The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform
Oriel M M Thekisoe - One of the best experts on this subject based on the ideXlab platform.
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evaluation of Larviposition site selection of glossina brevipalpis
Veterinary Parasitology, 2016Co-Authors: S Renda, C J De Beer, Gert J Venter, Oriel M M ThekisoeAbstract:Abstract Tsetse species (Diptera: Glossinidae) are vectors of trypanosome parasites which cause disease in both humans and livestock. In South Africa Glossina austeni Newstead, 1912 and G. brevipalpis Newstead, 1911 are responsible for the cyclical transmission of animal trypanosomes causing African animal trypanosomiasis also referred to as nagana. Gravid tsetse females deposit a single larva in specific sites but little information is available on biotic and abiotic factors that govern site selection. This study therefore aimed to characterize some of the substrate conditions that may influence selection of Larviposition sites. Colonised, gravid female G. brevipalpis were presented with a choice of four Larviposition sites. Sites differed in qualities of pH (5, 7, 9), salinity (0, 1.3, 4 g/L) and the presence of other tsetse pupae ( G. brevipalpis or G. austeni ). These trials indicated no significant selection by gravid females with regard to pH and salinity. Females selected significantly more often for sites with pupae ( P P G. brevipalpis. This may imply that G. brevipalpis larvae produce a pheromone during pupation as seen in G. morsitans morsitans . Isolation of such semio-chemicals would allow the development of Larviposition traps to attract gravid females.
P. Driessche - One of the best experts on this subject based on the ideXlab platform.
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estimating tsetse fertility daily averaging versus periodic Larviposition
Medical and Veterinary Entomology, 2020Co-Authors: Hugh J. Barclay, John W. Hargrove, P. DriesscheAbstract:: When computing mean daily fertility in adult female tsetse, the common practice of taking the reciprocal of the interlarval period (called averaged fertility) was compared with the method of taking the sum of the products of daily fertility and adult survivorship divided by the sum of daily survivorships (called periodic fertility). The latter method yielded a consistently higher measure of fertility (approximately 10% for tsetse) than the former method. A conversion factor was calculated to convert averaged fertility to periodic fertility. A feasibility criterion was determined for the viability of a tsetse population. Fertility and survivorship data from tsetse populations on Antelope Is. and Redcliff Is., both in Zimbabwe, were used to illustrate the feasibility criterion, as well as the limitations imposed by survivorship and fertility on the viability of tsetse populations. The 10% difference in fertility between the two methods of calculation makes the computation of population feasibility with some parameter combinations sometimes result in a wrong answer. It also underestimates both sterile male release rates required to eradicate a pest population, as well as the speed of resurgence if an eradication attempt fails.
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Modelling optimal timing and frequency of insecticide sprays for eradication or knockdown of closed populations of tsetse flies Glossina spp. (Diptera: Glossinidae).
Medical and Veterinary Entomology, 2020Co-Authors: Hugh J. Barclay, John W. Hargrove, P. DriesscheAbstract:: A population model for tsetse species was used to assess the optimal number and spacing of airborne sprays to reduce or eradicate a tsetse population. It was found that the optimal spray spacing was determined by the time (days) from adult emergence to the first Larviposition and, for safety, spacing was assigned to that duration minus 2 days. If sprays killed all adults, then the number of sprays required for eradication is determined by a simple formula. If spray efficiency is less than 100% kill per spray, then a simulation was used to determine the optimal number, which was strongly affected by spray efficiency, mean daily temperature, pupal duration, age to first Larviposition and the acceptance threshold for control, rather than eradication. For eradication, it is necessary to have a spray efficiency of greater than 99.9% to avoid requiring an excessive number of sprays. Output from the simulation was compared with the results of two aerial spraying campaigns against tsetse and a least squares analysis estimated that, in both cases, the kill efficiency of the sprays was not significantly less than 100%.
John R Anderson - One of the best experts on this subject based on the ideXlab platform.
