Seasonal population changes in cocoa capsids (Hemiptera, Miridae) in Ghana

1968 ◽  
Vol 58 (2) ◽  
pp. 279-294 ◽  
Author(s):  
D. G. Gibbs ◽  
A. D. Pickett ◽  
Dennis Leston
Keyword(s):  
Light Trap ◽  
West African ◽  
Mercury Vapour ◽  
Feeding Sites ◽  
Vegetative Tissues ◽  
Main Crop ◽  
Sahlbergella Singularis ◽  
Dry Conditions ◽  
Seasonal Population ◽  
Direct Counts

Pupulations of the West African cocoa capsids Distantiella theobroma (Dist.) and Sahlbergella singularis Hagl. were sampled in 1966–67 by several methods: fast knockdown over sheets with pyrethrum, mercury-vapour light-trap, direct counts in a small artificially established area of high population, and observations of presence or absence in randomly selected inspection squares.A population build-up in mature cocoa accompanies and probably directly depends on development of the main crop from July or August to October. When pods become scarce after harvesting there is in S. singilaris a period of dispersal in which the species becomes more widespread as feeding is transferred to vegetative tissues, and in D. theobroma a more local change of feeding sites.Subsequent events vary greatly between areas and between years. It is suggested that the extent to which capsids are able to utilise vegetative tissues varies and depends on nutritional changes in the external parenchymatous tissues from which their food is obtained.Low humidities during spells of harmattan in January and February almost certainly kill larvae in exposed situations, but feeding conditions following such periods may be particularly favourable to capsids as large rapid population increases can occur locally. The factors involved are obscure but may be related to processes of regeneration stimulated by leaf loss and other damage in dry conditions.The densities and seasonal patterns found are discussed in relation to results of previous workers and some implications for control briefly considered.

scholarly journals Phrynomerus Annectens (Werner), a rare frog in the Augrabies Falls National Park

Koedoe ◽  
1977 ◽  
Vol 20 (1) ◽  
Author(s):  
U. de V. Pienaar
Keyword(s):  
South Africa ◽  
National Park ◽  
West African ◽  
South West ◽  
Heavy Shower ◽  
Dry Conditions

During a visit (1977.01.28) to the Augrabies Falls National Park, Republic of South Africa, a heavy shower of rain brought relief to prevailing hot, dry conditions. A specimen of the rare South West African Red banded Frog Phrynomerus annectens (Werner) was collected that evening, on the lawn of the administration block.

scholarly journals West African Summer Monsoon Precipitation Variability as Represented by Reanalysis Datasets

Climate ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 111
Author(s):  
Kwesi Akumenyi Quagraine ◽  
Francis Nkrumah ◽  
Cornelia Klein ◽  
Nana Ama Browne Klutse ◽  
Kwesi Twentwewa Quagraine
Keyword(s):  
Summer Monsoon ◽  
Southern Oscillation ◽  
West African Monsoon ◽  
West African ◽  
Positive Trend ◽  
In Situ Data ◽  
Dry Conditions ◽  
Long Term Trends

Focusing on West Africa, a region riddled with in situ data scarcity, we evaluate the summer monsoon monthly rainfall characteristics of five global reanalysis datasets: ERA5, ERA-Interim, JRA-55, MERRA2, and NCEP-R2. Their performance in reproducing the West African monsoon (WAM) climatology, interannual variability, and long-term trends for the main monsoon months are compared to gauge-only and satellite products. We further examine their ability to reproduce teleconnections between sea surface temperatures and monsoon rainfall. All reanalyses are able to represent the average rainfall patterns and seasonal cycle; however, regional biases can be marked. ERA5, ERA-Interim, and NCEP-R2 underestimate rainfall over areas of peak rainfall, with ERA5 showing the strongest underestimation, particularly over the Guinea Highlands. The meridional northward extent of the monsoon rainband is well captured by JRA-55 and MERRA2 but is too narrow in ERA-Interim, for which rainfall stays close to the Guinea Coast. Differences in rainband displacement become particularly evident when comparing strong El Niño Southern Oscillation (ENSO) years, where all reanalyses except ERA-Interim reproduce wetter Sahelian conditions for La Niña, while overestimating dry conditions at the coast except for NCEP-R2. Precipitation trends are not coherent across reanalyses and magnitudes are generally overestimated compared to observations, with only JRA-55 and NCEP-R2 displaying the expected positive trend in the Sahel. ERA5 generally outperforms ERA-Interim, highlighting clear improvements over its predecessor. Ultimately, we find the strengths of reanalyses to strongly vary across the region.

A migration of grasshoppers, particularly Diabolocatantops axillaris (Thunberg) (Orthoptera: Acrididae), in the West African Sahel

1988 ◽  
Vol 78 (2) ◽  
pp. 251-271 ◽  
Author(s):  
D. R. Reynolds ◽  
J. R. Riley
Keyword(s):  
Light Trap ◽  
Volume Density ◽  
West African ◽  
Life History Strategies ◽  
Dense Layer ◽  
Class Iii ◽  
Long Distance ◽  
The West ◽  
Grasshopper Species ◽  
Migration Direction

AbstractA dense layer of large insects in windborne, migratory flight was observed by radar in the Tilemsi Valley in Mali between about 23.00 and 02.00 h on 10–11 October 1978. The volume density, height of flight, area density, displacement speed and direction, orientation and migration rate were determined for the overflying insects. Light-trap catches and radar signatures provided strong evidence that the pest grasshopper Diabolocatantops axillaris (Thunberg) contributed to the overflying layer. Other species contributing probably included Oedaleus senegalensis (Krauss) and possibly Ochrilidia spp. For D. axillaris, the migration can be regarded as a search for overwintering sites by adults in reproductive diapause, and thus is an example of C. G. Johnson's Class III migration. Estimated trajectories placed the probable source areas of the overflying grasshoppers in the Gourma, about 150 km west-south-west of the radar site. Migration direction was approximately downwind, but the grasshoppers showed a degree of common orientation towards the east-south-east, which added a southwards component to their displacement. At 02.30 h on the same night, a very dense line-concentration associated with a wind-shift moved across the radar site, and insects still in flight probably became entrained in this wind convergence zone and added to the line-concentration. Other evidence of long-distance, windborne migration in D. axillaris was adduced from records of captures on ships at sea, mainly off the West African coast. The consequences of downwind displacement and concentration for grasshopper ecology and pest management are discussed. The migration behaviour of D. axillaris and other grasshopper species probably reduces migration losses by the efficient location of new habitats and forms an essential part of life-history strategies for survival in a sahelian environment.

Relationship to human biting collections and influence of light and bednet in CDC light-trap catches of West African malaria vectors

1998 ◽  
Vol 88 (5) ◽  
pp. 503-511 ◽  
Author(s):  
C. Costantini ◽  
N.F. Sagnon ◽  
E. Sanogo ◽  
L. Merzagora ◽  
M. Coluzzi
Keyword(s):  
Light Trap ◽  
West African ◽  
Malaria Vectors ◽  
Prototype Model ◽  
Light Traps ◽  
Mosquito Net ◽  
Cdc Light Trap ◽  
Incandescent Bulb ◽  
Human Landing ◽  
Trap Catches

AbstractThe efficiency of miniature CDC light-traps in catching West African malaria vectors was evaluated during two rainy seasons in a village near Ouagadougou, Burkina Faso. Traps were employed both indoors and outdoors using human baits protected by an insecticide-free mosquito-net and different sources of light. Indoors, light from incandescent bulbs increased the catch of Anopheles gambiae s.l. (mainly A. arabiensis Patton and the Mopti chromosomal form of A. gambiae s.s. Giles) and A. funestus Giles c. 2.5 times as compared to traps whose light bulb was removed. Conversely, the difference was not significant when a UV ‘Blacklight-blue’ fluorescent tube was compared to the incandescent bulb. Protecting the bait with a mosquito-net increased the catch c. 3 times for A. gambiae s.l. and c. 3.5 times for A. funestus. A prototype model of double bednet gave intermediate yields. Outdoors, the addition of incandescent bulbs to unlighted traps did not significantly increase the number of vectors caught, but the addition of the mosquito-net to the unprotected human bait did so by c. 1.5–4 times. Thus, the CDC light-trap hung close to a human sleeping under a bednet and fitted with an incandescent bulb, was considered the most practical and efficient in terms of numbers of vectors caught, consequently its indoor efficiency was compared to human landing catches on single collectors and estimated to be 1.08 times and density-independent. Outdoor light-trap catches were either not significantly correlated to biting collections (as for A. gambiae s.l.), or density-dependent in their efficiency (as for A. funestus); thus, they were not considered a reliable means for estimating malaria vector outdoor biting densities in this area. No difference was found in the parous rate of A. gambiae s.l. samples obtained with CDC light-traps and human landing collections.

