bluuebunny/crossref_metadata_2025 huggingface dataset:
Salivary apyrase in New World blackflies (Diptera: Simuliidae) and its relationship to onchocerciasis vector status
Authors: CUPP M. S. , CUPP E. W. , OCHOA‐A J. O. , MOULTON J. K.
Published: March 2008

Abstract. Salivary gland apyrase is believed to be critical to blood‐feeding in arthropod vectors. This enzyme was measured in six New World blackflies representing three taxonomic pairs of non‐vectors and vectors of Onchocerca volvulus. In Simulium (Psilopelmia) ochraceum, a highly anthropophilic vector in Mexico and Guatemala, apyrase exhibited maximum activity between pH 8.0 and 9.0, mean 39.8 pM 4.7 milliUnits/pair of gland equivalents (mU), and was enhanced when ATP was used as a substrate. In the zoophilic non‐vector Simulium (Psilopelmia) bivittatum maximum activity was significantly less (5.1 pM 0.7 mU) under all conditions examined. Preference for ADP or ATP as substrate was a function of the pH of the reaction for this species. Apyrase activity in Simulium (Simulium) metallicum Bellardi (29.5 pM 11.5 mU), a zoophilic secondary vector in Mexico and Guatemala, resembled that of S.(Ps.)ochraceum (24.8 pM 13.7 mU at pH 8.5) with ADP as substrate, but showed reduced activity with ATP. Both these Central American vectors had higher apyrase activity than found in Simulium (Notolepria) exiguum, a vector of O. volvulus in Ecuador and Colombia. However, maximum apyrase activity, measured at pH 8.0 with ADP as substrate, was greater in S.(N.) exiguum (10.9 pM 0.6mU) than in Simulium (Notolepria) gonzalezi (5.9pM1.9mU), a non‐vector species widespread in Central America. Therefore, for the consubgeneric species pairs examined, a positive association was detected between higher concentrations of apyrase activity and their vector status for O. volvulus.
Activation of Anopheles gambiae mosquitoes by carbon dioxide and human breath
Authors: HEALY T. P. , COPLAND M. J. W.
Published: March 2008

Abstract. Female Anopheles gambiae Giles mosquitoes were observed individually in a cage within a wind tunnel and their responses to pulses of carbon dioxide recorded on video tape. The range of concentrations tested revealed an ‘activation’ threshold concentration of carbon dioxide in the region of 0.01% above background. At this concentration, approximately 60% of the mosquitoes took off and flew upwind. Pulses of human breath, diluted with wind tunnel air to reproduce equivalent concentrations of carbon dioxide, elicited similar levels of response and the same ‘activation’ threshold concentration. These findings are discussed in relation to the activation of host‐seeking mosquitoes.
A cost‐benefit analysis of feeding in female tsetse
Authors: HARGROVE J. W. , WILLIAMS B. G.
Published: March 2008

Abstract. Three models for feeding in female tsetse are considered. Model I: there is a prolonged non‐feeding phase after each meal followed by feeding at a constant rate, with a constant probability of dying as a consequence of feeding. Model II: the feeding rate increases linearly after each meal. Model III: the feeding rate increases exponentially after each meal. In Models II and III the feeding hazard is a linear function of the probability of feeding. Production of viable female offspring is estimated under each model, making allowance for losses of adults due to starvation and to background and feeding mortality, losses of pupae due to predation and parasitization, and losses of young flies if their mothers take insufficient blood during pregnancy. Under Model I, if females require three meals to produce viable pupae in 9 days, then for a non‐decreasing population with a background mortality of 1%/day, and 25% pupal losses due to predation and parasitism, the feeding risk must be ≤5%/feed. At this maximum level the non‐feeding phase should be 2–2.5 days for optimal productivity, with a mean feeding interval of 60–72 h. If the background mortality is 2%/day, feeding losses cannot exceed 1%/feed for a non‐decreasing population. If four or five meals are required for the production of fully viable pupae, the optimal values of the non‐feeding phase and mean feeding interval tend towards 1 and 2 days respectively. Under Models II and HI the mean feeding interval is 50–60 h for optimal productivity (with variances 3 times as large as for Model I), in good agreement with estimates from recent models for feeding and digestion. Field evidence suggests that feeding tsetse take greater risks as their fat levels dwindle. This should result in feeding (and feeding mortality) rates which increase during the feeding phase ‐ as assumed in Models II and III but not in Model I. These models allow greater flexibility than Model I, because flies can feed early in the hunger cycle, at low probability, as long as the feeding risk is also low.
Mosquito control in Dar es Salaam.
Authors: CHAVASSE C. , LINES J. D. , ICHIMORI K. , MARIJANI J.
Published: March 2008

Abstract. In preparation for a trial of polystyrene beads and pyriproxyfen for the control of Culex quinquefasciatus mosquitoes, surveys of their breeding were carried out in two contrasting areas of Dar es Salaam, Mikocheni and Ilala, during the dry season.

Sanitation structures (latrines, soakage pits, septic tanks and cess pits) were the most prolific breeding places, totalling 780 in Mikocheni and 1544 in Ilala. Those in Mikocheni were estimated to contain about 1.4 times more mosquito pupae, per site, than in such structures in Ilala. This was both because a higher proportion of sites contained visible water and because sites with water were more likely to contain pupae in Mikocheni. The relative importance of the different types of structure, in terms of productivity, was the same in both areas. Although septic tanks and cess pits made up only 10.5% of the on‐site sanitation structures in Ilala, they contained 53% of the total number of pupae in enclosed sites; they were therefore particularly important targets for treatment with polystyrene beads. A survey during the rainy season of sites in Ilala revealed little change in the proportion that were wet, or in the frequency of breeding in those with visible water.

