bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breeding‐site productivity of the swamp forest mosquitoes Mansonia bonneae and Ma.dives in Sarawak, East Malaysia
Authors: CHANG M. S. , JUTE N. , LAH J. 
Published: March 2008

Abstract. Studies on larval population densities and adult emergence rates of the Brugian filariasis vectors Mansonia bonneae Edwards and Ma.dives Schiner were conducted in freshwater swamp forest bordering the Sadong River, Serian District, Sarawak, East Malaysia, during 1984–85.Three species of aquatic host‐plants in the Family Araceae were identified as supporting immature stages of the Ma. bonneae/dives complex. Proportions of positive plants were 4.7%, 6.5% and 3.4% with 6.4±2.6, 7.3±2.8 and 10.1±1.1 larvae per positive plant, respectively, for the plant species Homalomena cordata Schott, H.rostrata Griffiths and Hydrostemma motleyi (Hook. f.) Mabberley. These data indicate no significant preferences between the three types of host‐plant.Detailed monitoring of the host‐plant H.cordata revealed no significant monthly fluctuations in larval density per plant nor the proportion of positive plants. 11.6% of larvae were Ma.dives and 88.4% were Ma.bonneae. Mean daily yields of Ma.bonneae/dives adults per square metre of H.cordata vegetated water surface were 0.45 males plus 0.57 females during the wet season (December‐February) compared with 0.2 males plus 0.31 females during the dry season (June‐August). Thus output of adults per plant was approximately halved, and suitable breeding areas were further reduced, during the dry season. By extrapolation from these rates, a crude mean estimate for productivity of Ma.bonneae/dives females is 1.6 million per hectare per annum in swamp forest habitats vegetated with any of the host‐plants studied.
Juvenile hormone mimics as effective sterilants for the tsetse fly Glossina morsitans morsitans
Authors: LANGLEY P. A. , FELTON T. , OOUCHI H. 
Published: March 2008

Abstract. The development of puparia of Glossina morsitans morsitans Westwood was disrupted by topical applications of the juvenile hormone mimics S‐methoprene (the resolved enantiomer of 11‐methoxy‐3, 7, 11‐trimethyl‐2, 4‐dodecadienoic acid 1‐methyl ester) (Zoecon), S21149 (propionaldoxime‐0–4‐phenoxyphenoxyethylether) (Sumitomo), or S31183 (2‐[1‐methyl‐2‐(4‐phenoxyphenoxy)ethoxy]pyridine) (Sumitomo) dissolved in acetone. Puparia so treated during the first 4 days of life suffered developmental abnormalities, the severity of which were dose‐dependent. Similarly, puparia produced by adult females treated with these compounds were abnormal. Dose–response data showed that effects were greatest with S31183 and least with S‐methoprene. Abnormalities in the form of abdominal lesions and wing crumpling were typical of flies emerging from puparia produced by S‐methoprene‐treated females. However, arrested development at the red eye and pigmented seta stage within the puparium were typical of offspring of females treated with S21149 and S31183. A dose of 2 μg per female of S31183 was sufficient to prevent emergence of offspring produced for the rest of the life of the fly. The same dose resulted in partial recovery of females treated with S21149 some 18 days following treatment. Treatment with 2 μg S‐methoprene did not suppress completely the production of normal offspring and recovery was complete some 27–35 days after treatment. Exposure of males to 20 μg S31183 did not impair their ability to inseminate females; transfer of material during copulation was sufficient to prevent the production of viable offspring by their mates.Although the doses involved in the present experiments were high, the low mammalian toxicity of S31183 makes it an attractive candidate for further evaluation as a safe chemosterilant for tsetse. Of particular interest is the lack of similarity between the molecular structures of juvenile hormones and this mimic which tends to arrest development at a precisely defined stage within the puparium of the tsetse fly.
Physiological characteristics of Culex pipiens populations in the Middle East
Authors: NUDELMAN SERGIO , GALUN RACHEL , KITRON URIEL , SPIELMAN ANDREW 
Published: March 2008

Abstract. We determined whether exposure to a short day‐light regime of 14 h 15 min induces ovarian diapause in Culex pipiens L. mosquitoes from Israel and whether differences occur in certain morphological, physiological and behavioural traits. Samples from nineteen localities in Israel, from 33°05' N to 29°35' N latitude, conformed to the morphological criteria of Cx pipiens, sensu stricto (i.e. wider spread of dorsal than of ventral arms of the aedeagus) as determined by negative DV/D ratios of the male.Autogenous females occurred at frequencies of 4–55% in all areas of Israel throughout the breeding season. No mating barriers were detected between individuals of autogenous and anautogenous genotypes. Autogenous females were no more prevalent from polluted or enclosed breeding sites than from others with various degrees of openness. In general, Cx pipiens females fed equally well on human (35% engorgement) and avian (22% engorgement) hosts (P<0.01). Although females from the southern part of the study region appeared to be incapable of ovarian diapause, at least some of those from the north experienced diel‐mediated diapause. We conclude that, in the Middle East, the 33rd parallel provides a southern limit to the range of Cx pipiens with capability for diel‐mediated ovarian diapause, but that non‐diapausing Cx pipiens s.l. are present at least as far south as Elat (20°25'N) on the coast of the Gulf of Aquaba.
Tsetse: the limits to population growth
Authors: HARGROVE J. W. 
Published: March 2008

ABSTRACT. Growth rates of tsetse populations were estimated by calculating the dominant eigenvalues of appropriate Leslie matrices. The individual effects of four variables (pre‐adult and adult survival probability, interlarval period and pupal duration), have been investigated by varying each one over a wide range of values, while the other three are held constant. R, the log of the growth rate, was found to vary approximately linearly with adult and pre‐adult death rate; a 1% change in the adult death rate causes approximately a 10‐fold change in R. R varies linearly with the log of fecundity and of the pupal duration. An increase in the pupal duration results in a decrease in the growth rate for populations which have a positive growth rate, but an increase for populations which have a negative growth rate. For a population at equilibrium, a change in the pupal duration has no effect. Small changes in fecundity have less effect on the growth rate than small changes in the death rate; this fact is advanced as an important contributor to the generally very cautious nature of female tsetse, and their aversion to man, particularly as a potential host.A simple linear model is described which relates R to all four variables and their first order interactions. The model is used to produce a set of graphs which encapsulate the relationship between the growth rate and the vital parameters over a wide range of values. It is also used to draw the loci on one side of which tsetse populations grow, and on the other of which they decline.Population resilience is discussed in relation to the problem of tsetse eradication; it is concluded that if one can impose and sustain an added mortality of 4% per day on any female tsetse population then it must go extinct, regardless of the strength of the density dependent processes; and it seems likely that in most field conditions only an added 2–3% is required. It is pointed out that ground and aerial spraying techniques produce much higher daily mortalities than this, but they may often not be sustained for sufficiently long to achieve eradication. When odour‐baited targets are used the increased death rate is much smaller, but it can be sustained as required; recent work in Zimbabwe shows that there is a good correspondence between the calculated imposed death rate and the observed rate of decline of tsetse populations.
Evaluation of permethrin‐impregnated mosquito‐nets against mosquitoes in China
Authors: JINJIANG XU , MEILUAN ZAO , XINFU LUO , RONGEN GENG , SHIXIAN PAN , SHUYOU LIU 
Published: March 2008

ABSTRACT. In Yishan County, Guangxi Province, China, where malaria and Brugian filariasis are transmitted by vectors belonging to the Anopheles hyrcanus Pallas group, a study was conducted from June to November 1986 to evaluate the effectiveness of permethrin‐impregnated mosquito bednets to reduce man/vector contact. In three experimental villages a total of 246 mosquito nets were treated with permethrin EC at a dosage of 0.5 g/m2.Control bioassays (1 h exposure) of treated nets gave up to 100% mortality of Armigeres subalbatus (Coquillett), Anopheles sinensis Wiedemann and Culex tritaeniorhynchus Giles for up to 19 weeks. During 5 months evaluation in the villages, permethrin‐impregnated mosquito‐nets reduced the number of mosquitoes found inside nets by 99.3% for Culex quinquefasciatus Say, by 94.4% for Anopheles sinensis Wiedemann and by 75% for Anopheles lesteri anthropophagus Xu & Feng. This measure could thus be considered an appropriate means of controlling vectors in villages.
Feeding strategies of the horseflies Hybomitra expollicata and Tabanus bromius in southern France
Authors: BALLARD J. W. O. , WAAGE J. K. 
Published: March 2008

