proportion of blood‐fed females in sprayed than in unsprayed houses, probably due to an insecticidal effect on post‐blood‐feeding behaviour. The proportion of Lu. verrucarum was significantly higher in light trap than in human bait catches, indicating that Lu. peruensis is either more anthropophilic or less phototropic than Lu. verrucarum.
Evaluation of deltamethrin‐impregnated bednets and curtains against phlebotomine sandflies in Valle del Cauca, Colombia
Authors: ALEXANDER B. , USMA M. C. , CADENA H. , QUESADA B. L. , SOLARTE Y. , ROA W. , TRAVI B. L.
Published: March 2008

Abstract. The effectiveness of bednets and curtains (nylon mesh 64 per cm2) impregnated with deltamethrin at 26 mg a.i./m2 in reducing the biting nuisance caused by three phlebotomine sandfly species: Lutzomyia columbiana, Lu. lichyi and the predominant Lu. youngi (Diptera: Psychodidae), was evaluated at La Guaira, a rural settlement in Valle de Cauca near Cali, Colombia.

Pairs of volunteers collected sandflies under impregnated bednets, in rooms protected by impregnated curtains or in unprotected rooms in a randomized matched design. Collections were made in three houses per night on three consecutive nights, so that each house was sampled under each of the three treatments. This routine was repeated at 2‐week intervals for 6 months. There was no significant difference between the overall numbers of sandflies collected in rooms with or without impregnated curtains. Only 0.14 sandflies/man‐hour were caught on human bait under impregnated bednets, significantly fewer than the numbers collected on human bait outside the nets in the same room (1.91) or in unprotected rooms (3.29).

In a second set of experiments carried out in La Guaira and the neighbouring community of Jiguales, the effect of deltamethrin impregnation was evaluated by comparing numbers of sandflies collected on human bait under treated and untreated nets. Significantly fewer were collected under the impregnated nets (0.25 v. 0.69/man‐hour). Wild‐caught female Lu. youngi exposed to treated netting for 2 min in the laboratory all died with 24 h. The impact of deltamethrin‐impregnated bednets was considered to be useful against Lu. youngi and other potential vectors of leishmaniasis in such communities.
Field studies on the effect of cattle skin secretion on the behaviour of tsetse
Authors: WARNES M. L.
Published: March 2008

Abstract. The effect of ox skin secretions (sebum) on the behaviour of tsetse flies, Glossina spp., was investigated in the field using electrified targets, some of which operated intermittently, and by direct observations of flies landing on treated and untreated cloth. As the off‐period of an intermittently operating electrified target increased, the catch decreased both with and without the sebum present. Targets with sebum always caught more flies than targets without sebum, but there was no evidence to suggest that sebum increased the duration of stay on a target. Direct observations of flies on cloth targets revealed that for both species the presence of sebum reduced the duration of contact and for G. pallidipes the number of return contacts was increased. The results from direct observations were used to predict the number of repeat landings that would need to be made by flies in order to account for the catch of tsetse at intermittently electrified targets.
The effect of host resistance on the metabolic rate of engorged females of Rhipicephalus evertsi evertsi
Authors: RECHAV YIGAL , FIELDEN LAURA J.
Published: March 2008

Abstract. This study investigated the effect of acquired resistance in guinea‐pigs on the metabolic rate of adult females of the tick Rhipicephalus evertsi evertsi. Guinea‐pigs were subjected to three successive infestations of ticks and the rate of CO2 production (Vco2) measured in first and third infestation engorged females. Ticks which fed on resistant hosts showed a 52% decrease in mass compared to ticks that fed on naive animals. Reduction in mass was accompanied by a decrease in Vco2 (mlh‐1) per tick but an increase in mass specific Vco2 (mlg_1h_1). However, both groups shared a single allometric relationship between body mass and metabolic rate (Vco2). We suggest that the differences in size rather than any factor directly relating to the mechanism of acquired resistance account for the differences in metabolic rate between ticks fed on naive and resistant guinea‐pigs.
Simulium metallicum cytospecies E larval habitat characterization in the Altamira focus of onchocerciasis, northern Venezuela
Authors: GRILLET MARIA EUGENIA , BARRERA ROBERTO , CONN JAN
Published: March 2008

Abstract. Simulium metallicum sibling species E was identified cytotaxonomically from an onchocerciasis focus at Altamira in northern Venezuela. S. metallicum E larvae were sampled monthly from two small mountain streams over a 15‐month period (July 1990 to September 1991) and eleven habitat variables were measured at two altitudes. One stream consistently harboured much higher densities of S. metallicum E larvae than the other, with three annual peaks of abundance: during the dry season and at the beginning and end of the rainy season. These peak densities were correlated with high rainfall 4 months previously. Larvae were most abundant on submerged rocks and fallen leaves, in small shallow areas characterized by slow water current, high conductivity and sparse terrestrial vegetation cover. Stream variables which best explained the temporal changes in abundance were water discharge and conductivity. The population dynamics of S. metallicum E appeared to be influenced primarily by interactions between stream discharge and substrate stability. Relevance of these results to vector control with larvicides is discussed.
Comparison of different insecticides and fabrics for anti‐mosquito bednets and curtains
Authors: CURTIS C. F. , MYAMBA J. , WILKES T. J.
Published: March 2008

Abstract. Various formulations of six insecticides (a carbamate and five pyrethroids), were impregnated into bednets and curtains made from cotton, polyester, polyethylene or polypropylene fabric. For bioassays of insecticidal efficacy, female Anopheles gambiae mosquitoes were made to walk on the fabrics for 3 min and mortality was scored after 24 h. The main concentrations tested were: bendiocarb 400 mg/m2, cyfluthrin 30–50 mg/m2, deltamethrin 15–25 mg/m2, etofenprox 200 mg/m2, lambda‐cyhalothrin 5–15 mg/m2 and permethrin 200–500 mg/m2. Field trials in Tanzania used experimental huts (fitted with verandah traps) entered by wild free‐flying Anopheles gambiae, An. funestus and Culex quinquefasciatus mosquitoes.

Results of testing the impregnated fabrics in experimental huts showed better personal protection provided by bednets than by curtains. Permethrin cis:trans isomer ratios 25:75 and 40:60 were equally effective, and the permethrin rate of 200 mg/m2 performed as well as 500 mg/m2. Bioassay data emphasized the prolonged insecticidal efficacy of lambda‐cyhalothrin deposits, except on polyethylene netting. Most of the impregnated nets (including the ‘Olyset’ net with permethrin incorporated during manufacture of the polyethylene fibre) and an untreated intact net performed well in preventing both Anopheles and Culex mosquitoes from feeding on people using them overnight in the experimental huts. Anopheles showed high mortality rates in response to pyrethroid‐treated nets, but only bendiocarb treated curtains killed many Culex. Holed nets treated with either cyfluthrin (5 EW formulation applied at the rate of 50 mg a.i./m2) or lambda‐cyhalothrin (2.5 CS formulation at 10 mg a.i./m2) performed well after 15 months of domestic use. Treatment with deltamethrin SC or lambda‐cyhalothrin CS at the very low rate of 3 mg/m2 gave good results, including after washing and re‐treatment.
Vector‐borne diseases and the basic reproduction number: a case study of African horse sickness
Authors: LORD C. C. , WOOLHOUSE M. E. J. , HEESTERBEEK J. A. P. , MELLOR P. S.
Published: March 2008