The number, type and area of open breeding sites varied greatly between the two study areas. In Mikocheni the area of open breeding sites was 100 times greater than in Ilala, with 97% of the13,000 m2 being flooded grassland. In Ilala all but four of the sixty‐six open breeding sites were puddles of sullage water derived from bathrooms. Different strategies for control in open breeding sites are required in the two areas of Dar es Salaam.
An assessment of host resistance to ticks on cross‐bred cattle in Burundi
Authors: MORAN M.C. , NIGARURA G. , PEGRAM R.G.
Published: March 2008

Abstract. Groups of cattle of four different cross‐breeds (Ankole × Friesian, Ankole × Brown‐Swiss, Ankole × Guernsey, Ankole × Sahiwal) plus a group of pure Ankole cattle were immunized against tick‐borne diseases: East Coast Fever, using a Theileria parva trivalent vaccine, and anaplasmosis, babesiosis and, subsequently, heartwater. With the exception of two small subgroups of Ankole and Ankole × Sahiwal which were treated by weekly spraying using Delnav, all the groups were exposed to natural field challenge of ticks to quantify the development of host resistance to ticks. The results indicate resistance to the most abundant species, Rhipicephalus appendiculatus, as follows: Ankole > Ankole × Sahiwal > Ankole × Brown Swiss > Ankole × Friesian > Ankole × Guernsey. In both Amblyomma variegatum and Rhipicephalus evertsi evertsi, the manifestation of different levels of resistance between breeds is inapparent. Correlations between total ticks and standard female ticks were good for R. appendiculatus (r = 0.73) and R. evertsi (r ‐ 0.51) but poor for A. variegatum (r= 0.31). Correlations between species were reasonably consistent (r = 0.43‐0.59). There was no significant correlation between tick burdens and daily liveweight gain (DLWG) over the. whole period of the study. Of the cross‐bred groups, Ankole × Sahiwal, which had the highest level of resistance, had the highest DLWG. In contrast, the Ankole × Guernsey which developed the lowest level of resistance had only marginally lower DLWG, the difference being only 8 g/day. During the first period of exposure to ticks, however, the untreated Ankole × Sahiwal group had markedly lower DLWG, which may indicate that the development and manifestation of resistance is at the expense of productivity.
The influence of microfilaria! density of dog heartworm Dirofilaria immitis on infection rate and survival of Aedes notoscriptus and Culex annulirostris from Australia
Authors: RUSSELL RICHARD C. , GEARY MERILYN J.
Published: March 2008

Abstract. The mosquitoes Aedes notoscriptus and Culex annulirostris, previously shown to be competent vectors of Dirofilaria immitis, were allowed to feed on dogs with densities of microfilariae ranging from 2665 to 33,055 microfilariae/ml. Filaria developed in both species at a similar rate independent of the initial microfilarial density. Cx annulirostris ingested more microfilariae although the number of developing larvae was consistently greater in Ae. notoscriptus; one female Ae. notoscriptus carried sixty‐two third‐stage larvae 10 days after feeding, although no more than twelve were found in Cx annulirostris. The mortality rate of Ae. notoscriptus in the first 3 days of filarial development was related to increasing microfilarial density, and was greater than that of Cx annulirostris, which quickly reduced its worm load and survived with fewer third‐stage larvae but for longer than Ae. notoscriptus. The vector efficiency index was higher at all microfilarial densities for Ae. notoscriptus, but its survival was much reduced, and therefore Cx annulirostris may be the more effective vector in localities where dogs have very high parasitaemias.
Anthropophilic blackflies (Diptera: Simuliidae) and onchocerciasis transmission in southwest Ethiopia
Authors: GEBRE‐MICHAEL T. , GEMETCHU T.
Published: March 2008

Abstract. From May 1984 to May 1985, the transmission of onchocerciasis by blackflies (Dipteria: Simuliidae) was studied around Gilgel Ghibe and Gojeb rivers in southwest Ethiopia. The predominant anthropophilic species of Simulium at both localities were S.(Edwardsellum) damnosum sensu law and S.(Lewisellum) ethiopiense. Some S.(Anasolen) dentulosum also landed on human bait at Gilgel Ghibe river.

Dissections of S. damnosum from Gilgel Ghibe and Gojeb revealed mean parous rates of 92% (n = 18,291) and 84%(n = 9530), respectively. S. ethiopiense from Gilgel Ghibe and Gojeb showed mean parous rates of 53% (n = 322) and 93% (n = 14), respectively. Of the parous S. damnosum, 1.3% at Gilgel Ghibe and 0.5% at Gojeb harboured infective third‐stage larvae (L3) of Onchocerca volvulus (or morphologically indistinguishable from it). Unknown filariae of animal origin, indicative of zoophily, were found in 0.3% and 0.7% of Simulium damnosum complex females from Gilgel Ghibe and Gojeb, respectively. S. ethiopiense harboured developing (L,) larvae only, with 7.7% infection rate in both localities. In contrast, S. dentulosum did not harbour any filaria larvae. The annual infective biting rate (AIBR) and transmission potential (ATP) of the S. damnosum complex at Gilgel Ghibe river were 858 and 5478, respectively. The AIBR and ATP of S. damnosum s.I. at Gojeb river were 519.5 and 1963, respectively. These results emphasize the predominant role of the S. damnosum complex in the transmission of O. volvulus in southwest Ethiopia
The roles of Phlebotomus martini and P. celiae (Diptera: Phlebotominae) as vectors of visceral leishmaniasis in the Aba Roba focus, southern Ethiopia
Authors: GEBRE‐MICHAEL T. , LANE R. P.
Published: March 2008

