Investigations on storage insects infesting stored groundnuts was carried out in farms, markets, stores and out-door storage sites in order to find out the source of infestation. Farm samples were found to be free from infestation. Freshly harvested groundnuts that were just stacked into pyramids were also free from infestation. However, groundnuts stacked into pyramids at central storage areas of Kano and Gusau were highly infested following a year of storage. Groundnuts from stores and markets were moderately infested. The most abundant and widely distributed insect pests were Tribolium castaneum (Herbst) and Oryzaephilus mercator (Fauvel). Ephestia cautella (Wlk.) constituted less than 1% of insect pests found on the groundnuts, but Plodia interpunctella (Herbst) was absent in out-door pyramid storage.

Groundnuts kept in in-door storage had high moisture content, while nuts from farm and open air pyramid storage had low moisture content. Lipid, peroxide and free fatty acid (F.F.A) values from groundnuts were directly related to the levels of infestation.

From field screening of two international nurseries of the sorghum shootfly (Atheriaona saccata), seven promising cultivars were selected for investigating the mechanism(s) of resistance. These cultivars were IS 1054, IS 1082, IS 2146, IS 2195, IS 2312, IS 3962 and IS 5613. CSH-1, a hybrid variety from India, was used as a susceptible control. Results from observations on larval development and mortality and the longevity and fecundity of resulting females when released on either CSH-1 or the parent cultivars are reported.

Mortality among the first-instar larvae was very high on IS 2146 followed by IS 2312 and IS 5613. IS 2146, IS 3962 and IS 2312 sustained the least growth of larvae. The larvae in these cultivars were often confined to the upper region of the central shoot.

The survival rate of flies from IS 2146 was very low, and the longevity was significantly reduced in the case of flies from IS 2146 and IS 2195. The preoviposition period was significantly longer when flies were released on IS 1082 and IS 2312. Fecundity of the flies did not differ significantly when released on CSH-1; however, it was significantly reduced when released on parent cultivars in all cases except IS 1054. It is concluded that IS 2146 possesses strong antibiosis for the sorghum shootfly followed by IS 2312 and IS 5613.

Storage method encompasses the patterns and periods of storage as well as particular storage techniques. Storage management is therefore a major determinant of post-harvest losses in stored cereals: affecting the magnitude of losses and their susceptibility to reduction. Key issues are the location and scale of grain storage which, in most developing countries, involves both rural domestic storage and larger seal “buffer” storage at district centres, commonly near towns.

Various storage techniques are described and discussed against the background of available informatio on storage losses and with regard to the common patterns and periods of storage in Africa at the farr level and in “centralized” storage. The importance of long-term development planning for cereal crop production and utilization is stressed as a major factor in storage pest management and the reduction of storage losses.

The handling of imported food grains is discussed with regard to storage management problems arising from moisture content/relative humidity equilibria as affected by grain temperature.

Patterns of stemborer life history and the foraging patterns exhibited by a taxonomically diverse array of stemborer parasites are described. Foraging strategies provide functional descriptions of natural parasite groupings and include elements of the guild concept plus ecological, behavioural, and morphological adaptations that enable a parasite to locate and exploit a particular host effectively. Elements of the foraging strategy include: host stage attacked, microhabitat of the host, cues employed to locate and identify the host, and method of host attack. Possible constraints presented by the crop plants to the success of different foraging strategies exhibited by groups of parasites are explored.

Sorghum, maize and cowpea serve as staple food for people in Africa and are grown mostly by small-scale farmers. A major constraint on the production of these crops is attack by insect pests among which crop borers are most important, causing 30–80% yield losses. Use of pesticides to control these pests is hazardous and not feasible for the farmers. Alternative strategies for the integrated pest management (IPM) are being developed at the International Centre of Insect Physiology and Ecology (ICIPE) and include the following components: (1) Intercropping and other cultural practices, (2) Plant resistance to insect pests, and (3) Biological control. These IPM components have now been developed to a stage where they can be taken for on-farm trials under farmers' management for subsequent use by them. But, adoption and diffusion of agricultural innovations requires a prior knowledge of the farming systems and the socio-economic circumstances in which the target farmers operate, and their bearing on the use of innovations. Information on these aspects has therefore been obtained through a survey of farming households in Kendu Bay and Oyugis Divisions in western Kenya during April—August 1986. The survey was conducted jointly with UNECA and Ministry of Agriculture, Kenya, under a project funded by the Royal Government of Belgium.

