摘要:

The status ofDysdercus superstitiosus(F.) andD. voelkeriSchmidt as pests of the jute‐substitute cropUrena IobataL. in Sierra Leone is discussed. A significant correlation between the proportion of seeds with evidence ofDysdercusfeeding and the proportion with non‐viable or abnormal embryos revealed these insects to be serious pests ofU. Iobataseed crops. Damage is confined to the seeds and resulted in up to 70% non‐viability of seeds in some samples. The fibre yield is unaffected. Typical damage symptoms are described.Dysdercusadults migrated toU. Iobatacv. Ex‐Mokwa soon after the onset of flowering and remained throughout the period of seed production. High population densities were reached, and migration to later flowering varieties may have occurred. A wide range of alternative food sources enablesDysdercuspopulations to survive between successiveU. Iobatacrops. It is suggested that chemical control may be necessary for successful seed production.

ISSN:0143-6147    

DOI:10.1080/09670878309370760

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The effects of a tsetse control programme onSimuliumspp. on the Komoe river in the Guinea savanna of Upper Volta have been investigated by samplingSimuliumpopulations using sticky aluminium plaque traps. Flies were taken in several physiological states, among which gravid, non‐gravid and newly emerged individuals could easily be recognised. Daily sampling began two days before insecticide application and continued for 10–12 days afterwards, and the results were compared with a parallel study using human bait to sampleS. damnosums.l. populations only. Applications of deltamethrin at 12.5 g a.i./ha caused immediate reductions in the numbers ofSimuliumtrapped. Endosulfan at 100 g a.i./ha gave an immediate reduction of 30–50%, increasing to 70% after three days. Populations had recovered after 12 days. The use of endosulfan at 10 g a.i./ha, deltamethrin at 12.5 g a.i./ha and dieldrin at 400 g a.i./ha to form an insecticidal ‘barrier’ on the river had relatively little effect. Dieldrin had a limited effect on the day of spraying only, and only on gravid females of species other thanS. damnosum.It is possible that flies were traversing the barrier without coming into contact with the insecticide.

ISSN:0143-6147    

DOI:10.1080/09670878309370761

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The partial success of applications of dieldrin, deltamethrin and endosulfan for tsetse control in also reducing populations ofSimuliumspp. in a riverine Guinea savanna habitat in Upper Volta has been established. However, there is insufficient information available concerning the resting sites of adultSimuliumto determine the best location of spray swaths to achieve the maximum effect. Further trials based on knowledge of the biology of adultSimuliumcould improve the success of the technique for blackfly control. It is suggested that localised adulticiding in onchocerciasis control schemes could be effective, particularly where a high level of reinvasion causes unacceptable levels of disease transmission for short periods of the year.

ISSN:0143-6147    

DOI:10.1080/09670878309370762

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Following reports of ethion resistant cattle ticks (Boophilus microplus(Canestrini)) in New Caledonia, a series of dosage mortality tests was undertaken in an attempt to establish the extent of this resistance. Thirty samples ofB. micropluswhich was introduced from Australia in 1942, were taken from various locations on the main island, and the results compared with similar tests carried out using an Australian susceptible reference strain (Yeerongpilly) and an Australian resistant strain (Biarra). Larvae 6–15 days after hatching were exposed to different concentrations of ethion in olive oil for 24 h. The study showed that varying levels of ethion resistance had developed in New Caledonia, and that it was most strongly marked in tick populations from the east coast region. Some very low levels of resistance are probably of no practical importance, but the LC50value of the most resistant population was eight times that of the Yeerongpiily reference strain. Ethion resistance has appeared on the island after seven years of application. Reasons for the observed regional variation in resistance level are discussed. It is suggested that the concentration of ethion cattle dipping baths should be increased before introducing new acaricides. Alternative control methods should be considered.

ISSN:0143-6147    

DOI:10.1080/09670878309370763

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Granivorous birds are a major constraint to rice production in West Africa, but effective control is difficult. A partial crop treatment method, whereby only 1–10% of the total area under cultivation is treated with a non‐repellent pesticide of high oral toxicity, is described. Weaver birds (Ploceus cucullatus(Müller) andP. melanocephalus(L.)) and, to a lesser degree, golden sparrows (Passer luteus(Licht.)) and queleas (Quelea quelea(L.)) were attracted to the treated areas by artificial roosting sites and deflected from untreated areas by traditional bird scaring methods. Trials in Senegal and Gambia showed that carbofuran applied at rates of 0.1–0.3 g a.i./m2, with a droplet size of 200–1000μm vmd, resulted in up to 22 bird kills/g a.i. at a maximum pesticide cost of US$ 0.016 per bird killed. This compares with an estimated grain loss of 1 kg rice or US$ 0.20 per bird. The treated areas should be at least 200–2000 m2, and the treated rice should be used as seed grain only. More than 80% of the dead birds were collected within the treated area, and the method was particularly effective against weaver birds (Ploceusspp.). Non‐target birds were not affected.

ISSN:0143-6147    

DOI:10.1080/09670878309370764

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Radio transmitters weighing 1.8 g were attached to red‐billed quelea (Quelea quelea(L.)) in southwestern Ethiopia during May and June 1981 to determine the feasibility of this technique for rapidly locating nesting colonies and following local movements. Queleas are probably the smallest birds to which external radio transmitters have been successfully attached. Radio‐equipped birds were tracked to four nesting colonies, three of which were in the nest construction stage which occurs during the first three days of colony establishment. This early stage is not normally found using conventional survey methods. Adults usually foraged within 3 km of the colony at the nestling and fledgling stages, indicating that surveys must pass within this distance if the colony is to be located by conventional techniques. The study showed that quelea nesting colonies could be more easily and inexpensively located in remote areas using radiotelemetry than by using only ground or aerial surveys. The early detection of colonies allows almost 30 days for the organisation of control operations and permits increased flexibility in selecting colonies for control. The implications of radiotelemetry for use in various quelea damage situations in Africa are discussed.

ISSN:0143-6147    

DOI:10.1080/09670878309370765

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Investigations of the effect of various fungicides and antagonistic species on the radial growth in culture of three pathogens of oil palm and rubber showed only phenylmercury acetate and cycloheximide to be effective againstCorticium salmonicolorBerk. & Br. below 10 μg a.i./ml. Other promising fungicides were examined and seven were effective againstRigidoporus lignosus(Klotzsch) Imazeki and eight againstGanodermasp.Trichodermaspp. were antagonistic to all the pathogens. The practical application of these results in the field are discussed.

ISSN:0143-6147    

DOI:10.1080/09670878309370766

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The potential use of chaya (Cnidoscolus aconitifolius(Mill.) Johnston) as a food crop in Brunei is discussed. Chaya leaves have a high protein content (25.4%) which compares favourably with other vegetables, such as cowpea (26.4%) and ricebean (24.9%). Growth is rapid and edible leaves are available in 4–5 months. The plant is drought resistant making it a valuable crop in areas with short dry periods when other green vegetables are scarce. Propagation is simple and little maintenance is required; thereareno significant pests or diseases on the plant. Chaya could be an important addition to local vegetable diets.

ISSN:0143-6147    

DOI:10.1080/09670878309370767

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Anthracnose(Colletotrichum lagenarium(Pass.) Ell. & Halst.) is a serious disease of watermelons in Brunei although other diseases also contribute to yield losses. Previous work has shown that chemical control of the disease is possible. Field trials were carried out to test the effectiveness of several fungicides. As a result of the trials benomyl and mancozeb or captafol were recommended for the control of anthracnose. The integration of chemicals for controlling pests and diseases, correct cultural practices and improved cultivars resulted in a continuous supply of fresh fruits, although a particularly high standard of management was necessary during August to December, the wettest months of the year. Farmers yields increased three to four times with consequent increases in profitability and self sufficiency for the State in this popular fruit.

ISSN:0143-6147    

DOI:10.1080/09670878309370768

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The history of the development of ‘rope‐wick’ and comparable devices in North America and Europe is described. The range of designs is considered and their uses, advantages and disadvantages in large‐scale farming are discussed. Some of the major problems against which they are used in large‐scale farming should not arise in small‐scale farming, but the various ‘wipers’ could be of value for certain uses, particularly the safe application of herbicides to perennial weeds growing above or between crop rows. Some other potential uses are also noted which would be economic because the devices are much cheaper than hand‐held sprayers. Further developments in design are needed, however, to improve reliability of transfer of herbicide under varying conditions of climate and vegetation type.

ISSN:0143-6147    

DOI:10.1080/09670878309370769

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor