Fly Catches Research Articles

Simplified and improved monitoring traps for sampling sand flies

Simplified and improved monitoring traps for sampling sand flies Gunter C. Muller1, Edita, E. Revay2, and John C. Beier3 1Department of Microbiology and Molecular Genetics , IMRIC, Kuvin Centre for the Study of Infectious and Tropical Diseases, Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel, guntercmuller@hotmail.com 2Department of Anatomy and Cell Biology, Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel 3Department of Epidemiology and Public Health, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A.

Temporal and spatial trends in adult nuisance fly populations at Australian cattle feedlots

AbstractA comprehensive trapping program to determine the species composition, seasonality and distribution of adult nuisance fly populations at a southern Queensland feedlot was conducted from 2001 to 2003. Short‐term information on nuisance fly populations was also collected from two feedlots located in other climatic regions. Twenty‐five species of Diptera were identified. The more commonly trapped species were the house fly, Musca domestica L. (Muscidae) (38%), the hairy maggot blowfly, Chrysomya rufifacies (Macquart) (Calliphoridae) (27%) and the bush fly, Musca vetustissima Walker (Muscidae) (15%). Seasonal effects were the major determinant of fly populations. All commonly trapped fly species had low abundance during the coldest winter months, July and August. Musca domestica had one annual, broad peak in abundance starting in spring and extending over about 8 or 9 months. Musca vetustissima had a major abundance peak in October/November and a smaller peak around April. Stomoxys calcitrans (L.) (stable fly) (Muscidae) showed two annual peaks in abundance, with the major peak in May. Chrysomya spp. were most abundant during spring, summer and autumn, whereas the highest numbers of Calliphora augur (F.) (blue‐bodied blowfly) (Calliphoridae) were trapped in winter.The sites within the feedlot with the highest catches of M. domestica were the feed mill, cattle pens and the hospital area and of S. calcitrans the manure piles, silage pits and the feed mill. The lowest catches of M. domestica and S. calcitrans were obtained in the traps situated a few kilometres outside the feedlot. In contrast, M. vetustissima and blowfly catches were higher in outside traps and traps near the manure piles than any other feedlot site.There was a correlation between the animals' number of fly avoidance movements and M. domestica catches and between the number of leg stomps and stable fly catches, respectively.

