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Efficacy of Electrocuting Devices to Catch Tsetse Flies (Glossinidae) and Other Diptera.

Vale GA, Hargrove JW, Cullis NA, Chamisa A, Torr SJ - PLoS Negl Trop Dis (2015)

Bottom Line: At energies per pulse of 35-215mJ, the efficiency was enhanced by reducing the pulse interval from 3200 to 1ms.Efficiency was low at 35mJ per pulse, but there seemed no benefit of increasing the energy beyond 70mJ.Grids that are less efficient, but more economical, are recommended for studies of relative numbers available to various baits.

View Article: PubMed Central - PubMed

Affiliation: South African Centre for Epidemiological Modelling and Analysis, University of Stellenbosch, Stellenbosch, South Africa; Natural Resources Institute, University of Greenwich, Chatham, United Kingdom.

ABSTRACT

Background: The behaviour of insect vectors has an important bearing on the epidemiology of the diseases they transmit, and on the opportunities for vector control. Two sorts of electrocuting device have been particularly useful for studying the behaviour of tsetse flies (Glossina spp), the vectors of the trypanosomes that cause sleeping sickness in humans and nagana in livestock. Such devices consist of grids on netting (E-net) to catch tsetse in flight, or on cloth (E-cloth) to catch alighting flies. Catches are most meaningful when the devices catch as many as possible of the flies potentially available to them, and when the proportion caught is known. There have been conflicting indications for the catching efficiency, depending on whether the assessments were made by the naked eye or assisted by video recordings.

Methodology/principal findings: Using grids of 0.5m2 in Zimbabwe, we developed catch methods of studying the efficiency of E-nets and E-cloth for tsetse, using improved transformers to supply the grids with electrical pulses of ~40kV. At energies per pulse of 35-215mJ, the efficiency was enhanced by reducing the pulse interval from 3200 to 1ms. Efficiency was low at 35mJ per pulse, but there seemed no benefit of increasing the energy beyond 70mJ. Catches at E-nets declined when the fine netting normally used became either coarser or much finer, and increased when the grid frame was moved from 2.5cm to 27.5cm from the grid. Data for muscoids and tabanids were roughly comparable to those for tsetse.

Conclusion/significance: The catch method of studying efficiency is useful for supplementing and extending video methods. Specifications are suggested for E-nets and E-cloth that are ~95% efficient and suitable for estimating the absolute numbers of available flies. Grids that are less efficient, but more economical, are recommended for studies of relative numbers available to various baits.

No MeSH data available.


Related in: MedlinePlus

Fitting curves to the estimated absolute efficiency of electrocution of tsetse contacting grids operated at various pulse intervals.A: E.net grid beside cloth. B: E-cloth. The plots of percent absolute efficiency derive from pooling and adjusting the data for relative catches at various energies per pulse in Fig 4, as detailed in the text. Vertical bars through the plots indicate the 95% confidence limits. The curves labelled Set 1 and Set 2 refer to those modelled with the various sets of parameter values indicated in the text. The curve labelled Combined is the average of the Set 1 and Set 2 curves.
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pntd.0004169.g005: Fitting curves to the estimated absolute efficiency of electrocution of tsetse contacting grids operated at various pulse intervals.A: E.net grid beside cloth. B: E-cloth. The plots of percent absolute efficiency derive from pooling and adjusting the data for relative catches at various energies per pulse in Fig 4, as detailed in the text. Vertical bars through the plots indicate the 95% confidence limits. The curves labelled Set 1 and Set 2 refer to those modelled with the various sets of parameter values indicated in the text. The curve labelled Combined is the average of the Set 1 and Set 2 curves.

Mentions: Based on the above principles of interpreting present catches, the estimates of absolute efficiency at various pulse intervals are as in Fig 5. To simplify that figure, all of the data for separate energies at each pulse interval have been pooled, consistent with the extensive overlaps evident in almost all of the confidence limits shown previously (Fig 4). The number of different lengths of pulse interval studied during the present work was 21, ranging from 1ms to 3200ms, as against only three different lengths in the video work, ranging from 5ms to 100ms [12]. Not surprisingly, therefore, present data expose greater detail for the relationship between catches and pulse interval. In trying to make sense of this relationship it is pertinent to consider a theoretical model, as below.


