bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental comparison of anthropophily between geographically dispersed populations ofLutzomyia whitmani(Diptera: Psychodidae)
Authors: Campbell‐Lendrum D. H. , Pinto M. C. , Brandão‐Filho S. P. , De Souza A. A. , Ready P. D. , Davies C. R. 
Published: March 2003

SummaryLutzomyia whitmani, a major vector of cutaneous leishmaniasis in Brazil, occupies diverse habitats from the Amazon forest canopy to suburban animal pens. Three mitochondrial lineages ofLu. whitmani(‘Amazonian’, ‘North–South’ and ‘North‐east’) have parapatric distributions coinciding with different ecological zones. We assessed the host preferences of populations representing the three lineages in standardized field experiments, and found thatLu. whitmaniin all sites were significantly more attracted to humans than to dogs or chickens. Females from a southerly population of the North–South lineage showed the greatest degree of anthropophily.Lu. whitmanifrom Amazonia were also strongly attracted to human baits, contradicting previously published accounts. Intraspecific comparisons in non‐Amazonian sites suggest thatLu. whitmaniis less anthropophilic thanLu. intermediabut more so thanLu. longipalpis. No significant difference was detected in anthropophily betweenLu. whitmaniin the Amazon and eitherLu. dendrophylaorLu. gomezi. Anthropophilic behaviour was demonstrated in the same site forLu. complexa,Lu. flaviscutellataandLu. brachyphalla, but not forLu. infraspinosa.
Laboratory testing of a lethal ovitrap for Aedes aegypti
Authors: Zeichner B. C. , Perich M. J. 
Published: March 2003

SummaryLaboratory tests were conducted to determine the feasibility of making the mosquito ovitrap lethal to Aedes aegypti (L.) when they attempt to oviposit in the trap. Heavy‐weight velour paper strips (2.54 × 11 cm) were used as an alternative to the wooden paddle normally provided as a substrate for mosquito oviposition. The paper strips were pretreated with insecticide solutions and allowed to dry before being used in oviposition cups of 473 ml capacity, filled with water initially to within 2.5 cm of the brim. Insecticides chosen for their quick knock‐down efficacy were bendiocarb 76% WP (1.06 mg a.i./strip) and four pyrethroids: permethrin 25% WP (0.16 mg a.i./strip), deltamethin 4.75% SC (0.87 mg a.i./strip), cypermethrin 40% WP (2.81 mg a.i./strip), and cyfluthrin 20% WP (0.57 mg a.i./strip). For experimental evaluation, two oviposition cups (one with an insecticide‐treated strip and one with an untreated strip) were placed in cages (cubic 30 cm) with gravid female Ae. aegypti mosquitoes (aged 6–8 days) from a susceptible laboratory strain. Mortality‐rates of female mosquitoes were 45% for bendiocarb, 47% for permethrin, 98% for deltamethrin, 100% for cypermethrin, and 100% for cyfluthrin. Young instar larvae added to the treated cups died within 2 h. After water evaporation from the cups for 38 days, fresh mosquito females had access to previously submerged portions of the velour paper paddle, and mortality rates of 59% or more occurred. Cups that had water (360 ml) dripped into them, to simulate rain, produced female mosquito mortality rates of > 50% and all larvae died within 3 h of being added. These tests demonstrate that the ovitrap can be made lethal to both adults and larvae by insecticidal treatment of the ovistrip. Field efficacy trials are underway in Brazil to access the impact of this simple, low‐cost, environmentally benign approach on populations of the dengue vector Ae. aegypti.
Identification of bloodmeals in haematophagous Diptera by cytochrome B heteroduplex analysis
Authors: Boakye D. A. , Tang J. , Truc P. , Merriweather A. , Unnasch T. R. 
Published: March 2003

