Aircraft applications of insecticides in East Africa

1961 ◽  
Vol 52 (2) ◽  
pp. 293-303 ◽  
Author(s):  
R. Foster ◽  
P. J. White ◽  
D. Yeo
Keyword(s):  
Meteorological Conditions ◽  
Small Scale ◽  
Central Province ◽  
Biological Factors ◽  
Cent Solution ◽  
Glossina Morsitans ◽  
Operational Costs ◽  
Low Volume ◽  
Aircraft Application ◽  
Savannah Woodland

SummaryFollowing successful small-scale trials, an attempt was made, by aircraft application of insecticide, to eradicate Glossina morsitans Westw. and G. pallidipes Aust. from an isolated block of savannah woodland, approximately 11 sq. miles in extent, at Chungai in the Central Province of Tanganyika between July 1958 and January 1959. A single-engined aircraft, fitted with two belt-driven rotary-cage atomisers, was used to apply a 5 per cent, solution of γ BHC in power kerosene at a nominal dosage of 0·08 gal. per acre (0.04 lb. γ BHC per acre). Seven applications were made at approximately 28-day intervals, the time taken to complete an application varying from five to eight days. The operation failed to control the flies. Although each of the first two applications reduced the apparent density of G. morsitans by about 90 per cent, and that of G. pallidipes by a lesser, although still considerable, factor, later applications gave varying and often low mortalities, and the populations increased slowly for some time, the insecticide applications causing only temporary depressions in numbers. Numbers fell towards the end of the operation, but final reductions were only about 50 per cent, or less. Kills of female flies were low, and this undoubtedly led to the eventual failure.The low volume-dosage, a drop spectrum that possibly contained too few droplets of the required size, meteorological conditions, and biological factors that apparently favoured the survival of female flies are suggested as contributory elements to the low mortalities.Operational costs were considerably lower than in previous work.

Aircraft Applications of Insecticides in East Africa. IV.—The Application of Coarse Aerosols in Savannah Woodland containing the Tsetse Flies Glossina morsitans and G. swynnertoni

1953 ◽  
Vol 44 (4) ◽  
pp. 627-640 ◽  
Author(s):  
K. S. Hocking ◽  
H. C. M. Parr ◽  
D. Yeo ◽  
D. Anstey
Keyword(s):  
East Africa ◽  
Meteorological Conditions ◽  
The Other ◽  
Tsetse Flies ◽  
Small Populations ◽  
Central Province ◽  
Glossina Morsitans ◽  
Short Period ◽  
Savannah Woodland ◽  
Mass Median

Attempts have been made to eradicate the tsetse flies G. morsitans and G. swynnertoni from two blocks of savannah woodland situated in the Central Province of Tanganyika.The insecticides were applied from aircraft. Coarse aerosols were used, with mass median diameters of approximately 90 microns; droplet diameters varied from 4 microns to 250 microns approximately.Eight applications of insecticides were made at intervals of two weeks. Each application was carried out at a nominal dosage of 0·25 gallons per acre, which was equivalent to 0·20 1b. per acre of the p, p'isomer of DDT or 0·03 lb. per acre of the γ isomer of BHC.In the area treated with DDT it is possible that both species of flies were eradicated for a short period, but small populations were re-established there by immigrant flies. In the other block the reduction was not so great, but it is not considered that this was due to a lesser effectiveness of the BHC, but to a combination of circumstances that led to less effective applications.Some general observations are made upon the use of aircraft for this sort of work, particularly in connection with the effect of meteorological conditions.

Aircraft applications of insecticides in East Africa

1961 ◽  
Vol 52 (2) ◽  
pp. 305-316 ◽  
Author(s):  
G. F. Burnett ◽  
D. Yeo ◽  
A. W. D. Miller ◽  
P. J. White
Keyword(s):  
Large Scale ◽  
Lethal Dose ◽  
Central Province ◽  
Cent Solution ◽  
Glossina Morsitans ◽  
Pregnant Females ◽  
The North ◽  
Reliable Performance ◽  
Median Diameter ◽  
Coarse Aerosol

SummaryIn the North Block at Chungai, comprising about 11 sq. miles of thorn savannah and thicket in Central Province, Tanganyika, an Auster J5G aircraft was used between July 1959 and March 1960 to apply a 2·5 per cent. solution of dieldrin in oil at the rate of 0·125 gal. per acre in an attempt to eradicate Glossina morsitans Westw. and G. pallidipes Aust. Eight applications were made at approximately four-weekly intervals. Swath width was 55 yd., and the aircraft emitted the insecticide as a coarse aerosol of volume median diameter 50–60μ as it flew in both directions over the block.The operation suffered delays, and three applications were incomplete to varying degrees. Kills of G. morsitans per application appeared to be 85 per cent. or higher, but the final reduction of 99·5 per cent. could theoretically have been attained with consecutive mortalities of only 65 per cent. It is suggested that this discrepancy may be due to the higher lethal dose required by pregnant females. G. pallidipes was also reduced by 99·5 per cent. Numbers of fly were reduced sufficiently for large-scale settlement with cattle, which should complete the work of exterminating the fly.The experiment is compared with that of the previous year in the same block, using γBHC, which reduced fly catches by less than 50 per cent. It is concluded that a combination of reduced swath width, greater volume dosage, more lethal insecticide and smaller lethal drop, together with improved flying technique and the more reliable performance of the disseminating equipment, was responsible for the improved result. It is thought that without delays, interruptions, incomplete applications and reinfestation, even better results would be obtained.This was the cheapest and one of the most successful aerial operations carried out against savannah tsetse. Costs actually over the ground were £301 per sq. mile; incidental costs due to the locality of operations were £66 per sq. mile. There is little chance of reducing the costs of flying directly, but economies are possible by the use of other insecticides or, more probably, by more efficient dispensing equipment.

Aircraft applications of insecticides in East Africa XIV.—Very-low-volume aerosols of dieldrin and isobenzan for the control of Glossina morsitans Westw

1964 ◽  
Vol 55 (3) ◽  
pp. 527-539 ◽  
Author(s):  
G. F. Burnett ◽  
P. R. Chadwick ◽  
A. W. D. Miller ◽  
J. S. S. Beesley
Keyword(s):  
Tsetse Fly ◽  
Tsetse Flies ◽  
Cent Solution ◽  
Glossina Morsitans ◽  
Local Conditions ◽  
Aerosol Generator ◽  
Additional Costs ◽  
Low Volume ◽  
One Year ◽  
The Cost

Two experiments were conducted simultaneously in 1962–63 at Chungai, in central Tanganyika, to test new equipment for disseminating insecticides from aircraft and a new insecticide, isobenzan (Telodrin), in the eradication of Glossina morsitans Westw. and G. pallidipes Aust. The new equipment consisted of an aerosol generator fitted to the exhaust of a Cessna 182E high-wing monoplane, and was used in both experiments. The isobenzan was compared with dieldrin, and the two insecticides were applied at rates inversely proportional to their toxicities to G. morsitans as previously determined in the laboratory.Two blocks of woodland, each 11 sq. miles in area, were treated, one with a 12·3 per cent, solution of dieldrin at the rate of 0·0254 gal. per acre, giving a dosage of 0·5 oz. (14 g.) toxicant per acre, and the other with a 10 per cent, solution of isobenzan at the rate of 0·0124 gal. per acre, giving a dosage of 0·2 oz. (6 g.) per acre. The former block received eight treatments with dieldrin at approximately 3-week intervals, the fourth treatment being incomplete; the latter block received six treatments with isobenzan at intervals ranging from 20 to 45 days. The effects were assessed by means of fly-catches along fixed paths which continued for one year after treatments had ceased.Both species of tsetse fly disappeared from the two blocks before the final treatments took place, and no more were caught until 11 months after spraying ended, when one example of G. morsitans was caught in each block; both were probably immigrants. None was found in the following month, and it is concluded that the flies were exterminated in both blocks. The fact that the blocks were unusually well isolated from sources of reinfestation probably contributed to the success of the operations.The cost per sq. mile was £224 using dieldrin and £190 using isobenzan. These were the basic costs, independent of the locality in which spraying took place. Additional costs were incurred which would vary with local conditions; for the present experiments they were £34 and £30, respectively. It is considered that there is good scope for further reductions in costs, particularly with dieldrin, and that these might make dieldrin economically competitive with isobenzan. Owing to the low fly density in the block treated with isobenzan, the efficacy of this insecticide cannot be regarded as conclusively proved until further experiments have been carried out. It may then merit serious consideration as a toxicant for aerial spraying against tsetse flies.

Aircraft Applications of Insecticides in East Africa. VI.—Applications of a coarse Aerosol containning DDT to control the Tsetse Flies, Glossina morsitans Westw., Glossina swynnertoni Aust. and Glossina pallidipes Aust.

