摘要:

The red bollwormDiparopsis castaneaHmps. is an important pest of cotton in Central and Southern Africa. The adult moth can be effectively sterilised by the aziridine chemosterilant tepa applied topically. This substance is rapidly degraded once applied to the insect and this would therefore minimise possible environmental hazards associated with the release of chemosterilised mass-reared insects. Oral application of tepa is also effective and the recent isolation and synthesis of the sex-pheromones of the female moth has given stimulus to the possible development of chemosterilising bait-stations. For direct application methods, potentially less hazardous chemosterilants are required. Representatives of other groups of potential chemosterilants have therefore been evaluated, including other alkylating agents, phosphoramides, s-triazines, organo-metals, antibiotics, juvenile hormone analogues and insecticides. Application of certain s-triazines and sub-lethal doses of the insecticide carbaryl to female moths enhanced the rate of egg-laying without reducing fertility. Treatment of male moths with these substances often caused an increase in mating disfunction possibly associated with hyperactivity of the accessory glands. Spectrophotofluorometric analysis showed that such activity was associated with an increased level of catecholamines, a major component being noradrenaline. In contrast application of reserpine induced sterility and suppressed egg-laying in female moths, in association with detectable amounts of serotonin. The induction of such biogenic amines as the result of chemosterilant application may therefore have a direct effect on the insect endocrine system, thereby causing a stimulation or suppression of an insect hormone at the wrong time in its life-cycle. Application of such substances may result in the absorption of mature eggs, a suppression of later larval or even adult stages after apparently normal initial embryological development in the egg, and aberrant mating behaviour.

ISSN:0030-7793    

DOI:10.1080/09670877509411427

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Considerable expenditures are being made in the developing countries in terms of money and manpower for the control of diseases such as malaria, sleeping sickness, arboviruses, etc. with arthropod vectors and rodent reservoirs. Responses to a questionnaire sent out by the World Health Organization show that surprisingly large sums are also being expended in urban insect and rodent control in these countries some of which may be considered disease control and some pest control. Unfortunately few of these programmes have adequate professional supervision, direction or evaluation.

ISSN:0030-7793    

DOI:10.1080/09670877509411428

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The location and climate of Bangladesh are described, together with the crops grown and organisations related to agriculture. The entomological problems of the main crops; rice, jute, sugarcane, and fruit crops such as mango, citrus, litchi, jack fruit, guava, banana, coconut and plum are presented. Some serious pests; aphids, epilachna beetles, ants, fruit flies, termites, cutworm and mealybugs are reviewed.

ISSN:0030-7793    

DOI:10.1080/09670877509411429

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Mycoplasma-like organsims (MLO) were observed in the phloem of a ‘weed variant’ ofIpomoea batatason Malaita in the Solomon Islands, and appear to cause stunting, and a reduction in size and puckering of the leaves. No MLO or virus particles were observed in the cultivated sweet potato showing similar symptoms.

ISSN:0030-7793    

DOI:10.1080/09670877509411430

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Fungicide spray trials showed that high volume applications (1121lha) of mancozeb, captafol and vondozeb reduced foliage and stem disease and substantially increased marketable yields of rain-fed tomatoes in northern Nigeria. The results suggest that captafol had a more persistent fungicidal action as there was no yield difference between the 7 and 14 day frequencies of application. U.I.v. methods (<12l/ha) using three fungicides were compared with high volume treatments. The u.I.v. captafol treatment was particularly effective. An assessment was made of droplet distribution in relation to atomiser disc rotation speed and the height of carriage of the sprayer.

ISSN:0030-7793    

DOI:10.1080/09670877509411431

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

AMycosphaerellasp. distinct fromMycosphaerella musicolaLeach has been found in a banana plantation in Zambia and has caused severe losses in the 1973–1974 season.

ISSN:0030-7793    

DOI:10.1080/09670877509411432

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Three rates of the post-emergent herbicide paraquat, 0.7, 0.35 and 0.175 kga.i./ha in 560 //ha were applied to weeds between rows of rubber seedlings. At each rate of paraquat, spray drift caused some defoliation of the seedlings but this was considerably higher at 0.7 kg a.i./ha than at the two lower rates. Death of individual seedlings was negligible at 0.175 kg a.i./ha. Weed control increased with dosage, but 0.175 kg a.i./ha gave acceptable control, which was also completely safe to budgrafts. At this rate, bud development was not affected and growth was comparable to the hand-weeded control.

ISSN:0030-7793    

DOI:10.1080/09670877509411433

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Different mechanical cultivations and herbicide treatments were compared for controllingIschaemum afrumin a heavily infested fallow area. Of the mechanical cultivations, disc ploughing to a depth of more than 15 cm, following removal of tufts and watering, was found very effective (83% reduction). Incorporated pre-emergence triluralin (1.90 kg a.i./ha) alone or in tank mixtures with oxadiazon (0.95 + 0.95 kg a.i./ha) was also found promising (79 and 76% reduction respectively). Three applications of dalapon (8.09 kg a.i./ha), as post-emergence, at two weekly intervals or two applications followed by another application at 4.05 kg a.i./ha gave almost complete eradication ofIschaemum afrumseedlings for about 12 weeks (99% reduction).

ISSN:0030-7793    

DOI:10.1080/09670877509411434

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0030-7793    

DOI:10.1080/09670877509411435

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0030-7793    

DOI:10.1080/09670877509411436

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor