The probability of a Glossina pallidipes picking up an infection from a single blood meal in Lambwe Valley was estimated to be 0.0092 for Trypanosoma vivax, 0.0028 for T. congolense, 0.00097 for T. brucei and 0.00024 for the human infective T. brucei. In cattle, the prevalence of blood protozoa was Trypanosoma spp. 5.55%, Babesia spp. 2% and Theileria spp. 33.06%. Thirty-eight point three per cent of the cattle with trypanosomes also had Theileria spp., 2.12% of the cattle with trypanosomes also had Babesia spp. and 88.28% of the cattle with babesia had also Theileria spp.

Commercial cotton growing in the Sudan dates from 1867. At present, about 400,000 ha of various cotton cultivars are grown under different irrigation systems. The production of this main cash crop has been faced with a multitude of entomological and pathological problems, some of which were tackled through the adoption of specific cultural practices or enforcement of legislative regulations.

When cotton treatment with synthetic organic insecticides was initiated in the mid 1940s against Empoasca lybica de Berg, the impressive preliminary results have encouraged over-reliance on chemical control at the expense of other measures. This rather limited approach of control strategy has contributed partially to the appearance of new pests in damaging levels e.g. Heliothis armigera (Hbn.), Bemisia tabaci (Genn), Aphis gossypii (Glov) and Spodoptera littoralis. The principal measure for their control is insecticide application.

The cost of crop protection soared to ten-fold during the last 20 years. The annual number of sprays applied to cotton increased from one to seven sprays. To overcome the ever increasing use and high costs of pesticides on cotton growing, the Agricultural Research Corporation undertook intensive research programmes to find answers to major crop protection problems. Since 1978 researchers are directing their efforts towards the development and implementation of integrated pest management strategies to include cultural and legislative measures, as well as the use of more selective insecticides.

Lepidopteran stem borers account for heavy losses in cereals in areas where they are prevalent throughout Africa. Microsporidia, especially Nosema sp. may be developed for use in the management of this group of insect pests. Studies carried out so far show that the application of Nosema spores may increase yield up to 34% in sorghum when the plants are infested with Chilo partellus eggs and sprayed with the pathogen, and up to 80% in sorghum infested with borer larvae.

The procedure for spore production is simple, and may easily be adapted for small scale industrial production by local or regional communities and organizations. In trials aimed at the mass production of Nosema sp. for the management of C. partellus, a yield of 109 spores/larva has been attained. If this production level can be maintained, then a system that produces only 6000 larvae/day would yield enough cadavers for preparation of 6000 1 daily. At the rate in which the pathogen suspension is applied as foliar sprays in the field, this would be sufficient to treat 5373 ha. If widely adopted, use of microsporidia would revolutionize cereal stem borer management in the tropics.

In the present work, influence of food plants on different life table parameters of the parasitoid Trioxys indicus Subba Rao and Sharma was studied as affected through its host Aphis gossypii Glover. Age-specific survival of T. indicus on aphids bred on Lagenaria vulgaris was greater (7 days) than on Luff a cylindrica and Cucurbita maxima (4 days). The net fecundity rate, total reproductive period, intrinsic rate of natural increase, intrinsic rate of total fecundity and weekly multiplication rate of T. indicus fed on L. vulgaris was higher than on other cucurbit food plants. Doubling time of the parasitoid fed on L. vulgaris was lower than on other food plants, whereas the mean generation time of the parasitoid on L. vulgaris was slightly higher than on L. cylindrica but lower than on Cajanus cajan and C. maxima. All these measurements (considered indices of fitness of the entomophages) indicated that population growth pattern of T. indicus fed on L. vulgaris is faster than those fed on other food plants.

The potential of plant genetics in the overall context of integrated pest control could be viewed simply as the potential of plant resistance in pest management. Genetic resistance in plants is one of the most effective and economic means of controlling plant pests. Resistant plants are the first line defence against pests. Successes in breeding for pest resistance depend upon the sound knowledge of the plant genes controlling resistance to pests.