SummaryWe developed a DNA assay for bloodmeal identification in haematophagous insects. Specific host cytochrome B gene sequences were amplified by PCR and classified on the basis of their mobility in a heteroduplex assay. In the blackfly Simulium damnosum s.l. (Diptera: Simuliidae), human cytochrome B DNA sequences were identifiable up to 3 days following ingestion of the bloodmeal. In the tsetse Glossina palpalis (Diptera: Glossinidae) collected from tsetse traps in Ivory Coast, bloodmeals were identified as taken from domestic pigs on the basis of their heteroduplex pattern and DNA sequence. Evidently the cytochrome B sequence shows sufficient interspecific variation to distinguish between mammalian host samples, while exhibiting minimal intraspecific variation. The stability of DNA in bloodmeals, for several days post‐ingestion by haematophagous insects, allows PCR‐HDA assays to be used reliably for host identification.
Susceptibility of British head lice, Pediculus capitis, to imidacloprid and fipronil
Authors: Downs A. M. R. , Stafford K. A. , Coles G. C. 
Published: March 2003

SummaryThe head louse, Pediculus capitis De Geer (Phthiraptera: Pediculidae) has developed resistance to organochlorines, the organophosphate malathion and to pyrethroids in the U.K. Therefore, headlice from Bristol school children were bioassayed against two new insecticides, fipronil and imidacloprid. Pediculus capitis was fully susceptible to imidacloprid, but it required a relatively high dose and acted slowly. Fipronil acted faster at lower dose, but seemed to be affected by cross‐resistance in a small proportion of P. capitis.
Permethrin resistance ratios compared by two methods of testing nymphs of the German cockroach, Blattella germanica
Authors: Ladonni H. 
Published: March 2003

SummaryFor the German cockroach, Blattella germanica L. (Dictyoptera: Blattellidae), the permethrin resistance ratio (RR) was assessed by topical application and by tarsal contact tests, using first‐instar nymphs of five strains from Tehran, Iran. Each test was replicated three or four times with 10 nymphs aged 2–3 days; mortality was scored 24 h post‐treatment. The reference susceptible strain showed LD50 permethrin 0.0175 μl/nymph from topical application, KT50 of 8.41 min and LT50 of 12.82 following tarsal contact with permethrin 15 mg/m2. In four wild strains (F1 generation) the RR varied from 4.14 to 4.7 for mortality after topical application, from 4.2 to 6.45 for mortality and 17–27 for knockdown following tarsal contact tests. Hence, overall knockdown results gave much higher RRs than for mortality data. Resistance ratios based on both methods of treatment were very similar: one strain showed a slightly higher value by topical application (RR 4.6 vs. 4.2, i.e. 1.1‐fold difference) whereas the other three strains gave slightly greater RR (1.2–1.4 fold) by tarsal contact. Resistance was abolished by cotreatment with the synergist piperonyl butoxide plus permethrin (ratio 3 : 1 required for full efficacy), indicating that mixed‐function oxidases were inhibited as a major metabolic pathway in all four resistant strains.
Cost‐comparison of DDT and alternative insecticides for malaria control
Authors: Walker K. 
Published: March 2003

SummaryIn anti‐malaria operations the use of DDT for indoor residual spraying has declined substantially over the past 30 years, but this insecticide is still considered valuable for malaria control, mainly because of its low cost relative to alternative insecticides. Despite the development of resistance to DDT in some populations of malaria vector Anopheles mosquitoes (Diptera: Culicidae), DDT remains generally effective when used for house‐spraying against most species of Anopheles, due to excitorepellency as well as insecticidal effects. A 1990 cost comparison by the World Health Organization (WHO) found DDT to be considerably less expensive than other insecticides, which cost 2 to 23 times more on the basis of cost per house per 6 months of control. To determine whether such a cost advantage still prevails for DDT, this paper compares recent price quotes from manufacturers and WHO suppliers for DDT and appropriate formulations of nine other insecticides (two carbamates, two organophosphates and five pyrethroids) commonly used for residual house‐spraying in malaria control programmes. Based on these ‘global’ price quotes, detailed calculations show that DDT is still the least expensive insecticide on a cost per house basis, although the price appears to be rising as DDT production declines. At the same time, the prices of pyrethroids are declining, making some only slightly more expensive than DDT at low application dosages. Other costs, including operations (labour), transportation and human safety may also increase the price advantages of DDT and some pyrethroids vs. organophosphates and carbamates, although possible environmental impacts from DDT remain a concern. However, a global cost comparison may not realistically reflect local costs or effective application dosages at the country level. Recent data on insecticide prices paid by the health ministries of individual countries showed that prices of particular insecticides can vary substantially in the open market. Therefore, the most cost‐effective insecticide in any given country or region must be determined on a case‐by‐case basis. Regional coordination of procurement of public health insecticides could improve access to affordable products.
Impact of irrigation on malaria in Africa: paddies paradox
Authors: Ijumba J. N. , Lindsay S. W. 
Published: March 2003