ABSTRACT.Blood‐feeding success of female horseflies,Hybomitra expollicataPandellé andTabanus bromiusL. (Diptera: Tabanidae), was studied. Bloodmeal weights of flies permitted different periods of residence on a horse's belly were estimated, and related to subsequent ovarian development and the number of mature eggs produced.Fitness gain per visit to a host (as estimated by the number of mature eggs produced) increased more rapidly with residence time on the host forH. expollicatathan forT. bromius. H. expollicataimbibed blood more rapidly and, above a threshold bloodmeal size, produced a consistently higher number of eggs per unit weight of blood ingested. The feeding strategies of the two species are compared.
Morphogenetic diapause in Amblyomma variegatum (Acari: Ixodidae)
Authors: PEGRAM R. G. , MWASE E. T. , ZIVKOVIC D. , JONGEJAN F. 
Published: March 2008

ABSTRACT. In southern Africa, Amblyomma variegatum Fabricius is characterized by a strict seasonal activity. Experiments were carried out to determine whether a diapause mechanism regulates this seasonality. Engorged A. variegatum females were exposed to controlled laboratory conditions or natural field conditions at different times of the year. Females exposed in a natural environment in September‐October (short day) had significantly longer pre‐oviposition periods than females exposed from November to March. The season in which the previous instar fed had no apparent effect on the engorgement or pre‐oviposition periods of the females. Furthermore, artificial changes in photoperiod during and after female engorgement had no significant effects on pre‐oviposition periods.It is tentatively concluded that the unfed female is the responsive stage to photoperiodic changes which induce diapause. Diapause could be terminated and oviposition induced by exposing females to a short period of chilling (18OC for 48 h). It is concluded that a morphogenetic diapause mechanism exists in A. variegatum, which is probably induced by short day responses and terminated following rainfall and a concomitant decrease in soil temperature. The diapause, which occurs in females which fed early in the season, causes a delay in oviposition and therefore effectively synchronizes the life‐cycle to ensure that eggs and larvae occur at a climatically favourable period.
Oviposition habitat preferences of Toxorhynchites moctezuma mosquitoes in four types of tropical forest in Trinidad
Authors: O'MALLEY SEAN L. C. , HUBBARD STEPHEN F. , CHADEE DAVE D. 
Published: March 2008

ABSTRACT. 1. Oviposition of the mosquito Toxorhynchites moctezuma Dyar & Knab was investigated in four types of tropical forest in Trinidad, West Indies, using surrogate and natural ovitraps. Larvae of Tx. moctezuma are obligate predators that might be useful for the biological control of Aedes aegypti (L).2. Significantly more oviposition occurred in seasonal‐deciduous forest than in either montane or evergreen‐seasonal forest.3. Oviposition in surrogate containers (black‐painted polystyrene cups, 90 mm diameter) was compared with that occurring in typical natural containers (nutpots of Lecythis zapucajo Aublet). Surrogate ovipots were relatively insensitive indicators of oviposition activity, and would be an inefficient means of harvesting Tx. moctezuma eggs.4. Implications for the collection, culture and mass release of Tx. moctezuma are discussed.
The potential geographical distribution of the Old World screw‐worm fly, Chrysomya bezziana
Authors: SUTHERST R. W. , SPRADBERY J. P. , MAYWALD G. F. 
Published: March 2008

ABSTRACT. The potential geographical distribution and relative abundance of the Old World screw‐worm fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae) as determined by climate, was assessed using CLIMEX, a computer program for matching climates. CLIMEX describes the relative growth and persistence of animal populations in relation to climate.The observed global distribution of C. bezziana was compared with the potential distribution predicted by CLIMEX. The differences in the two distributions indicate the areas at risk of colonization, with particular reference to Australia and the Americas. According to the model, the potential area of permanent colonization in Australia extends south to the mid‐coast of New South Wales. Comparison of areas suitable for permanent establishment with the potential summer distribution indicates that large additional areas, carrying most of the continent's livestock, could be colonized in the summer months. Seasonal population growth indices are presented for three ports in Australia at which screw‐worm fly specimens have been collected by quarantine authorities. They indicate the relative risk associated with introductions at different places in different seasons and so provide valuable planning information for quarantine authorities.The CLIMEX predictions for C. bezziana in North America are shown to be similar to the recorded distribution limits of the New World screw‐worm fly, Cochliomyia hominivorax (Coquerel). The fly could also colonize South America, as far south as southern Brazil and midway through Argentina.
Effectiveness of zooprophylaxis in malaria control: a theoretical inquiry, with a model for mosquito populations with two bloodmeal hosts
Authors: SOTA T. , MOGI M. 
Published: March 2008

