Ctenocephalides felis adults obtained from young goats belonging to the Faculty of Veterinary Medicine (SUA) were reared in captivity and the offsprings used for testing against permethrin. A total of 1260 fleas were exposed to 0.005% permethrin dust (0.5% a.i. diluted with fine sand) for periods varying from 30 min to 24 hr. Additionally, white rats infested with 2400 fleas were exposed to a similar mixture for 24 hr.

In the first set of tests, 100% mortality was obtained after a 2-hr exposure of the insects to the insecticide. Similarly, in the second set of tests, all the fleas were found dead at the end of 24-hr exposure.

It was generally concluded that permethrin is very effective against this flea species and that it could be used for controlling the ectoparasite in livestock, animal barns and residential houses in the area. It was finally recommended that similar tests with other flea species in the country, especially in plague endemic areas were desirable.

Neem oil (NO), and different formulations of neem oil in a solution of Tetrapleura tetraptera as emulsifier, including neem oil emulsifiable concentrate (NOEC), neem oil slurry emulsifiable concentrate (NOSEC) and 5% NOEC obtained from the seeds of the neem plant, were tested for their efficacy in the control of Maruca testulalis Geyer, under laboratory conditions using flowers of Ife Brown, cowpea variety.

The different concentrations of NOEC (5, 10 and 20%) exhibited a high degree of insecticidal activity on M. testulalis larvae. All the treated flowers were protected from larval damage 2 days after treatment as compared to the 100% damage recorded on untreated flowers and on the flowers treated with T. tetraptera solution alone.

The NOSEC and the 5% NOEC prepared using different volumes of the emulsifier also exhibited some insecticidal activity which decreased with a decrease in concentration. NO/NOEC were superior to NOSEC and the 5% NOEC prepared in different volumes of the emulsifier.

Grainage parameters, viz. pupal weight, rate of moth emergence, fecundity and hatching were studied among four bivoltine pure races and their five single and four double cross hybrids of silkworm Bombyx mori L. The significant increase in double cross hybrids over pure races was 11.72, 7.43, 19.45 and 12.26% for pupal weight, rate of moth emergence, fecundity and hatching, respectively. The fecundity in double cross hybrids improved significantly over single cross hybrids to the extent of 16.03% whereas pupal weight, rate of moth emergence and hatching increased to the extent of 4.38, 5.90 and 5.76%, respectively.

The extent of standard heterosis and heterobeltiosis was maximum in double cross hybrids and the heterosis was more pronounced for fecundity.

The insecticide application techniques on cotton were compared in a series of trials. The new techniques compared well with knapsack sprayers and can play an important role in the control of Heliothis and other insect pests of cotton in Zambia. The ‘Electrodyn’ knapsack and ULV sprayers gave similar yields and pest control with cypermethrin at 30 g a.i./ha. A new pyrethroid lambda cyhalothrin (12 g a.i./ha) gave similar yields to cypermethrin (30 g a.i./ha) irrespective of the spraying techniques (Electrodyn, knapsack and ULV). The new application techniques have more potential for small-scale cotton farmers in developing countries as they receive limited training on the dilution of insecticides with water and calibration of knapsack sprayers.

An experimental microspodiosis has been stimulated within Heliothis armigera (Lepidoptera, Noctuidae). The microsporidian used was Nosema manierae, a natural parasite of Chilo zacconius (Lepidoptera, Pyralidae). Nosema manierae causes high mortality in the larvae and the nymphs.

The charged and partially discharged Electrodyn was evaluated at various swath rows of cotton. The results of field trials suggest that under a low pest pressure, a wider swath up to two or even more rows is possible, with the current version of Electrodyn sprayer, without any significant effect on the yield of seed cotton. Similar yields of seed cotton were also obtained with both charged and partially discharged Electrodyn.

The xerophytic perennial plant, Agave cantala Roxb. was studied for its biological activity on diamondback moth Plutella xylostella (L.). When cabbage leaves treated with acetone extract of A. cantala leaf were fed to the larvae in all instars, the extract was found to be weakly toxic at the highest concentration of 60 mg/ml, but it prolonged the larval and pupal periods, decreased the percentage of adult emergence and adult longevity. The fecundity and egg hatchability of adults emerging from final instar larvae fed with treated leaves decreased significantly. The eggs laid on treated leaves showed reduced hatchability.

Following the introduction in Congo of the cassava mealybug, Phenacoccus manihoti in 1973, a French Congolese team was set up to tackle the problem. The main results of the team's studies that aimed to the effectiveness of Epidinocarsis lopezi a parasitoid introduced in Africa from South America by IITA, are reported here.

The studies were simultaneously developed in the laboratory and in the field, In the areas of biology, physiology, behaviour and ecology of the Encyrtidae. These studies allowed the drawing up of a balance of its qualities and limits observed, its effectiveness in natural conditions and provide the opportunity to share some ideas on the use in Africa of the South American's auxiliary. The different areas of the studies are successively examined.