SummaryThe high population growth rate of the African continent has led to an increased demand for food and is in danger of outstripping agricultural production. In order to meet this need, many governments have sought ways of improving food production by initiating large‐scale irrigation projects, involving reclamation of arid and semi‐arid areas for the cultivation of crops. Although crop irrigation promises one solution to alleviating hunger and encourages economic growth, irrigation has often been blamed for aggravating disease in local communities. Malaria is one of the major tropical diseases associated with irrigation schemes, and changes in the transmission pattern of this disease following irrigation development have been a perennial subject of debate. It has often been assumed that high numbers of malaria vector Anopheles mosquitoes (Diptera: Culicidae) resulting from irrigation schemes lead inevitably to increased malaria in local communities. However, recent studies in Africa have revealed a more complex picture. Increased numbers of vectors following irrigation can lead to increased malaria in areas of unstable transmission, where people have little or no immunity to malaria parasites, such as the African highlands and desert fringes. But for most of sub‐Saharan Africa, where malaria is stable, the introduction of crop irrigation has little impact on malaria transmission. Indeed, there is growing evidence that for many sites there is less malaria in irrigated communities than surrounding areas. The explanation for this finding is still unresolved but, in some cases at least, can be attributed to displacement of the most endophilic and anthropophilic malaria vector Anopheles funestus Giles by An. arabiensis Patton with lower vectorial capacity, as the latter thrives more than the former in ricefields. Similarly, among members of the An. gambiae complex, some cytotypes of An. gambiae sensu stricto are more vectorial than others. For example, the Mopti form has high vectorial capacity and breeds perennially in irrigated sites, whereas the savanna form is often sympatric but more seasonal. Also we suggest that many communities near irrigation schemes benefit from the greater wealth created by these schemes. Consequently irrigation communities often have greater use of bednets, better access to improved healthcare and receive fewer infective bites compared with those outside such development schemes. Thus, in most cases, irrigation schemes in Africa do not appear to increase malaria risk, except in areas of unstable transmission. However, developers should take the opportunity to improve health‐care facilities for local communities when planning irrigation schemes wherever they occur.
Computer‐aided learning: an overvalued educational resource?
Authors: Devitt Peter , Palmer Edward 
Published: March 2003

Aim The aim of this study was to evaluate the place of computer‐aided learning in a basic science course in the undergraduate medical curriculum at the University of Adelaide.Methods A software program was written which would allow students to study the anatomy and physiology of the liver and biliary tree in three different styles. Identical content was produced, matched for each style (problem‐based, didactic and free text response) and students randomly allocated to one of four groups (three computer and one control). Students were tested before and after access to the program.Results Ninety second‐year students completed the study. Those students who had access to the material in the problem‐based and free text response styles did no better in the post‐study test than the controls, whilst the group who had studied the didactically presented computer material performed significantly better than the other three groups. All three computer groups accessed the material on a similar number of occasions, but the group who had access to the free text entry program spent significantly less time on computer study.Conclusions If computer materials are to be provided as a learning resource for the basic medical sciences, provision must be made for the style of teaching of the course and the style of learning of the students attending that course.
Genetic structure of harbour porpoisePhocoena phocoenapopulations in the northwest Atlantic based on mitochondrial and nuclear markers
Authors: Rosel P. E. , France S. C. , Wang J. Y. , Kocher T. D. 
Published: March 2003

