Although biconical traps are now widely used for the sampling of tsetse populations, they provide only relative population estimates determined by the fly density, activity and trap response. Studies were therefore undertaken to convert such biconical trap indices into unbiased absolute population density estimates. The first step was to determine the range of attraction of such traps for the main trypanosome vector in Kenya, Glossina pallidipes, although some data were also obtained for G. brevipalpis. Two different techniques were used. Firstly traps were placed at varying distances apart, resulting in competition and consequent reduction of catch sizes per trap when ranges of attraction overlapped. Secondly, the catches in grassland at varying distances from a forest edge were compared with two predicted functions relating catch size to distance. Results from the competition experiments showed a marked decline in catch per trap when the intertrap distance was less than 30–40 m. The resultant estimate of maximum range of attraction of 15–20 m for G. pallidipes was compatible with the observed pattern of decline of catches at increasing distances from the forest edge. The range for G. brevipalpis was tentatively estimated as up to 10–15 m.

Use of synthetic organic chemical pesticides introduced after World War II has resulted in a number of health, environmental, and socioeconomic problems discussed here. Both developed and developing countries have been affected. The problems in the developing countries of the tropics came about largely because of an error in transfer of technology. Pesticide technology developed by and for use in the developed countries was exported to countries with cultures and social structures that were not prepared to absorb this technology. Integrated pest management (IPM), an approach that reduces pest damage to tolerable levels through a variety of techniques, including natural enemies, genetically resistant crops, environmental modifications, and, when necessary and appropriate, chemical pesticides, represents an important trend toward rational management of crop pests in the developing countries. However, simply exporting IPM ‘packages’ from developed to developing countries would also be an error in transfer of technology. Each situation must be evaluated individually under actual farming conditions, and the IPM program must be tailored for the particular group of intended beneficiaries. Some of the interrelated social, attitudinal and institutional factors that should be evaluated are discussed.

Temperature-time and temperature–velocity equations are given for egg, larval and pupal stages of the sorghum shootfly, Atherigona soccata. Preimaginal development (from egg deposition to adult emergence) on sorghum CSH-1 seedlings lasted 19.5, 26.3, 33.8 and 76.8 days at 30, 25, 20 and 15°C, respectively. The sorghum shootfly showed optimal development and survival at 30°C. Lower threshold temperatures were 13.8, 10.2 and 11.8°C for the egg, larva and pupa, respectively. Host plant condition affected larval development and survival; pupal weight was higher and larval mortality lower in insects reared on fertilized and normally watered seedlings than on unfertilized and water stressed seedlings.

Cowpea is one of the most widely grown leguminous crops in Africa: in Kenya it occupies over 66,000 ha and Coast Province ranks second to Eastern Province with about 5200 ha. It is an important food item consumed both as a vegetable and as a grain. Unfortunately, it suffers from both preharvest and postharvest infestations which accounts for serious losses of the crop. With the introduction to Kenya of improved varieties from IITA, Nigeria, such losses would be increased due to varying susceptibility in different pest ecosystems. The objective of this study therefore was to observe the infestation of the IITA varieties and compare them with local cowpea varieties collected from different parts of Kenya. The work was conducted at C.A.R.S., Mtwapa from 1979 to 1981 inclusive. From the study, five different bruchid species were identified as infesting cowpea varieties in the field. These were Collosobruchus rhodensienus; C. phaseoli; C. chinensis; Bruchidius atrolineatus; and C. analis; in order of decreasing abundance. Over 50% of the bruchids found in the field were C. rhodensienus while Zabrotes spp. and C. maculatus (F) were never encountered in the field. Although the IITA materials were introduced because of their yield potential, it was found that some of them were as susceptible to preharvest bruchid attack as the locally available materials. The short rains season had more bruchid infestations than the long rain season. There were also fewer eggs on pods of local varieties and fewer bruchids emerging from seeds of local as compared to IITA varieties. The results however were not significantly different. Further work should be done to establish the complex of bruchids found in stored cowpea varieties, the losses caused and control measures applicable to reduce damage.