Increasing costs of tick control have necessitated a complete re-assessment of its economic impact. There are two main approaches to studies on production economics. Some researchers advocate a “systems approach” in which all production traits and their interactions are monitored simultaneously, whilst others claim that studies must produce specific data on selectively identified components in the system which can then be used in process/simulation type models.

Studies were carried out in Zambia using a farming systems approach to quantify the effects of tick control on traditionally managed Sanga cattle. It seems that this decision was justified, because it is evident from the results that the determinants of the effects of tick control are extremely complex.

Overall herd productivity, i.e. outputs of milk and weaner calf per livestock unit carrying capacity, was about 25% higher in a tick-free herd. However, the annual cost of control in 1988 at ZK286.26 per livestock unit was greater than the increase in value of the products at ZK175.48 per livestock unit carrying capacity.

From this study, the intensive tick control in this system is not justified in the absence of serious tickborne disease. However, the analysis of various interactions indicate that limited seasonal tick control of adults from November to April would be economically viable. Calves should not be treated until they are 3 months of age.

In the years prior to independence, farmers had access to the international market through the production of export crops which at that time received considerable input from research. Access to export crops has dwindled, support for research by national governments is disappointing, human resource development is inadequate, donor funding is uncoordinated, and the food crisis has taken on political dimensions. The assumption that direct importation of western technology can solve the problems of Africa is no longer valid in the face of several failures. The challenge to national agricultural research systems and the problems associated with the generation or adapting of farmer-oriented, location-specific technologies for sustaining agricultural production are discussed. Examples are drawn from India and an agenda for action, involving national governments, the international agricultural research centres and donors, in resolving these problems is presented.

The Integrated Pest Management (IPM) Programme under development at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) calls for a proper monitoring system. Experiments conducted in groundnut fields at ICRISAT Center near Hyderabad, in peninsular India, to establish the optimum height for pheromone traps to monitor Spodoptera lituta (F), indicated that the male flight pattern changes considerably during the cropping period. During the seedling stage (sowing to 6 weeks), most moths were caught at 0.5 and 1.0 m. In the initial growth phase (7–11 weeks), the traps at 4.0 m caught most moths. During the optimum growth phase (12th week to harvest) of the crop the traps at 1.0 m height trapped most moths. After harvest, the traps at 4.0 m again recorded the highest catch. These data are interpreted in terms of the migration pattern of S. litura moths during the crop season. We suggest monitoring this species, using 1 m height traps.

Males were found to be more active around 0300 hr, with a small peak after sunset (2000 hr). Irrespective of season, the peak flight activity of this species was around 0300 hr in groundnut fields.

A drop off rhythm of engorged Rhipicephalus appendiculatus Neumann was demonstrated for females and engorged nymphs, but not for larvae. Seventy per cent of 1279 engorged R. appendiculatus females dropped off the animals between 0800 and 1000 hr, while 66% of 2736 engorged nymphs dropped between 1600 and 1800 hr.

Females which were put on the animals at night (2000 hr), started to drop-off 24 hr later, than those put on in the day (0900 hr). Ticks which were fed on tick-sensitized animals also started to drop off 24 hr later, than those on tick-naive animals.

The implications of these results on tick control management are discussed.

Seven cowpea cultivars and a susceptible and two resistant checks were evaluated for their preference by Clavigralla tomentosicollis for oviposition and feeding under free-choice condition in the screenhouse and under no-choice in mesh cages. Female bugs had no distinct ovipositional preference for any of the test cultivars than the susceptible check. There was a distinct preference for egg laying on the undersurface of the leaves than on the other plant parts.

The susceptible check was more preferred for feeding by the bug than the other test cultivars. Thus, percentage seed damage was significantly reduced on the test cultivars than the susceptible check. There was no significant difference in percentage seed damage between the free-choice and the no-choice tests among the test cultivars except TVu 1890 (the resistant check) and Ife Brown (the susceptible check). The implications of the results are discussed.

Genetic analyses were carried out to determine inheritance of resistance, heterotic effects and reciprocal effects for resistance to the spotted stem borer, Chilo partellus in three maize crosses. Resistance was found dominant over susceptibility. Highly significant heterosis was detected for percentage dead hearts. Both additive and nonadditive gene effects were important in the inheritance of resistance to C. partellus in all crosses. Additive gene effects were highly significant for all the three resistance parameters: leaf-feeding, dead hearts and stem tunnelling. However, a high magnitude of nonadditive (dominance and epistatic) gene effects were detected for dead hearts. No cytoplasmic effects were detected in reciprocal crosses between resistant and susceptible maize lines, suggesting that the resistance to C. partellus is conferred only by nuclear genes. Recurrent selection methods should be used to accumulate alleles for resistance. Resistant F1 hybrids could be developed between resistant and susceptible lines in reciprocal combinations.