ABSTRACT. A model for a vector mosquito population with two bloodmeal hosts (man and a domestic animal) was developed to study the influences of domestic animals on the frequency of mosquito bites on man and the endemicity of human malaria. The vector population model, including blood‐feeding success in the adult stage (depending on host density and biting efficiency) and density‐dependent regulation in the larval stage, was combined with the Ross‐Macdonald malaria transmission model.Model analyses suggested that introduction of domestic animals easily fed upon by mosquitoes increases mosquito density and, in some situations, frequency of mosquito bites on man and the infection rate of malaria through increased success of blood‐feeding. Extinction of malaria was predicted only when an extremely large number of easily accessible (as compared to man) domestic animals are introduced. Limitations in the concept of zooprophylaxis and problems of livestock management in malaria control are discussed.
Efficacy of mosquito nets treated with permethrin in Suriname
Authors: ROZENDAAL J. A. , VOORHAM J. , VANHOOF J. P. M. , OOSTBURG B. F. J. 
Published: March 2008

ABSTRACT. In the rain‐forest of Suriname, where malaria is endemic, 95% of the Maroons (who call themselves bush‐negroes) and all Amerindians use mosquito nets made of cotton cloth or, less frequently, nylon or cotton gauze over their hammocks or beds. Bush‐negroes usually wash their nets weekly; Amerindians wash nets at 1–4‐month intervals.Females of the principal local malaria vector, Anopheles darlingi Root, were seen blood‐feeding through cotton cloth netting (at 22.30‐23.30 hours) on a person sleeping in a hammock; others fed successfully after the net was opened in the morning.Cotton cloth impregnated with permethrin at a rate of 0.5 g/m2 killed all An. darlingi females exposed for 2 min, but after the material had been washed twice in soapy water the bioassay mortality fell to only 21.4%.Exit traps on a hut with a single sleeper protected by a permethrin‐impregnated net yielded 185 An. darlingi females (12% blood‐fed) in 74 nights, compared with 276 females (19% blood‐fed) from another hut with a sleeper using an untreated net on the same nights (P< 0.001). No An. dar‐lingi females remained resting alive indoors in these huts during the daytime, and very few were found dead on the floor in the mornings (one treated, seven untreated). The 24 h mortality rate for those collected in exit traps was 58.4% for the test hut and 27.1% for the control hut (P< 0.001).Bioassays of permethrin‐treated cotton cloth using laboratory‐reared sugar‐fed Culex quinquefasciatus Say females showed that sprayed nets were less effective than nets impregnated by soaking (at equivalent dosages of 0.16‐1.34 g/m2 measured by chemical assay) and confirmed that washing causes severe decline in insecticidal activity.The feasibility of local mass treatment of mosquito nets is discussed.
Permethrin‐impregnated bednets reduce nuisance arthropods in Gambian houses
Authors: LINDSAY S. W. , SNOW R. W. , ARMSTRONG J. R. M. , GREENWOOD B. M. 
Published: March 2008

ABSTRACT. The prevalence of bedbugs (Cimex hemipterus L.), chicken ticks (Argas persicus Oken) and headlice (Pediculus capitis De Geer) was surveyed in a rural area of The Gambia. At the beginning of the study 37.5% of children's beds were infested with bedbugs and 3.9% with chicken ticks, whilst the prevalence rate of pediculosis in children under 10 years old was 28.8%. Both bedbugs and headlice were clustered within compounds. Headlice prevalence increased with hair length and they were more common on girls than boys.Following this cross‐sectional survey all bednets in the sixteen hamlets were either dipped in permethrin or a placebo. About 4 months later it was found that bedbugs and chicken ticks had disappeared from homes in which the bednets had been impregnated with permethrin. There was no reduction in hamlets with placebo‐treated bednets. The rate of acquiring headlice between the two surveys was reduced by 91.1% in children who slept under insecticide‐treated bednets compared with children with placebo‐treated bednets. There were also significantly fewer day‐flying and crawling insects, except earwigs, in homes of children who slept under insecticide‐treated bednets compared with those with placebo‐treated nets. These additional benefits of permethrin‐treated bednets should contribute to their widespread acceptance and utilization by the community for personal protection.
Midgut and salivary gland barriers to La Crosse virus dissemination in mosquitoes of the Aedes triseriatus group
Authors: PAULSON SALLY L. , GRIMSTAD PAUL R. , CRAIG GEORGE B. 
Published: March 2008