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risk spreading Larviposition behaviour of female nose bot flies cephenemyia attacking black tailed deer
Medical and Veterinary Entomology, 2013Co-Authors: John R AndersonAbstract:: While baited deer models were under observation nine Cephenemyia jellisoni Townsend (Diptera: Oestridae) females and seven C. apicata Bennett & Sabrosky engaged in a risk-spreading Larviposition behaviour by larvipositing on models only once and then flying away. Additionally, analysis of 225 unobserved larvipostions in which larvae were trapped in adhesive on the muzzles of deer models showed that 94% of C. apicata and 95% of C. jellisoni larviposited on a model only once. The number of single Larvipositions was highly significant for both species. The principal adaptive significance of such risk-spreading Larviposition behaviour is that it spreads the reproductive output of a female among many hosts, and in years when adult eclosion and survival rates are low, it ensures that the larvae of the few surviving females will be distributed among a maximum number of hosts. Several other benefits of such behaviour also are discussed.
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Anatomical modifications, viviparous reproduction and hydraulic expulsion of larvae by Cephenemyia nasopharyngeal bot flies of deer.
Medical and Veterinary Entomology, 2013Co-Authors: John R AndersonAbstract:: Several specialized adaptations of the reproductive and respiratory systems associated with the retention and expulsion of larvae in ovoviviparous Cephenemyia species (Diptera: Oestridae) are described and illustrated. In these flies the anterior section of the common oviduct is modified into a large sac-like uterus that contains larvae, and the posterior section is modified into a larvipositor with a central tubular vagina. During Larviposition, contraction of abdominal muscles forces haemolymph into a perivaginal sinus, causing a hydraulically driven exsertion of the larvipositor. A group of larvae and uterine fluid sealed off within the lumen of the vagina are then expelled from the vulva via hydraulic pressure as the stretched vagina is compressed. A one-way, non-return valve between the uterus and vagina prevents a reflux of larvae upward into the uterus during Larviposition. All mutually dependent actions associated with Larviposition occur almost simultaneously. All species have evolved a similar mechanism of expelling their larvae, but the shape of the non-return valve is different in each species studied.
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The Response of Host-Seeking Cephenemyia Females to Visual Cues Associated with Anatomically-Modified Baited Deer Models
Journal of Insect Behavior, 2012Co-Authors: John R AndersonAbstract:Females of C . jellisoni larviposited significantly more often on deer models with black or blue muzzles than on models with red or white muzzles. Females of C . apicata only larviposited on models with black muzzles. For C . jellisoni , which sprays larvae into nostrils, a model having a muzzle with no nostrils received no Larvipositions, but females larviposited into all nostril depressions placed in abnormal positions on muzzles. For C . apicata , which targets the lips, there was no significant difference in the number of Larvipositions on muzzles with nostrils in abnormal positions or when muzzles were oriented in different positions. For both species there was no significant difference in the number of Larvipositions on models when CO_2 was released at different parts of the body.
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Larviposition by nasopharyngeal bot fly parasites of columbian black tailed deer a correction
Medical and Veterinary Entomology, 2001Co-Authors: John R AndersonAbstract:Abstract. Previous reports of Cephenemyia jellisoni Townsend (Diptera: Oestridae) larvipositing onto the lips/lower muzzle of deer, with larvae invading via the mouth, are shown to be erroneous. Additional studies with deer models baited with CO2, 1-octen-3-ol and Deer Trail Scent, and muzzle and nostrils treated with insect adhesive, revealed that only C. apicata Bennett & Sabrosky larviposited onto the lips/lower muzzle; C. jellisoni, by contrast, larviposited into the nostrils. Larval depositions were associated with females of both species observed attacking models. Females of both species also were found stuck on adhesive-treated, baited models not attended by observers. During several seasons of exposure, such models received 89 C. jellisoni Larvipositions into the nostrils and 87 C. apicata Larvipositions onto the lips/lower muzzle. In laboratory experiments nearly all larvae of both species remained stuck in adhesive within 1 mm or less of where they were deposited.
Hugh J. Barclay - One of the best experts on this subject based on the ideXlab platform.