The survey involved interview with 150 farmers, (75 in each Division. In Kendu Bay 27 were men and 48 women whereas in Oyugis 40 were men and 35 women.) and was based on a questionnaire which comprised six sections. Five sections covered the farmers' background, farming practices, pest problems and their control, socio-economic conditions, and accessibility/willingness of the farmers to participate in the project. The last section included field observations on the insect pests of sorghum, maize and cowpea.

On the basis of the information obtained on above-mentioned aspects, criteria were defined and assigned appropriate weigh tage for selecting 25 farmers in each Division for on-farm trials. The selected farmers included 12 men and 13 women in Kendu Bay while in Oyugis 13 men and 12 women were selected.

The measures that need to be taken to counter these limitations and thereby assist the farmers in increasing food production have been recommended.

Cassava is one of the most important staple crops in Ghana. Losses from the cassava mealybug (CM), Phenacoccus manihoti, and cassava green mite (CGM), Mononychellus tanajoa, infestations in 1983 were estimated at 0.8 m metric tons of tubers. An integrated control programme with biological control playing a key role has been established within the Plant Protection and Quarantine Unit of the Ministry of Agriculture. Of the five beneficial insect species released, only the parasitoid, Epidinocarsis lopezi has so far been established against the CM over the greater part of Ghana. Damage caused by the CM has been reduced quite remarkably, largely due to E. lopezi, with local beneficial insects playing some contributory role. The activity of hyperparasitoids is high and reduces the overall efficiency of E. lopezi.

The effect of CGM is prominent now, perhaps because of the reduction in CM. Exotic phytoseiid mite species were released but no establishment could be documented.

The larval critical weight (Lcw) in the spotted stem borer, Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) was 54.6 ± 1.0 mg for average sized male and female final instar larvae and was 63 and 39% of the larval maximum weight (Lmw) of males and females, respectively. There was a consistent decrease in weight from Lmw to pupal weight of 35% in both males and females over successive generations of rearing two laboratory populations. The adult weight was consistently about 37 and 22% lower than the pupal weight for males and females, respectively. During starvation, 25% of the final instar larvae produced a supernumerary moult. A positive correlation was derived between female pupal weight and fecundity. The results were similar to those derived from a study on the progeny of a wild population. A model representing the various fresh weight changes in relation to the Lmw has been suggested for this species. The model is similar to that proposed for other Lepidoptera. The results of this study are largely consistent with those carried out on other species of Lepidoptera and underline the value of using stable standards in assessing the quality of laboratory reared insects.

The predacious mite, Cydnodromella negevi (Swirski & Amitai) completed life cycle when fed on the tetranychid mites Eutetranychus orientalis (Klein), Tetranychus urticae Koch and pollen grains of Ricinus communis (L.) as an alternative food substance in the laboratory. The duration of the immature stages and adult stage were determined. Immature stages of C. negevi consumed in total an average of 27 E. orientalis and 34 T. urticae, whereas each day throughout her life, the adult female consumed an average of 11 of E. orientalis and T. urticae. While feeding on these prey, C. negevi laid 1.3 and 1.0 eggs per day. The number of eggs deposited per day increased (3.3 eggs/female/day) when fed on eriophyid mites. Females neither fed nor reproduced on liquid nutrients.

Investigations have been made to evaluate the development of Spodoptera littoralis as affected by feeding on a standard artificial diet containing powder of some plant species known to be resistant to the infestation of this insect. Trials were also made to find out whether the effect of these plants facilitate the potency of Bacillus thuringiensis var entomocidus HD-635 vs. the target insect. The results revealed that powders of pomegranate peel, guava leaves and lemon grass, greatly affected the insect development in terms of larval duration, larval and pupal weights, deformities in pupae and moths, percentage of emergence, egg production and hatching. This may be correlated to the chemical constituents of these plants. A marked increase was observed in the potency of B. thuringiensis endotoxin preparation vs. S. littoralis when combined with some of the tested powdered plants or its extracts but in varying degrees.