1954 ◽  
Vol 45 (3) ◽  
pp. 585-603 ◽  
Author(s):  
K. S. Hocking ◽  
D. Yeo ◽  
D. G. Anstey
Keyword(s):  
Random Effects ◽  
Glossina Pallidipes ◽  
Tsetse Flies ◽  
Glossina Morsitans ◽  
Median Diameter ◽  
Coarse Aerosol ◽  
Savannah Woodland ◽  
Mass Median ◽  
Glossina Swynnertoni ◽  
Mass Median Diameter

An experiment is described where applications of a coarse aerosol were made to savannah woodland containing the tsetse flies, Glossina moritans Westw., G. swynnertoni Aust. and G. pallidipes Aust.Seven applications were made, each at a nominal dosage of 0·25 lb. of technical DDT per acre and 0·25 gallons of solution per acre. The applications in any particular part of the treaed woodland covered an interval of 90 days, or rather more than two pupal periods.The coarse aerosol was produced by emitting the insecticidal solution under pressure through fine nozzles fitted to a boom. It had a mass median diameter of approximately 60 microns, and droplet dismeters varied from a few microns to approximately 200 microns.The population of G. pallidipes was so drastically reduced that it has subsequently dies out. The reduction of G. morsitans was approximately 95 per cent. The differences between the reductions are attributed mainly to differences between the ease with which the three species can be killed. It is pointed out that this is not necessarily equivalent to differences in susceptibility.Comparisons are made with previous experiments, and the different results of the various experiments are difficult to explian satisfactory. The increased cover in savannah areas during the leafy period may have reduced the effectiveness of the applications, and the total periods covered by the various series of applications were probably also important. Random effects, leading to ineffective treatments, may also be important.Costs are discussed.

An Agronomic and Economic Evaluation of Soyabean Planting Methods in the Central Province of Zambia

1990 ◽  
Vol 26 (4) ◽  
pp. 441-445 ◽  
Author(s):  
K. S. Chanda ◽  
M. Bezuneh ◽  
P. T. Gibson ◽  
F. J. Olsen ◽  
R. E. Hudgens
Keyword(s):  
Economic Evaluation ◽  
Present Method ◽  
Seedling Emergence ◽  
Small Scale ◽  
Central Province ◽  
Planting Methods ◽  
Small Scale Farmers ◽  
Planting Method ◽  
New Crop ◽  
New Cultivars

SUMMARYSoyabean (Glycine max) is a relatively new crop for small-scale farmers in Zambia which has been adopted following the introduction of new cultivars, greater opportunity to obtain credit, easier marketing and an attractive guaranteed price. However, low yields limit production partly due to the lack of a planting method that establishes optimal populations. The present method is to plough and plant in the same operation, dribbling the seed behind the ox-plough. This often leads to uneven depth of planting, and hence to poor seedling emergence and erratic stands. Alternative planting techniques evaluated on farmers' fields for three seasons (1985/86–1987/88) suggest that farmers should replace their practice of planting behind the plough with either hand seeding following a plough–harrow operation or the use of a modified ox-drawn planter (Taparia).

An Agronomic and Economic Evaluation of Soyabean Planting Methods in the Central Province of Zambia

1990 ◽  
Vol 26 (4) ◽  
pp. 441-445
Author(s):  
K. S. Chanda ◽  
M. Bezuneh ◽  
P. T. Gibson ◽  
F. J. Olsen ◽  
R. E. Hudgens
Keyword(s):  
Economic Evaluation ◽  
Present Method ◽  
Seedling Emergence ◽  
Small Scale ◽  
Central Province ◽  
Planting Methods ◽  
Small Scale Farmers ◽  
Planting Method ◽  
New Crop ◽  
New Cultivars

SUMMARYSoyabean (Glycine max) is a relatively new crop for small-scale farmers in Zambia which has been adopted following the introduction of new cultivars, greater opportunity to obtain credit, easier marketing and an attractive guaranteed price. However, low yields limit production partly due to the lack of a planting method that establishes optimal populations. The present method is to plough and plant in the same operation, dribbling the seed behind the ox-plough. This often leads to uneven depth of planting, and hence to poor seedling emergence and erratic stands. Alternative planting techniques evaluated on farmers' fields for three seasons (1985/86–1987/88) suggest that farmers should replace their practice of planting behind the plough with either hand seeding following a plough–harrow operation or the use of a modified ox-drawn planter (Taparia).

scholarly journals Laboratory Evaluation and Construction of Fully Recycled Low-Temperature Asphalt for Low-Volume Roads