In West and Central Africa attention has recently been drawn to the role of commercial crop plantations in the creation of new tsetse habitat, and the problems this poses to trypanosomiasis control. Reported here is the colonization by the tsetse, Glossina pallidipes Austen, of a plantation of a very different kind—exotic coniferous forest. This has been observed in two localities in Kenya: the Lambwe Valley in the west, and the Shimba Hills near the coast. The features of this habitat, and the factors associated with its exploitation by tsetse, are described, with particular reference to the Lambwe Valley situation. While extension of tsetse fly-belts by afforestation practise is unlikely to be a problem of widespread significance in Kenya, afforestation policy ought, in particular circumstances, to take into account the tsetse and trypanosomiasis situation, the Lambwe Valley being a case in point.

An analysis of the variation of fore-, mid- and hindgut contents in third- to sixth-instar nymphs of the African grasshopper, Zonocerus variegatus, freshly caught every hour in the field, and also left without food for 1, 6 and 12 hr, showed that gut motility and the movement of ingesta through the gut was maximal at 08.00–10.00, 13.00–14.00 and 16.00 hr. Movement of ingesta was very slow at night. A diurnal rhythm therefore governs gut emptying. Nymphs, confined in jars with leaf discs, fed from 07.00 to 19.00 hr over the temperature range 17–34°C. Most food was eaten after 13.00 hr when it is warmer. Field insects feed during the night as well. Midgut α- and β-glucosidase activity was detected at all times of testing (06.00, 12.00, 19.00 and 24.00 hr), but the levels of activity were lowest at 12.00 and 19.00 hr.

Between 1984 and 1988, a survey of fruit-infesting ceratitid fruitflies was conducted in 11 agricultural districts in Kenya. Samples of up to 18 different fruit crops were examined for infestation. The four species of fruitfly found were Ceratitis capitata, C. rosa (Pterandrus rosa), C. nigra (Trirhithrum coffeae) and C. cosyra (Pardalaspis cosyra). The first three were sympatric infestants of coffee, while the latter was exclusively found in mangoes. In addition, C. rosaalso infested loquat, guava and custard apple. C. capitata infested commercial orange cultivars. This species was predominant in the main arabica coffee growing areas in the central highlands. C. rosa and C. nigra were more widespread, occurring in high proportions in most parts of the country. Generally, the proportions of the three species per coffee sample, and the mean number of each species per kg of coffee, tended to vary considerably over time and space.

Resting site preferences of the tsetse Glossina morsitans submorsitans Newstead were studied in a savanna woodland and gallery forest in the Northern Guinea Savanna of Mali. Five site-types [boles, fallen logs, undergrowth (‘bushes’), branches and tree canopies] were observed. Flies alighting to rest on these site-types were trapped on tanglefoot. Observations were made in the warm rainy, warm dry and hot dry seasons.

Boles were dominant as the preferred resting sites in the savanna woodland in all seasons; fallen logs were the next preferred site-type, while few flies were collected from the undergrowth, branches and tree canopies. Approximately 90% of flies on boles were collected below 1.0 m and none were found above 2.5 m.

During the hot dry season in the gallery forest, the undergrowth was the most preferred site-type; unshaded undergrowth accounted for approximately 98% of all flies on the undergrowth. Fallen logs and boles were the next preferred site-types; branches and tree canopies recorded very few flies. Probable reasons for the results obtained and the importance of these results in tsetse control operations are discussed.

The queen's fresh weight can be deduced from her external dimensions, or less accurately from the size of the royal cell in the case of single queens. Cell shapes and methods of enlarging the cell are described.

Stem-borer incidence on upland and irrigated rice varieties is compared under natural or artificial infestation, and with simulated damage by sectioning tillers. In the early stages, Diopsids lay more eggs on irrigated varieties, but these are less suitable for the development of Diopsids larvae than upland varieties, whose stems are thicker.

