Simple methods for production of all life stages of the banana weevil on its natural diet, banana rhizome and pseudostem are presented. Their effectiveness, labour demands and applicability for different purposes are discussed. The most effective method for the production of eggs, pupae and adults is the utilization of the rhizome part of suckers, whereas larvae are easier to recover from pseudostem. The hatchability of the eggs produced is high.

Nigeria livestock population is estimated at about 12.3 M cattle, 9 M sheep, 23 M goats, and 1 M pigs distributed nation-wide, but with over 90% in the savannah zones in the country. Ticks and tick-borne diseases are endemic although incidence rate varies with seasons and livestock concentration. Ixodid ticks of the genera Amblyomma, Boophilus, Hyalomma and Rhipicephalus are of the greatest economic importance in livestock production in Nigeria. Control measures have been based mainly on dipping and spraying with acaricides, although a lot of management problems have characterized the drive towards effective tick control.

There is as yet no research centre for ticks and tick-borne diseases in Nigeria. Much of the work being done is carried out at the Veterinary Faculties of five Nigerian universities at Nsukka, Ibadan, Zaria, Sokoto and Maiduguri. A proper epidemiological base line data is still needed in the formulation of effective control measures. Economic losses, attributable to ticks and tick-borne diseases in Nigeria run into several millions of Naira per annum.

An Integrated Pest Management (IPM) approach is considered a long term option for effective tick control in Nigeria.

During the 1977/78 dry season an experiment was conducted in the Volta Noire source tributaries area of Upper Volta, to assess the feasibility of controlling human trypanosomiasis by reducing the vector, Glossina palpalis gambiensis, by a combination of techniques. The objective was to suppress the target tsetse population by chemical means and then to achieve a further reduction or eradication by the release of sterile males.

Sixteen kilometres of the fringing forest of the upper River Guénako were treated with the synthetic pyrethroid decamethrin (OMS-1998) applied from a helicopter as an aerosol at a dosage of 0.2 g/ha. Two applications at 14 days interval reduced the target G.p. gambiensis population by over 95% and caused important changes in the qualitative composition of both G.p. gambiensis and G. tachinoides populations. Subsequent over-flooding of the residual G.p. gambiensis population by sterile males was easily achieved.

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.

Research on stem borer pests of sugarcane, maize and rice in Ghana is briefly reviewed. The work on the biology of the borers carried out at Asutsuare between October 1977 and January 1980 has pinpointed the fact that the practice of ratooning is the principal cause of a devastating build up of stem borers in the sugarcane fields. Cost/benefit analysis has revealed that as a result of discontinuation of this practice, there would be an initial gain of $13.4/ha. The profit should increase in subsequent years when the foci of borer infestations are removed as a result of the discontinuation of ratooning. The use of imported parasites as well as insecticide treatment in controlling the borer populations has been ineffective. Further work in developing novel control measures against sugarcane borers is still in progress. Only cultural methods have been found useful in limiting the damage caused by stem borers to maize. Losses caused by stem borers to the rice crop in Ghana are still not well established.

Studies were conducted in several ecological regions of Côte d'lvoire from 1986 to 1990 to monitor maize cob-borer populations and to investigate losses in maize grain yield due to this pest. The relationship between borer abundance and crop losses was studied using regression analyses, in which two regression models were developed. One model related yield loss to number of damaged grains and the other related yield loss to grain weight. Mussidia nigrivenella Ragonot (Lepidoptera: Pyralidae) was the dominant pest in most localities. Its population density was particularly high in the semi-deciduous rain forest and decreased westwards and northwards. The models explained 85.6% (yield loss vs damaged grains) and 72.5% (yield loss vs loss in grain weight) of the observed variation. Moreover, they showed that the weight loss due to cob-borers was much lower than that due to stem borers and also that the number of damaged grains increased rapidly with borer density.