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Christiane Raab ◽  
Manfred N. Partl
Keyword(s):  
Ambient Temperature ◽  
Laboratory Experiments ◽  
Traffic Simulation ◽  
Traffic Load ◽  
Laboratory Evaluation ◽  
Small Scale ◽  
Medium Scale ◽  
Low Volume Roads ◽  
Low Volume

Growing economy and increasing pollution evoke the need for more environmentally friendly road construction techniques and the saving of natural resources. In this context, cold recycling plays an important role since, on the one hand, it allows to reduce CO2 emissions drastically and, on the other hand, it offers a variety of opportunities for high percentages of recycling. Inspired by experience in Sweden, the international project “Optimal Recycling of Reclaimed Asphalts for low-traffic Pavement” (ORRAP) for low-volume roads in the Upper Rhine region aims to develop and establish a new strategy for 100% reclaimed asphalt pavement (RAP) at ambient temperature (20°C) without adding virgin bituminous binders or rejuvenators. The still ongoing research project involves laboratory experiments as well as in situ test sections. The link between small-scale laboratory experiments and in situ testing is provided by medium-scale traffic simulation in the laboratory. This paper describes results from medium-scale compaction in the laboratory using different methods as well as traffic simulation with a medium-scale mobile traffic load simulator. The results show that compaction in the laboratory at ambient temperature (20°) is very difficult to achieve. Nevertheless, it was found that compaction at a temperature of 60°C appears possible and provides promising results regarding stability and rutting enabling the in situ construction. The in situ pavement construction at ambient temperature on a low-volume road in Switzerland resulted in a visibly well-compacted and stable base course which was covered by a hot mix asphalt surface course the day after. The test section will be monitored closely over the next 12 months.

Improving Unpaved Roads in Virginia: Case Study

2003 ◽  
Vol 1819 (1) ◽  
pp. 149-154
Author(s):  
Michael W. Dunn ◽  
S. Noelle On
Keyword(s):  
Cost Effective ◽  
Weather Conditions ◽  
Small Scale ◽  
Elected Officials ◽  
Unpaved Roads ◽  
The Road ◽  
Improvement Process ◽  
Key Factor ◽  
Low Volume ◽  
Virginia Department

Minimizing costs and streamlining the construction of low-volume roads offers an opportunity for transportation agencies to effectively meet the needs of rural citizens. The Virginia Department of Transportation (VDOT) maintains approximately 56,941 mi of the state’s roads, including Interstate, primary, and secondary facilities. Between 1987 and 1994, VDOT paved nearly 1,900 mi of unpaved roads. In rural parts of the state, many miles of state-maintained roads still have gravel and dirt surfaces. Each year the local transportation residency offices, in conjunction with local elected officials, contractors, and area citizens, strive to improve and pave as many miles of gravel and dirt roads as possible. The Hillsville Residency of VDOT, located in rural Carroll and Floyd Counties, has developed an efficient and cost-effective method for improving low-volume gravel and dirt roads. This process relies heavily on cooperative efforts by VDOT, contractors, elected officials, and especially citizens. Land donations from citizens represent the cornerstone of this process, signifying that citizen cooperation is the key factor in a project’s success. Because most of the decisions in the improvement process are at the local residency level, trusting relationships and frequent communication can be established, small-scale and local contractors are given more business opportunities, and local VDOT personnel can better understand citizen concerns and perform road improvements accordingly. In addition, the time line for the road improvement process is based on seasons—the most appropriate weather conditions are considered for the work being performed. This program enables more roads to be paved each year, improving the level of service and quality of life for local citizens.

Identifying Areas Prone to Dusty Winds for Gas Turbine Inlet Specification

2007 ◽  
Author(s):  
Charles Brake
Keyword(s):  
Risk Factors ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Meteorological Conditions ◽  
Small Scale ◽  
Local Factors ◽  
Intake System ◽  
Geographical Spread ◽  
The World ◽  
High Concentrations

The role and geographical spread of gas turbines is increasing. Because of this, there are more situations where the operator is likely to experience problems with high concentrations of dust overloading the intake system. This work summarizes the causes of dusty winds, areas where they are found, and offers recommendations to assist the inlet specifier. The causes of dusty winds are identified and discussed including desertification, small-scale local factors and meteorological conditions. Areas of the world where dust originates from and areas to which it can be carried are identified. In conclusion, the combinations of these factors are then offered as recommendations for the inlet specifier, to assist in choosing the correct type of filtration for inlets for areas likely to be affected by dust, and identify risk factors with specific types of inlet filter systems in these locations.

Sign in / Sign up

Export Citation Format

Share Document