A remote sensing method for the estimation of light-trap efficiency

1988 ◽  
Vol 78 (3) ◽  
pp. 379-385 ◽  
Author(s):  
W. J. McGeachie
Keyword(s):  
Remote Sensing ◽  
Insect Flight ◽  
Light Trap ◽  
Video Camera ◽  
Light Sensitivity ◽  
Trapping Efficiency ◽  
Mercury Vapour ◽  
Trap Catch ◽  
Preliminary Results ◽  
Trap Efficiency

AbstractA description is given of the use of a video camera to estimate light-trap efficiency in the field. This camera relies on the extra light sensitivity provided by the Newvicon detector tube to enable insect track discrimination. Recorded insect flight tracks were classified into three distinct categories, new arrivals, passers by and local flights, the numbers of which were compared to the moth catch in a Robinson mercury vapour light-trap. Calculations of efficiency were made using two methods, the best-estimate efficiency, obtained by comparing the new-arrival tracks to the light-trap catch, and the worst-estimate efficiency, obtained by comparing new-arrival tracks plus passer-by tracks to the light-trap catch. Preliminary results indicate that efficiency varies with windspeed but with a maximum of 39%, obtained in virtually calm conditions, suggesting that some aspect of moth behaviour limits trapping efficiency. It is suggested that the speed of migration of screening pigment from the dark-adapted state to the light-adapted state in superposition eyes may have a bearing on the catching mechanism of a light-trap.

scholarly journals Abundance and diurnal activity patterns of hooded vulture (Necrosyrtes monachus Temminck,) in Addis Ababa abattoirs enterprise, Addis Ababa, Ethiopia

2021 ◽  
Vol 44 (1) ◽  
pp. 129-134
Author(s):  
Mebrat Teklemariam ◽  
Bezawork Afework
Keyword(s):  
Addis Ababa ◽  
Activity Patterns ◽  
Diurnal Activity ◽  
Human Disturbances ◽  
Negative Attitudes ◽  
Feeding Sites ◽  
Critically Endangered Species ◽  
The Status ◽  
Direct Counts

Hooded vulture (Necrosyrtes monachus) is an African endemic scavenger listed as Critically Endangered species. The population is declining across its range and there is threat of significant decline in population and distribution in Ethiopia. Little efforts have been made to properly document the status of vulture population and their diurnal activity patterns in the country for ensuring long term conservation measures. A study was conducted in Addis Ababa Abattoirs enterprise, Ethiopia from November 2019 to January 2020 to investigate the abundance and diurnal activity patterns of hooded vultures. The abundance of these vultures was estimated by direct counts method at their feeding sites and scan sampling was employed to study the diurnal activity patterns of hooded vultures from dawn to dusk. Hooded vulture mean abundance was 216±40 at the abattoir. Their diurnal activity pattern showed that they were observed feeding, resting (perching, watching and basking), preening, roosting and others activities such as walking, drinking, chasing and flying. They spent 37.73% of their time in resting followed by others (including walking, drinking, chasing and flying) (27.73%). The major threat recorded for theses vultures in the abattoir includes shortage of food, human disturbances, negative attitudes and lack of awareness on the importance of the species. Further ecological studies and impacts of human activities on Addis Ababa Abattoirs enterprise should be conducted for the conservation of hooded vulture and other conspecifics in the area.

Detection of interannual population trends in seven herbivores from a West African savannah: a comparison between dung counts and direct counts of individuals

2017 ◽  
Vol 55 (4) ◽  
pp. 609-617 ◽  
Author(s):  
Emmanuel M. Hema ◽  
Massimiliano Di Vittorio ◽  
Richard F.W. Barnes ◽  
Wendengoudi Guenda ◽  
Luca Luiselli
Keyword(s):  
West African ◽  
Population Trends ◽  
West African Savannah ◽  
Direct Counts

Effects of light-trap design and illumination on samples of moths in an English woodland

1974 ◽  
Vol 63 (4) ◽  
pp. 583-594 ◽  
Author(s):  
L. R. Taylor ◽  
R. A. French
Keyword(s):  
Spatial Model ◽  
Light Trap ◽  
Mercury Vapour ◽  
Tungsten Filament ◽  
Trap Design ◽  
A Site

AbstractOperated in sheltered woodland, the samples obtained by Rothamsted tungsten-filament and Robinson mercury-vapour traps are best described by a spatial model different from that used in a site exposed to wind. Differences between the proportions of Noctuidae and Geometridae were accountable to differences in height of flight. The Rothamsted traps gave more consistent samples than the Robinson traps and averaged about onequarter the number of moths.

