The special circumstances of plant protection in tropical developing countries, particularly in Africa, are considered within the context of the needs of the preponderant rural farming community, and in respect of food production. The problems are exacerbated by the existence of complex cropping systems (intercropping), the abundance and diversity of pests, the meagre knowledge of the plant-host-pest relationships, and the poor availability of the scientific understanding of the components of pest control and inputs essential for integrated pest management. Institutional innovations, including stepped-up professional training of experts in the field of plant protection, are required to usher in a more sustained effort in efficacious plant protection in these regions. Attempts in this direction are briefly discussed.

The importance of rice in West Africa and the problem posed by pests were highlighted. Stem-borers are regarded as major insect pests of rice and available information on yield losses attributable to insect pests in general and stem-borers in particular, was reviewed. Damage caused by stem-borers usually results in “dead hearts” and “white heads” though other effects including a synergistic interaction between stem-borers and rice blast have been recorded. Survey methods and sampling of rice stem-borers were discussed and brief descriptions on distribution, behaviour and biology of the major rice stem-borers namely, Chilo spp., Maliarpha separatella, Scirpophaga spp., Sesamia spp. and Diopsis spp. were given. Current control tactics under investigation in West Africa include chemical, cultural and biological methods.

The ecology of the red locust, Nomadacris septemfasciata Serv. in its outbreak areas plays an important part in the survival of all its developmental stages. Some of the important ecological factors affecting the multiplication and formation of red locust swarms are described briefly. Different methods of controlling the red locust are discussed including ecological, biological and chemical methods. It is concluded that the various control methods play some part in regulating the locust population but at present, when the populations are high, only the chemical method is capable of reducing the population to acceptable levels. The ‘preventive control’ now used to control the red locust is effective and takes advantage of the biology and the ecology of the red locust in the outbreak areas.

Moths of the genus Anaphae (Lepidoptera, Thaumetopoeidae) cause skin eruptions in Africa, conveniently called ‘papillonite’ or Lepidopterism. The hairs or ‘flechettes’ of adult female moths may be responsible for this disease. The morphology of the urticant apparatus of the moths, Anaphae venata and A. panda, has been studied with the scanning electron microscope. In these two species, the ‘flechettes’ are implanted in individual sockets. Although their morphology is identical, their size is different in A. venata and A. panda. Morphological differences with other urticating species of the genus Hylesia (Saturniidae), are discussed.

Efficacy of olfactory attractants incorporated in biconical traps to enhance the catch size of Glossina pallidipes Austen was investigated. Preliminary studies considered the effectiveness of a mixture of waste products from buffalo (Syncerus caffer) and that of warthog (Phacochoerus aethiopicus). The results were compared with the known tsetse olfactory attractants, carbon dioxide and acetone. When the waste product components from buffalo were used in the traps separately, buffalo urine was found to be by far the most effective. This component, used in its natural state inside the trap, increased G. pallidipes catches almost 10-fold when compared with the control catch.

Greenhouse studies were conducted by artificially infesting potted rice plants with first instar larvae of Maliarpha separatella and Sesamia botanephaga Tarns and Bowden at two stages of plant growth, namely: early tillering stage and at the booting stage. Early infestation by M. separatella resulted in reduction of plant height and the number of filled grains. At the booting stage, the number of filled grains and their weight were higher in uninfested plants. Infestation by S. botanephaga at both stages of plant growth mainly affected the number of productive tillers. Grain weight was unaffected. Field studies on individual hills gave erratic results and there were instances when hills containing tillers bored by M. separatella produced higher yields than unattacked hills.

Whole body tick collections, carried out at 6-day intervals for 2 months at Nisheishiba, showed significant differences in tick counts between three breeds of cattle. Crossbred (Bos taurus × B. indicus) cows carried 4.5 times more ticks (mean tick count 70.5 ± 84.8) than the B. indicus Kenana (mean tick count 16.7 ± 24.4) and Butana cows (mean tick count 15.0 ± 18.4). In all cases, the SD's were larger than the means reflecting the usual wide variability in tick numbers between individuals. Significant differences also existed in the degree of engorgement achieved by female Hyalomma anatolicum anatolicum ticks on different breeds of cattle. The weight of detaching fully engorged females feeding on Kenana and crossbred cattle was 374.8 mg and 422.0 mg respectively. This was reflected in the amounts of eggs laid by the females which were 191.3 mg for the Kenana-fed ticks and 261.1 mg for those from the crossbreds. The resulting larval challenge from the crossbred-fed ticks was 36.5% greater than from the ticks fed on Kenana cattle.

The body weight of the host was considerably reduced on attack by the parasitoid, Apanteles glomeratus Linnaeus. It varied from 466.65 ± 87.78 mg to 177.94 ± 52.01 mg. Average weight of the parasitoids per host was 268.54 ± 80.86 mg and individual parasitoid weighed 3.12mg. There was a reduction in the total body lipid: from 8.85 ± 1.27% (wet wt) in the normal caterpillar to 1.93 ± 0.42% in one batch and to 5.16 ± 0.80 in another batch of infected caterpillars. The haemolymph protein content of the host also showed a reduction from 9.89 ± 1.29 to 3.59 ± 0.76%.