Recent report on the existence of two nonatlelic and independent genes, Rac1 and Rac2 in cowpea cultivars ICV 10 and TVu 310, and ICV 11 and ICV 12, respectively, from the ICIPE has broadened the scope of cowpea breeding against aphid biotypes. Use of biotechnology as a plant breeding tool in transferring resistance genes into agronomically suitable cultivars appears to hold good promise for the future.

Buprofezin treatment of brown planthopper, Nilaparvata lugens Stal. at sub-lethal doses resulted in the survival of individuals with varying reproductive potentials. From this reproductive potential of different stages, population build up of second generation was calculated. Logistic function was found to fit more closely the data on population growth at different concentrations. It could thus serve as a mathematical model for predicting the second generation population build up in a buprofezin treated population.

A range of materials were collected from a number of ecological and environmental zones within Kenya as being likely sources of entomopathogenic bacteria. These were soils, insect frass and dead insect material. Using an isolation protocol involving use of a selective medium, over 150 Bacillus thuringiensis (B. t.) strains were recovered from the sample material. Their identity as B. t. strains was confirmed by their growth characteristics, morphology and presence of a parasporal delta-endotoxin crystal.

All strains were screened for activity against two Lepidopteran pest species, the spotted stem borer, Chilo partellus and the African army worm, Spodoptera exempta. Isolates causing over 80% mortality in the screening assays were retained for further evaluation. The selected isolates were subjected to bioassay against C. partellus and S. littoralis. Following bioassay, the most toxic isolates were selected for screenhouse trials against C. partellus and field trials against a natural outbreak of S. exempta.

In the screenhouse trials all of the B. t. treated plants showed reduced levels of damage and yields were 5 to 7 times higher than the yield obtained from the untreated, infested control plots. Three isolates, A-3, A-C-2 (isolated from insect material) and M-44–2 (isolated from soil) seemed to offer superior levels of protection. Two new B. t. isolates, K-26–21 and MF-4B-2, both isolated from soils, showed high levels of toxicity to S. littoralis and S. exempta in the laboratory. When isolate K-26–21 was applied to maize seedlings in the field, almost total control of the larval population was achieved within 48 hr at each of the concentration levels tested.

Preponderance of Musca spp. and their accessibility to goat feeds and faeces containing Eimeria oocysts prompted an investigation into the role of these flies in the dissemination and/or transmission of goat eoccidiosis. Seventy per cent of the dissected 300 Musca spp. caught in the goat pens where faeces containing Eimeria oocysts were widely scattered, possessed the oocysts in their digestive organs, with the highest number found in the gut. When Musca spp. were induced to feed on faecal solution containing Eimeria oocysts, oocysts were recovered from the flies through regurgitation during subsequent feeding on glucose solution. At low concentrations of 300 and 500 oocysts per g faeces, substantial numbers of oocysts were recovered from the flies only up to 1/2 hr after feeding on the infected faeces; at higher concentrations, oocysts were recovered up to 2 hr. Results of other experiments also showed that the nurriber of flies in which oocysts were found and the number of oocysts recovered were highest when the flies were dissected immediately and 1/2 hr after exposure to infected faeces. The circumstances under which Musca spp, could sustain eoccidiosis and coccidiosis in a goat herd are discussed.

Studies aimed at setting up a system of rational control of pests were carried out at the Vallée du Kou rice irrigation scheme near Bobo-Dioulasso in 1986. The first part of the study focuses on the phytosanitary survey of the above mentioned rice irrigation scheme of 1043 ha through a network of observation sites. This part has given prominence to the fact that the development and importance of the pest infestation were affected by the spacing out of the rice planting and has also allowed us to locate the critical periods of the infestations and their economic incidence. These pests consist mainly of lepidopterous stem borers: Chilo sp., Sesamia sp., and Maliarpha separatella.

The second part of the study focused on phytosanitary experiments. Using Decis (Deltamethrin) at 12.5 g a.i. per ha at the intervention thresholds of 5% dead heart and 1% whitehead, has proved to be the most interesting formula as it combines efficiency and profitability.

The system of rational control that has been set up based on phytosanitary survey and insecticide application at threshold levels, presents a double advantage, it reduces the number and cost of interventions, and limits the anarchical use of pesticides, hence their harmful effect on the environment. Such experience in insect pest management will be extended to other rice growing areas throughout the country.

The first report on the entomopathogenic fungi in the tropics dates back to 1853. Despite their variety, little attention has been focused on their incidence on agricultural pests. Studies over the last 20 years in the tropics have revealed that entomogenous fungi (Deuteromycetes and Entomophthorales) may play an important role in natural control of arthropod populations. Therefore, the use of insect pathogenic fungi as pest control agents is promising.

An important consideration in developing an entomopathogenic fungus as a mycoinsecticide is the selection of the correct and well-adapted strain. New techniques in biotechnology will help in developing methodology for mass production and formulations. Other factors which can be considered, and which may be determinants on the potential of insect pathogenic fungi include the environmental conditions and cultural techniques (e.g. intercropping, planting density, irrigation). The cultural techniques can result in change of the environment favourable to the disease.

Three aromatic juvenoids were evaluated for morphogenetic activity on Schistocerca americana. Fenoxycarb, the most active insect growth regulator examined, was found to induce a significant mortality in developing fifth stage nymphs and caused severe morphogenetic damage during ecdysis to the adult. Juvenoid treatments were also observed to increase the duration of the last nymphal stage and to induce chromotropic colour changes similar to that observed in the solitary phase of the desert locust, Schistocerca gregaria Forskal.

Seven species of stored grain pests were found infesting underground storage pits “bakars” in the Bay Region of Somalia. These species and their relative abundance (%) in “bakars” are as follows: Alphitobius laevigatus (Fabricius) (Coleoptera, Tenebrionidae) (3.7%), Palorus subdepressus (Wollaston) (6.1%), Tribolium castaneum (Herbst) (29.2%); Rhizopertha dominica (Fabricius) (Bostrichidae) (23.9%); Sitophilus oryzae (Linneaeus) (Curculionidae) (4.7%); Cryptolestes ferrugineus (Stephens) (Cucujidae) (32.4%); Sitotroga cerealella Oliver (Lepidoptera, Gelechiidae) (unsampled). The mean percentage damage by insects for the region was 10.4 and by rats was 8.4 for sorghum grain stored as heads in 100 “bakars”. Actellic, K-Othrine and Malathion, applied as a 2% dust to threshed durra sorghum grain stored in sacks above ground, provided 99.2, 99.5 and 94.5% control, respectively.

Plant associations and rates of population interchange between two food plant areas for the armoured ground cricket, Acanthoplus speiseri Brancsik were investigated. A. speiseri was associated with 40 species of plants spread over 11 families. The ground cricket had a significantly high frequency of association at P = 0.05 with Rottboelia exaltata Linn. F. and Hyparrhenia nyassae (Rendle) Stapf. The ground cricket preferred members of the Gramineae to those of other families, 69% of the total number of ground crickets collected from the plants in this study were from grasses and among these Zea mays L. and Sorghum vulgare Pers. were opportunistic associations.

The rates of population interchange between two areas dominated, respectively, by Nicandra physaloides (L.) Gaertn. and R. exaltata with several species of Hyparrhenia were unequal. There was net emigration of 76.69 ground crickets to the N. physaloides area in 10 days.

The significance of the findings on plant associations and rates of population interchange between food plant areas of A. speiseri to future sampling and control of the ground cricket is discussed.

Spatial dispersion patterns of Acanthoplus speiseri were inestigated. Four indices of dispersion derived from either Iwao's measure or Taylor's Power Law were used to study spatial dispersion patterns. All indices were in agreement in identifying aggregated dispersion patterns in the cricket populations sampled. Iwao's index of basic contagion revealed that individual crickets formed the basic components in the aggregated dispersion of the populations.

An initial study of the extension service and pest control in Iganga district was made between 14 July and 20 August 1987. This was part of a more extensive on-farm study of pest control problems in the district. This study covered 36 small scale farmers randomly picked from the three agricultural sub-zones in the district.