1845.1 The Knickerbocker Rules — and the Long History of the One-Bounce Fielding Rule

If a ball be struck, or tipped, and caught, either flying or on the first bound, it is a hand out.2The famous Knickerbocker rules of 1845 may not be comprehensive enough to fully define a playable game, and may not even be baseball's first written rules,3 but they did indeed survive, and they give us the first coherent picture of the roots of the New York game.At first taken as evidence of the Knickerbocker Club's knack for inventive genius, the 13 playing rules have recently been freshly reconsidered in an evolutionary context, and their reputation for originality has taken several hits.4 At this point, it appears that only three rules that endure today lack clear precedent in prior safe-haven ballgames.5 These are (1) the tag-out rule, which supplanted the plugging of base-runners to put them out6; (2) the characteristic 90-degree territory defining fair hits; and (3) the three-out inning. The three-strike rule, for example, was already in use in predecessor games-as was the dropped-third strike rule that freed the batter who whiffed to run the bases. (Such familiar modern icons as the nine-inning game, the nine-player team and the ninety-foot basepath came along more than a decade later.)It seems ironic, when discussing rule innovations, that what may have been early game's most contentious rule (the issue remained unsettled for four decades) was perhaps actually the most ancient aspect of ballplay. The basic fly rule for putting batters out seems to have been a part of ballplaying since, at least, the earliest accounts of English stoolball and cricket, centuries ago.What Know About the Prehistory of the Bound RuleThe Knickerbocker Club's rule 12, cited above, includes a provision that to baseball fans seems quaint, if not alien, today; a batter could be retired if a fair or foul hit is caught after it bounces once.There has been, until recently, reasonable speculation that this provision was another Knickerbocker innovation, and why it appeared. Over time, the weight and dimension of the ball had been evolving toward that of the cricket ball, making it heavier-and, reportedly, harder. One might surmise, then, that a fielder's hands might be better protected from pain and injury if he were afforded the option of letting the ball bounce once, and then to field it once it was spent. A closer look, however, reveals some evidence that the one-bounce rule was known even before the New York game took shape.The bound rule actually has a solid place in ball sports-and not just in the children's game of jacks and in assorted playground fungo games. It is seen today mostly in tennis and related sports like handball and squash and table tennis, where the objective is to return a ball before it bounces twice, an event that would abruptly add one to the opponent's score. For many centuries the bound rule has been an essential part of the old form of tennis, played long before modern lawn tennis was invented (keeping the bound rule) in 1873. Very early forms of collegiate football in the United States, and rugby-rules football in England, also included rules that specified what a player could and could not do when catching a ball on the bound.7But was the bound rule also part of earlier safe-haven ballgames? One baseball pioneer certainly thought so. Describing the rules set for the new Gotham Base Ball Club in 1837, William Wheaton wrote, a half-century later: We abandoned the old rule of putting out on the first bound and confined it to fly catching.8 (If true, of course, this means that the Knickerbocker Club had actually decided to reverse the Gotham Club's decision, and had reverted to the bound rule.) A second pioneer agrees: Knickerbocker mainstay Doc Adams seems to have suggested that one reason that players still liked the bound rule in 1860 was that it was a familiar feature of their boyhood ballgames.9The direct evidence on broad prior use of a bound rule is suggestive, but it is not overwhelming. …

Evaluation of a metofluthrin fan vaporizer device against phlebotomine sand flies (Diptera: Psychodidae) in a cutaneous leishmaniasis focus in the Judean Desert, Israel

The OFF! Clip-On fan vaporizer device releasing metofluthrin was evaluated against phletobomine sand flies in the Judean Desert, Israel, in October, 2009. A total of 76,400 sand flies was collected, with male flies representing 98.3%Phlebotomus sergenti and 1.7%P. papatasi. Females comprised 43.0% of the total catch and included 6.7% blood-fed females. Similar proportions of flies were collected in both suction and sticky traps. In trials with unbaited suction traps, similar numbers of sand flies were collected in traps with a metofluthrin device, blank device, or no device (i.e., suction only). In suction traps baited with CO(2) , higher numbers of P. sergenti males and blood-fed females were collected in traps with a blank device compared to traps with a metofluthrin device. In sticky traps baited with CO(2) , there were no significant differences between catches in traps with a metofluthrin device, blank device, or no device. The results suggest metofluthrin from the device is not repellent against sand flies in a field environment despite showing insecticidal activity against flies collected in suction traps.

Seasonal and spatial changes of sand fly species in a canyon in the Carmel Mountains

Altogether, 4,008 sand flies belonging to seven species were collected over a period of one year in the micro-habitats of a single canyon in the Carmel Mountain ridge. The three most abundant were P. arabicus, P. tobbi, and P. simici. Our results suggest that none of the seven sand fly species was indifferent to the heterogeneity of the microenvironment inside the canyon. Apart from the rare P. perfiliewi, which was only collected on the upper part of the south-facing slope, and P. tobbi, which clustered on the north-facing slope, the bulk of the other sand flies were caught on the bottom of the canyon. During the summer, the catches of all sand fly species increased to reach their maximum number in August and September. In April and May, there was lush vegetation and humidity, so species were distributed evenly throughout their habitats. With the onset of summer dryness, the sand flies concentrated in the humid habitats. The rate of concentration was essentially higher for males than for females, and this variation may result from differences in the behavior of the two sexes. During our study, none of the 2,318 dissected female sand flies were positive for Leishmania promastigotes.

Abundance and seasonality of Cochliomyia macellaria (Diptera: Calliphoridae) in Southern Pantanal, Brazil

Cochliomyia macellaria (Diptera: Calliphoridae), known as the secondary screwworm, occurs in the Americas and has medical-veterinary and forensic importance. This study aimed to describe the seasonal fluctuation of this species in the Pantanal region, Central-Western Brazil. From December 2004 to November 2007 fly catches using four windoriented traps baited with decaying bovine liver were carried out at the Nhumirim ranch, Nhecolândia subregion, Southern Pantanal. Traps remained active throughout the study period and collections were carried out on a weekly basis. A total of 159,397 Calliphoridae were caught and C. macellaria (57.33%) was the most abundant species. C. macellaria occurred all over the year showing a bimodal behavior with peaks in May-July (late autumn/early winter) and October-December (spring).

Blowfly (Diptera, Calliphoridae) damage on stockfish in northern Norway: pest species, damage assessment and the potential of mass trapping

Production of high quality stockfish in northern Norway takes place from February to May. The dominant blowfly species (Diptera: Calliphoridae) with adults present during stockfish production were Calliphora vicina and Protophormia terraenovae. Larval collections identified the damage-causing species to be C. vicina. Other saprophagous blowfly species were only found after the production period. Fish dried in sun-exposed locations experienced more damage than fish in shaded locations, and the risk of damage was higher in fish dried later in the production period. Yellow sticky traps and funnel traps baited with dimethyl trisulphide were tested for their potential in mass trapping. Sticky traps caught flies during early spring, while funnel traps increased in efficiency closer to summer. Attraction to dimethyl trisulphide was found to be significantly higher for C. vicina compared to P. terraenovae, and the catch of C. vicina consisted of 92% females. The catch of female flies during the critical drying period consisted of 5–30% of the estimated number of flies having caused damage. The target specificity with high female catches and the cost efficiency of these traps indicate that mass trapping can be used as an integrated part of a management program to reduce damage from blowflies in stockfish producing areas.

Prospects for the Development of Odour Baits to Control the Tsetse Flies Glossina tachinoides and G. palpalis s.l.

Field studies were done of the responses of Glossina palpalis palpalis in Côte d'Ivoire, and G. p. gambiensis and G. tachinoides in Burkina Faso, to odours from humans, cattle and pigs. Responses were measured either by baiting (1.) biconical traps or (2.) electrocuting black targets with natural host odours. The catch of G. tachinoides from traps was significantly enhanced (∼5×) by odour from cattle but not humans. In contrast, catches from electric targets showed inconsistent results. For G. p. gambiensis both human and cattle odour increased (>2×) the trap catch significantly but not the catch from electric targets. For G. p. palpalis, odours from pigs and humans increased (∼5×) the numbers of tsetse attracted to the vicinity of the odour source but had little effect on landing or trap-entry. For G. tachinoides a blend of POCA (P = 3-n-propylphenol; O = 1-octen-3-ol; C = 4-methylphenol; A = acetone) alone or synthetic cattle odour (acetone, 1-octen-3-ol, 4-methylphenol and 3-n-propylphenol with carbon dioxide) consistently caught more tsetse than natural cattle odour. For G. p. gambiensis, POCA consistently increased catches from both traps and targets. For G. p. palpalis, doses of carbon dioxide similar to those produced by a host resulted in similar increases in attraction. Baiting traps with super-normal (∼500 mg/h) doses of acetone also consistently produced significant but slight (∼1.6×) increases in catches of male flies. The results suggest that odour-baited traps and insecticide-treated targets could assist the AU-Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) in its current efforts to monitor and control Palpalis group tsetse in West Africa. For all three species, only ∼50% of the flies attracted to the vicinity of the trap were actually caught by it, suggesting that better traps might be developed by an analysis of the visual responses and identification of any semiochemicals involved in short-range interaction.

The elimination of the onchocerciasis vector from the island of Bioko as a result of larviciding by the WHO African Programme for Onchocerciasis Control

The island of Bioko is part of the Republic of Equatorial Guinea and is the only island in the World to have endemic onchocerciasis. The disease is hyperendemic and shows a forest-type epidemiology with low levels of blindness and high levels of skin disease, and the whole population of 68,000 is estimated to be at risk. Control of onchocerciasis began in 1990 using ivermectin and this yielded significant clinical benefits but transmission was not interrupted. Feasibility and preparatory studies carried out between 1995 and 2002 confirmed the probable isolation of the vector on the island, the high vectorial efficiency of the Bioko form of Simulium yahense, the seasonality of river flow, blackfly breeding and biting densities, and the distribution of the vector breeding sites. It was proposed that larviciding should be carried out from January to April, when most of the island's rivers were dry or too low to support Simulium damnosum s.l., and that most rivers would not need to be treated above 500 m altitude because they were too small to support the breeding of S. damnosum s.l. Larviciding (with temephos) would need to be carried out by helicopter (because of problems of access by land), supplemented by ground-based delivery. Insecticide susceptibility trials showed that the Bioko form was highly susceptible to temephos, and insecticide carry was tested in the rivers by assessing the length of river in which S. damnosum s.l. larvae were killed below a temephos dosing point. Regular fly catching points were established in 1999 to provide pre-control biting densities, and to act as monitoring points for control efforts. An environmental impact assessment concluded that the proposed control programme could be expected to do little damage, and a large-scale larviciding trial using ground-based applications of temephos (Abate 20EC) throughout the northern (accessible) part of the island was carried out for five weeks from 12 February 2001. Following this, a first attempt to eliminate the vectors was conducted using helicopter and ground-based applications of temephos from February to May 2003, but this was not successful because some vector populations persisted and subsequently spread throughout the island. A second attempt from January to May 2005 aimed to treat all flowing watercourses and greatly increased the number of treatment points. This led to the successful elimination of the vector. The last biting S. damnosum s.l. was caught in March 2005 and none have been found since then for more than 3 years.

"A Mirthful Spectacle": Race, Blackface Minstrelsy, and Base Ball, 1874-1888

To sum up [Blue Stocking vs. Pink Stocking] game in general, it need only be said that, saving single item of color it like other well-played games. One peculiarity, however, noticeable, whether accidental or usual we don't know. It consisted in irresistible propensity for tumbling head over heels when in act of running bases or going for fly catches. The life of stereotype resides in death of its model, and perceptual deadening of those who carry it in their heads as a schematic search template for identifying other Sambo has caught baseball fever, and two clubs from Alabama and Mississippi respectively, have recently had a match in Demopolis, Alabamians winning. Heah now, why didn't you frow dat ball to de fust base y'rascal you? Was blackness a metaphor for material excesses of postbellum Gilded Age--or for stereotypical notion of African American baseball? One answer examines how minstrel theater penetrated baseball sporting world and how business of minstrelsy paralleled rise of professional baseball--burnt cork artists played ball, literary and graphic artists portrayed games as blackface farce, and nines reputedly engaged in Negro comedy. Current baseball scholarship seldom mentions post-bellum ballplayer, who brought to game a peculiar style and became object of blackness and agency in baseball representations. Perhaps most dramatic case of ethnic stereotypes is found in melding of blackface performance and baseball representations. This image-repertoire circulated in print media: sports narratives, illustrations, and cartoons. While life of black baseball stereotypes has been incorporated into scholarship on subject of minstrelsy--most recently, in works by Michael Hatt, Mark Ribowsky, David Zang, Michael D. Harris, and Brian F. Le Beau--any analysis of relationship between performance and visual-verbal representations has yet to be undertaken.1 One reason for this lack of critical inquiry is controversy surrounding blackface performance and its integral relation to history of American black cultural production. Iconologist W. J. T. Mitchell declares blackface minstrelsy's image-repertoire to be despicable and worthy of destruction, but he warns that racial and ethnic stereotypes seem to have a life of their own. If life of black baseball stereotype resides in death of its models, as this blurring of line between blackface comedic mask and colored ballplayers suggests, then who does image-killing and image-resurrecting? The answer can be found by examining specific works that reflect on adaptability of baseball representations. (2) Recently, minstrelsy has been subject to intense scholarly study. Historian Eric Lott defines blackface minstrelsy as an established nineteenth-century theatrical practice, principally of urban North, in which white men caricatured blacks for sport and profit. For Lott, one of its functions was precisely to bring various class fractions into contact with one another, to mediate their relations, and finally to aid in construction of class identities over bodies of black people. The primary purpose of minstrel mask may have been as much to maintain control over a potentially subversive act as to ridicule, though blackface performers' attempts at regulation also appear to have been capable of producing aura of blackness. Lott calls this antebellum aura the seeming counterfeit. (3) For literary critic Saidiya Hartman, antebellum minstrelsy represents desire to don, occupy, or possess blackness or black body as a sentimental resource and locus of excess enjoyment. According to Hartman, fungibility of commodity--specifically its abstractness and immateriality--enabled black body or blackface mask to serve as a vehicle of self-exploration, renunciation, and enjoyment. …

Stable fly (Stomoxys calcitrans: Diptera, Muscidae) trap response to changes in effective trap height caused by growing vegetation

Stable flies (Stomoxys calcitrans L.) are blood-feeding pests of cattle, whose populations are often monitored using sticky traps. Trap responses at different heights were compared with: 1) a choice and no-choice test, with sticky cards set at 30 and 121 cm heights (above ground), and 2) tall (120 cm) traps placed in short (3 cm) and tall (40 cm) grass to assess how vegetation height affects trap catches. In the first experiment, the percentage of upper to lower trap catches were similar at choice (16%) and no-choice traps (15%). In the vegetation study, stable fly catch height data were fitted to gamma distributions to determine the most productive trap heights; 20 cm above short grass and 24 cm above tall grass (from lower edge of trap). The results indicate that traps used to monitor stable fly populations should be maintained at a constant distance above surrounding vegetation rather than ground surface, otherwise trap data can be misleading.

Evaluation of lure dispensers for fruit fly surveillance in New Zealand

Fruit flies (Diptera: Tephritidae) represent a major biosecurity threat to the horticulture sector of New Zealand, which is entirely free of these invasive pests. A nationwide surveillance programme is conducted to ensure any incursion is detected as early as possible. A review of the lure dispensers used is reported here. Lure dispenser emission trials found that the currently used lure plugs release lure more slowly under New Zealand subtropical to temperate climates than wafer dispensers. Subsequent trapping experiments at high altitude in Hawaii (as a mimic of New Zealand meteorological and expected fruit fly ecological conditions) compared Lynfield traps baited with the existing lure plug dispensers and newer wafer dispensers. Catches of wild Oriental fruit flies, Bactrocera dorsalis (Hendel), were 9.5-fold higher with methyl eugenol wafers than with the plugs. Recaptures of sterile melon flies, Bactrocera cucurbitae (Coquillet), were 2.6-fold higher with cuelure wafers than with the plugs. Recaptures of sterile Mediterranean fruit flies, Ceratitis capitata Weid., were not significantly higher with trimedlure wafers than with the plugs. Release rate and trapping experiments found new lure dispensers differed in release rate characteristics from existing dispensers under temperate and subtropical conditions, and indicated some potential for improvement in surveillance efficacy.