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estimating tsetse fertility daily averaging versus periodic Larviposition
Medical and Veterinary Entomology, 2020Co-Authors: Hugh J. Barclay, John W. Hargrove, P. DriesscheAbstract:: When computing mean daily fertility in adult female tsetse, the common practice of taking the reciprocal of the interlarval period (called averaged fertility) was compared with the method of taking the sum of the products of daily fertility and adult survivorship divided by the sum of daily survivorships (called periodic fertility). The latter method yielded a consistently higher measure of fertility (approximately 10% for tsetse) than the former method. A conversion factor was calculated to convert averaged fertility to periodic fertility. A feasibility criterion was determined for the viability of a tsetse population. Fertility and survivorship data from tsetse populations on Antelope Is. and Redcliff Is., both in Zimbabwe, were used to illustrate the feasibility criterion, as well as the limitations imposed by survivorship and fertility on the viability of tsetse populations. The 10% difference in fertility between the two methods of calculation makes the computation of population feasibility with some parameter combinations sometimes result in a wrong answer. It also underestimates both sterile male release rates required to eradicate a pest population, as well as the speed of resurgence if an eradication attempt fails.
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Modelling optimal timing and frequency of insecticide sprays for eradication or knockdown of closed populations of tsetse flies Glossina spp. (Diptera: Glossinidae).
Medical and Veterinary Entomology, 2020Co-Authors: Hugh J. Barclay, John W. Hargrove, P. DriesscheAbstract:: A population model for tsetse species was used to assess the optimal number and spacing of airborne sprays to reduce or eradicate a tsetse population. It was found that the optimal spray spacing was determined by the time (days) from adult emergence to the first Larviposition and, for safety, spacing was assigned to that duration minus 2 days. If sprays killed all adults, then the number of sprays required for eradication is determined by a simple formula. If spray efficiency is less than 100% kill per spray, then a simulation was used to determine the optimal number, which was strongly affected by spray efficiency, mean daily temperature, pupal duration, age to first Larviposition and the acceptance threshold for control, rather than eradication. For eradication, it is necessary to have a spray efficiency of greater than 99.9% to avoid requiring an excessive number of sprays. Output from the simulation was compared with the results of two aerial spraying campaigns against tsetse and a least squares analysis estimated that, in both cases, the kill efficiency of the sprays was not significantly less than 100%.
John W. Hargrove - One of the best experts on this subject based on the ideXlab platform.
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estimating tsetse fertility daily averaging versus periodic Larviposition
Medical and Veterinary Entomology, 2020Co-Authors: Hugh J. Barclay, John W. Hargrove, P. DriesscheAbstract:: When computing mean daily fertility in adult female tsetse, the common practice of taking the reciprocal of the interlarval period (called averaged fertility) was compared with the method of taking the sum of the products of daily fertility and adult survivorship divided by the sum of daily survivorships (called periodic fertility). The latter method yielded a consistently higher measure of fertility (approximately 10% for tsetse) than the former method. A conversion factor was calculated to convert averaged fertility to periodic fertility. A feasibility criterion was determined for the viability of a tsetse population. Fertility and survivorship data from tsetse populations on Antelope Is. and Redcliff Is., both in Zimbabwe, were used to illustrate the feasibility criterion, as well as the limitations imposed by survivorship and fertility on the viability of tsetse populations. The 10% difference in fertility between the two methods of calculation makes the computation of population feasibility with some parameter combinations sometimes result in a wrong answer. It also underestimates both sterile male release rates required to eradicate a pest population, as well as the speed of resurgence if an eradication attempt fails.
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Modelling optimal timing and frequency of insecticide sprays for eradication or knockdown of closed populations of tsetse flies Glossina spp. (Diptera: Glossinidae).
Medical and Veterinary Entomology, 2020Co-Authors: Hugh J. Barclay, John W. Hargrove, P. DriesscheAbstract:: A population model for tsetse species was used to assess the optimal number and spacing of airborne sprays to reduce or eradicate a tsetse population. It was found that the optimal spray spacing was determined by the time (days) from adult emergence to the first Larviposition and, for safety, spacing was assigned to that duration minus 2 days. If sprays killed all adults, then the number of sprays required for eradication is determined by a simple formula. If spray efficiency is less than 100% kill per spray, then a simulation was used to determine the optimal number, which was strongly affected by spray efficiency, mean daily temperature, pupal duration, age to first Larviposition and the acceptance threshold for control, rather than eradication. For eradication, it is necessary to have a spray efficiency of greater than 99.9% to avoid requiring an excessive number of sprays. Output from the simulation was compared with the results of two aerial spraying campaigns against tsetse and a least squares analysis estimated that, in both cases, the kill efficiency of the sprays was not significantly less than 100%.