Some varieties of Oryzae glaberrima show a high level of resistance to stem-borers and Hispids. Little difference is noticed for antibiosis of the Oryzae sativa studied, and losses depend on the tolerance of varieties. Irrigated varieties have a better tolerance because of their high tillering, preventing the attack, and of their ability to compensate for early losses by producing new tillers. This compensation does not exist for upland varieties. Their tolerance depends on tillering rate, the ability of infested stems to produce fertile panicles, and the difference in productivity between primary and secondary tillers, the former being more frequently infested. For the same population of stem-borers, losses observed on upland rice are three times lower on tolerant varieties than non-tolerant ones.

The study of the population dynamics of Helicoverpa armigera (Hübner) in Cicer arietinum (chickpea), Lycopersicon esculentum (tomato), Abelmeschus esculentus (okra) and Zea mays (maize) crops revealed that the insect passed through five overlapping generations in a year. The growth of the population of H. armigera and its generation survival were maximum in second generation followed by fourth, third, fifth and first generations. Parasitoids, predators, fungal and viral diseases and abiotic factors were among the various observed mortality factors, although the role of predation was not specifically investigated. The key mortality factor within generation was an unidentified pupal parasitoid. The key mortality factor operating between generations was the variation in natality (log of ratio of maximum potential natality and actual eggs). In spite of the biotic mortality factors operating on H. armigera populations, the number of eggs laid is the most important factor that governs the trend of the population growth in all generations. Therefore, a powerful control measure is necessary by either trapping the adult moths or by cultivating trap crop to distract egg laying for those crops to be protected.

Indoor-resting blood-fed Anopheles gambicie s.l. were collected from selected localities in Ethiopia. Anopheles arabiensis was the only sibling species identified. Paracentric chromosomal inversion polymorphisms were observed on the 2R and 3R arms. A significant excess of heterozygotes was obtained in samples from Siile carrying the 3Ra inversion. Similarly, significant variation was seen in the frequencies of the 3Ra inversion between the study localities. The observed intraspecific inversion polymorphisms relative to indoor resting behaviour are discussed.

FAO's role in integrated pest management (IPM) in Africa has many components. Broadly speaking, it is the promotion of IPM in member countries, done within the context of strengthening plant protection in general and under the guidance of the FAO/UNEP Panel of Experts on Integrated Pest Control.

Activity areas undertaken by FAO which have links with IPM, include:

Awareness, creation and promotion of IPM

Organizes meetings, seminars, workshops, etc. to discuss and present results obtained in field projects; participates in meetings organized by other organizations; prepares publications on IPM in general, or on specific components of IPM, and on results obtained in field projects; and prepares teaching and training materials on improved plant protection and IPM.

Infrastructure

Sets up or strengthens plant protection services or plant research institutes to make them functional, giving due consideration to regulatory functions; gives training in improved plant protection at all levels within the framework of the field programme.

Development

Develops appropriate pest control measures in line with the IPM strategy.

Implementation

Conducts field projects to strengthen capabilities in plant protection at the national level; conducts IPM implementation projects and plant production/protection projects.

Policy development

Convenes regular meetings of statutory bodies (various panel meetings); convenes meetings or expert consultations on special topics; advises member countries on strategies to increase capabilities in plant protection.

Co-ordination

Convenes donor meetings; co-ordinates donor activities and inputs; conducts regional or global activities on specific topics such as quarantine, pesticide residues, etc.

Screen house studies on the incidence and yield losses in three cowpea (Vigna unguiculata) varieties, TV × 3236, Ife Brown and Ife Bimpe due to the leaf beetle Ootheca mutabilis Sahl were carried out. Artificial infestation was done at two growth stages of cowpea: the 5-leaf stage (2 weeks after emergence) and 4 weeks after emergence. Variety TV×3236 was found to be the least susceptible, while var. Ife Bimpe was the most susceptible to leaf beetle damage. Young plants were more susceptible than older ones.