Mature (5- to 6-day-old) male and female pupae of C. partellus were irradiated at 5 to 20 kilo-Roentgen (kR) and 5 to 10 kR respectively. Emergence of normal appearing moths, pupal periods and adult longevities remained statistically unaffected. Fecundity of normal (nonirradiated) females mated with males irradiated as pupae was nonsignificantly different from control, but fecundity of females irradiated as pupae at 10 kR was significantly reduced when they were mated with normal mates. Dominant lethals of varying intensities were induced at 5–20 kR. However, induction of dominant lethality was sex- as well as dose-dependent. Radiation doses inducing 100% dominant lethals in sperm (20 kR) and ova (5 kR) did not mitigate the mating ability of males and receptivity of females. However, receptivity of females was reduced significantly when they were irradiated as pupae at 10 kR. Rates of embryonation in F1 eggs were significantly reduced when normal females were crossed with males irradiated as pupae at 20 kR, but similar effect was observed at 10 kR in reversed crosses. Embryonic development was delayed in eggs obtained from crosses, where male or female parent was irradiated in pupal stage, but in both cases most of the dominant lethals acted late in embryonic development.

The millet stem borer, Acigona ignefusalis Hampson, can cause total crop failures when severe infestations occur such as happened in northern Nigeria in 1984. Research at the Institute for Agricultural Research at Samaru has shown that various millet types and varieties exhibit different levels of susceptibility to the stem borer, although no resistant varieties are yet available. Infestation and damage by the stem borer are strongly influenced by date of planting and rate and time of nitrogen fertilizer. The effect of mixed cropping with sorghum depends on the spatial arrangement of the component crops in the mixture as well as on the insect population pressure. Systemic insecticides, particularly granular carbofuran, have been found to control the stem borer more effectively than contact insecticides like carbaryl. Seed dressing with carbofuran has been found to be ineffective. Some natural enemies of the stem borer have been identified but their role in lowering damage to millet is minimal. The destruction of infested stems before the beginning of the rainy season is a very important control measure against the insect. The possibilities of integrating these various methods for stem borer control are discussed.

Three populations of C. mbila originating from the rain forest (Ibadan), southern part of sudan savanna (Kadawa, Kano) and the Jos Plateau, and C. triangula population from Ibadan (Moor Plantation) were compared in relation to their ability to acquire and transmit maize streak virus (MSV). Acquisition and transmission efficiency increased with time of access feeding. Joint regression analysis showed that the populations did not differ significantly from each other in transmission efficiency of the virus. Nymphs and adults of some populations acquired MSV in 30 sec and adults transmitted the virus during the 2-hr inoculation access. Efficiency of virus transmission generally increased with acquisition or inoculation time.

The minimum latent period of maize streak virus in the various Cicadulina populations was 14–18 hr and the medium latent period (LP 50) was 16–20hr. Some individuals in all populations retain the virus throughout their lives.

Since the various Cicadulina populations were largely similar in their ability to acquire and transmit the virus into healthy maize, other factors which might be implicated in the epidemiology of maize streak disease are discussed.

Most fifth instar Argina cribraria female larvae reared in paired groups on fresh sunnhemp leaves practised cannibalism on the male. A potential cannibal pounced on the victim and severed its dorsal vessel, causing profuse bleeding of haemolymph, immobility and contraction. The cannibal fed on victim's carcass and might consume 1–2 larvae and 1–3 pupae. More females emerged from an experiment having larval cannibalism. The cannibals were lighter, but the relative titres of sugars, proteins and phenols were higher in cannibals than those in control female caterpillars.

The behavioural process by which a mosquito finds a potential host organism is mediated by olfactory receptors on the insect's antennae. Lactic acid (LA) is a host-related odour common to all potential hosts. On the antennae of the female are two LA-sensitive neurons; one of these is excited by LA but the other is inhibited by LA. Furthermore, the sensitivity of the LA-excited neuron is correlated 1:1 with the presence of host-seeking behaviour such that when host-seeking behaviour is inhibited following a blood meal, the sensitivity of the LA-excited neuron is markedly decreased. The inhibition of host-seeking behaviour and the decrease in LA-sensitivity are induced by a hemolymph-borne factor released during oocyte maturation. The source of this factor is the fat body of blood-fed females, which requires a vitellogenic ovary for its production and/or release. The combined activity of the two types of LA-sensitive neurons together with the shift in sensitivity of the LA-excited neuron from a range where host levels of LA are present to a range exceeding LA levels expected from a host are sufficient to account for the inhibition of host-seeking behaviour following a blood meal.

