A survey to establish the distribution of tsetse flies (Diptera: Glossinidae) in southern Sudan was conducted using biconical traps. Only Glossina fuscipes fuscipes was caught. The results obtained revealed a further northern advance of G. f. fuscipes of c. 29 km along River Bahr el Jebel and 48 km along River Luri, and a southern contraction of Glossina morsitans submorsitans belt from Lewis' distribution limit. Glossina f. fuscipes was encountered in gallery forest along water courses with no significant differences in sex ratios and proportions of tenerals and non-tenerals between trap catches (P>0.1). Flies were absent from villages and open savanna woodland forests away from water courses. Trap catches were significantly higher during wet than dry season (t = 2.681; P < 0.025), although flies could be caught in any one location during both seasons. These results are discussed in relation to the current epidemic of human African trypanosomosis (HAT) in southern Sudan.

A questionnaire survey was conducted to find out the information and knowledge of extension workers on thresholds of cotton bollworms, (Helicoverpa armigera and Diparopsis castanea). A sample of 30 extension officers was interviewed in Southern and Central provinces of Zambia. The results showed crucial deficiencies in extension worker's knowledge on thresholds of key pests and their implementation in cotton IPM. More than 60% extension officers were not aware of the basic information and knowledge such as thresholds of cotton bollworms, the recommended time to start scouting (weeks after germination of cotton) and the number of cotton plants to be examined for pest observance in each field. All extension officers indicated a desperate need for more field oriented practical training on thresholds. The recent increase in the incidence of aphids, Aphis gossypii as reported by 50% extension workers is obviously due to calendar sprays of synthetic pyrethroids and the lack of a suitable aphicide in current spray programme. Demonstrations on the practical aspects of thresholds deserve much more attention at college level and also during the in-service training. More co-operation in cotton IPM training for extension officers within Central and Southern Africa is suggested.

Transgenic plants expressing Bacillus thuringiensis δ-endotoxins are now being used commercially in several crop species. These toxins have demonstrated good control of temperate (Ostrinia nubilalis) and tropical (Diatraea grandiosella and D. saccharalis) stemborers in maize. Resistance to B. thuringiensis toxins has been reported in over 11 species in both field and laboratory studies, demonstrating the need for resistance management strategies to prolong the efficacy of this valuable pest management tool within an integrated control programme. Resistance involves reduced binding of toxins to midgut epithelial cells and is generally considered to be a recessive trait. Resistance management will require the use of spatial and temporal refugia which may require unique schemes for each pest complex. Information is presented on the mode of action of cry toxins, resistance mechanisms, interaction of transgenic plants and biocontrol agents, and management/deployment strategies for transgenic maize in tropical ecologies.

Pearl millet, Pennisetum americanum L. occupies a large proportion of the area growing millets in Africa. Consequently the insect pests that attack this species have received attention over other millets. A list of the major species is presented. Actual data on losses due to insect pests on pearl millet are not readily available. Crop loss assessment methods using incidence and damage ratios are discussed. Quantitative losses determined from insecticide trials at research station are also presented.

Plumbagin, a napthoquinone from the plant Plumbago zeylanica, delayed pupation when topically applied to newly moulted final instars of the leaf eating caterpillar Opisina arenosella Walker (Lepidoptera: Oecophoridae). Pupae from treated larvae emerged into non-viable adults and had abnormalities such as deformed wings and shrunken abdomens; they also died much before the control insects. The results suggest that plumbagin interferes with the process of development and ecdysis of the insect.

Four cultivars of maize, Zea mays L. viz., CM 600, Basilocal, CM 500 and Kisan were examined for their relative resistance to the maize stem borer, chilo partellus (Swinhoe) in relation to nutrition. Freshly hatched larvae of C. partellus were allowed to grow on the leaf whorls of the cultivars in the laboratory at 27 ±.2°C and 70–90% r.h. The rate of growth, food consumption and its utilization, egg laying and egg hatchability were studied. The insects showed better growth when fed CM 600 or Basilocal maize; this was shown by a higher percentage pupation (56.8 and 54.8, respectively on CM 600 and Basilocal) as compared to (24.4 and 5.6 respectively) on CM 500 and Kisan. Pupal weights were higher (40.2, 45.2, 34.4 and 32.8 mg for male pupae and 57.6, 63.7, 51.8 and 35.8 mg for female pupae), when larvae were reared on CM 600, Basilocal, CM 500 and Kisan, respectively. The growth index decreased from 1.65 on CM 600 and 1.49 on Basilocal to 0.40 on CM 500 and 0.09 on Kisan. A better consumption and utilization of the cultivars CM 600 and Basilocal was shown as also expressed by the higher weights attained by larvae grown on these two than on CM 500 and Kisan. Growth rate slowed down to 0.068 on CM 500 from 0.161 on CM 600 maize. A similar trend was observed in egg-laying and hatchability of eggs. Number of eggs laid per female decreased from 290 on CM 600 reared C. partellus to 157 on Kisan reared insects and none of the eggs laid by the latter could hatch. The degree of resistance of the cultivars to C. partellus on the basis of nutritional factors in a decreasing order is: Kisan > CM 500 > Basilocal > CM 600.

A laboratory study of the biology of Corcyra cephalonica (Staint.) was made at 30°C and 70% r.h. on sorghum. The number of eggs laid per female, oviposition period, development time and survival from egg to adult were determined. The data were used to estimate the finite rate of increase and the intrinsic rate of natural increase of the moth. For the finite rate of increase (λ) the estimated value was 18 per lunar month, corresponding to an intrinsic rate of natural increase (r) of 2.9. The results are compared with published data and it is concluded that the pest potential of C. cephalonica has been, hitherto, underestimated.

Field studies were conducted with the synthetic pheromone of peach twig borer to determine the effect of trap distance from host plant, pheromone concentration on number of captured males and seasonal flight patterns in plum and apricot orchards. Traps placed in pomegranate plantation and in fallow land caught significantly fewer males than those placed at the centre and border of plum orchard. However, significantly more moths were caught in traps placed in pomegranate orchard than those in fallow ground. Males captured increased as the concentration of synthetic pheromone increased from 2 to 6 mg per septa. Thereafter, males captured decreased as the concentration increased.

In a study to determine the costs of tsetse trapping in terms of construction materials, labour, transport and maintenance, two hundred forty-six traps used to control Glossina pallidipes in an area of 100 square kilometres at Nguruman, Kenya were evaluated from November 1990 to July 1992. The total cost of materials, labour and servicing per trap per year, was US$ 30.6 which, at that time was equivalent to 1071 Kenya shillings.

Investigations of the phlebotomine sandflies fauna in a visceral leishmaniasis focus of Aba Roba in Ethiopia were carried out. This resulted in finding Phlebotomus celiae for the first time in the country. Previously, this species was incriminated as a vector of visceral leishmaniasis in Kitui, Kenya where the disease is endemic. It is possible that P. celiae has a wide distribution covering areas of similar ecological niches as those of its first description.

Available pieces of information on Cicadulina sp. leafhopper biology, with specific references to the suitability of various species for mass rearing and resistance screening for maize streak virus (MSV) are critically reviewed. The following are summarized: (a) effect of distribution pattern and species composition on the efficiency of collection of live specimens for establishing a colony for mass rearing; (b) species biology and fecundity as affected by temperature and humidity; (c) species specificity in MSV transmission; (d) host plant preference and adaptation to mass rearing conditions. All these parameters affect the suitability of various Cicadulina species used as vectors in maize resistance screening and breeding to MSV disease.

This study was conducted on both station and farmers' fields during the 2010 dry cropping season in the Vallée du Kou rice scheme. We investigated the effect of three rice-transplanting periods (8–10 days) on the population dynamics, damage and parasitism associated with rice stem borers. The on-station experiment was designed as a randomized complete block with three treatments (planting dates) and four replications. Regular intervals of 14 days were observed between subsequent planting dates. Weekly agronomic and entomological assessments were performed from the 21st day after transplanting (DAT) to the 84th DAT. The on-farm experiment covered 1200 ha divided into two zones in which 48 farmers' fields were selected according to the periods of rice transplanting (resulting in 16 fields per period). On-station results indicated 10.1% of deadhearts and 7.5% of whiteheads due to stem borers in the first transplanting period, resulting in the lowest yield (2 metric tons/ha). In farmers' fields, the genus Chilo was found to be the most injurious rice stem borer in Vallée du Kou. The highest larval parasitism (38.5%) was recorded in the third treatment. These results provide important data that can be used in the development of an integrated management strategy for rice insect pests in Vallée du Kou.

Dormancy is described for adults of the stalk-eyed fly, Diopsis longicornis Macquart (Diopsidae: Diptera) in the tropical savanna of coastal Guinée, West Africa. Populations of diopsids maintained themselves within each chosen refugium throughout the dry season unless the site dried up. Sex ratio within the populations at each refugium remained constant throughout the dry period. Slightly more females than males were found (56%), and of these only 0.8% were gravid. Movement of stalk-eyed fly adults from the rice field to the refugia corresponded with the end of the rice cropping period (stage of ripening and harvest) at the end of the wet season (late October to November), whereas movement from the refugia to the rice field occurred towards the end of the dry season Gate (May/early June), but well in advance of the rice crop planting (July and August) of the following wet season. Insects retained their state of reproductive arrest in the dry season even when offered suitable oviposition sites, i.e. rice plants. Secondary host plants were investigated as possible oviposition sites and food sources for adult flies.

