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1

Digitale Medien

Strategies for controlling cassava mosaic virus disease in Africa (2005)

Thresh, J. M. ; Cooter, R. J.

Oxford, UK : Blackwell Science Ltd

Plant pathology 54 (2005), S. 0

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ISSN: 1365-3059

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Cassava mosaic disease (CMD) is caused by whiteflyborne viruses of the genus Begomovirus (family Geminiviridae). The disease has long been regarded as the most important of those affecting cassava in sub-Saharan Africa, and has been the subject of much research, especially since the onset of the current very damaging pandemic in eastern and central Africa. This review considers the main features of CMD and the various possible means of control. The main emphasis to date has been on the development and deployment of virus-resistant varieties. These are widely adopted in countries where CMD has caused serious problems, and provided a powerful incentive for farmers to abandon some of the most susceptible of their traditional varieties. Only limited use has been made of phytosanitation involving CMD-free planting material and the removal (roguing) of diseased plants. Cultural methods of control using varietal mixtures, intercrops or other cropping practices have also been neglected, and there is a need for much additional research before they can be deployed effectively. Nevertheless, the severe losses now being caused by CMD in many parts of sub-Saharan Africa could be greatly decreased through the application of existing knowledge.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-3059.2005.01282.x

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2

Digitale Medien

The natural flight of the migratory locust,Locusta migratoria L. (1981)

Baker, P. S. ; Gewecke, M. ; Cooter, R. J.

Springer

Journal of comparative physiology 141 (1981), S. 233-237

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ISSN: 1432-1351

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin

Notizen: Summary High speed cine film ofLocusta migratoria swarms was analysed. The following variables were studied and compared where possible with laboratory data: 1. Wing-beat frequencies of locusts of Australian and New Guinea swarms (mean 22.9 Hz) were higher than laboratory figures (19.8 Hz; Fig. 1). 2. Mean flight speed was 4.6 m/s, which was higher than laboratory figures (3.3 m/s; Fig. 2). 3. Mean body angle to horizontal was 7.4°, and to flight path (in the vertical plane) was 5.2°. Flight speed was found to be correlated with wing-beat frequency with a similar regression line to that found in laboratory work (Fig. 4). Ascent angle was positively correlated with the body angle to horizontal, but not correlated with body angle to flight path (Figs. 3, 5, 6).

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01342669

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3

Digitale Medien

The natural flight of the migratory locust,Locusta migratoria L. (1979)

Baker, P. S. ; Cooter, R. J.

Springer

Journal of comparative physiology 131 (1979), S. 89-94

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ISSN: 1432-1351

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin

Notizen: Summary 1. High speed film of naturally flyingLocusta migratoria has revealed gliding in these animals. 2. Glides last from a few milliseconds up to about one third of a second. 3. The glide always starts when the forewings reach the top of their stroke; the hindwings stop at the same instant although they have already started their downstroke. 4. The basic wing positions during the glide are described. 5. A lift drag ratio of 1.7∶1 has been calculated, and a minimum sinking rate of just over 2 m/s has been measured. 6. Glides commence with a positive body angle of up to 30° but this is rapidly reduced during the glide as the animal pitches forward. 7. Glides tend to end when the animal is diving, i.e. with a negative body angle. 8. The end of a glide is heralded by the hindwings moving downwards, followed by the forewings. Body angles are restored to a positive value very quickly after the end of a glide.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00613087

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4

Digitale Medien

The natural flight of the migratory locust,Locusta migratoria L. (1979)

Baker, P. S. ; Cooter, R. J.

Springer

Journal of comparative physiology 131 (1979), S. 79-87

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ISSN: 1432-1351

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin

Notizen: Summary 1. High-speed film of naturally flyingLocusta migratoria was taken in two locations in the Southern Hemisphere. 2. Wing tip movements were traced from the film and revealed considerable variation in shape, both from one animal to another and from one wing beat to the next in the same animal (Figs. 4a, b, 5a, 8a, b). 3. The ratio of upstroke to downstroke is not constant for either pair of wings (Figs. 2, 3 a-f). 4. A wide range of stroke plane angles were recorded for the forewing, but there was no evidence of active control of this variable to suit specific conditions (e.g. climbing) (Figs. 6, 7). 5. Stroke angles of the wings (amplitudes) were also subject to considerable variation and one forewing can travel through a different amplitude to that of the other forewing. 6. Close-up shots of climbing locusts revealed the hindwings performing a ‘clap and fling’ type stroke (Figs. 8, 9a, b, c). 7. Front and ventral views of flying locusts revealed varying amounts of bending and twisting of the forewings (Figs. 10, 11a, b, 12 a, b).

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00613086

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5

Digitale Medien

Visually induced yaw movements in the flying locust,Schistocerca gregaria (Forsk.) (1979)

Cooter, R. J.

Springer

Journal of comparative physiology 131 (1979), S. 67-78

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ISSN: 1432-1351

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin

Notizen: Summary Movement of a small object in the lateral visual field of a flying locust mounted on a balance induces a turning response expressed as a yaw towards the stimulus. Wing movements have been filmed (Figs. 2, 3, 4) and analysed in detail. During the response there are: 1. A transient shortening of wing beat period (Fig. 5), more marked and occurring earlier, in the forewings. 2. Fore and hindwing pairs move in phase at the start of the response. Contralateral wings tend to move out of phase, wing on side of turn follows that on other side initially but then changes can occur in either direction (Fig. 6). 3. Forewing twisting was recorded. The forewing on the side of the turn remains pronated during the upstroke portion of the damped initial stroke. 4. Wing stroke amplitude is reduced initially and then rapidly increases but, more importantly, the starting and finishing points of the contralateral wing strokes are different. Wings on the side of the turn start from a lower point and move down further than those on the opposite side (Figs. 7, 8). 5. The hindleg on the side of the turn may be extended and the abdomen bent to that side also. This response develops and declines more slowly than the observed changes in wing motion. It is postulated that these changes, in different combinations, can account for the observed behaviour and that in free flight the insect would perform a banked turn towards the stimulus.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00613085

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6

Digitale Medien

Comparison of the performance of Cicadulina leafhoppers on flight mills with that to be expected in free flight (1997)

Riley, J. R. ; Downham, M. C. A. ; Cooter, R. J.

Springer

Entomologia experimentalis et applicata 83 (1997), S. 317-322

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ISSN: 1570-7458

Schlagwort(e): Cicadulina storeyi ; leafhopper ; flight mill ; flight energetics

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Flight mills are commonly used to assess the relative flight performance of migratory insects, but uncertainties about the rate of energy expenditure on the mill mean that absolute estimates of flight endurance are not usually attempted. In this paper we describe how we measured the power delivered to a lightweight flight mill by tethered Cicadulina storeyi China leafhoppers (Homoptera: Cicadellidae), and compared this to estimates of the power they use to maintain free flight. Our results showed that the leafhoppers were generating more than 0.90 μW of mechanical power when on the mill, and that they probably have 3–4 μW available for free flight. We conclude that whilst flying on the mill, the insects were generating at least 20–30% of the mechanical power needed for free flight, and that this percentage may have been significantly higher.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1003034517752

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