Food plant preferences and spatial dispersion patterns of the armoured ground cricket, A canthoplus speiseri Brancsik were investigated. The average numbers of the ground cricket found feeding on each food plant per transect in each of the three study areas were tested for differences at the 0.05 level of probability by Duncan's multiple range test. The variance/mean ratio was used to analyse spatial dispersion patterns. A. speiseri fed on 12 plant species from the Compositeae, Gramineae and Solanaceae families. Hyparrhenia nyassae (Rendle) Stapf., (Gramineae) and Rottboelia exaltata Linn, f., (Gramineae), were the most preferred food plants. The armoured ground cricket densities on the two food plants were insignificantly different from each other. The cultivated plants, Zea mays L., and Sorghum vulgare Pers., were fed upon opportunistically by the ground crickets. The variance/mean ratio identified aggregation in the armoured ground cricket populations in all three study areas . The significance of the findings on food plant preferences and dispersion patterns are discussed in relation to future sampling and control of A. speiseri.

Correlations were established between an endemic infestation of the coffee margorodid, Icerya pattersoni Newst and the characteristics of the veins of the leaves it infested in four coffee species in Kenya. The attack was variable between species although there was an affinity for it to be confined to midribs of definite length and thickness and laminal veins of quantifiable dimensions.

Thirty-six cowpea cultivars were evaluated for their resistance to the pod-sucking bug, Clavigralla tomentosicollis Stål, in the screenhouse and in field experiments. Absolute resistance was not found in any of them, although cultivars with relatively low percentage seed damage were present. Seventeen cultivars were significantly less damaged than the susceptible check in the field experiments. Seven cultivars had less than 60% seed damage. Of these, TVu 3354, TVu 3355, TVu 3372, TVu 8525 and TVu 3199 were the least damaged. Per cent seed damage on cultivars in the field was not consistent with that in the screenhouse, because of the influence of other pod-sucking bug species and environmental factors.

Yield components such as 100 seed weight and the number of pods per plant were related to the resistance of the test cultivars to the bug attack. Cultivars with smaller seeds and more pods per plant were less damaged. The number of seeds per pod was not related to the degree of seed damage. Similarly, morphological parameters of the cultivars were not related to the degree of seed damage.

Seven selected cultivare of common beans Phaseolus vulgaris L. were evaluated for resistance at two sites under different weather and beanfly population pressures in the field. The indices of resistance were the number of leaf punctures, eggs, larvae and puparia and per cent dead plants. Beanfly species, Ophiomyia spencerella (Greathead) and Ophiomyia phaseoli (Tryon) infested the bean plants in the field. There were seasonal differences in the response of the cultivare to beanfly infestation attributed to differences in the level of attack of the bean crop, being highest in the non-cropping season of 1985 and lowest in the long rains of 1985. Despite the variation in results, Gip 1004 and Gip x-92 showed some resistance on the basis of their least plant mortalities and low larvae/puparia surviving on them. When the beanfly population was high enough to cause death of the bean plants, percentage plant mortality was correlated to the numbers of larvae and puparia of beanflies and it may be the best parameter for resistance.

Students in the 2-year diploma course in crop protection at the CILLS (French acronym for “Permanent Interstate Committee for Drought Control in the Sahel”) Crop Protection Training Centre (Département de Formation en Protection des Végétaux) in Niger undertake laboratory or field research work on specific subjects under the supervision of resident lecturers. It is in this context that studies on the biology of the rice armyworm, Mythimna loreyi, were conducted in the laboratory on two host plants, maize and sorghum. The studies were conducted at a mean temperature of 27.01°C and mean r.h. of 41.65%. The egg-laying habits of the insect and parameters such as the length of the preovipositional period, larval and pupal developmental period and longevity of adults were studied. Larval developmental time was significantly shorter on maize than on sorghum, but there was no significant difference in the length of the pupal period. The preovipositional period ranged from 1 to 8 days with a mean of 4.32 days. There was no significant difference between the longevity of adult males and females.

The susceptibility of maize germplasm from CIMMYT — Mexico, Malawi and Zimbabwe — to attack by the maize weevil, Sitophilus zeamais (Motsch.) was investigated under controlled temperature (28°C) and r.h. (70–75%). An index of susceptibility (I), derived from the numbers of F1 progeny and the mean development period was used as the basis for measurement of the susceptibility. The indices of susceptibility of the CIMMYT germplasm ranged from 9.25 for Rattray Arnold (I) 8149 to 14.48 for Poza Rica 7737. Of the 17 collections of Malawi local maize evaluated MLM#20 was the least susceptible (I = 10.72), while MLM#24 was the most susceptible (I = 13.25). The least susceptible of the Zimbabwean germplasm was a local collection of an indigenous maize, Variety 8 (I = 10.61), while the most susceptible was a hybrid PNR 6334 (I = 14.74). Further, the nine Mexican materials and a local hybrid SR 52 were evaluated under field conditions in small farmers' granaries. Rattray Arnold (I) 8149 and Population 68 were the least damaged and produced the lowest numbers of weevils. Maize classified as susceptible in laboratory tests also suffered high damage levels in on-farm storage trials.