AbstractThe harbour porpoise,Phocoena phocoena, experiences high levels of nonnatural mortality owing to interactions with commercial fisheries throughout its range. To accurately evaluate the significance of this bycatch, information on population structure is required. We have examined the population structure of this species in the northwest Atlantic Ocean using mitochondrial DNA (mtDNA) sequence and nuclear microsatellite data. Samples from four previously proposed summer breeding populations—the Gulf of Maine, eastern Newfoundland, the Gulf of St Lawrence and West Greenland—were analysed. Control‐region sequences revealed a significant partitioning of genetic variation among most of these summer populations, indicating that northwest Atlantic harbour porpoises should not be considered one panmictic population. Analysis of females alone yielded the highest levels of population subdivision, suggesting that females are more philopatric than males. At least three management units may be defined for harbour porpoises in the northwest Atlantic based on these data. Analysis of six microsatellite loci failed to detect significant population subdivision. Male‐mediated gene flow may maintain homogeneity among nuclear loci, while female philopatry is sufficient to produce a signal of population subdivision in the maternally inherited mtDNA genome. mtDNA analyses also indicate that winter aggregations of harbour porpoises along the US mid‐Atlantic states comprise animals from more than one summer breeding population.
Can multiple‐copy sequences of prey DNA be detected amongst the gut contents of invertebrate predators?
Authors: Zaidi R. H. , Jaal Z. , Hawkes N. J. , Hemingway J. , Symondson W. O. C. 
Published: March 2003

AbstractThe first experiments to clearly demonstrate that DNA techniques might be used to detect predator–prey interactions between arthropods are reported. The accurate modelling of such interactions has depended until now upon a mixture of laboratory experiments, population monitoring and biochemical tests. The latter involve gut‐content analyses, and have most recently depended upon the development of prey‐specific monoclonal antibodies. Although these are excellent for detecting predation on a target prey, they are impractical for analysing the prey range of a particular predator. Molecular detection depends upon the ability of DNA to resist digestion in the predator gut and of the polymerase chain reaction (PCR) to amplify prey‐specific DNA from semidigested material. As a first step, experiments using carabid beetles, Pterostichus cupreus L., as predators and mosquitoes as prey are reported. The target sequences were fully characterized multiple‐copy esterase genes from two laboratory strains of Culex quinquefasciatus Say. Although DNA was extracted from homogenates of whole beetles (minus appendages), a 146 bp product could be amplified from both mosquito strains digested in the beetle gut for 28 h. The larger, 263 bp product was detectable for 28 h in one mosquito strain, but could not be amplified after 5 h from the other. Whether the beetles had eaten one mosquito or six, digested for zero or 28 h, the prey were equally detectable. Having demonstrated that shorter, multiple‐copy sequences survive digestion for a considerable period in the gut of a predator, the opportunity exists to develop new detection systems for studying predation in the field.
Extra‐pair paternity in relation to male age in Bullock’s orioles
Authors: Richardson D. S. , Burke T. 
Published: March 2003

AbstractSingle‐locus minisatellite DNA profiling was used to assign paternity in a population of Bullock’s orioles,Icterus galbula bullockii, and to determine the contribution of age to a male’s success in obtaining extra‐pair paternity. There was a very low rate of intraspecific brood parasitism (2/202 = 1.0% of chicks). Older adult males lost less within‐pair paternity and gained more extra‐pair fertilizations than did yearling subadult males. This resulted in adult males benefiting from an annual reproductive success more than double that of subadult males. Behavioural observations, used to determine the role of female choice in extra‐pair copulations (EPCs), indicated that females actively participate in EPCs and that they prefer to obtain them from older males. While it was possible that females obtained EPCs as an insurance against the possible infertility of their social mate, the results of this study fit best with the hypothesis that females were attempting to obtain better‐quality genes for their offspring by obtaining EPCs with older, better‐quality males.
Genetic diversity and gene flow among southeastern Queensland koalas (Phascolarctos cinereus)
Authors: Fowler E. V. , Houlden B. A. , Hoeben P. , Timms P. 
Published: March 2003