Fleas are vectors of bubonic plague, murine typhus and several other rodent borne diseases. As with other vectors of medical importance there is widespread insecticide resistance among the flea population. In our efforts to find alternative insecticides 20 plants were screened for their pulicidal properties by obtaining extracts from these plants. It was observed that extracts of plants Acorus calamus, Allium sativum, Anona Squamosa, Brassica nigra, Croton tiglium, Ocimum sanctum, Piper nigrum possessed pulicidal activity.

Decrease in trehalose (40–60%) and total sugar (58–68%) content was observed in both sexes of ageing Callosobruchus maculatus. The variations in the level of trehalose and total sugar with age, suggest that these serve as energy sources responsible for the maintenance of metabolism in the process of ageing in bruchids.

The African armyworm, the larva of the night flying moth Spodoptera exempta (Walk.), feeds on young stages of cereal crops, sugar-cane and all types of grasses in some 30 countries of Africa, from Mauritania and Senegal in the north-west to Ethiopia and Somalia in the north-east, and southwards to Namibia and South Africa. Between 1960 and 1982, outbreaks of armyworms were recorded regularly in East Africa during the ‘outbreak season’ between November/December and June/July, often from southern Tanzania towards the north or north-west at monthly intervals. Analysis of occurrence of outbreaks in Tanzania, Kenya and Uganda in the 1971/72–1973/74 seasons, and rainfall records in Tanzania for 1969–1975, showed that the occurrence of armyworms in Tanzania coincided with the onset and northward progression of the rains up to Kenya and Uganda. Additional results from monthly maps, tables, graphs and histograms of armyworm occurrences in administrative units (Districts and Provinces) in Tanzania, Kenya and Uganda for 20 years (1960–1979), showed that the onset, progress and duration of armyworm attacks in all districts and provinces in each country, tend to follow certain geographical patterns which can be monitored through the use of insect traps and Agricultural Extension Services. In this way, coordinated surveillance of priority areas could enable farmers, pastoralists, Plant Protection and Pest Control Units of the Ministries of Agriculture to identify likely areas and periods of armyworm attacks, so that they could organize strategic or emergency control of armyworms with insecticides when the larvae are still young.

Bendiocarb 80WP, applied at 1 and 2 g/m2, was compared with BHC 30WP, applied at 0.5 g/m2 of gamma isomer, for the control of the important Chagas' disease vector Triatoma infestans, in Brazil. The insecticides performance was evaluated in groups of about 20 heavily infested, mud- or adobe-walled houses selected on the basis of pre-spray sample data. These houses, together with a check group of untreated, infested houses, were sampled for the presence of T. infestans pre-spray and at 1, 3, 5, 7 and 9 months post-treatment employing a systematic search technique with the aid of a flushing-out agent. This method was found to detect infestations in from 71 to 95% of the samples taken in groups of infested, untreated houses. Treatment with bendiocarb 80WP at 2 g/m2 resulted in the elimination of T. infestans from 40 to 50% of the infested houses, whereas BHC 30WP at 0.5 g/m2 reduced the number of infested houses by 70–80%. In the houses where the bugs were not eliminated the populations were markedly reduced in size by the insecticides, but became reestablished by 5 months post-spraying. Detailed analysis of the field trial sample data together with the results of a simple laboratory experiment suggest that although bendiocarb WP powder may be intrinsically more toxic to triatomines than BHC WP, it is less persistent when applied in house largely constructed of mud.

The effect of five juvenile hormone analogues (JHAs) on the embryonic development of Panstrongylus megistus, a vector of Chagas' disease, was studied. Four compounds, N-(2,5-dichlorophenyl)-3, 7-dimethyl-2™6-octadienylamine, N-(5-chloro-2-methylphenyl)-3, 7-dimethyl-2, 6-octadienylamine, 3,7-dimethyl-6, 7-epoxy-l-(3,4-methylenedioxyphenoxy)-2-nonene, and 6, 7-epoxy-3-ethyl-7-methyl-l-(3, 4-methylenedioxyphenoxy)-2-nonene, which are potent JHAs for P. megistus, were effective in blocking eclosion when applied at 0.5μg/egg to eggs during the first half of embryonic development. If these compounds were applied after the start of blastokinesis, then they were no longer active as ovicides. The possibility is raised that JHAs may be useful as control agents in complementation with insecticides which do not possess ovicidal activity.

The effects of population density on nymphal development and mortality, synchronism in moulting, body weight and reproductive development of ensuing adults were studied in Dieuches femoralis Eyles. The development time of larvae was found to vary with density such that the development time decreased as the number of larvae per cage increased through 5, 10, 15 and 30. The most crowded cages also produced the heaviest adults and females from these cages developed the greatest number of eggs. The solitary larvae produced more females than males.