Effects of timber harvest on phlebotomine sand flies (Diptera: Psychodidae) in a production forest: abundance of species on tree trunks and prevalence of trypanosomatids

The Amazon forest is being exploited for timber production. The harvest removes trees, used by sand flies as resting sites, and decreases the canopy, used as refuges by some hosts. The present study evaluated the impact of the timber harvest, the abundance of sand flies, and their trypanosomatid infection rates before and after selective logging. The study was accomplished in terra-firme production forest in an area of timber harvest, state of Amazonas, Brazil. Sand fly catches were carried out in three areas: one before and after the timber harvest, and two control areas, a nature preservation area and a previously exploited area. The flies were caught by aspiration on tree trunks. Samples of sand flies were dissected for parasitological examination. In the site that suffered a harvest, a larger number of individuals was caught before the selective extraction of timber, showing significant difference in relation to the number of individuals and their flagellate infection rates after the logging. The other two areas did not show differences among their sand fly populations. This fact is suggestive of a fauna sensitive to the environmental alterations associated with selective logging.

Biting flies and Trypanosoma vivax infection in three highland districts bordering lake Tana, Ethiopia

An epidemiological study was conducted to determine the prevalence of trypanosomosis in cattle, small ruminants and Equidae, and to identify biting flies; potential mechanical vectors of trypanosomes in the three districts of Bahir Dar Zuria, Dembia and Fogera, bordering lake Tana, Ethiopia. About 1509 cattle, 798 small ruminants and 749 Equidae were bled for the prevalence study using the buffy-coat method and the measurement of the hematocrit value. Sixty-six NGU and 20 monoconical traps were deployed for the fly survey. The results indicated the presence of trypanosomes in 6.1% (92/1509) of the cattle with a maximum during the late rainy season (9.6%) than the early dry season (3.6%) at Fogera district. Prevalence at the district level varied from 4% to 9.6%. Only one sheep (1/122) and one goat (1/676) were found positive for T. vivax-like trypanosomes and none of the Equidae was positive. All the trypanosomes encountered in cattle belong to the single species of T. vivax. The PCV was negatively associated with detection of T. vivax (21.6% in infected versus 25.4% in non-infected cattle). A total of 55,398 biting flies were caught of which 49,353 (89.08%) belong to Stomoxys, 4715 (8.51%) to horse flies and 1330 (2.4%) to Chrysops species. There was no tsetse fly. Species identification has indicated the presence of Atylotus agrestis, Chrysops streptobalia, Stomoxys calcitrans, S. nigra, S. pulla, S. pallida, S. sitiens, S. taeniata, S. uruma, Haematopota lasiops and Hippobosca variegata. The overall apparent density was 214.7 flies/trap/day. Seasonal comparison showed higher fly catches in the late rainy season than the early dry season. This study indicated that T. vivax infections culminate in cattle at the same time as mechanical vectors such as Stomoxys sp. and Atylotus agrestis. Therefore, attention towards T. vivax infection in cattle is essential to control the impact of the disease on productivity. A further study on biting flies is recommended.

Effect of altitude on seasonal flight activity of Rhagoletis cerasi flies (Diptera: Tephritidae).

The effect of altitudinal variation on the seasonal flight activity of Rhagoletis cerasi (Linnaeus) flies was evaluated along an altitudinal gradient from 150 to 1170 m in Mount Uludag, northwestern Turkey. The predicted dates of fly emergence, flight duration and dates of 5%, 50% and 95% cumulative fly catches at various altitudes were estimated from a degree-day model. Degree-day predictions were compared with those obtained from observations made with yellow sticky traps. The observed and predicted dates of appearance of adults were delayed by 1.4 and 2.0 days for every 100 m increase in altitude, respectively. The delay in phenology events was less at high altitudes than postulated by Hopkins' bioclimatic law, whether observed or predicted. The average absolute difference in predicted and observed dates of cumulative percentage catch of adults was 4.9 and 3.0 days in 1997 and 1998, respectively, but these differences were not significant. Prolonged flight activity was predicted and observed at higher altitudes, but the flight period lasted significantly longer than predicted. The observed flight period varied from 29 to 43 days in 1997 and from 36 to 52 days in 1998 between the lowest and highest altitude on the transect. Altitudinal variation between geographically close locations should be taken into account to properly time monitoring activities and hence to manage R. cerasi populations more effectively.

Studies on the Effectiveness of Coroplast Sticky Traps for Sampling Stable Flies (Diptera: Muscidae), Including a Comparison to Alsynite

Stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), are a blood-feeding pest of cattle worldwide. A new trapping material, Coroplast, was compared with Alsynite sticky traps based on the number, sex, and parity of stable flies caught. Coroplast sticky traps caught more stable flies than Alsynite (trap catches of 2384 versus 753 on 15 traps), with this increase attributed to catching more males (1531 versus 532) and nulliparous females (817 versus 175); parous catches were similar (36 versus 46). The spectral reflectance of Alsynite and Coroplast sticky traps is reported. We also examine Coroplast traps in detail with respect to trap color. Although clean sheets of Alsynite had a higher solar reflectance than Coroplast (90 versus 82% at 450 nm), Coroplast with debris had a higher reflectance than debris-covered Alsynite (62 versus 30% at 450 nm). White Coroplast was most effective, followed by closely by gray. Black and blue were the least effective trapping colors.

Transmission of Onchocerca volvulus and prospects for the elimination of its vector, the blackfly Simulium neavei in the Mpamba–Nkusi focus in Western Uganda

The transmission of Onchocerca volvulus Leuckart (Spirudida: Onchocercidae) and the prospects of Simulium neavei Roubaud (Diptera: Simuliidae) vector elimination through ground larviciding were investigated in the Mpamba-Nkusi focus, western Uganda. Transmission levels and the initiated vector elimination activities were assessed to supplement the ongoing ivermectin mass distribution programme. Searches for breeding sites, adult fly catches, dissection of flies, river treatment with temephos (Abate) and a review of annual ivermectin treatment data were conducted. High levels of crab infestation with S. neavei sensu stricto immature stages were recorded; 57.9% and 100% for the Mpamba and Nyabugando river systems, respectively. The mean numbers of larvae/pupae per crab were 3.6 +/- 0.5 in the Mpamba and 20.6 +/- 1.8 in the Nyabugando systems. Pre-intervention mean biting densities were 39 and 32 flies/(man day) in 2001 and 2002, respectively, and an annual biting rate in 2001 of > 14 000. The bimodal biting pattern of S. neavei s.s. consisted of two peaks; one in the morning (09.00-10.00 hours) and one in the afternoon (14.00-15.00 hours) with a mid-day lull in biting. The infection/infective rates were 13.3%/2.8% and 16.6%/2.9% in the dissected parous flies from the Mpamba and Nyabugando river systems, respectively. Out of approximately 1000 parous flies, 129 and 109 were found to be harbouring infective larvae of Onchocerca volvulus in their heads from the Mpamba and Nyabugando river systems, respectively. In spite of the > 10 years of ivermectin treatment, at a mean coverage of 71.3%, infection remained relatively high. Ground larviciding with temephos (Abate) initiated in June and October 2002 had a significant impact. In the Mpamba river system there was a significant (P < 0.001) reduction in positive crabs from 57.9% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 3.6 +/- 0.5 in 2001 to 0.0007 +/- 0.0001 (P < 0.002) in 2003. Similarly, in the Nyabugando river system, a significant (P < 0.001) reduction in crab infestation from 100% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 20.6 +/- 1.8 in 2001 to 0.06 +/- 0.03 in 2003. Drastic reductions were observed in the mean number of biting flies from 3 flies/h in 2001 to 0 flies/h in 2003 and the annual biting rates fell from 14,235 flies/year in 2001 to only 730 flies/year in 2003. These data suggest that substantial progress towards the goal of S. neavei s.s. vector elimination has been made and this will enhance the ongoing ivermectin treatment in this isolated focus.