AbstractHabitat fragmentation and destruction associated with the rapid urban and rural development of southeast Queensland presents an immediate threat to the survival of koala populations within this region. A sensitive method combining heteroduplex analysis (HDA) with temperature gradient gel electrophoresis (TGGE) was optimized to detect within‐species variation in a mitochondrial DNA (mtDNA) control‐region fragment, ≈ 670 bp in length, from the koala. Eight different haplotypes were characterized in koalas, of which four were novel. Analysis of mtDNA diversity in 96 koalas from five populations in southeast Queensland revealed that the number of haplotypes in a single population ranged from one to five, with an average within‐population haplotype diversity of 0.379 ± 0.016, and nucleotide diversity of 0.22 ± 0.001%. Nucleotide divergence between populations averaged 0.09 ± 0.001% and ranged from 0.00 to 0.14%. Significant genetic heterogeneity was observed among most populations, suggesting that koala populations may be spatially structured along matrilines, although this may not be universal. The limited distribution of the central phylogenetic haplotype suggested the possibility of historical population bottlenecks north of the Gold Coast, while the presence of two highly divergent haplotypes at the Moreton site may indicate the occurrence of one or more undocumented translocation events into this area.
Patterns of paternal relatedness in British grey seal colonies
Authors: Wilmer J. Worthington , Overall A. J. , Pomeroy P. P. , Twiss S. D. , Amos W. 
Published: March 2003

AbstractPrevious studies of breeding behaviour in the grey seal, Halichoerus grypus, have painted conflicting pictures. Behavioural observations suggest a classical polygynous system with a small number of dominant males fathering most of the offspring. However, genetic analysis suggests that many potential fathers spend little time ashore, that some pairs of seals show partner fidelity and that the dominant males are not as successful as their behaviour would suggest. Here we used paternal relatedness between pups with known mothers, sampled over an 11‐year period, to show that behavioural dominance leading to enhanced fitness is a feature of only a handful of males located near the centre of the breeding colony. The vast majority of pups are fathered by any of a large number of males who all share approximately equal success, including virtually all those males who have previously escaped our best sampling efforts. As expected, the frequency of full‐sibs is reduced in this longer time series relative to the original study. However, absolute estimates of the frequency of full‐sibs seem to be confounded by a tendency for females who produce paternally unrelated pups to have conceived to males who are more genetically dissimilar from each other than expected by chance alone. Together, these elements of breeding behaviour would help to maintain maximum genetic diversity and to minimize the effects of inbreeding.
Molecular ecology and biological control: the mating system of a marsupial pest
Authors: Sarre S. D. , Aitken N. , Clout M. N. , Ji W. , Robins J. , Lambert D. M. 
Published: March 2003

AbstractMany studies in molecular ecology have focused on the use of repeat DNA markers to determine the nature of mating systems in a wide variety of animal species. Whilst these studies typically have focused on important issues such as the evolutionary consequences of fitness variation among males, genetic studies of mating systems are potentially also important because they can generate information of significance to wider issues in wildlife management. For example, genetically modified, sexually transmitted viral diseases have been suggested as potential agents for the control of vertebrate pest species. An understanding of the epidemiology of such agents requires an intimate knowledge of the sexual contact rates between individuals of the target species. Here, we report the use of minisatellite DNA profiling to reveal the mating system in two New Zealand populations of the introduced Australian brushtail possum. The brushtail possum is New Zealand’s most important mammalian pest and a species for which control by a sexually transmitted immunocontraceptive has been proposed. Encouragingly, we report considerable variation in the reproductive success of males at both study sites, with one male siring offspring from four females in one year (mean no. of offspring/reproductively successful male/year at the two sites is 1.95–2.15), while many sired none. This bias in the pattern of reproductive success among males will probably facilitate the spread of an immunocontraceptive agent and thereby increase the power of this approach to biological control.