The egg follicle C of the left ovary was developing first, indicating reversed ovarian sequences in 5.8, 4.8, 4.2, 2.2, 1.1 and 2.0% newly-emerged female G. pallidipes from pupae kept at 29.5 ± 0.5, 27.5 ± 1.0, 25.0 ± 0.5, 22.5 ± 0.5, 20.5 ± 1.0°C and then maintained at ambient temperature (19 to 31°C) in the local colony. There was a highly significant positive correlation between the frequency of reversed ovarian sequences in flies and temperature in the range 19.5–30.0°C. The incidence of the abnormality was very low (0.2%) in wild-caught females from the Lambwe Valley, probably reflecting the constancy of favourable temperatures in that location. Old females with altered ovarian sequence had apparently both normal pregnancy and alternate maturation of eggs between the ovaries. This appears to be the first report suggestive of a temperature-induced reversed sequential ovarian development in Glossina.

Insecticides belonging to the four major groups were bioassayed against Helicoverpa armigera Hubner collected from cotton in the Guntur region of Andhra Pradesh, India, during the 1989/90, 1990/91 and 1991/92 cropping seasons. High levels of resistance to all groups of insecticides were recorded. Tolerance to quinalphos had increased drastically in the 1991/92 season, while resistance to endosulfan, monocrotophos and carbaryl had increased moderately. The populations were also highly resistant to cypermethrin and deltamethrin and mildly resistant to fenvalerate. The resistance levels varied from season to season, thus reflecting the selection pressure created through insecticides.

Species composition and behavioural patterns were determined for anopheline mosquito samples collected between October and September 1990, from Gambella region, south west Ethiopia. At least eight anopheline species, which differed in their habits, were found to be prevalent in the region. Findings of indoor-resting collection and hut density determinations showed the relative prevalence, in decreasing order of magnitude, to be Anopheles pharoensis, A. gambiae s.l., A. nili, A. coustani, and A. ziemanni. On the other hand, the relative frequency of occurrence based on outdoor human-bait capture was A. pharoensis, A. ziemmani, A. coustani, A. squamosus, A. paludis and A. funestus, in decreasing order of importance. The rate of human feeding of A. nili, A. gambiae s.l., A.pharoensis and A. coustani were 37.5, 33.0, 22.5 and 6.7%, respectively. Among the endophilic mosquitoes assayed, the overall infectivity rate was found to be 0.56%. Sporozoite rates of 0.77% for A. gambiae s.l. and 0.47% for A. pharoensis were determined.

In view of the present environmental awareness, the reduction of spray wastage, which in turn lessens environmental contamination, can be achieved by reducing spray volumes and improvement on spray efficiency through the use of correct ranges of spray droplet sizes. Published data on droplets collected by some insects consistently suggest that the optimum droplet sizes lie below 60 μm.

An experiment was conducted in a wind-tunnel to assess the locust collection efficiency when subjected to a spectrum of droplet size ranges with a view to determine the optimum droplet size.

Locusts were induced to fly in a wind-tunnel and then exposed to spray droplets which were produced by a spinning disc atomiser. Droplets collected on antennae, head, abdomen, legs and wings were sized and counted. The collection efficiency at wind-speeds ranging from 2 m/sec to 6 m/sec was calculated for the different body parts in the droplet size range 10–40, 40–60 and 60–80 μm. The calculated collection efficiency for the 10–40 μm size range was comparatively higher for all locust body parts.

Food production in Africa is declining, while her population is increasing rapidly. Some factors responsible for low food productivity are mentioned; special attention is given to the problem of agricultural pests. The hazards of overuse of pesticides in developed countries are cited to caution farmers in developing countries from getting drawn into a similar situation when attempting to solve pest problems. Integrated pest management (IPM), which aims to increase food productivity and profitability without endangering the environment, is recommended as a sustainable solution to the pesticide problem. The role of biological control agents, i.e., introduction, augmentation and preservation of natural enemies is emphasized. In developing sustainable agriculture through IPM, the importance of incorporating farmers' traditional methods of farming into an IPM package and of identifying farmers' overriding concerns, is recommended as a prerequisite to the acceptability and success of such packages.