Efficacy of Electrocuting Devices to Catch Tsetse Flies (Glossinidae) and Other Diptera.

Vale GA, Hargrove JW, Cullis NA, Chamisa A, Torr SJ - PLoS Negl Trop Dis (2015)

Fitting curves to the estimated absolute efficiency of electrocution of tsetse contacting grids operated at various pulse intervals.A: E.net grid beside cloth. B: E-cloth. The plots of percent absolute efficiency derive from pooling and adjusting the data for relative catches at various energies per pulse in Fig 4, as detailed in the text. Vertical bars through the plots indicate the 95% confidence limits. The curves labelled Set 1 and Set 2 refer to those modelled with the various sets of parameter values indicated in the text. The curve labelled Combined is the average of the Set 1 and Set 2 curves.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4631496&req=5

pntd.0004169.g005: Fitting curves to the estimated absolute efficiency of electrocution of tsetse contacting grids operated at various pulse intervals.A: E.net grid beside cloth. B: E-cloth. The plots of percent absolute efficiency derive from pooling and adjusting the data for relative catches at various energies per pulse in Fig 4, as detailed in the text. Vertical bars through the plots indicate the 95% confidence limits. The curves labelled Set 1 and Set 2 refer to those modelled with the various sets of parameter values indicated in the text. The curve labelled Combined is the average of the Set 1 and Set 2 curves.
Mentions: Based on the above principles of interpreting present catches, the estimates of absolute efficiency at various pulse intervals are as in Fig 5. To simplify that figure, all of the data for separate energies at each pulse interval have been pooled, consistent with the extensive overlaps evident in almost all of the confidence limits shown previously (Fig 4). The number of different lengths of pulse interval studied during the present work was 21, ranging from 1ms to 3200ms, as against only three different lengths in the video work, ranging from 5ms to 100ms [12]. Not surprisingly, therefore, present data expose greater detail for the relationship between catches and pulse interval. In trying to make sense of this relationship it is pertinent to consider a theoretical model, as below.

Bottom Line: At energies per pulse of 35-215mJ, the efficiency was enhanced by reducing the pulse interval from 3200 to 1ms.Efficiency was low at 35mJ per pulse, but there seemed no benefit of increasing the energy beyond 70mJ.Grids that are less efficient, but more economical, are recommended for studies of relative numbers available to various baits.

View Article: PubMed Central - PubMed

Affiliation: South African Centre for Epidemiological Modelling and Analysis, University of Stellenbosch, Stellenbosch, South Africa; Natural Resources Institute, University of Greenwich, Chatham, United Kingdom.

ABSTRACT

Background: The behaviour of insect vectors has an important bearing on the epidemiology of the diseases they transmit, and on the opportunities for vector control. Two sorts of electrocuting device have been particularly useful for studying the behaviour of tsetse flies (Glossina spp), the vectors of the trypanosomes that cause sleeping sickness in humans and nagana in livestock. Such devices consist of grids on netting (E-net) to catch tsetse in flight, or on cloth (E-cloth) to catch alighting flies. Catches are most meaningful when the devices catch as many as possible of the flies potentially available to them, and when the proportion caught is known. There have been conflicting indications for the catching efficiency, depending on whether the assessments were made by the naked eye or assisted by video recordings.

Methodology/principal findings: Using grids of 0.5m2 in Zimbabwe, we developed catch methods of studying the efficiency of E-nets and E-cloth for tsetse, using improved transformers to supply the grids with electrical pulses of ~40kV. At energies per pulse of 35-215mJ, the efficiency was enhanced by reducing the pulse interval from 3200 to 1ms. Efficiency was low at 35mJ per pulse, but there seemed no benefit of increasing the energy beyond 70mJ. Catches at E-nets declined when the fine netting normally used became either coarser or much finer, and increased when the grid frame was moved from 2.5cm to 27.5cm from the grid. Data for muscoids and tabanids were roughly comparable to those for tsetse.

Conclusion/significance: The catch method of studying efficiency is useful for supplementing and extending video methods. Specifications are suggested for E-nets and E-cloth that are ~95% efficient and suitable for estimating the absolute numbers of available flies. Grids that are less efficient, but more economical, are recommended for studies of relative numbers available to various baits.

No MeSH data available.


Related in: MedlinePlus