Recent entomological surveys in the Bouaflé sleeping sickness focus of the Ivory Coast have revealed that Glossina tachinoides is considerably more widely distributed than hitherto. Some flies were found in the fringing riverine forests of tributaries of the River Marahoué. However, the greatest concentrations were found in villages and settlements where domestic pigs were kept. The southern limit of G. tachinoides now appears to lie one half degree of latitude further south than that reported by earlier investigators. The authors think there is good evidence that G. tachinoides is extending its range eastwards and southwards through and beyond the Bouaflé area, and the epidemiological significance of this is briefly discussed.

Eight cultivars of the common bean (Phaseolus vulgaris L.) and the Tepary bean (Phaseolus acutifolius) were used to study the distribution of puparia of the bean fly species Ophiomyia phaseoli (Tyron) and O. spencerella (Greathead). The puparia of the two bean fly species were distributed differently in the plant, O. spencerella predominating in the root and O. phaseoli in the shoot. There were significant differences between some of the bean cultivars and the number of puparia found. Tepary had the least puparia and P. vulgaris cultivars GLP 806 and GLP 1131 the most. There was a low correlation between the number of puparia and the final yield or root dry weight.

Various neem products were compared with copra oil, palm oil and 0.25% diazinon dust for protection of stored maize against the grain weevil, Sitophilus zeamais Motsch. Maize kernels treated with neem oil or ash were damaged less than the control. Although copra and palm kernel oil reduced S. zeamais attack, these edible oils were not as effective as neem oil. Neem wood ash was however, less effective than 0.25% diazinon dust. Neem derivatives inhibited oviposition and/or deterred feeding.

Effect of fluctuating and constant temperatures on different population growth parameters of Chilo partellus (Swinhoe) infesting sorghum was studied in the laboratory. On the basis of intrinsic rate of natural increase (rm) values, the optimum constant and fluctuating temperatures for the multiplication of this pest was 30 ± 1°C and 31.0 to 35.8°C, respectively. But the favourable range of temperature varied from 27.5 to 30.0°C under both constant and fluctuating temperature conditions. Mean length of generation (T) at this range of temperature varied from 38 to 41 days. It seems that Chilo partellus may not persist at or above 40°C and below 20°C, as the rm values at these temperatures were negligible or zero. This information can be used in working out the strategy for controlling Chilo partellus.

Gravid Lucilia treated topically with ivermectin (0.05μg/g, which represented approx. 4% of the 48 hr LD50) laid fewer viable egg batches (less than 50% of controls) and more sterile ones, when compared to untreated (P = 0.019) and acetone-treated flies (P = 0.028). This effect was also seen when mature third instar larvae were dosed with 7.6 μ g ivermectin/g (P = 0.0075 and 0.016 respectively); number of viable egg batches produced were only 25% of the number laid by the progeny of untreated larvae.

Dosage with fenthion stimulated an increase in the number of viable egg batches laid when incorporated in the original larval feeding medium at 0.2 μg/g liver; fewer viable egg batches were laid by the flies which developed from mature larvae treated with 7.6 μ g fenthion/g. Acetone solvent alone had a mild stimulatory effect on topically dosed flies.

A comprehensive review of the major investigations on the biology of African ixodid ticks is made with a view to identifying weaknesses in the life systems which may be employed as control components in an integrated package. The possibility of breeding ticks with low oviposition capacities needs to be confirmed and further studied with respect to the economically important ticks in Africa. Studies on the membrane or artificial feeding of ixodid ticks must be conclusive and more importantly the disease transmission abilities of these membrane fed ticks is worthy of being looked into. Additionally, the hybrid status of both Genus Rhipicephalus and Genus Amblyomma ticks should be studied. Efforts must also be made to intensify research on selecting resistant host breeds to multihost ticks, R. appendiculatus and A. variegatum, among the very many cattle breeds present in Africa.

In south-eastern Uganda the natural hosts of Glossina pallidipes, G. fuscipes fuscipes and G. brevipalpis appear to influence trypanosome infection rates in these vectors. The transmission index of these vectors also differs. Temperature is yet another factor affecting trypanosome infection rates in these tsetses. Other factors probably also form important components in the transmission cycle. In this region of Uganda and its contiguous lake shore area of Kenya there are extant foci of the infections, and man and his symbiotic livestock are exposed to a high challenge of trypanosomiases. Furthermore, in this high endemic/enzootic ecological zone of tropical Africa, the transmission of trypanosome infections to the adventitious hosts, via the tsetse vectors, depends upon a variety of complex interacting factors.

Laboratory studies were conducted on the role of flood on egg development, survival and hatchling weight in the solitary phase of Locusta migratoria migratorioides (Reiche and Fairmaire). Egg development is retarded by flood, particularly if the eggs develop for a long period in ordinary moist soil prior to flooding. Floods are also detrimental to egg survival; eggs that are flooded immediately after oviposition and those flooded when they are about to hatch are particularly susceptible. Egg age at flooding is a major determining factor of hatchling weight; heavier hatchlings are produced if eggs develop in ordinary moist soil for longer, rather than shorter, period before being flooded. Length of flooding period has no apparent effect on hatchling weight.

Tests on the quantitative adsorption of polyhedra of nuclear polyhedrosis virus of Heliothis armigera to black and red soil showed an increase in the adsorption of polyhedra with an increase in the amount of soil. The increase was higher in the red soil than black soil, but the number of polyhedra adsorbed per unit weight of soil decreased as the amount of soil increased; the rate of decrease being faster in black soil than in red soil. The adsorption of polyhedra of nuclear polyhedrosis virus of Heliothis armigera is discussed based on certain physico-chemical properties of both red and black soils.

Spatial dispersion of the nymphs of the jassid, Amrasca biguttula biguttula (Ishida), and the adults of the whitefly, Bemisia tabaci Genn. on F414, a Gossypium hirsutum variety, was systematic in Ludhiana (Punjab). Both the jassid and the whitefly displayed no definite pattern along the height of the plant, though a maximum number of whiteflies were recorded at middle canopy (21–40 cm from bottom). Sample sizes of 10–15 plants, selected in a statistically linear fashion represented populations of jassid nymphs and adult whitefly on all four varieties. Sampling jassid nymphs by visual counting and whitefly by split-cage were the most suitable sampling methods for local cotton growers among the various methods compared.

Larvae of the Caribbean fruit fly, Anastrepha suspensa Loew (Diptera: Tephritidae) parasitized by the wasp, Biosteres longicaudatus Ashmead (Hymenoptera: Braconidae), were topically treated with diflubenzuron (Dimilin®), a chitin synthesis inhibitor, at 100, 500 and 1000 ppm. Each dosage was initiated during the parasite's egg stage, each of four larval stages and the pupal stage (pharate pupa + pharate adult). Adults emerging from all immature stages treated with the two higher dosages were significantly (P < 0.05) fewer than the controls. Developmental stages, in decreasing order of susceptibility to diflubenzuron were: egg, first instar, pharate adult, pharate pupa and larval stages two to four. Abnormally developed ovipositors occurred in some adults which emerged from eggs, pharate pupa and pharate adults that were treated with the two higher concentrations. Such females were unable to successfully locate and parasitize hosts. Females with normal ovipositors which emerged from treated eggs and pharate adults were able to find and attack hosts but had significantly fewer eggs in their ovaries and oviposited less than the controls. The F1 eggs laid by these females developed normally and survived to adulthood with no apparent abnormalities.

Biconical traps were studied for their efficiency in sampling for Glossina morsitans morsitans Westw., G. pallidipes Aust., G. austeni Newst. and G. brevipalpis Newst. in three localities in Mozambique where these species occur sympatrically or singly. Studies were also carried out to determine whether acetone vapour was effective in enhancing the efficiency of the biconical trap. Various comparisons were also made between biconical traps and Langridge traps, and with fly-round patrols, with and without bait oxen.

It was demonstrated initially that the blue biconical trap (BBT) was more efficient for G. morsitans and G. pallidipes than red or white models or Langridge traps. In all subsequent studies, therefore, the BBT was used. It was concluded that: the BBT was ineffective for sampling G. morsitans, with or without acetone; the BBT was markedly more effective than fly rounds for sampling G. pallidipes, and its efficiency was significantly enhanced by acetone; and G. austeni was attracted to the BBT, but not all flies would enter the non-return cage—G. brevipalpis was readily caught in the BBT. Acetone with the BBT gave inconclusive results for these species.

The flight phenology of the stem borer, Chilo partellus (Swinhoe) at the ICIPE's Mbita Point Field Station (MPFS) and on a nearby farmer's field was monitored using pheromone traps. The relation between pheromone trap catches of males and sorghum plant age, infestation, larval/pupal population density and sorghum cultivars used was examined. At MPFS C. partellus males were caught throughout the year in pheromone traps. Fluctuations of trap catches indicated that the pest completes two main generations on each of the long and short rain sorghum crops. On farmers' fields, males continued to be caught in large numbers after harvest, implying that the pest continues to breed on the sorghum stalks and tillers. Significantly lower observed catches of males occurred only on one (MB-3) of the eight different sorghum cultivars, during the period of 2–6 weeks after plant emergence. In general, positive correlations were observed between the number of males caught in pheromone traps and larval pupal population density, males and percentage plants infested, and males and plant age. However, the pheromone trap appeared to be less effective under high population density, particularly during the flight of the second generation moths, due to competition between pheromone trap and wild females. But the flight phenology as monitored by pheromone traps appeared to reflect major events in population development of C. partellus. Pheromone traps would be useful in detecting C. partellus and for monitoring its flight phenology.

The control of Trypanosoma rhodesiense sleeping sickness by clinical methods is often complicated by the existence of animal reservoir hosts which greatly contribute to the persistence of the disease in many parts of East Africa. The control of sleeping sickness should, therefore, include control of the vector and elimination of the reservoir hosts. Another factor which is often ignored, when planning sleeping sickness control measures, is the influence of cultural practices of the resident human population on the epidemiology of the disease in any given location in East Africa. At Lower Kitete, northern Tanzania, trypanosomiasis due to T. rhodesiense is occupational in nature so that many of the individuals are infected in Lossitete Forest while engaged in various activities. The factors favouring infection within the area, and the role played by the cultural practices of the Masai around the area in bringing about the outbreak of an epidemic, are discussed. The importance of understanding the cultural practices and occupational tendencies of the Masai in Lower Kitete, where trypanosomiasis outbreaks have occurred in the last 10 years, is stressed. With such an understanding the management of trypanosomiasis at Lower Kitete may be successful.

The effect of fly age, sex, and period of starvation on the uptake and development of Trypanosoma congolense infection was examined in Glossina morsitans morsitans. In a study consisting of 1739 specimens of various ages, young unfed 16-hr-old flies and 2-day-old starved flies developed significantly higher mature infections than 2-day-old and 7-day-old flies which had been fed previously on a clean blood meal. Females displayed significantly higher immature infections, while mature infections were recorded more frequently in males, suggesting that females possess a stronger barrier to trypanosome development. The possible factors involved are discussed.

The major alkanone constituents of the resin of Commiphora rostrata, 2-decanone and 2-undecanone, and a series of structural analogues were bioassayed for their repellency against the maize weevil, Sitophilus zeamais in olfactometric assays. All the aliphatic ketones and aldehydes showed comparable or greater activity than the synthetic commercial insect repellent N, N-diethyl toluamide (DEET). In the 2-alkanone series the C-8 and C-9 compounds demonstrated significantly higher activity than their shorter- and longer-chained congeners. Analogues differing in the relative positions of the carbonyl group, including aldehydes, showed a variable pattern of repellency. Alkanols appeared to be mildly attractive to the weevil. The results support our previous suggestion that the resin constituents may play an allomonal role in the ecosystem where the plant thrives.

The relationship between seasonal numbers of outbreaks of African armyworm (Spodoptera exempta) in Kenya and Tanzania, and early season rainfall in source areas has been examined using records for 21 seasons. Significant inverse relationships were found between numbers of Kenya outbreaks and early season rains in the Kisumu area, and between numbers of Tanzania outbreaks and early season rains in the Morogoro and Mtwara areas. Total Kenya and Tanzania outbreak numbers were significantly inversely related to early season rainfall for 8 areas combined. These results suggest that early season rainfall totals, either from specific likely source areas or countrywide, could be used in January to give a seasonal forecast of likely numbers of armyworm outbreaks during the rest of the season. Seasons with more than average numbers of outbreaks often follow poor early season rains and visa versa. Further work is needed to establish biological causes of this apparent relationship.

The length of the reproduction cycle of Lasioderma serricorne (F.) under ambient laboratory conditions (temperature range 28.0–32°C and 72.5–80.5% r.h.)was shown to depend on the identity and state of division of various cereal grains, cowpeas, groundnuts and dried root crops. Cut dried yams allowed the shortest cycle andwholericethelongest.The rate of population increase by L. serricorne was also assessed and this was maximal when cut wheat and minimal when whole rice was provided. Fecundity was highest with sorghum and lowest with rice as food source. Females of the species lived longer than males.