Flowering was delayed in plants infested with beetles and the extent of defoliation had a pronounced effect on the yield of cowpea.

The percentage grain yield loss ranged from 19.48% to 59.77% depending on level of beetle infestation, variety and age of the plant at infestation.

The coffee berry borer, Hypothenemus hampei, which originates from Africa, is one of the most serious pests of commercial coffee and is now present in most of the major coffee growing parts of the world. Quite recently, this beetle spread into Mexico and Ecuador and is now causing serious economic losses in these two countries. In 1985, a classical biological control programme was started to control the pest using the bethylid, Prorops nasuta and other hymenopterous natural enemies from Africa. During the programme, various studies were conducted in Kenya on P. nasuta and H. hampei including their field distribution and life history. A technique of rearing and screening P. nasuta against plant diseases was developed and several shipments have now been made to Ecuador and Mexico. In 1988 a continuous laboratory culture of P. nasuta had been established in Ecuador and the wasp was also reported to be reproducing in sleeves cages in the field.

The introduction of high yielding sorghum hybrids in the mid-1960s indicated that the new cultivars were highly susceptible to insect pest attack. Use of chemicals for the control of the snootily, Atherigona soccata (Rondani), became necessary to realise a full yield potential.

This paper briefly reviews the earlier work on conventional foliar sprayings and dustings of the available insecticides which generally failed to give an effective control of the shootfly.

Work carried out in the early 1960s showed that the application of phorate, disulfoton, aldicarb and carbofuran granules in the soil at the time of sowing was very effective in controlling the pest. Recently two more insecticides, viz. isofenphos and fensulfothion have been found to be equally effective. However, the cost of applying these insecticides is rather high.

Seed treatment with carbofuran at 5 parts a.i. per 100 parts of seed proved to be highly effective and economical. It is now being widely used by farmers in the major sorghum growing area of the country. It has been found that dosage of carbofuran can be further reduced by using a 6:4 mixture of treated and untreated seed.

Trials have been conducted to determine the residues of effective insecticides in the soil and in plants at different intervals. Investigations have also been carried out to establish the correlation between the residues of different insecticides in plants and their efficacy in controlling the shootfly. A future strategy for the chemical control of the shootfly is outlined.

In a screen cage study, the pattern of flower and pod development at the various flowering nodes of three cowpea varieties with known susceptibility to the pod-borer Maruca testulalis, was mapped out. The period of flower opening over the whole plant spanned an average of 13 days in TVu946, 17 days in ICV-2 and 18 days in Vita-1 with 85–100° of the pods retained to maturity coming from flowers opening within 8 days of anthesis. The efficiency of pod production from open flowers was highest in TVu 946 (54°), lowest in Vita-1 (11°) and median in ICV-2 (31°). However, as a consequence of the individual pod size, the overall pod and seed characteristics in decreasing order were Vita-1, ICV-2 and TVu 946. The bulk of flowers and pods on the plants were produced at the basal plant nodes where primary branches were developed.

Pod elongation and enlargement were initially rapid in all varieties, but the TVu 946 pods reached physiological maturity 2 days before the other two varieties. The eventual pod size and rate of pod growth appear to be important factors in the susceptibility of cowpea to the pod-borer attack.

This paper considers the status of pests and pesticides in Mauritius, including pesticide legislation and flow.

Climatic factors, namely altitude, temperature and rainfall, influence the spatial and seasonal distribution and population dynamics of economically important pests as well as their hosts (crops and livestock). The case histories of a few selected pests (leaf miner, fruit flies, stable flies), their control measures as well as research efforts in this connection are reviewed.

An appraisal is also made on some aspects of pesticide legislation along with the distribution pattern of pesticides, in relation to pesticide management. The setting up of a recent Pesticides Management Advisory Committee is regarded as a move in the right direction to safeguard pesticide misuse and abuse. Food crop production is at the expense of huge pesticides input. A series of recommendations are made with a view to improving pesticide practices in the country.