It was observed that: (i) information on crop protection was scanty, (ii) the majority of the farmers were aware of the presence of pests on their farms, (iii) there is a minimal use of pesticides on small scale farms in the district, (iv) a number of pests occur in varying frequencies on small scale farms in the district and (v) the extension staff are still too few to handle even the general aspects of crop production.

Vegetable oil and palm oil were tested for their ability to suppress the populations of Rhyzopertha dominica Fabr. and Dinoderus distinctus Lesne on maize, sorghum and wheat grains using three dosages of 1 ml/kg, 5 ml/kg and 10 ml/kg. A dosage of 5 ml/kg of each oil, completely protected the three grains from D. distinctus and R. dominica on maize grain. Vegetable oil at 10 ml/kg dosage controlled R. dominica on sorghum and wheat. Palm oil had a similar effect, but did not control R. dominica on wheat even at 10 ml/kg dosage. The populations of R. dominica when treated with 1 ml/kg dosage were not significantly lower at 5% level than the control, with the exception of maize. Percentage weight losses of all grains at 5 ml/kg and 10 ml/kg dosage were significantly lower at 5% level than the control. Oil treatment did not significantly affect the germination of grains and protected the grains from the two pests for only 3 months. The highest population of R. dominica after 2 months of reinfestation was 67 and the highest mean population of D. distinctus was 1.4. The use of vegetable oils in the management of insect pests in storage is discussed.

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.

Insect pest problems on cowpeas can be reduced by use of strategies which involve ecological manipulations. These include crop diversification (mixed cropping, etc.), alteration of planting dates, crop rotation, trap-cropping and weed control. The merits of these cultural methods of pest control are discussed.

The status of biological control of cowpea pests is still low but promising. The crop is an annual and therefore offers very limited possibilities for the application of the classical biological control techniques. However, a large number of parasitic Hymenoptera, Diptera and predatory Hemiptera, notably Reduviids have been identified in the cowpea ecosystem. Ecological studies of some of these have been carried out and levels of parasitism determined in a few cases, but their significance in the dynamics of cowpea pest populations have not been fully established.

It is however known that conservation of parasites and predators in their wild environment is one of the traditional biological control methods. Therefore, a rationalized pesticide programme for the control of cowpea pests should aim at preventing hazards to their natural enemies so as to increase their biocontrol efficiency.

Effect of fluctuating and constant temperatures on different population growth parameters of Chilo partellus (Swinhoe) infesting sorghum was studied in the laboratory. On the basis of intrinsic rate of natural increase (rm) values, the optimum constant and fluctuating temperatures for the multiplication of this pest was 30 ± 1°C and 31.0 to 35.8°C, respectively. But the favourable range of temperature varied from 27.5 to 30.0°C under both constant and fluctuating temperature conditions. Mean length of generation (T) at this range of temperature varied from 38 to 41 days. It seems that Chilo partellus may not persist at or above 40°C and below 20°C, as the rm values at these temperatures were negligible or zero. This information can be used in working out the strategy for controlling Chilo partellus.

Data from regular field samples throughout the life cycle for five generations of the legume pod borer, Maruca testulalis on cowpea crops at one site, and three generations at another, were used to construct life tables and through key factor analysis to determine the key mortality factor. The total mortality from egg to adult was 98.4–98.6% at site 1 and 98.2–99.4% at site 2. At both sites the highest mortality occurred between the eggs and the third instar larvae, whilst the fourth instar larvae suffered the lowest mortality. The commonest cause of mortality was classified as disappearance, followed by disease. Parasitism contributed minimally to M. testulalis mortality. At site 1 disappearance at the egg stage was the key mortality factor and was significantly correlated with the total generation mortality. At site 2, disappearance operating at the larva 1 and 2 stage was tentatively identified as the key mortality factor. The data from site 1 showed no significant correlation between population density and mortality at the same stage. This study provides the first detailed analysis of M. testulalis populations and should contribute towards developing control strategies for this important pest of cowpea.