Abstract. The basic reproduction number, R0, can be used to determine factors important in the ability of a disease to invade or persist. We show how this number can be derived or estimated for vector‐borne diseases with different complicating factors. African horse sickness is a viral disease transmitted mainly by the midge Culicoides imicola. We use this as an example of such a vector‐transmitted disease where latent periods, seasonality in vector populations, and multiple host types may be important. The effect of vector population dynamics which are dependent on either host or vector density are also addressed. If density‐dependent constraints on vector population density are less severe, Ro is more sensitive to vector mortality and the virus development rate. Host‐dependent vector dynamics change the relationship between R0 and host population size. Seasonality can either increase or decrease the estimate of R0, depending on the lag between the peak of the midge population and the infective host population. The relative abundance of two host types is a factor in the ability of a disease to invade, but the strength of this factor depends on the differences between the hosts in recovery from infection, mortality and transmission. Removal of a reservoir host may increase RQ.
Control of Karoo paralysis ticks through vegetation management
Authors: FOURIE L. J. , KOK D. J. , KRUGEL L. , SNYMAN A. , LINGEN F. VAN DER
Published: March 2008

Abstract. Karoo paralysis, caused by feeding Ixodes rubicundus females, is a major disease of small stock in South Africa. Control methods currently practised are almost exclusively chemical based. To limit overdependance on chemicals, vegetation management was investigated as a possible method for control, to be incorporated in an integrated tick management system. Laboratory and field experiments were conducted to determine, firstly, the extent of vertical migration and survival of ticks on long and short copper rods which simulated grasses as questing substrates; secondly, the infestation burdens of sheep exposed to similar tick challenges in pens with long and short grass; and thirdly, the effect of trimming the lower crown line of wild olive trees, simulating the browsing effect of goats, on tick density in the immediate environment of the trees. When ticks were exposed to optimal (>45 cm) and sub‐optimal (<10 cm) length rods on which to quest, the extent of vertical migration over extended periods of time (up to 87 days) was significantly higher (P < 0.001) for the ticks exposed to long rods. Also, almost 3 times as many ticks exposed to long rods survived compared to those exposed to short rods. Sheep exposed to long grass were infested by twice as many ticks compared to those exposed to short grass. Tick density at modified wild olive trees (Olea europaea africana) (0.027 ticks/m2) differed significantly (P < 0.05) from that at control trees (0.088 ticks/m2). It is recommended that coarse grazers such as cattle and horses should be used to graze down long grasses before sheep are introduced into camps known to be infested with I. rubicundus. Similarly, domestic goats can, through their browsing effect on shrubs and trees, modify the vegetation and as such play an important role in an integrated tick management system.
The effects of selection for size in cattle on horn fly population density
Authors: STEELMAN C. D. , BROWN C. J. , McNEW R. W. , GBUR E. E. , BROWN M. A. , TOLLEY G.
Published: March 2008

Abstract. Statistically significant differences were observed in the population density of the horn fly, Haematobia irritans irritans L., on Angus cows having significantly different frame sizes. Angus cows, averaging <112.5 cm in height at the hip, had significantly lower numbers of horn flies than Angus cows that measured 112.5–117.5 cm, 117.5–120 cm, 120–126 cm and >126 cm in height at the hip. The Angus I cows(<l 12.5 cm in height at the hip) were significantly shorter in length (mean distance from the withers to the hip bone) and were smaller in girth than the Angus II (112.5–126 cm) and Booneville Angus cows (>126 cm). The estimated heritability (h2) of horn fly resistance was 0.43 ± 0.07 and 0.95 ± 0.31 for 1989 and 1990, respectively. Horn fly counts on the Angus I herd (<112.5 cm in height) was 118.1 (probable breeding value, PBV = ‐20.69) to 165 horn flies per cow (PBV = 26.9 flies per cow in 1989) and from 75.9 (PBV = ‐29.1) to 134.5 (PBV = 29.5) flies per cow in 1990. Angus I bulls had PBV = ‐23.7 to 13.4 and from‐26.5 to 14.75 in 1989 and 1990, respectively. The Angus II cows had horn fly counts that ranged from 159.6 (PBV of‐23.5) to 208.1 (PBV of 25) per cow in 1989 and from 232.3 (PBV of‐56.2) to 378.7 (PBV of 90) per cow in 1990. Angus II bulls had PBVs that ranged from‐17.1 to 18.9 in 1989 and from ‐28.1 to 48.8 in 1990. The Angus I cows had significantly (P < 0.0001) lower numbers of hom flies (mean of 63.8 horn flies per m2) than the small, medium or large Angus II cows (mean of 129.4, 149.6 and 145.5 hom flies per m2, respectively). The data indicated that some specific factor(s) associated with cow size contribute(s) to innate resistance of cattle to the horn fly.
Permethrin‐impregnated bednets are more effective than DDT house‐spraying to control malaria in Solomon Islands
Authors: KERE N. K. , ARABOLA A. , BAKOTE'E B. , QALO O. , BURKOT T. R. , WEBBER R. H. , SOUTHGATE B. A.
Published: March 2008