Abstract. During field studies (December 1988 to April 1990) to determine the vectors of visceral leishmaniasis (kala‐azar) in the Aba Roba (Segen Valley) focus of southern Ethiopia, a total of 40,770 sandflies (Diptera: Psychodidae: Phlebotominae) were collected and identified as six species of Phlebotomus and seventeen Sergentomyia spp. Nine of these species were anthropophilic (four Phlebotomus and five Sergentomyia spp.), the dominant being Phlebotomus (Synphlebotomus) martini, P.(S.)celiae and Sergentomyia (Sergentomyia) schwetzi. P. celiae adult populations increased during the rainy season. Of 2326 P. martini and 1044 P. celiae dissected, the parous rate was 29.9% and 24.4%, respectively. Leishmania promastigotes were detected in sixteen P. martini (eleven identified as L. donovani by isoenzyme analysis and/or a DNA probe) and in three P. celiae (two identified by DNA probe), giving overall infection rates of 0.7% (1.9% parous infection rate) and 0.3% (1.2% parous infection rate), respectively. Four isolates from P. martini were typed by their isoenzyme profile as L. donovani zymodeme MON‐37 = LON‐44, identical to one of the zymodemes isolated from patients in this focus. This is the first evidence that P. celiae is a vector and the first time that P. martini has been implicated in Ethiopia. Based on observations of abundance, seasonality and prevalence of infection of the two Synphlebotomus spp., it is concluded that P. martini is the major vector and P. celiae a secondary vector in the Aba Roba focus. The risk of infection with L. donovani is greatest during the wet season.
Dengue 3 virus distribution in the mosquito Aedes aegyptl: an immunocytochemical study
Authors: LINTHICUM K. J. , PLATT K. , MYINT K. S. , LERDTHUSNEE K. , INNI B L. , GHN D W. VAU
Published: March 2008

Abstract. The dissemination of dengue (DEN) 3 virus in parenterally infected female Aedes aegypti mosquitoes was studied imrnunocytochemically. Antigen was first detected in fat body cells near the thoracic site of virus inoculation. The intussuscepted foregut, salivary glands and nervous tissue were the first major tissues infected. Nervous tissue appeared to be the primary site of amplification. Muscles, tracheae, Malphigian tubules and the posterior midgut did not become infected. The only part of the reproductive system to be infected was the calyx (71% of specimens 16–22 days post‐infection) consistent with low rates of vertical transmission. After 7 days post‐inoculation the salivary glands of 100% of the specimens examined were infected. Virus dissemination was slow and the most common sequence of infection following intrathoracic inoculation was as follows: thoracic fat body, intussuscepted foregut, salivary glands, cardial epithelium, thoracic ganglion, brain, compound eye, anterior midgut, intermediate midgut/anterior abdominal ganglia, and calyx/hindgut/posterior abdominal ganglia. Fat body and intussuscepted foregut tissues lost infections after 16 days post‐inoculation.
Rapid isolation of anopheline mosquito eye‐colour mutants, based on larval colour change
Authors: BENEDICT MARK Q. , CHANG HANS
Published: March 2008

Abstract. A method is presented for the rapid isolation of eye‐colour mutants in anopheline mosquitoes based on their inability to undergo a background‐stimulated morphological colour change. For application of this method, larval mosquitoes, whose grandfathers had been mutagenized, were reared in black containers and examined with the naked eye en masse during the third or fourth instar. The vast majority of larvae became dark‐coloured; however, rare exceptional pale larvae were observed and examined individually microscopically. Approximately half of the pale types examined were eye‐colour mutants. By this method, seven sex‐linked mutations in the mosquito Anopheles gambiae s.s. were easily isolated. Additional existing anopheline eye‐colour mutants in An. gambiae and An. stephensi were tested and were found to be unable to undergo colour change. Several applications of this simple technique are suggested.
Four new cytotypes of the onchocerciasis vector blackfly Simulium guianense in Brazil
Authors: CHARALAMBOUS M. , SHELLEY A. J. , HERZOG M. MAIA , DIAS A. P. A. LUNA
Published: March 2008

Abstract. Simulium (Trichodagmia) guianense is an important Amazonian vector of onchocerciasis. Examination of the polytene chromosome banding patterns of larvae from five sites in Brazil revealed the occurrence of four cytotypes, designated A, B, C and D. The chromosomal standard, Simulium guianense A, occurred at two localities in Goias State (on the Rio Tocantins and Rio Mucambao) where it was the only cytotype. The other three sites examined yielded one different cytotype from each: B from Rio Oyapoque in Amapa State, C from Rio Tocantins in Maranhao State, and D from Rio Xingu in Para State. All cytotypes differed by at least two fixed inversions, but a sex determining system was not evident in any cytotype. As the cytotypes have been found allopatrically it is not certain that they represent sibling species; sampling of sympatric populations would resolve this. During certain times of the year, voracious anthropophagy by S.guianense sensu lato occurs at the localities sampled for cytotypes A, C and D (biting data are not available for the cytotype B locality). In some other areas, however, S.guianense s.l. is entirely zoophilic. Further studies are needed, therefore, to elucidate the biting habits, vectorial capacity, geographic distribution and taxonomic status of these four, and perhaps additional, cytotypes comprising the S.guianense complex.
The effect of host nutrition on itch mite, Psorergates ovis, populations and fleece derangement in sheep
Authors: JOHNSON P. W.
Published: March 2008

