Notes on the Tachinid Parasites of Cotton Stainers (Dysdercus spp., Pyrrhocoridae) in South Africa

1947 ◽  
Vol 38 (2) ◽  
pp. 305-310 ◽  
Author(s):  
R. C. Rainey
Keyword(s):  
South Africa ◽  
Larval Period ◽  
Cotton Crop ◽  
Economic Significance ◽  
Winter Conditions ◽  
Cotton Stainers

(1) Up to 35 per cent, of adult Dysdercus nigrofasciatus from a heavily infested late cotton crop at Barberton were found to be parasitised by Tachinid larvae at the end of the season.(2) The predominant Tachinid species was Alophora nasalis; Bogosilla fasciata was present in smaller numbers, and appears to be more common in regions of higher rainfall.(3) The development of the Tachinid larva within the stainer was a protracted process under local winter conditions, the larval period of A. nasalis being of the order of 2–3 months, and parasitised stainers were correspondingly long-lived.(4) The possible economic significance of the parasites is discussed.

Introductory remarks

1979 ◽  
Vol 287 (1022) ◽  
pp. 249-249
Keyword(s):  
South Africa ◽  
Practical Importance ◽  
Applied Science ◽  
Desert Locust ◽  
African Armyworm ◽  
Economic Significance ◽  
Written Comments ◽  
New Knowledge ◽  
History Of ◽  
Informed Opinion

This meeting was concerned with pests whose control remains a matter of international concern, illustrated both by a new upsurge of the Desert Locust since the meeting and, almost at the same time, by serious infestations of African armyworm in every country from South Africa to Yemen (in several of them the heaviest on record); both these developments have indeed contributed unavoidably to the delay in the appearance of these proceedings. Each of the pests discussed at the meeting has a human importance beyond its purely economic significance; each presents problems so daunting in magnitude that any attempt at control must, as was said, have an element of audacity; and perhaps no one who has been involved in such attempts is ever quite the same again. The effective deployment of applied science within such subjective constraints has involved a long history of invaluable international meetings with administrative and logistic objectives for which a consensus of technical opinion has been essential. But in each case knowledge and understanding are still sufficiently incomplete to leave scope - and need - for sharp differences of informed opinion, often on points of major practical importance. At the start of the present meeting it was emphasized that no collective recommendations would be attempted; that there would be no drafting committee; but that the objective was to use the forum provided by the Society to get on record a really comprehensive presentation of the range of informed opinion on these various points of disagreement: because these are the growing-points for new knowledge. Written comments and afterthoughts were accordingly invited, and have been used to supplement the taped record of the discussions.

Notes on the Bionomics of Cotton Stainers (Dysdercus) in Nigeria

1928 ◽  
Vol 18 (3) ◽  
pp. 319-334 ◽  
Author(s):  
F. D. Golding
Keyword(s):  
Embryonic Development ◽  
Alternative Food ◽  
Food Plants ◽  
Forest Zone ◽  
Cotton Crop ◽  
Cotton Stainers ◽  
Hibiscus Esculentus ◽  
Prevalent Species

(1) There are two forms of D. superstitiosus, F., in Nigeria, which are designated banded and spotted forms in the present paper. The banded form appears on cotton earlier in the season than the spotted, and it remains on the crop longer. Migration to cotton is gradual in the case of the banded form, while a sudden influx of migrants of the spotted form commences in October. Many spotted adults migrate to Bombax and Sterculia between January and March, whereas the banded form remains on the cotton until it is uprooted at the end of March. The spotted form is far more numerous than the banded on maize and guinea corn.(2) There is considerable variation in the colouration of adults of the spotted form; at Ibadan about 99 per cent. of the migrants to cotton are yellow or orange in colour, while the adults of the filial generations produced on cotton are almost always red in colour (a few individuals are deep orange-red). These colour variations are thought to be of seasonal origin.(3) D. superstitiosus is the most prevalent species on cotton at Ibadan, Ilorin, Oyo, Zaria and Kano; melanoderes is of equal or greater importance in the forest zone at Ilugun and occasionally is numerous at Ibadan; fasciatus is of importance in savannah country at Oyo; haemorrhoidalis is rare on cotton. No evidence has been obtained that any one of these species is a varietal form of another species. Both forms of superstitiosus are widely distributed in Nigeria.(4) Migration to cotton is induced by the flowering of that crop. The maximum weekly migration has occurred between the weeks ending 15th October and 7th November in five localities in the last three years; viz., at the time of, or soon after, the maximum flowering of the cotton crop. There are indications that there is a tendency for stainers to migrate in a southerly direction, probably as a result of the desiccating harmattan wind from the Sahara.(5) The principal alternative food-plants of stainers in the Ibadan district are: Bombax sp., Sterculia sp., Hibiscus esculentus, H. sabdariffa, Urena lobata, and Abutilon zanzibaricum. At Ilorin, silk-cotton trees (Bombax), H. esculentus, H. lunariifolius and U. lobata are the most important alternative food-plants.(6) A rhythm exists in the weekly proportions of the sexes during the cotton season; males predominate among the early migrants to cotton and among the first individuals to mature of each generation. This rhythm appears to be the result of shorter period of post-embryonic development in the case of males than in that of females derived from the same batch of ova.