Abstract. A field trial compared DDT house‐spraying with permethrin‐impregnated bednets for malaria control in Solomon Islands from 1987 to 1991. Mortality‐rates of malaria vector Anopheles farauti in exit window traps were 11.6% from an untreated hut, 10.1% from a hut sprayed with DDT 2 g/m2, and 98% of those from a hut in which the occupants used bednets treated with permethrin 0.5 g/m2. Since bioassays of the DDT‐sprayed walls (15 min exposure in W.H.O. standard test cones) gave 77% mortality of Anfarauti, it was concluded that the insignificant impact of DDT could be explained by the exophilic behaviour of endophagic vectors, whereas the greater impact of permethrin was attributed to the more effective exposure of Anfarauti females to the impregnated bednets ‐ attracted by the occupants. The parous rate was higher indoors, except in the area with permethrin‐impregnated bednets. It was therefore concluded that permethrin‐impregnated bednets reduced the mean longevity of Anfarauti and hence its vectorial capacity. The circumsporozoite (CS) antigen positivity rate of Anfarauti in the DDT area was 0.18% outdoors, significantly less than 1.42% indoors. In the comparison area CS rates were 0.65% outdoors and 0.75% indoors. CS antigen was not detected in Anfarauti from the bednet area, indicating the apparent prevention of malaria transmission. As DDT spraying was so much less effective, it was discontinued in 1993 and permethrin‐impregnated bednets are now the principal malaria control method in Solomon Islands.
Mitochondrial DNA variation in screwworm
Authors: TAYLOR DAVID B. , SZALANSKI ALLEN L. , PETERSON II RICHARD D.
Published: March 2008

Abstract. Polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) analysis was used to characterize mitochondrial DNA (mtDNA) variation in screw‐worms, Cochliomyia hominivorax, and secondary screwworm, C.macellaria, from the Caribbean, North America and South America. Four amplicons, totaling 7.1 kb, were analysed with sixteen restriction enzymes. A total of 133 restriction sites was observed in the two species, 104 in C.hominivorax, of which nineteen were variable, and ninety‐five in C.macellaria, none of which was variable. Fourteen mtDNA haplotypes were observed among eighteen C.hominivorax examined. Mean divergence between C.hominivorax haplotypes (d) was 0.0064 substitutions per base‐pair and genotypic diversity (G) was 0.97. Mean divergence between C.hominivorax and C.macellaria was 0.0824. Cochliomyia hominivorax haplotypes could be divided into three assemblages representing North America, South America and Jamaica, based on UPGMA clustering with d values. The assemblages did not exhibit complete geographic fidelity. These data were discordant with previously published allozyme data indicating little differentiation between screwworm populations. A scenario invoking historically isolated populations coming into contact with the introduction and movement of European livestock is proposed to explain the observed population structure of screwworm.
The relationship between female body size and survival rate of the malaria vector Anopheles arabiensis in Ethiopia
Authors: AMENESHEWA BIRKINESH , SERVICE M. W.
Published: March 2008