Abstract. A group of thirty‐two Merino sheep infested with itch mites (Psorergates ovis) and fed a maintenance diet which imposed moderate nutritional stress had a significantly higher mite population, significantly more skin scurf, and significantly more fleece damage or derangement (P < 0.05) than a second group of thirty‐two infested sheep fed a diet designed for unrestricted body weight gain and wool growth. Histologically there were no significant differences between the groups in the numbers of mast cells, neutrophils or eosinophils observed in skin sections, but sheep that had high mite counts (>10 per 200 cm2 of skin area) in both groups, had more dermal mast cells than sheep with fewer mites irrespective of the plane of nutrition. Skin thickness and greasy fleece weight in die group maintained on the low plane of nutrition were significantly less (P < 0.05) than in die well‐nourished group, reflecting the difference in protein and energy content of the two diets. Within the nutritionally stressed group, the sheep with low mite counts had a significantly lower (P < 0.05) greasy fleece weight and a shorter mean staple length than the sheep with high mite counts. There was no significant difference in greasy fleece weight between sheep with low or high mite counts in the group fed on the high plane of nutrition.
Effect of weather conditions on the flight activity of Nigerian blackflies (Diptera: Simuliidae)
Authors: ROBERTS D. M. , IRVING‐BELL R. J.
Published: March 2008

Abstract. A vehicle‐mounted net was used to make hourly catches of blackflies at 700–1000 m altitude in the River Assob valley, central Nigeria, on 20 days during the dry season. Pearson Correlation Matrix analysis of the collection data and meteorology showed that the main factors affecting flight activity of each of the four most abundant blackfly species were primarily light intensity and secondly wind velocity, whereas relative humidity was the least important factor. Right activity showed a negative linear regression against wind, with some activity occurring in wind speeds up to 15 km/h. Distance‐weighted least‐squares (DWLS) regressions showed little correlation of temperature with activity for Simulium hargreavesi and S.adersi, but S.squamosum and S.vorax had small peaks at 28d̀C and 31d̀C, respectively. DWLS regression against light intensity showed an activity peak at 6000 lux, except in Simulium adersi.
Surveillance of the mosquito Aedes aegypti and its biocontrol with the copepod Mesocyclops aspericornis in Australian wells and gold mines
Authors: RUSSELL B. M. , MUIR L. E. , WEINSTEIN P. , KAY B. H.
Published: March 2008

Abstract. A survey of the dengue vector mosquito Aedes aegypti was undertaken using runnel traps to detect immature stages (larvae and pupae) in flooded disused mine shafts and wells in Charters Towers, Queensland, Northern Australia. The town has a history of dengue fever since 1885 when goldminers were the first recorded victims. During the latest dengue epidemic in 1993, 2% of the population had laboratory‐confirmed dengue virus Type 2, despite source reduction of Ae.aegypti breeding‐sites at ground level or above. This led to suspicions that dengue vector Ae.aegypti breeding‐sites might be below ground level. When surveyed in March 1994, Ae.aegypti immatures were found in 9/10 wells and 1/6 mine shafts. The water in wells and mines had similar characteristics ‐except that turbidity was higher in the mines, which more often contained predators of mosquito immatures.

The copepod Mesocyclops aspericornis was collected from water in 1/10 wells and 2/6 mine shafts. Laboratory predation trials resulted in 95.5–100% predation by 25 copepods/1 on Ae.aegypti first‐instar larvae up to 200 larvae/1. Five wells containing Ae.aegypti in the survey were inoculated with fifty indigenous M.aspericornis, and five wells (one positive and four negative in the survey) were left untreated as controls. Nine months later, in December 1994, Ae.aegypti had been eliminated from all five treated wells but all untreated control wells contained Ae.aegypti, except for one well that contained a natural population of M.aspericornis. The role of wells and mines as winter/ dry season refuges of Ae.aegypti in northern Australia is reviewed, and we recommend the use of M.aspericornis as a cost‐effective, environmentally acceptable and persistent agent for the sustainable control of Ae.aegypti, especially in inaccessible breeding sites.
Seasonal variation of Leishmania major infection rates in sandflies from rodent burrows in Isfahan province, Iran
Authors: YAGHOOBI‐ERSHADI M. R. , JAVADIAN E.
Published: March 2008

Abstract. In preparation for field trials of killed Leishmania major vaccine, natural infections with Leishmania promastigotes were monitored in Phlebotomine sandfly vectors from villages of Borkhar rural district, northeast of Isfahan in central Iran, where Lmajor zymodeme MON‐26 (=LON‐l) has been identified as causing zoonotic cutaneous leishmaniasis (ZCL). Sandflies were collected and dissected weekly, from burrows of rodent colonies, during the ‘sandfly season’, June‐October 1991. Leptomonad infection rates were 12% of 26 Phlebotomus ansarii, 8% of 280 P.caucasicus, 11 % of 1042 P.papatasi and none of 126 Sergentomyia sintoni, being greatest during late August through September, coinciding with peak activity of the sandflies, 2–3 months before the highest incidence of ZCL human cases in November‐December.
Molecular phytogeny and typing of blackflies (Diptera: Simuliidae) that serve as vectors of human or bovine onchocerciasis
Authors: TANG JIANMING , PRUESS KENNETH , CUPP EDDIE W. , UNNASCH THOMAS R.
Published: March 2008