ABSTRACT. Vector competence for La Crosse virus (LACV) was compared for four species in the Aedes (Protomacleaya) triseriatus group: Ae.triseriatus (Say), Ae.hendersoni Cockerel], Ae.zoosophus Dyar and Knab and Ae.brelandi Zavortink (Diptera: Culicidae). Rates of replication and dissemination of virus in the mosquito hosts were compared and rates of oral transmission of virus to suckling mice were determined. Barriers to virus dissemination which limited the ability of each species to transmit virus were identified. Ae.zoosophus displayed the highest vector competence for LACV. Both infection and transmission rates were high: 99% and 85% respectively; no significant barriers to LACV were found. Disseminated infection of Ae. triseriatus with LACV was controlled primarily be a midgut escape barrier. When virus was introduced directly into the haemocoel, transmission rates were significantly increased (37% v. 79%). Ae.hendersoni showed high susceptibility to LACV infection but a very low rate of oral transmission (7%). Ae.brelandi was also highly susceptible to infection by LACV and transmitted virus at an intermediate rate (27%). Modulation of vector competence in both Ae.hendersoni and Ae. brelandi resulted from a salivary gland escape barrier.As these four species of mosquitoes comprise a closely related monophyletic series, their differences of vector competence for LACV provide an excellent model for studying the genetic basis of the barriers involved.
Influence of habitat and temperature on dispersal behaviour of two pteromalid parasitoids of houseflies during an inundative release at a dairy barn
Authors: SMITH LINCOLN , RUTZ DONALD A. , SCOLES GLEN A. 
Published: March 2008

ABSTRACT. 1. About 11,000 each of Muscidifurax raptor Girault and Saunders and Urolepis rufipes (Ashmead) were released weekly for 7 weeks at a commercial dairy farm in central New York state, U.S.A. Dispersal behaviour was monitored by parasitism rates of house fly, Musca domestica L., pupae placed in sentinel bags.2. M.raptor, which was released inside the barn, parasitized fly pupae both inside and outside, and it achieved highest rates of parasitism in indoor straw calf‐bedding and in outdoor manure and silage.3. U. rufipes, which was released outside the barn, did not attack pupae inside the barn, and its highest rates of parasitism occurred in outdoor manure and silage.4. M. raptor appeared to be more effective than U. rufipes in parasitizing pupae located at sites where natural fly‐breeding occurred.5. Interspecific competition did not appear to explain these distribution patterns.6. There was no significant trend in parasitism by M.raptor as a function of distance from the release station. Furthermore, high rates of parasitism near open doorways and at an outdoor site 30 m away suggests that M.raptor dispersed throughout the barn and its immediate surroundings.7. Air temperature was positively correlated to flight activity, but not to parasitization activity in natural fly‐breeding substrates.
Facultative blood‐feeding in the crabhole mosquito, Deinocerites cancer
Authors: O'MEARA GEORGE F. , MOOK DAVID H. 
Published: March 2008

ABSTRACT. 1. Most of the female crabhole mosquitoes Deinocerites cancer Theobald entering bait traps had undeveloped ovaries.2. Nearly half of the D.cancer females that were captured in bait traps, but denied blood, were gravid following a 1 week holding period; they developed relatively small egg clutches autogenously (mean=7.4 eggs per gravid female).3. Although both parous and nulliparous D. cancer females were captured exiting from crabholes, only parous females were attracted to and collected in bait traps.4. Much larger egg clutches (mean=41.8 eggs per female) were produced anautogenously by mosquitoes that blood‐fed on chickens.5. All D. cancer females from field collected pupae developed eggs autogenously when allowed to mate and sugar feed in the laboratory. These mosquitoes produced an initial egg clutch with a mean size equivalent to that found in blood‐fed, parous mosquitoes from bait traps.6. In the field, mating and sugar feeding rather than blood‐feeding seem to stimulate production of the initial egg clutch.7. D.cancer blood‐feeding appears to be delayed until after the first egg clutch has been laid; some parous crabhole mosquitoes are facultative blood feeders and can produce an egg clutch either with or without a blood meal.