Abstract. The relationship between female mosquito body size and survival rate was studied in field populations of Anopheles arabiensis in the Awash valley, central Ethiopia. Body size was quantified by measuring the wing‐length. Highly significant correlations were found between size, parousness and insemination. It was concluded that larger An.arabiensis females have a higher probability of survival, being inseminated and producing more egg batches than smaller adults. Implications for vectorial capacity and vector competence of mosquitoes are discussed.
Density, survival and dispersal of Anopheles gambiae complex mosquitoes in a West African Sudan savanna village
Authors: COSTANTINI CARLO , LI SONG‐GANG , TORRE ALESSANDRA DELLA , SAGNON N'FALE , COLUZZI MARIO , TAYLOR CHARLES E.
Published: March 2008

Abstract. To obtain information on adult populations of Afrotropical malaria vector mosquitoes, mark‐release‐recapture experiments were performed with Anopheles females collected from indoor resting‐sites in a savanna area near Ouagadougou, Burkina Faso, during September 1991 and 1992. Results were used to estimate the absolute population densities, daily survival rates, and dispersal parameters of malaria vectors in that area.

In 1991 a total of 7260 female Anopheles were marked and released, of which 106 were recaptured in the release village and 6 in the neighbouring villages, a total recapture rate of 1.5%. The following year 13, 854 female Anopheles were released and 116 recaptured in Goundri and 8 in the neighbouring villages, a total recapture rate of 0.9%. Recaptures were found in three of eight villages near Goundri. Nearly all of the recaptured mosquitoes were An.gambiae s.l. Of these, molecular determination revealed that An.gambiae s.s. and An.arabiensis were present in a ratio of ‐2:3.

Two simple random models of dispersal were simulated and the parameters of the models determined by searching for the least‐squared fit between simulated and observed distributions. The mean distance moved by individual mosquitoes, estimated in this way, ranged 350–650 m day‐1, depending on die model and the year considered. Population densities were estimated using the Lincoln Index, Fisher‐Ford and Jolly's methods. The estimates of population size had high standard errors and were not particularly consistent. A ‘consensus’ value of 150,000–350,000 mosquitoes is believed to apply for ht An.gambiae s.l. female population. Survival was estimated to be 80–88% per day.
Colour discrimination by the sheep blowfly Lucilia sericata
Authors: WALL R. , SMITH K. E.
Published: March 2008

Abstract. In laboratory trials designed to examine the alighting response of the blowfly Lucilia sericata Meigen to colour, yellow sticky cloth targets caught the largest number of both males and females, followed by pale blue, black, green, dark blue and red. The number caught by any colour showed a strong positive relationship with the percentage of its spectral reflectivity in the 450–580 nm wavelength band. In field trials, targets baited with the synthetic attractant ‘swormlure’ caught significantly fewer L.sericata than targets baited with liver and sodium sulphide, suggesting that the former bait is a relatively poor attractant for this species, at the release rates used in the present study. However, there was no effect of target colour on catch, neither was there any interaction between colour and odour bait type. The results, from both the laboratory and field trials, suggest that the strength of responses by Lsericata to visual cues are weak relative to responses to odour. Responses to hue are readily overridden by a range of factors such as brightness and contrast with the background and are therefore likely to be difficult to detect or manipulate reliably in trapping systems in the field.
Post‐engorgement dynamics of haemagglutination activity in the midgut of phlebotomine sandflies
Authors: VOLF PETR , KILLICK‐KENDRICK R.
Published: March 2008