Over 300 male specimens of Atherigona lineata from the Natural History Museum, London, the Regional Museum of Wales, Cardiff, and various parts of Nigeria including the Institute for Agricultural Research Insect Museum, Samaru, were examined using the binocular microscope, to determine the extent of variability in this species. Three hundred and twenty-six male specimens of Atherigona lineata (Adams) segregated into 10 forms based on variability in the shape and chaetotaxy of the trifoliate process, with minor individual variations observed within some of the forms. Variability was observed in the extent of infuscation of the fore femur. Generally, the hypopygial prominence, which is bilobed, also showed some variability in the length and width of the lobes.

Rodent flea control to prevent spread of diseases of which rodents are reservoirs has often been carried out using insecticides. The insecticides are either dusted or sprayed in the entire area affected or placed in baiting boxes sometimes with rodenticides to control rodents and fleas, simultaneously. Systemic insecticides to control rodent fleas though found efficient, easy to apply and less hazardous to the environment, have only been demonstrated in the laboratory and field, but have not been commercially available.

It is suggested that using novel pesticide formulation techniques such as microencapsulation, tableting, employing bait attractants and additives and synthesis of metabolites of effective systemic insecticide could lead to the use of baits containing systemic insecticide to control rodents and fleas simultaneously and avoid undue expenses and hazards.

The oak tasar silkworm, Antheraea proylei J., was reared on the foliage of Quercus serrata Thunb., Q. griffithii Hook. fil. and Thoms, and Q. dealbata Hook, fil and Thoms. under controlled indoor conditions to assess the suitability of these plants as feed for the silkworm. Relative growth rate of the silkworm was lowest on Q. dealbata, perhaps due to the relatively low level of crude protein and high level of crude fibre in this species. These results show that Q. dealbata is a nutritionally inferior food plant in comparison with Q. serrata and Q. griffithii.

In Zambia, termites have been recognized as pests of agricultural crops, plantation trees, structural timber, manufactured wooden goods as well as paper. This makes their control imperative. In line with the concept of pest management, appropriate control measures of termites must take into account their taxonomy, biology and ecology, as well the assessment of crop damage and yield losses. This paper discusses some of the problems inherent in developing such a scheme in Zambia and provides alternative solutions.

Field tests were carried out to compare the performance of a new tsetse trap, the Nitse (I and II) with the biconical, F3 and NGU traps respectively at the Yankari Game Reserve, Bauchi State, Nigeria. The game reserve harbours Glossina palpalis, G. tachinoides and G. morsitans submorsitans species. The biconical trap was used as the standard. The sites had been cleared of vegetation; they were 5–10 m away from vehicle paths and about 100 m apart. Each trap was moved rotatingly until all traps were exposed to each of the five sites. Traps were emptied each morning after 24 h and the tsetse sorted according to species and sex. The data on the different trap catches were analysed using the one-way ANOVA and the multiple range test via the SPSS statistical package. The performance of the Nitse I on G. tachinoides in one area with high tsetse density was significantly better than that of each of the three traps. But for G. m. submorsitans, Nitse I and the biconical trap performed better than only the F3 (P ≤ 0.05) in the high density area. Only the biconical performed significantly better than the F3 trap in an area with low tsetse density. The new Nitse trap was more effective for G. tachinoides than for G. m. submorsitans.

The design and construction of the Nitse trap are described. The materials required are: royal blue cotton, black cotton, mosquito netting, brass pipe, metal rods and galvanised wire. The cutting and joining of the various parts to produce the trap and the method of placement are also described. Finally a rough estimate of the cost of the trap is given.

Restriction analysis of total DNAs from Leishmania donovani complex strains revealed heterogeneous distribution of kDNA fragments among the reference strains of L. donovani. The cloned kDNA fragments used as probes in the hybridisation analysis have proven useful for identifying and characterising L. donovani subspecies when screening newly isolated leishmanial parasites from patients, vectors and reservoir hosts. This genetic heterogeneity was confirmed by karyotyping by pulsed field gel electrophoresis of four L. donovani reference strains. A high degree of polymorphism was shown, affecting not only the chromosome size, but also their number.