Observation on natural enemies of the stem-borer complex on sugar-cane in southern Ghana indicated that Descampsina sesamiae Mensil (Diptera:Tachinidae) is the most important larval parasite of Sesamia species. The relative abundance of this tachinid parasite appeared to vary with the rainfall pattern throughout the year and with the phenology of the sugar-cane plant. The rate of parasitism was found to be higher in the outgrowers fields than in the sugar estate's fields. Differences in cultural practices used as well as the type of vegetation bordering the sugar-cane fields, were believed to be responsible for the difference in the rate of parasitism of D. sesamiae on Sesamia species.

Chilo species are the most important stem borers of sugar-cane. They cause heavy losses to sugar-cane crop and continue to suppress yield in the sugar industry. The control of these borer species through insecticides has been difficult as the damaging larvae spend most of their life-cycle within the cane plant. The breeding of borer resistant varieties is an ideal approach for controlling the damage as it does not cost the grower anything extra, is effective at all levels of pest infestation and its effects are cumulative and long lasting in reducing the pest population. Many plant characters such as leaf surface, rind hardness, leaf sheath tightness, fibre content, stalk pith and diameter and plant vigour have been associated with borer resistance. In sugar-cane breeding, the inclusion of borer resistance characters, in addition to many other agronomic characters required of a commercial variety, is rather difficult due to the segregating nature of this plant. Therefore, it is better to use, as parent varieties the few varieties showing marked resistance without knowing the actual reasons of resistance. The joint efforts of sugar-cane breeders and entomologists in production and selection of a large number of seedlings for desired characters can help to solve this problem to a greater extent.

Field studies revealed the nettle caterpillar, Latoia ( = Parasa) viridissima, to be multivoltine with four discrete generations a year. The maximum egg (1800/100 fronds) and larval (1500/100 fronds) densities were attained in April/May 1980. The pupal population was generally low; the highest recorded density of 54/100 fronds was attained in March 1980 during the first generation.

Samples of larvae and pupae from the field were attacked by parasitoids in the families Bombyliidae, Braconidae, Chalcididae, Chrysididae, Eulophidae, Ichneumonidae and Tachinidae. These contributed to mortalities ranging from 6 to 30%, but their combined action with microorganisms (bacteria and fungi) accounted for 28–65% mortality of the insect.

Trypanosomiasis outbreaks of great severity, both medical and veterinary, still occur. At the present time some of these outbreaks can be contained by implementation of plans based on sound knowledge of tsetse distribution. However, for many countries such knowledge is fragmentary. For this reason the second edition of tsetse distribution maps is to be regarded as provisional only, pending the availability of more accurate data. Some of the new information that has been received since 1973 is reported. It is concluded that a programme of intensive revision is needed before it can be claimed that tsetse situation in Africa is well understood.

Experiments carried out in a coffee plantation to determine the developmental period of Icerya paltersoni (Newst.) showed that the female and male scales lasted 157 and 129 days on average, respectively. The different stages of I. pattersoni females were found to be recognizable by the number of antennal segments. The antenna of the stage I nymphal instar is six segmented, stage II is nine segmented and stage III is eleven segmented. The antenna of adult males is eighteen segmented. Females are neotenic but the males possess a pair of grey wings and atrophied mouthparts. In the field the I. pattersoni pest population size is highest in the heavy rainfall months of April and May.

Four species in the genus Amblyseius Berlese are reported from Tanzania, A. serengati sp.n., A. fustis Pritchard and Baker, A. largoensis (Muma) and A. sawaga Pritchard & Baker. Descriptions and comparisons with similar species are provided for the new species.

The biophysical characters of the mosquito, Culex quinquefasciatus, a dreaded vector of bancroftian filariasis was investigated. The data represents the “system” in bioaerodynamics which comprises the adult mosquito and induced air, and constitutes “action-reaction pair” for the hovering flight. Hence the static and dynamic parameters of this species are determined. An expression for moment of inertia of the flight surface (wing) is deduced considering wing design and geometry. Further aerodynamic requirements in relation to flight performance of the insect are elaborated. It is concluded that this study provides useful information on the hovering flight behaviour of the mosquito C. quinquefasciatus.