Abstract. Haemagglutination activity (HA) was studied in gut extracts of both sexes of adults of six sandfly species. HA was sex dependent, with the activity in males more than 50 times lower man that of unfed females. In females, high HA was demonstrable in both the thoracic and abdominal midgut but not in the hindgut. In unfed flies the activity was similar in the midgut wall and the gut contents whereas, in fed females, a high increase was seen in the midgut contents. After blood‐feeding, HA was elevated, reaching peak titres 2 days later and then falling to the base level or less immediately after defaecation. The magnitude of the HA response differed according to species, ranging from 2‐fold in Lutzomyia carmelinoi up to 16‐fold in Phlebotomus duboscqi. Quantitative differences between sandflies in their HA response may influence their ability to support the development of Leishmania spp.
Effect of fenthion treatment on larval densities of insecticide‐resistant Culex quinquefasciatus in an urban area of Sri Lanka
Authors: PEIRIS H. T. R. , HEMINGWAY J.
Published: March 2008

Abstract. In Sri Lanka the national Anti‐Filaria Campaign (AFC) has routinely employed fenthion since 1974 for larvicidal control of Culex quinquefasciatus, the vector of Bancroftian filariasis in urban areas, where this mosquito breeds prolifically in polluted waters. During 1994 the efficacy of AFC fenthion treatment against organophosphate‐resistant Cx quinquefasciatus was investigated at Dehiwela, near Colombo.

The AFC target rate of fenthion application was 1 mg a.i./l, but the actual concentrations of fenthion in freshly treated pits ranged from 0.64 to 63.2 mg a.i./l. There was significant suppression of larval densities in treated soakage pits, the predominant breeding site of Cx quinquefasciatus, although the mosquito population was 6‐fold resistant to fenthion at the LCW level. Production of pupae was almost completely prevented in soakage pits which were sprayed weekly with fenthion, indicating that adult mosquito emergence from this source was minimal. The rapid decline in concentration of fenthion detected in the water of soakage pits indicated that a weekly treatment schedule is essential for effective control. With the rapid recolonization of treated sites, the weekly schedule must be strictly implemented in order to achieve control of resistant larvae. Fenthion activity levels detected in treated pits suggest that a 7–10 day schedule of retreatment would completely suppress susceptible Cx quinquefasciatus.
Uniformity of protective antigens among isolates of the cattle tick, Boophilus microplus
Authors: KNOWLES A. G. , OPDEBEECK J. P.
Published: March 2008

Abstract. Gut membrane antigens were extracted from ten isolates of the cattle tick Boophilus microplus;the antigen extracts were probed with bovine antisera and three murine monoclonal antibodies (mAbs) in Western blots and dot‐ELISA. The antisera had been obtained from cattle which were vaccinated with larval and gut extracts of B.microplus, and which were subsequently protected (84% and 94% respectively) against challenge with B.microplus.One of the mAbs (QU13) has been demonstrated to precipitate protective antigens from the midgut of B.microplus.Gut antigens from all ten isolates displayed similar reactivity profiles against bovine antisera and also against mAbs in Western blots. The end‐point titres of antigens in dot‐ELISA showed four‐fold variation between isolates against bovine antisera, and also against mAb QUI 3. Larval membrane antigen extracted from N‐strain B.microplusreacted with QU13 in dot‐ELISA, indicating that protective antigens are common to both larval and adult stages of B.microplus.It was concluded that protective antigens recognized by QUI3 and antigens recognized by sera from protected cattle were conserved between the ten isolates examined, and between life‐cycle stages.
Phenology of Stomoxyinae in a Kenyan forest
Authors: MIHOK STEVE , MUNYOKI ELI , SALEH KHALFAN
Published: March 2008