Malaise traps are often used in trapping Muscidae flies for studying species dynamics, but there has been no specific evaluation of the influence of the duration of exposure of the traps in the field and their normal wear and tear on the relative richness and abundance of individuals of different species caught. To evaluate the possible influence of these factors, we installed Malaise traps at Arroio Grande and Pelotas, Rio Grande do Sul, which are located inside the Campos Sulinos biome in Brazil. In Arroio Grande, new and 18-month-old Malaise traps were installed between March and May, 2004, and in Pelotas, new and 12-month-old traps were installed between April and June of the same year. At each site, the traps were installed 10 m apart, and collections of trapped insects were made at intervals of 7 days. The age of the traps significantly influenced both abundance and richness of the Muscidae trapped, probably because of the changing colour profile at the top of the traps. From these results, we concluded that the use of Malaise traps in the field for long periods to evaluate richness and abundance of muscid flies in biodiversity studies needs re-evaluation.

Recent studies on the chemical ecology of the desert locust, Schistocerca gregaria, have unravelled a rich and complex system of pheromonal and other semiochemical-mediated communication in this insect. The key pheromones associated with such behavioural processes as social cohesion and communal egg-laying have been characterised. The semiochemical bases of such physiological processes as maturation of solitarious insects before the arrival of seasonal rains, development of gregarious traits in crowded solitarious insects, development of maturation synchrony in gregarious insects, and maternal transfer of gregarious characters to the offspring are better understood. Desert locust semiochemicals are finding two principal uses: as tools for studying the processes associated with gregarisation and, therefore, for elucidating the eco-physiological mechanisms underlying the development of locust outbreaks; and as agents for interfering or reversing the process of gregarisation. The status of this research and its implication for the development of novel ecologically friendly tactics for the management of different locust species are highlighted.

The African armyworm is a migrant moth which, in its larval form, can cause severe plagues which destroy cereal crops, sugarcane and pastures in many parts of Africa. This paper reviews the relevant aspects of a multidisciplinary study into the dispersal behaviour and re-concentration of moths, migratory flight, source areas, population upsurges and the seasonal movement of moths. It introduces the new concepts of primary and critical outbreaks.

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.

Ticks, and the diseases they transmit, are of great economic and medical importance worldwide, and especially in Africa, where they are considered to be the greatest animal disease problem. The four major genera of ticks are Amblyomma, Rhipicephalus, Hyalomma and Boophilus. Ticks harm their animal hosts by sucking their blood thus reducing growth rate and milk yield, cause mechanical damage to hides and skins causing tick worry, introduce toxins and predispose the animals to myasis. Theileriosis, cowdriosis and dermatophilosis are the major tick-borne and tick-associated diseases of grazing cattle in Africa. The conventional method of tick control is the application of chemical acaricides, but it is associated with a number of problems including environmental pollution, chemical residues in meat and milk products as well as in wool, development of tick resistance and high cost. Some of the alternatives to chemical control of ticks that are available in Africa are discussed in this paper.

Most germplasm lines and improved sorghum genotypes identified as resistant to shoot fly (Atherigona soccata Rond.), stem borer (Chilo partellus Swin.), midge (Contarinia sorghicola Coq.) and head bugs (Calocoris angustatus Leth.) are resistant to only one of these insects which usually will infest the same crop during the same season. At ICRISAT Center, India, a technique was developed in which entries were subjected to an array of combinations of pest infestations for identifying and separating genotypes with resistance to one or more insects.

Using this technique, 220 resistance sources and breeding lines were evaluated for multiple insect resistance. Less than 10% of shoot fly resistance sources had acceptable resistance (< 3 on a scale of 1–9) to shoot fly, but over 50% showed good resistance (scores of 1–3) to stem borer. IS 18551 and IS 2195 were the best entries with resistance to both shoot fly and stem borer. However, the majority (80–90%) of shoot fly and stem borer resistant sources were highly susceptible to midge with scores > 8. Similarly, all midge resistant sources were highly susceptible to shoot fly but less so to stem borer where seven midge lines had scores < 5. IS 22464 was the best midge line with a score of 3 for stem borer resistance. Advanced breeding lines showed a wider range of resistance to shoot fly, stem borer and midge with a higher frequency for resistance to stem borer, PS 28060−3 and PM 14388−1 were the most promising breeding lines.