The bionomics of swift moths. I.—The ghost swift moth, Hepialus humuli (L.)

1964 ◽  
Vol 55 (1) ◽  
pp. 147-160 ◽  
Author(s):  
C. A. Edwards
Keyword(s):  
Light Trap ◽  
Daily Intake ◽  
Small Cells ◽  
Mercury Vapour ◽  
Flight Period ◽  
Obvious Effect ◽  
Plaster Of Paris ◽  
Horticultural Crops ◽  
General Field ◽  
Trap Catches

The larvae of two species of swift moths, Hepialus humuli (L.) and H. lupulinus (L.), live in the soil and are common under grass in the British Isles, but do not usually have any obvious effect upon the grass. The larvae of H. humuli are polyphagous and when they occur under agricultural or horticultural crops they may cause damage by feeding on the roots. Lettuce, strawberry and chrysanthemum are most frequently damaged.The adults, which are described, fly at dusk, the female seeking the male. The female lays between 200 and 1,600 eggs, with a mean of about 600, over a period of four days. Sweep-net catches showed the ratio of the sexes to be approximately equal, and mercury-vapour light-trap catches showed that the flight period in southern England is principally in June.In the laboratory, never less than 80 per cent, of eggs hatched, even in dry air, and the shortest incubation period, between 11 and 24 (mean 18) days, was at 20°C. At 5°C. they did not hatch, but remained viable for at least six months.The larvae were reared in small cells drilled in blocks of plaster of Paris, which were stood in a tray of water, or in vials containing a layer of moist plaster of Paris, and were fed on pieces of carrot.The growth of the larval head capsules was geometric and allowed 12 instars to be distinguished at 15°C.; at higher temperatures there may be more.The growth curve of the larvae was S-shaped with a very distinct fall in weight in each instar for several days before moulting. The daily intake of food was weighed, and the conversion rate shown to be small, ranging from 0·00058 to 0·04, as compared with 0·205 to 0·49 recorded for other Lepidopterous larvae.At 5°C., larvae did not develop beyond the second instar, nor beyond the fourth at 10°C. The optimum temperature for their development (mean period 224 days) was 15°C., although mortality was high. They developed at 20°C. more rapidly (mean 197 days) but more died. Larvae kept in a container sunk in the soil outdoors developed more slowly than those at 15°C. and had only reached the eighth instar by February (239 days after hatching). This evidence, together with that from an artificially infested plot in the field and general field observations, suggests that the usual life-cycle lasts two years.

Trap design for monitoring moth biodiversity in tropical rainforests

1999 ◽  
Vol 89 (2) ◽  
pp. 153-163 ◽  
Author(s):  
J. Intachat ◽  
I.P. Woiwod
Keyword(s):  
Tropical Rainforest ◽  
Light Trap ◽  
Peninsular Malaysia ◽  
Tropical Rainforests ◽  
Mercury Vapour ◽  
Trap Design ◽  
Dipterocarp Forest ◽  
Tropical Conditions ◽  
Lowland Dipterocarp Forest ◽  
Experimental Comparisons

AbstractExperimental comparisons were made between samples of moths obtained by Rothamsted tungsten-filament and Robinson mercury-vapour light-traps operating in a lowland dipterocarp forest in Peninsular Malaysia. The Rothamsted trap gave more uniform and consistent samples and performed better in the tropical conditions than the Robinson trap. There were no significant differences between the overall measurement of diversity for the group Geometroidea between the two trap designs although the Robinson trap was much more erratic from night to night. The total catch of non-Geometroidea moths was remarkably similar in the two trap types. The choice of appropriate light-trap designs for biodiversity studies in tropical rainforest is discussed.

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