Abstract. A subregion of the mitochondrial large subunit (16s) rRNA gene was amplified by polymerase chain reaction (PCR) from nine species of blackflies (Diptera: Simuliidae) which serve as natural or experimental vectors of human or bovine Onchocerca parasites. PCR products from each species of blackfly were tested by directed heteroduplex analysis (DHDA), and their genotypes established according to diagnostic banding patterns of the heteroduplex products. Three alleles of mitochondrial 16s rRNA were found to exist in members of the Simulium (Ewardsellum) damnosum sensu lato complex from West Africa, and two alleles were found in the Neotropical Simulium (Psilopelmia) ochraceum Walker complex and the Simulium (Simulium) metallicum Bellardi complex. Different single alleles were detected in Austrosimulium bancrofti, in English S.(S.)noelleri and in two North American laboratory vectors: Simulium (Psilozia) vittatum Zetterstedt and S.(S.)decorum Walker. Phylogenetic analysis of 16s sequences indicated that blackflies from West Africa and the Americas formed distinct clades. Neotropical onchocerciasis vectors were found to be more closely related to Nearctic and Palaearctic non‐vector Simulium species than to the African vectors of onchocerciasis.
Frequent isolation of Francisella tularensis from Dermacentor reticulatus ticks in an enzootic focus of tularaemia
Authors: HUBALEK Z. , TREML F. , HALOUZKA J. , JURICOVA Z. , HUNADY M. , JANIK V.
Published: March 2008

Abstract. A total of 924 questing Dermacentor reticulatus (Fabricius), 504 Ixodes ricinus (L.), sixty Haemaphysalis concinna Koch and 718 mosquitoes (Aedes spp.) were examined in a floodplain forest ecosystem during the 1994‐95 outbreak of tularaemia in South Moravia, Czech Republic. Francisella tularensis was not isolated from H.concinna ticks or Aedes spp. mosquitoes, whereas twenty‐one isolates were recovered from the other haematophagous arthropods. Dermacentor reticulatus revealed a significantly higher infection rate (2.6%) than I.ricinus (0.2%). This tick species acts as principal vector for tularaemia in the enzootic focus. Monitoring of D.reticulatus for F.tularensis thus seems to be a very efficient approach in the surveillance of tularaemia in the flood‐plain forest ecosystems of Europe.
The impact of permethrin‐impregnated bednets on malaria vectors of the Kenyan coast
Authors: MBOGO C. N. M. , BAYA N. M. , OFULLA A. V. O. , GITHURE J. I. , SNOW R. W.
Published: March 2008

Abstract. The effects of introducing permethrin‐impregnated bednets on local populations of the malaria vector mosquitoes Anopheles funestus and the An.gambiae complex was monitored during a randomized controlled trial at Kilifi on the Kenyan coast. Pyrethrum spray collections inside 762 households were conducted between May 1994 and April 1995 after the introduction of bednets in half of the study area. All‐night human bait collections were performed in two zones (one control and one intervention) for two nights each month during the same period. PCR identifications of An.gambiae sensu lato showed that proportions of sibling species were An.gambiae sensu stricto > An.merus > An.arabiensis.

Indoor‐resting densities of An.gambiae s.l. and the proportion of engorged females decreased significantly in intervention zones as compared to control zones. However, the human blood index and Plasmodium falciparum sporozoite rate remained unaffected. Also vector parous rates were unaltered by the intervention, implying that survival rates of malaria vectors were not affected. The human‐biting density of An.gambiae s.l., the predominant vector, was consistently higher in the intervention zone compared to the control zone, but showed 8% reduction compared to pre‐intervention biting rates ‐ versus 94% increase in the control zone.

Bioassay, susceptibility and high‐performance liquid chromatography results all indicated that the permethrin content applied to the nets was sufficient to maintain high mortality of susceptible vectors throughout the trial. Increased rates of early outdoor‐biting, as opposed to indoor‐biting later during the night, were behavioural or vector composition changes associated with this intervention, which would require further monitoring during control programmes employing insecticide‐treated bednets.
Identification of electrophysiologically‐active compounds for the malaria mosquito, Anopheles gambiae, in human sweat extracts
Authors: CORK A. , PARK K. C.
Published: March 2008

Abstract. Human sweat samples were chemically fractionated into acid and non‐acid components. The most abundant volatile compounds present in the fractions were identified by linked gas chromatography mass spectrometry. The acid fractions were found to be composed of a range of twenty aliphatic and three aromatic carboxylic acids ranging, on average, from 0.02 to 20 ig per ml of sweat sampled. Non‐acid fractions were found to contain: 6‐methyl‐5‐hepten‐2‐one, l‐octen‐3‐ol, decanal, benzyl alcohol, dimethylsulphone, phenylethanol, phenol and 4‐mefhylphenol, collectively amounting to 0.1 and 3 |ig per ml of sweat. The major component of sweat was found to be L‐lactic acid which constituted from 1 to 5 mg/ml.

Using the intact antennae of the anthropophilic malaria vector mosquito Anopheles gambiae Giles, the peripheral olfactory activities of compounds identified in the sweat fractions were investigated by electroantennography (EAG). Short‐chain saturated carboxylic acids, methanoic, ethanoic, propanoic, butanoic, pentanoic and hexanoic acids were found to elicit significantly larger EAG responses than longer chain saturated carboxylic acids from female An.gambiae. For a given dose the largest amplitude EAG response was elicited by methanoic acid. Pentanoic acid elicited larger EAG responses than either butanoic or hexanoic acids. Two non‐acidic compounds, l‐octen‐3‐ol and 4‐methylphenol, were found to elicit significant dose‐dependent EAG responses from female An.gambiae. 1 ‐Octen‐3‐ol elicited larger EAG responses than 4‐methylphenol for a given dose, but both compounds elicited smaller EAG responses than the same dose of C]‐C6straight‐chain aliphatic carboxylic acids. The possible behavioural significance of the EAG‐active compounds identified in human sweat samples is discussed.
Adaptive larval thermotolerance and induced cross‐tolerance to propoxur insecticide in mosquitoes Anopheles stephensi and Aedes aegypti
Authors: PATIL NALINI S. , LOLE KAVITA S. , DEOBAGKAR DILEEP N.
Published: March 2008