Key mortality factors of sugar-cane top borer, Scirpophaga excerptalis Wlk. during the third brood were quantified on a susceptible sugar-cane variety, Co 1148 during 1981 and on susceptible CoJ 64, resistant CoJ 67 and collateral hoste, Sorghum halepense Peru, and Saccharum spontaneum L., during 1982 in Haryana (sub-tropical India). As artificial rearing of this borer is not possible, a methodology to have uniform age group at the beginning of the study by tagging the egg masses and the freshly attacked plants was developed. Results showed that parasitization of various stages and failure of neonate larvae to enter the midribs were the key mortality factors common to all the hosts. In S. halepense there was negative trend index (0.104) due to high mortality of larvae in all the instars. This revealed that it is not a suitable host for top borer. No predators were found to feed on any of the sub-imaginal stages of the borer due to the unique habits of the borer.

Plastic dishes 30 cm dia. and 15 cm depth filled with water as traps for Tropinota squalida Scop, adults and painted blue, green, red, white and yellow were exposed in infested peach areas at Abo-Sultan during 1987–1988. Traps painted blue showed high degrees of attractancy to the pest. White, yellow and green attracted the least number of beetles while red was found to have no attraction. Trapping is considerably influenced by microecological conditions, trap placement and trap diameter. Blue traps (25) were sufficient to suppress the pest population in an infested peach area. Blue trap could be considered as a new forecasting method and for studying the swarming dynamics of T. squalida adults.

Trichoid, basiconic and campaniform sensilla have been observed on the ovipositor and tarsi of the sorghum shootfly, Atherigona seccata Rondani. The ovipositor of A. seccata comprises abdominal segments 6–9, with most of the trichoid sensilla located on the ninth segment. Two olfactory pegs each are located on the paired leaflets of the ninth segment. Sensilla on the tarsi include long and short basiconic sensilla and campaniform sensilla located near the anterior margin of the last tarsal segment.

The sensory organs on the head capsule of the larva were studied by light, scanning and transmission electron microscopes. Four types of sensory receptors were observed on the cephalic lobes. They consist of four knob-shaped sensilla, two styloconic sensilla, two campaniform sensilla, and eight basiconic sensilla.

Seventy cultivare of sorghum representing recently released varieties, hybrids, experimental varieties, lines bred for stalk-borer resistance and local resistant stocks were tested for stalk-borer resistance under artificial infestation during monsoon (July–October) season. There were significant differences among varieties for leaf-feeding injury, per cent ‘dead hearts’, number of holes and tunnels and per cent tunnelling. Released hybrids and local varieties were susceptible for different parameters. Thirteen varieties viz., SPV Nos. 35, 103, 107, 110, 135, 140, 192, 229, E 302, E 304, P 37, R 133 and CSV-8R were at par with resistant varieties for per cent tunnelling per plant. Long peduncle varieties were relatively susceptible.

Leaf-feeding injury, per cent ‘dead hearts’ and tunnelling parameters were not significantly correlated and independent of each and none of them could be related to grain yield. Number of holes, number of tunnels and per cent tunnelling were positively correlated. Thus, number of holes per plant or internode may be a good indicator of per cent tunnelling and can conveniently be used as a criterion for evaluating germplasm to stalk-borer (Chilo partellus Swin.) resistance. The varieties CSV-8R, SPV-35, SPV-103, SPV-140 and SPV-192 were identified as promising sources of resistance to stalk-borer.

The behaviour of shootfly resistance is examined over the Fl, F2, F3 and advanced generations. The Fl is almost intermediate between two parents with an added heterotic advantage of a lower ‘dead-heart’ percentage. Resistance shows partial dominance under low to moderate shootfly infestation but this relationship may shift under heavy infestation conditions.

The resistance is polygenic in nature and governed by additive genes. In the absence of host immunity, gradual accumulation of favourable genes is possible by line breeding from R × I and I × I crosses by selecting 1 SD below the population mean. Selection for multiple characters limits the genetic advance for shootfly resistance—resulting in 0- 5% selection intensity and relatively less resistant but high yielding desirable progenies. Multilocation tests enable the selection of varieties stable for shootfly resistance.