The red locust, Nomadacris septemfasciata (Serville) (Orthoptera: Acrididae), is a threat to agricultural productivity in Malawi. The country has a single known red locust outbreak area, the Lake Chilwa flood plains in southern Malawi, in addition to several other areas where the locust occasionally breeds. Activities of the red locust in Malawi during the period 1988 to 1998 are discussed. Four major outbreaks occurred during the period—in 1993, 1995, 1996 and 1997. Control of these outbreaks was conducted by air except for the 1995 outbreak in Mpatsanjoka River Valley which was controlled by spot treatment on the ground. The use of both a helicopter and a fixed-wing aircraft, where the helicopter locates locust swarms and their concentrations and guides the spray aircraft, appears to be the most efficient and effective strategy for controlling locust outbreaks in Malawi.

In the forest zone of Côte d'Ivoire, Vavoua's traps and supports treated with pyriproxyfen® (Sumitomo) have been tested against Glossina palpalis palpalis. The supports were impregnated one time only at the dosage of 2 mg/cm2.

This juvenile hormone mimic acting as growth regulator has a good efficacy: apparent density was reduced by 87% after 2 months and was maintained at this level for 150 days; percentage of nulliparous females was equal to 0 between 40th and 120th days.

Pyriproxyfen may be recommended for the control of animal trypanosomiasis vectors—if it costs less than the insecticides; its slow effect on tsetse population does not favour its use for the control of human African trypanosomiasis which needs a drastic and immediate reduction of Glossina densities.

Entomopathogens have been isolated and developed for the control of various lepidopteran, coleopteran, dipteran, hymenopteran, homopteran, and even acarine pests. Among the orthopteran pests, the acridid defoliators are important in Africa, and the periodic outbreaks of the desert locust, Schistocerca gregaria; red locust, Nomadacris septemfasciata;migratory locust, Locusta migratoria migratorioides and brown locust, Locustana pardalina; as well as numerous grasshoppers, cause extensive crop losses. Laboratory and field tests carried out on control of locusts and grasshoppers using microorganisms have shown that there are key candidates which could be used for the management of these acridid pests.

A large and varied group of insects attack crops of the tropical farmer, and carry various disease-causing organisms to him and his animals. The control of these agricultural pests, and vectors of human and animal diseases relies mostly on chemical pesticides. However, investigations show that alternative methods such as biological control and resistant crop varieties are available, which may be used in the reduction of pest infestation, resulting in an Increase in food production by the African farmer.

Bruchid beetles cause high losses of stored legumes in the tropics. Chemical control is inappropriate for the small scale farmer and the use of alternative measures should be encouraged. Different biological methods of control such as cultural, physical, varietal, biological, biorational and genetic control are reviewed. Cultural control techniques such as timely and frequent harvesting, legumes planted away from granaries, crop hygiene and storage in pods, are within the technical and financial means of the small scale farmer. The use of inert substances, vegetable oils and repellent plants may be cheap and effective if properly managed. The use of controlled atmosphere, vacuum, heating, cooling and sterilizing, requires relatively advanced techniques. Growth regulators and pheromones are currently not available for control. Varieties resistant to bruchids have been identified, but incorporation of resistance into suitable varieties has proven to be difficult. Biological control of bruchids should receive more attention in particular research on the introduction and conservation of natural enemies. To effectively implement control measures at farmer's level socio-economic and cultural aspects should be taken into account. Proven appropriate techniques should be combined in an overall integrated pest management strategy.

The paper reviews the work done on the population patterns of Chilo spp. in relation to the phenological stages of sorghum, maize and millets. The stem borer Chilo partellus entered sorghum and maize crops at 2–3 weeks after emergence and continued till harvest. There were 3–4 peaks of larval population during a cropping season. Such studies not only reveal the relationship between the larval population density and the phenological stage of the plants at infestation time, but are also helpful in scheduling and timing pest management strategies.

Chilo species constitute one of the three major lepidopterous rice stem borers in Africa and their occurrence stretches across the different rice ecosystems; two major species, C. zacconius Bles. and C. diffusilineus (J. de Joannis) are found in West Africa, while C. partellus (Swinh.) and C. agamemnon Bles. appear to be the predominant species on rice in East and North Africa, respectively. A brief note is given on some aspects of the biology, especially the life history and behaviour of C. zacconius. Control measures are discussed as well as an integrated approach towards management based essentially on growing resistant varieties, conservation of natural enemies and adjusting planting dates.

Field and laboratory evidence now suggests that the African armyworm, Spodoptera exempta, is specifically adapted for survival at low population densities, providing a new basis for understanding the significance of its phase polyphenism and migratory strategy. This conclusion allows deductions to be made as to the expected extent of displacement of flying moths from low and, when they occur as a result of impeded or inadequate dispersal of parent moths, high density populations. The proposed migratory strategy which depends on the genetic determination of flight potential also provides a framework for interpreting observed patterns of armyworm outbreaks through the season and in relation to rainfall. Traits associated with a low-density, “armyworm” strategy are shared by other Noctuids which may have similar life histories.

The serpentine leaf-miner Liriomyza trifolii is a new proliferous and polyphagous agricultural pest in Mauritius, attacking crops, ornamentals and weeds. Urgent chemical control measures had to be developed in order to save total crop loss, in particular potato, tomato, haricot beans, crucifers and onions. This insect is resistant to most insecticides. In view of formulating an integrated management programme, this paper reports on some aspects of practical importance concerning the biology and ecology of the leaf-miner, the incidence of damage, and the possibility of its control by natural plant products such as extracts of neem (Azadirachta indica). Steam distillates of neem leaves seriously affect larvae and pupae upon treatment by contact at as low a dose as 0.3% of the extract. Field treatments of onion plantations with aqueous neem extracts (0.5%) gave good protection to the crop. The current control measures are briefly considered.