Predicting calyptrate fly populations from the weather, and probable consequences of climate change

Summary Calyptrate flies include numerous species that are disease vectors and have a high nuisance value, notably Musca domestica. Populations are often associated with livestock farms and domestic waste disposal facilities such as landfill, where the accumulating organic matter provides suitable breeding conditions for a range of species. We examined the relationship between fly numbers and weather conditions using a 4‐year data set of weekly fly catches from six sites in southern UK, together with meteorological data. The first 3 years were used to develop predictive models, and these were then used to forecast fly populations in the fourth year. The accuracy of these predictions was assessed by comparison with the actual fly catches for that year. Separate models were developed for M. domestica, Calliphora spp. and all calyptrate flies combined. Predictions based only on humidity, temperature and rainfall were strongly correlated with observed data (r2 values ranged from 0·52 to 0·84), suggesting that fly population changes are largely driven by the weather rather than by biotic factors. We can forecast fly populations so that control measures need only be deployed when weather conditions are suitable for a fly outbreak, reducing the need for prophylactic insecticide use. Climate change was simulated using the most recent predictions of future temperature increases. Our models predicted substantial increases in fly populations up to 244% by 2080 compared with current levels, with the greatest increases occurring in the summer months. Synthesis and applications. Models developed use weather data to predict populations of pestiferous flies such as M. domestica, which may prove valuable in integrated control programmes. These models predict substantial increases in fly populations in the future under likely scenarios of climate change. If this occurs we may expect considerable increases in the incidence of fly‐borne disease.

Factors affecting abundance and oviposition rates of a field population of the Old World screw-worm fly, Chrysomya bezziana (Diptera: Calliphoridae).

Sentinel cattle and a grid of swormlure-baited sticky traps were used to monitor a Malaysian population of the Old World screw-worm fly, Chrysomya bezziana Villeneuve. Observations were carried out on an isolated cattle station at monthly intervals during the period August 1996 to June 2000. The number of flies caught was unaffected by weather conditions at the time of trapping, but was positively correlated with the total rainfall and the average daily air temperature prevailing 15-28 days earlier, when trapped flies were still juveniles. Trap catches were biased in favour of females, but daily catch rates of both sexes increased significantly the longer traps were open, suggesting that efficacy was related to the differential volatility of the chemicals comprising swormlure. Oviposition on sentinel cattle occurred mostly in late afternoon or early evening but increased significantly as the wound aged. Oviposition rates were positively correlated with female catch rates, but the relationship was curvilinear, suggesting that fly populations may be subject to some form of density-dependent constraint. Consistent differences in oviposition rates on sentinel cattle at different localities on the cattle station suggested the existence of highly clumped, quasi-stationary populations. Differences in trap catches between traps located in pastoral areas and those sited in nearby oil palm or rubber plantations supported this interpretation of the data. These findings are discussed in relation to the use of the sterile insect technique for the control of screw-worm fly infestations.

Fences Excluding Cabbage Maggot Flies and Tiger Flies (Diptera: Anthomyiidae) from Large Plantings of Radish

The influence of a specially constructed insect exclusion fence on the number of cabbage maggot flies, Delia radicum (L.), and tiger flies Coenosia tigrina (F.) (a predator of cabbage maggot flies) entering large plots of radish was determined. Plots with or without the exclusion fence or with an exclusion fence surrounded by a trap crop of radish were evaluated in a single growing season in 1995. Overall during the growing season, the mean cabbage fly catch per trap in the completely fenced plots was 90% fewer than in the unfenced control plots. Fewer cabbage flies were caught inside the completely fenced plots than inside the fence surrounded by a trap crop, suggesting that trap crops do not ultimately impede the movement of cabbage flies into fenced enclosures. The general pattern of trap catch of tiger flies in the various treatments was similar to that observed for cabbage flies. During the heaviest infestation of cabbage maggot flies, infestation was highest in the control plots (84.5%), followed by the fence + trap crop plots with 39.8% infested radishes, and the completely fenced plots with 24.7% infestation. The potential of exclusion fences for use in pest management programs for Brassica crops is discussed.