Abstract. Fourth‐instar larvae of mosquitoes Anopheles stephensi and Aedes aegypti normally died within 90 min at 43d̀C. Pre‐exposure to high but sublethal temperatures conferred adaptive thermotolerance, dependent on the temperature and the duration of pre‐exposure. Adaptive cross‐tolerance to propoxur (a carbamate insecticide) was also induced in larvae by pre‐exposing them to sublethal temperatures. Pre‐exposure to sublethal concentrations of propoxur was found to confer cross‐thermotolerance to a lower extent. These results suggest that the shock proteins (e.g. heat shock proteins) induced by unrelated stress factors play an important role in the development of adaptive cross‐protection (stress response) to other stress conditions.
The role of cattle as hosts of Glossina longipennisat Galana Ranch, south‐eastern Kenya
Authors: MAKUMI J. N. , GREEN C. H. , BAYLIS M.
Published: March 2008

Abstract. Glossina longipenniswere recorded visiting and engorging on cattle in an enclosure and on a single ox in a crush using transparent electrocuting nets in an incomplete ring. Of the total flies caught, 3–6% of males and 5–6% of females in the total catches were engorged (a feeding success rate of up to 16.6% and 12.6%, respectively, depending on assumptions made about the proportion which had an opportunity to feed). Direct observation of tsetse from an observation pit showed 57% landing on the front legs, 13% on the hind legs, and 11 % on the belly of the host. The largest number of bloodmeals was taken from the front legs, although only 14% of landings there terminated in feeding; a higher proportion of the flies alighting on the hind legs and flank succeeded in feeding (28% and 21% respectively). Glossina longipenniswere attracted to targets baited with ox odour from an underground pit in a dose‐dependent manner. Odour of humans was much less attractive to G.longipennisthan that of oxen (for equivalent biomass). Analysis of bloodmeal samples from tsetse caught in two sites on die ranch showed that G.longipennispreferentially feeds on suids, bovids and hippopotamus.
Trapping oestrid parasites of reindeer: the relative age, fat body content and gonotrophic conditions of Cephenemyia trompeand Hypoderma tarandifemales caught in baited traps
Authors: ANDERSON JOHN R. , NILSSEN ARNE C.
Published: March 2008

Abstract. Dissection of flies caught in northern Norway revealed that only mated, gravid females of H.tarandi(L.) and larviparous C.trompe(Modeer) were caught in host‐mimicking C02‐baited traps. Trapped females had the same gonotrophic and fat body (FB) conditions as females caught on and around reindeer. Most trapped females of both species were of middle to old age, having only one‐half to no FB reserves left and only a few to moderate numbers of eggs or larvae remaining. Most young females trapped also had previously oviposited or larviposited at least once, and some newly eclosed, mated females were present throughout the fly season. Based on the known location of reindeer herds, it was evident that trapped flies that had recently oviposited or larviposited had dispersed into the trapping area from 25–100 km away. Declining FB reserves sustained wild‐caught C.trompefemales (and in uterolarvae) in the laboratory for 14 days and H.tarandifemales for 18 days. Reserve FB also was depleted during long flights. Females of both species that flew for the longest times (5.1–11.7 h) on a laboratory flight mill had low FB reserves, but nearly maximum numbers of eggs or larvae. Conversely, most females that flew for less than 5 h on the flight mill had little or no FB remaining, and few eggs or larvae. The large FB reserves accumulated as larvae feed in the vertebrate host enable the non‐feeding adults to survive and infect their hosts even after prolonged periods of flight‐inhibiting climatic conditions.
Differential application of lambda‐cyhalothrin to control the sandfly Lutzomyia longipalpis
Authors: KELLY DAVID W. , MUSTAFA ZEHRA , DYE CHRISTOPHER
Published: March 2008

Abstract. To study the impact of residual pyrethroid insecticide on the abundance and distribution of peridomestic Lutzomyia longipalpis, the sandfly vector of visceral leishmaniasis in Brazil, lambda‐cyhalothrin was applied at 20 mg a.i.m‐2 in the following interventions: (i) spraying of all animal pens in a village (blanket coverage); (ii) treatment of a subset of animal pens, either by spraying, or by installation of insecticide‐impregnated 1 m2 cotton sheets as ‘targets’ (focal coverage).

By sampling with CDC light traps, and using a novel analytical approach, we detected a 90% reduction in Lu. longipalpis abundance in sprayed sheds of the focal intervention. However, there was no discernible effect on the abundance of other phlebotomines trapped in sheds, or on the abundance of Lu. longipalpis in untreated dining‐huts and houses. This differential impact on Ludongipalpis abundance is explained in terms of the disruption of male pheromone production. Treated targets were approximately half as effective as residual spraying in reducing the abundance of Lu.longipalpis in sheds.

Following blanket intervention, the abundance of Lu.longipalpis in traps fell by only 45% (not significant): catches at untreated dining‐huts actually increased, possibly because the blanket coverage diverted Lu. longipalpis away from major aggregation sites at animal pens. It is recommended that care be taken during vector control programmes to ensure that all potential aggregation sites are treated. The possible consequences of leaving some sites untreated include poor control of peridomestic sandfly abundance and an increase in the biting rate on dogs and humans.
Abiotic and biotic determinants of the seasonal dynamics of the tick Rhipicephalus appendiculatus in South Africa
Authors: RANDOLPH SARAH E.
Published: March 2008

Abstract. The creation of a generic population model for the tick Rhipicephalus appendiculatus requires a detailed, quantified understanding of the interactions of these ticks with their biotic and abiotic environment in the different parts of their range, from the tropical regions of East Africa to the temperate regions of South Africa. The much greater seasonal variation in climatic conditions, particularly temperature, further from the equator introduces variable development rates and diapause into the life cycle. Estimates of natural temperature‐dependent interstadial development periods, derived from a combination of published laboratory and field data, were applied to published data on the seasonal abundance of R.appendiculatus on three farms in the Eastern Cape Province of South Africa. This enabled an assessment of which ticks of one stage give rise to which ticks of the next stage, from which (a) the onset and duration of diapause in unfed adults, and (b) seasonal interstadial mortality indices in the form of fc‐values, could be estimated. The contribution of biotic (tick density) and abiotic (climatic) factors as predictors of mortality at each life stage was investigated by step‐wise multiple regression. Density‐independent mortality at the female‐to‐larval stage is correlated with geographically variable climatic factors, minimum temperature at two farms and minimum relative humidity at the third. The other two stages are governed by density‐dependent mortality, which, it is argued, may be caused largely by the hosts' acquired resistance to ticks. As expected on theoretical grounds, this density dependence is weaker nearer to the edge of the tick's range and for the more vulnerable immature stages.
The vertical distribution of Culicoides impunctatus larvae
Authors: BLACKWELL A. , KING F. C.
Published: March 2008

Abstract. Soil cores were taken from three transects, representing the vegetation typical of much of the west coast and Highlands of Scotland, in an attempt to investigate the distribution of Culicoides impunctatus larvae. Sampling of soil cores was carried out at four periods throughout the day (00.00,05.00,12.00 and 17.00 hours). Each core sample was sliced into sections, 1 cm deep and Culicoides impunctatus larval numbers in the first 8 cm of the soil core were investigated, using a sugar‐flotation technique. At all sampling times, approximately 50% of the total numbers of larvae recovered were from the first 2cm of the soil. During the daylight sampling periods (05.00, 12.00 and 17.00 hours), there was a small but significant migration of larvae into the deeper layers (2–5 cm). The results are discussed in relation to those for other species from previous studies, and also to their application in larval collection for colonization techniques and in localized Culicoides control.
Growth of Anopheles mosquito larvae on dietary microbiota in aquatic surface microlayers
Authors: WOTTON R. S. , CHALONER D. T. , YARDLEY C. A. , MERRITT R. W.
Published: March 2008

Abstract. Hydrophobic organic matter accumulates under the surface film of water bodies to form the surface microlayers. Heterotrophic microorganisms use this organic matter for growth, and they, in turn, are fed upon by Anopheles mosquito larvae and other animals. From laboratory experiments we show that two species of mosquito larvae, Anopheles gambiae and An.quadrimaculatus, grew most rapidly where surface micro‐layers were present and, especially, where labile dissolved organic matter was added to promote growth of microorganisms. The importance of microorganisms was confirmed by the addition of gentamicin antibiotic, which suppressed the microbiota and reduced the growth of larvae feeding on surface microlayers. Anopheles larvae grew well on a suspension of finely ground fish food to which the antibiotic had been added, showing that reduced growth was not due to gentamicin itself. Because sub‐surface microorganisms are the components of the larval diet that most affect growth, we discuss their relevance to strategies for larval control of Anopheles mosquitoes.
Effect of the life‐span of female Glossina palpalis gambiensis on the weight and size of its progeny
Authors: DEKEN R. DE , BOSSCHE P. VAN DEN , SANGARE M. , GNANVI C. , MISSANDA J. H. , HEES J. VAN
Published: March 2008

Abstract. Pupae and teneral flies of Glossina palpalis gambiensis originating from three successive reproductive cycles were compared for their size and weight. In general, pupal weight and fly weight increased, whereas fly size, measured as wing vein length, decreased with the number of reproductive cycles. The linear regression observed between weight and wing vein length of the fly demonstrated that, particularly for flies originating from the first and second larvipositions, small changes in wing vein length reflected substantial differences in weight.

The results of these laboratory experiments were compared with some field data on Glossina morsitans from Zambia and related literature. The life span of the female tsetse, affecting the size of her progeny, could clarify partially some of the field observed seasonal changes in size, whereas the correlation between fly size and weight could eventually explain the differential mortality of some size classes of tsetse flies. However, whether these laboratory observations can be extrapolated to the field has still to be confirmed.
Esterases A5‐B5 in organophosphate‐resistant Culex pipiens from Italy
Authors: SEVERINI CARLO , ROMI ROBERTO , MARINUCCI MARINO , GUILLEMAUD THOMAS , RAYMOND MICHEL
Published: March 2008

Abstract. Culex pipiens mosquitoes from Lignano city, Udine province, northeast Italy, were found to carry over‐produced non‐specific esterases Al, A2‐B2 and A4‐B4 or A5‐B5, detected by starch gel electrophoresis, giving multiple resistance to organophosphorus insecticides. In order to differentiate between A4‐B4 and A5‐B5 esterases, the latter known only from Cyprus whereas the former is widespread in Italy and elsewhere, restriction fragment length polymorphism (RFLP) analysis was performed at the esterase B locus. Both B4 and B5 haplotypes were found. This is the first record of A5‐B5 esterase‐mediated resistance in continental Europe.
Ribosomal DNA difference between species A and D of the Anopheles dims complex of mosquitoes from China
Authors: XU JIAN‐NONG , QU FENG‐YI
Published: March 2008

Abstract. Species A and D of the Anopheles dints complex were found in China. Ribosomal DNA second internal transcribed spacers (ITS2) of both species A and D were sequenced and found to be 716 and 710 base‐pairs in length, respectively, with 699c GC content. No evidence of intraspecific variation was detected in the ITS2 sequence of species A, whereas the sequence of species D showed variation at one position in the ITS2. A large number of simple repeat motifs were dispersed throughout the ITS2 sequences. The level of interspecific difference was 5.4% of the nucleotide sequences. Some of the interspecific differences were located in regions with subrepeat structure.
Preliminary investigations of Aphodius species activity in cattle faeces treated with ivermectin
Authors: FINNEGAN PATRICIA M. , FLANAGAN DECLAN P. , GORMALLY MICHAEL J.
Published: March 2008