The outbreak areas of the red locust are seasonally inundated wetland areas supporting a rich biodiversity. The potential for environmental damage from the repeated use of broad-spectrum insecticides for locust control in these ecologically sensitive wetlands is therefore great. This paper describes the first trial of a Metarhizium anisopliae var. acridum (LUBILOSA isolate IMI 330189) mycoinsecticide as an alternative, more environmentally benign, intervention strategy for managing red locust populations in their outbreak areas. Following initial bioassay tests in the laboratory, which gave 90–93% kill of 3rd instar hoppers within 6–9 days, an oil based formulation of aerial conidia was applied at a rate of 5 × 1012 conidia/ha using a motorised ‘Solo’ knapsack sprayer to treat 3rd and 4th instar hopper bands in the Buzi outbreak area near Beira in Mozambique. Caged samples of 3rd instars succumbed quickly with a median time to kill of 3.6–3.9 days and 98–100% kill recorded within 8–9 days. The 4th instars took longer to die, with a median lethal time of 5.9–6.1days and > 90% mortality after 21 days. Mortality in control samples was low with 13–23% mortality after 21 days. During this mortality assessment period mean minimum and maximum air temperatures ranged from 26–34°C and relative humidity ranged from 85–100%. Observations on treated bands in the field showed that the cohesion of the 3rd instar bands broke down within 6 days, while controls still behaved normally. Unfortunately observations on the 4th instar band had to be terminated after 10 days due to heavy flooding. This preliminary field trial demonstrated the feasibility of using a Metarhizium mycoinsecticide, applied through conventional spray equipment, for controlling the red locust in its outbreak areas.

Screening of leishmanial parasites from domestic and wild animals was carried out in Kacheliba, West Pokot District. Spleens and livers of the animals were cultured in NNN diphasic medium. Thin smears of the same tissues were also made and stained with Giemsa stain and examined under microscope. Positive slide smears were obtained from goats and positive cultures obtained in four goats, one rat and two lizards.

In the Ecuadorian cloud forest, males of the parasitoid braconid wasp Napo townsendi Shaw displayed facultative lekking, appearing both singly and in groups of 2–7 on the leaf tops of various plant species. To attract females, they constantly employed a stereotypical, spread-winged calling behaviour, apparently releasing a sex pheromone combed from the lateral metasomal exocrine glands and applied to the wings and hind legs. Aggregated males used the same posture in conspecific agonistic displays, often leading to physical fighting. While female wasps were attracted to and mated with displaying singletons, they also made a choice among aggregated males. When females approached, males vibrated their wings in a brief courtship and mounted. Details of copulation behaviour, which lasted on an average of 3–4 min, are described. Without apparent physical weaponry, the displaying wasps successfully warded off attacks from an assortment of predatory arthropods, particularly salticid spiders. We present case studies of repeated unsuccessful predation attempts by salticids. Here, we postulate that calling and release of sex pheromone may double as both an intrasexual agonistic display and an aposematic advisory to predators that the wasps employ a chemical defence.

Studies were conducted during the dry period February to May 1986 in River Shelliekha, Bahr El Arab fly belt, Sudan, to obtain baseline data on catch and age compositions, reproductive status and trypanosome infection rates of trapped and fly round samples of Glossina morsitans submorsitans. The objective was to assess the tsetse situation before the establishment of trypanosomiasis treatment stations at the northern limits of the fly belt. Trapped tsetse included significantly higher proportions of teneral and non-teneral females and a lower male:female ratio. Insemination rates were over 98% in both samples. In any one group, the frequency of pregnancy with egg predominated, followed by the second, first and lastly the third instar larva. There were significant differences between the two groups of females in the proportions of nullipars and pregnancy with any one of the larval instars. Abortion was the predominant reproductive abnormality and no relationship could be found between abortion rate and the sampling method, age or trypanosome infection rate of females. Age compositions were similar in the two samples, save for age categories 0 and 1 for females and two and four for males. Flies were infected with Trypanosoma vivax and T. congolense only, though T. brucei infections could also be diagnosed in livestock.