Abstract. The biology of nineteen taxa of African Stomoxyinae was studied during experiments with odour‐baited Vavoua traps in Nairobi National Park, Kenya. Both male and female Stomoxyswere captured in similar numbers with C02 released at 2 1/min or octenol released at 2 mg/h. Some species of Haematoboscareacted synergistically to a combination of these two attractants, producing large increases in catch. Stygeromyiaand Rhinomuscaresponded only to C02, and Prostomoxysdid not respond to either bait. Many different activity patterns were documented in these genera, but most activity was concentrated just prior to sunset. For example, at peak densities nearly 1500 Stomoxyinae representing fourteen taxa were caught in a single trap between 18.00 and 19.00 hours. The Stomoxyinae community was exceptionally diverse when compared with other biting fly communities. Using data from traps set with different odour baits in the park forest, Shannon‐Wiener diversity indices (H′) varied from 2.5 to 2.8, and evenness (J′) varied between 0.61 and 0.68. The Stomoxyspopulation was extremely female‐biased at the start of the rainy season, with species such as S.inornatusand S.boueticonsisting of nearly 100% females. Sex ratios equalized when the first rainy‐season generation emerged. Population doubling times estimated from trap indices were approximately 12–16 days in two habitats (forest and riverine woodland).
Trypanosome characterization by polymerase chain reaction in Glossina palpalis gambiensisand G.tachinoidesfrom Burkina Faso
Authors: SOLANO P. , REIFENBERG J. M. , AMSLER‐DELAFOSSE S. , KABORE I. , CUISANCE D. , DUVALLET G.
Published: March 2008

Abstract. Following the discovery of four cases of African human trypanosomiasis, an entomological survey was conducted along the Mouhoun river in southwest Burkina Faso to collect Glossina palpalis gambiensisand G.tachinoides.Among 226 flies dissected, 4.87% (eleven individuals) were infected in midgut or proboscis, but never in the salivary glands. Polymerase chain reaction analysis was undertaken, and was able to characterize all the proboscis infections, and half of the midgut infections. Only Trypanosoma simiaeand T. vivaxwere found in the organs of infected flies, in single or mixed‐species infections. Ten more flies, negative with parasitological examination, were tested with Trypanozoonprimers and remained negative. The epidemiological significance of the absence of T.bruceigroup infections in wild tsetse populations and the presence of T.simiaein G.p.gambiensisare discussed.
Mosquito seasonality and arboviral disease incidence in Murray Valley, southeast Australia
Authors: DHILEEPAN K.
Published: March 2008

Abstract. Adult female mosquito populations were monitored at weekly intervals during spring‐autumn (November‐March) for 4 years (1991‐95) using dry‐ice‐baited light traps at forty sites in the Murray Valley of Victoria, Australia. Among twenty species of mosquitoes collected, Culex annulirostriswas the most abundant (66.6 ± 9.3%) followed by Cx australicus(15.3 ± 7.7%). From a total of 476, 682 mosquitoes collected, nearly all were females and only 1295 (0.27%) were males.

Mosquito population densities were generally higher in 1992‐93 and 1993‐94 seasons than in 1991‐92 and 1994‐95 seasons. Greatest densities of Cx annulirostrisand Cx australicusoccurred in 1992‐93, coinciding with outbreaks of Ross River (RR) and Barman Forest (BF) arboviruses causing human polyarthritis. In the majority of shires, Cx australicuswas the predominant species from spring to early summer (November and December), then was replaced by Cx annulirostrisfrom mid‐summer to autumn (January‐April). In three shires, Aedes bancroftianusand Ae.sagaxpredominated during the early part of the season. Densities of both Cx annulirostrisand Cx australicuswere related to temperature. Cx australicusadults were found to be trapped when the mean ambient temperature exceeded 6d̀C, with peak population recorded at 20d̀C. Cx annulirostrisadult density increased when the mean temperature rose above 12d̀C, reaching a peak during February and March when temperature exceeded 25d̀C. Cx annulirostrisdeclined rapidly from April onwards, with no adult activity evident from May to November.

Population densities of Aedesspp. were generally less than reported from earlier studies, possibly due to lower rainfall in spring and summer as well as reduced flood irrigation practices. In each year, a significant correlation was detected between Cx annulirostrisdensity and RR virus incidence in humans. As Cx annulirostrisis the predominant local mosquito species and feeds on a wide spectrum of hosts including man, it seems likely that Cx annulirostrisis the major vector of RR in the inland Murray Valley region.