Abstract. A.sphacelatus at densities of 0.5 and 1.0 beetle/g faeces caused significantly greater median percentage reductions (65.2% and 87.4% respectively) ofPilobolus sporangia than 0.1 beetle/g faeces (31 %) in untreated cattle faeces. The median percentage reduction in sporangia due to beetle activity (48.4%) was significantly lower (P < 0.02) in faeces mixed with ivermectin at l.Oppm (wet weight) than in untreated faeces (88.4%). After treating a bullock with ivermectin (IvomecR Pour‐On), the median percentage reduction in sporangia caused by beetles was significantly less (P < 0.05) on days 9 (78.9%) and 10 (76.9%) than in pre‐dose faeces (86.5% and 93.8% respectively). In microcosms without beetles, sporulation of Pilobolus in cattle faeces from a heifer treated with ivermectin was significantly less on days 5,10 and 15 after dosing. However, this difference was not apparent for days 5 and 10 after storage of faeces at 4oC for 55 and 50 days respectively.
The effects of the bont tick, Amblyomma hebraeum, on milk production of Sanga and Sanga x Brahman cattle
Authors: NORVAL R. A. I. , SUTHERST R. W. , JORGENSEN O. G. , KERR J. D.
Published: March 2008

Abstract. The effects of adults of the bont tick, Amblyomma hebraeum on the milk production of Sanga and Sanga x zebu (Brahman) cattle were measured over a period of 11 weeks in the lowveld of Zimbabwe in the summer of 1986. Four groups of lactating cows, consisting of two breeds, each divided into a high and low tick treatment, were exposed to very low or high challenges of ticks and their milk production measured by weighing their calves before and after suckling. The liveweight gains (LWG) of the calves were also measured.

Tick burdens on the infested groups averaged around fourteen engorging females of A.hebraeum per day, which amounted to infestations of about 150 adult ticks. That is greater than most observed field infestations. This caused no significant reduction in milk yield or calf growth over the whole period, provided the teats of the dams had not been damaged by ticks. Mismothering occurred when teats were damaged. No breed differences were observed so all data was pooled for further analysis. Average calf LWGs of the high tick groups were reduced by 2.2kg (P < 0.01) during one 4‐week period but overall the 3.9 kg difference in LWG of the tick treatment groups was not quite significant (P < 0.10). Although there was a poor relationship between tick numbers and reduced milk yield or calf LWG, the effects were always in the direction expected. The effects averaged 6 ± lOg reduction of milk and 2.6 ± 1.8g loss of LWG of calves for every female tick that engorged. It was concluded that milk production is not an important consideration when estimating the losses in production caused by A.hebraeum on Brahman x Sanga or Sanga breeds of cattle. Losses due to teat or udder damage could be much more important and need to be quantified.
Transmission of louping ill virus between infected and uninfected ticks co‐feeding on mountain hares
Authors: JONES LINDA D. , GAUNT MICHAEL , HAILS ROSIE S. , LAURENSON KAREN , HUDSON PETER J. , REID HUGH , HENBEST PAULINE , GOULD ERNEST A.
Published: March 2008

Abstract. Most of the data on oral infection of ticks by louping ill virus have been obtained from experiments in which animals were infected by syringe inoculation with infectious material. Using infected ticks to mimic the natural situation, we have demonstrated that louping ill (LI) virus transmission can occur from infected to uninfected Ixodes acinus feeding in close proximity on mountain hares (Lepus timidus). Under these conditions the hares developed either low or undetectable viraemias. Highest prevalence of LI virus infection was observed in recipient nymphs which had fed to repletion between days 3 and 7 post‐attachment of virus‐infected adults; following engorgement, 56% of nymphs acquired virus. These results demonstrate the efficient transmission of LI virus between co‐feeding ticks on naive mountain hares. However, when ticks were allowed to co‐feed on virus‐immune hares a significant reduction in the frequency of infection was observed. Neither red deer (Cervus elaphus) nor New Zealand White rabbits supported transmission of LI virus. The significance of virus transmission between cofeeding ticks on LI virus epidemiology is discussed.
Summer mastitis experimentally induced by Hydrotaea irritans exposed to bacteria
Authors: CHIRICO JAN , JONSSON PER , KJELLBERG SUZANNE , THOMAS GETHIN
Published: March 2008

Abstract. Summer mastitis is an acute suppurative bacterial infection of the udder in heifers and dry cows. To ascertain the possible role of flies in the transmission of the disease, experimental exposures of recipient heifers to Hydrotaea irritans previously exposed to bacteria were carried out. Flies were allowed to feed on secretions from clinical cases of summer mastitis. The pathogens present were the bacteria Staphylococcus aureus, Streptococcus dysgalactiae, Actinomyces pyogenes, Stuart‐Schwan cocci, Peptococcus indolicus, Fusobacterium necrophorum and Bacterioides species. The teats of eight heifers were exposed to flies with verified pathogen content. Two teats of each animal were deliberately damaged before fly exposure. One teat was cut, another pricked with insect needles to mimic insect bites. Two of the heifers developed summer mastitis in the quarters where teats had been cut. The bacterial species isolated from these quarters corresponded to those that had previously been fed to the flies. For the first time, it is now demonstrated that H.irritans is capable of transmitting summer mastitis pathogens and so causing summer mastitis in recipient heifers. Lesions on the teat orifice may be a predisposing factor in the development of the disease.