scholarly journals Magnetite layer formation in the Bushveld Complex of South Africa

2021 ◽  
Author(s):  
Zhuo-Sen Yao ◽  
James Mungall
Keyword(s):  
South Africa ◽  
Alternative Model ◽  
Ad Hoc ◽  
Bushveld Complex ◽  
Layer Formation ◽  
Layered Intrusions ◽  
Economic Significance ◽  
Magnetite Layer ◽  
Compositional Convection

Abstract The great economic significance of layered mafic-ultramafic intrusions like the Bushveld Complex of South Africa results from the existence within them of some layers highly concentrated in valuable elements. Here we address the origins of the Main Magnetite Layer, a globally important resource of Fe-Ti-V-rich magnetite. Previous models of in situ fractional magnetite crystallization require frequent ad hoc adjustments to the boundary conditions. An alternative model of rapid deposition of loose piles of magnetite crystals followed by compositional convection near the top of the pile and infiltration of the pile from beneath by migrating intercumulus melt fits observations without any adjustments. The data admit both explanations, but the latter model, with the fewest unconstrained interventions, is preferable. The choice of models has pivotal ramifications for understanding of the fundamental processes by which crystals accumulate and layers form in layered intrusions.

Soviet Involvement in Southern Africa

1985 ◽  
Vol 481 (1) ◽  
pp. 138-146 ◽  
Author(s):  
SAM C. NOLUTSHUNGU
Keyword(s):  
South Africa ◽  
Foreign Policy ◽  
Soviet Union ◽  
Southern Africa ◽  
Portuguese Empire ◽  
Economic Significance ◽  
The Soviet Union ◽  
Soviet Foreign Policy

This article explores Soviet foreign policy toward southern Africa. Moscow's approach to the region has been mainly one of restraint, and it has avoided additional economic and military burdens since the collapse of the Portuguese Empire. The region does not hold great strategic or economic significance for the Soviet Union, and Moscow is not willing to incur high risks. The author concludes that the changing pattern of Soviet influence in Africa is mainly a function of changes within African states. The deepening crisis in South Africa may point to the need for revolutionary solutions, but these would occur without Western aid and with minimal Soviet assistance.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Combining Professional Interests and Travel: People to People Citizen Ambassador Program

2011 ◽  
Vol 1 (2) ◽  
pp. 47-54
Author(s):  
Alex Johnson ◽  
Amanda Hitchins
Keyword(s):  
South Africa ◽  
Health Education ◽  
Communication Disorders ◽  
Social Conditions ◽  
Speech Language Pathologists ◽  
Exchange Program

Abstract This article summarizes a series of trips sponsored by People to People, a professional exchange program. The trips described in this report were led by the first author of this article and include trips to South Africa, Russia, Vietnam and Cambodia, and Israel. Each of these trips included delegations of 25 to 50 speech-language pathologists and audiologists who participated in professional visits to learn of the health, education, and social conditions in each country. Additionally, opportunities to meet with communication disorders professionals, students, and persons with speech, language, or hearing disabilities were included. People to People, partnered with the American Speech-Language-Hearing Association (ASHA), provides a meaningful and interesting way to learn and travel with colleagues.

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