The development and morphometrics of the whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) were studied on cassava and a description was made of the different nymphal instars and oter biological characteristics. The nymphal instars were distinguished using easily recognisable morphological characteristics. Abnormally developing individuals were also easily recognised. Regression analysis was highly significant between the length and width of nymphal instars modelled collectively indicating two-dimensional growth at least across three nymphal stadia. Males were smaller than females on the basis of body length, wing width and width of the abdomen. The insects showed better development on a Colombian cassava variety as compared to an African variety, Ebwanateraka from Uganda, and consistently showed a higher proportion of males than females (2.33: 1) for early-emerging individuals. Mean developmental period on both varieties was 22 days and the first instars accounted for the major part of the developmental period which ranged from 19 to 29 days. The mean number of eggs/female/day was 4.89. The actual events of first instar eclosion, which can last up to approximately five minutes, were described. The intervals of honeydew flow to the vasiform orifice lasted a minimum mean time of 20.8 seconds and a maximum mean time of 123 seconds.

Regular field surveys were carried out in 2 week intervals in 1986 and 1987 to determine population density, species composition, migration activity of Cicadulina leafhoppers and their infectivity with maize streak virus (MSV) in different ecological locations of southeastern Nigeria: mangrove swamp forest (IITA and RIART station at Onne), deltaic swamp forest (RSUST, Port Harcourt), seasonal swamp forest (Iriebe) and high forest zone (NCRI, Amakama near Umuahia).

Population density was always low during dry season, significantly lower in the rain forest zone and higher in the swamp forest, rapidly rising in the second rainy season in all ecological zones and reaching its maximum before the rains finally stopped. Sharp increase in the population density in Nov. and Dec. may indicate mass migration activity of Cicadulina leafhoppers from already dry areas of adjacent Guinea savanna at that period.

Six species of Cicadulina were collected from most of sampled areas. C. ghaurii was the predominant species in 1986 and 1987, averaging 55.9% for all locations and periods. Its portion was higher in the mangrove swamp forest (Onne) than in the high forest zone (Amakama). The predominance of other species declined in the order: C. triangula (18.2%), C. mbila (17.2%), C. arachidis (5.9%), C. similis (2.8%) and C. hartmansi (0.1%). In absolute values, the portion of individuals out of the total number of leafhoppers collected was for C. triangula 53.7%, C. ghaurii 25.5%, C. mbila 17.3%, C. arachidis 2.3%, C. similis 1.1% and C. hartmansi0.1%. A high population of C. triangula occurred only in the relatively short period in Nov.-Dec, especially in Iriebe and was correlated with the rapid increase of Cicadulina densities in all sampled areas; a high migration activity of C. triangula and C. mbila was confirmed.

Incidence of MSV in the surveyed farmers' field varied between 0–22% in the first rainy season (1987) and 12–25% in the second rainy season (1986). The portion of Cicadulina adults already infected with MSV under field conditions and capable of transmitting MSV to the susceptible maize seedlings varied from 3.3 to 23.3%, with higher values for leafhoppers collected at the end of the second rainy season.

Feeding deterrency tests by leaf disc dipping method revealed AZT-VR/K extract of azadirachtin as the most potent antifeedant against cabbage butterfly, Pieris brassicae L. larvae. The leaf damage on treatment with the extract (at 3, 2 and 1%) was minimum and ranged between 4.9 and 16.3 % as compared to 98 % in untreated check. High level of feeding deterrency was exhibited at all the concentrations of AZT-VR/K, while in neemark (at 1%) and neem oil (at 2 and 1%), the deterrent effects declined considerably on their decreased concentrations.

Effects of adult nutrition were investigated by measuring female longevity, body weight, fertility and ovariol yield in the grasshopper, Euprepocnemis plorans reared on 3 different host plants. Rearing the insect on lupine (Lupinus termis) and horsebean (Vicia faba) caused significant reduction in fertility and ovariol yield of its first and second pods compared with those reared on clover (Trifolium alexandrinum). Resorption bodies were significantly higher in the ovariols of females fed on L. termis and V.faba. Diet also affected longevity and body weight. Fecundity was highest in females reared on T. alexandrinum. Significant reduction in haemolymph protein was noted in females reared on L. termis and V. faba. Nitrile (allylcyanide) significantly reduced the approximate digestibility (AD), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD), inhibited nymphal growth, increased food consumption and decreased its assimilation. Feeding grasshoppers on T. alexandrinum treated with 125–250 μ mole/g resulted in various degrees of malformation and death.