Studies on developmental biology and feeding and ovipositional preferences of the pea leaf miner, Chromatomyia horticola (Goureau), were carried out on 11 varieties of field peas, Pisum sativum L. Two varieties, P-200 and P-402, offered maximum resistance to the development of pea leaf miner by inhibiting growth as both larval and puparial development were prolonged, and adult longevity, survival and fecundity reduced. These varieties were also least preferred for feeding and oviposition. Differences between the moderately resistant HFP-4 and highly susceptible varieties HFP-5, HFP-6, HFP-12, PG-3, RAU-21, RAU-25, RAU-37and T-163 were not well marked, as most of these had a relatively high value for the developmental success index, based on indices for larval-puparial development, adult longevity, survival and fecundity, and were also highly preferred by the ovipositing females. Variety PG-3, though offering some resistance to development, was highly preferred for oviposition. The local variety T-163, was the most susceptible variety, as it had the maximum value for the developmental success index, and was highly preferred by ovipositing females. The physiological basis of resistance in the two pea varieties is suggested to be mainly non-preference and antibiosis.

Observations on the fauna that live in close association with mounds constructed by Cubitermes testaceus (Isoptera: Termitidae) were made in a grassland area of Uganda. Termite nests were systematically excavated and dissected and a careful record of the fauna associated with each was made.

Arthropods belonging to three different classes were recorded in mounds of C. testaceus and with varying degrees of occurrence. They included insects (93%), chilopods (5%) and diplopods (2%). Ants were found to be the commonest insects in the mounds followed by other termites (21%) Coleoptera (9%) and Dictyoptera (1%).

In view of the carnivorous nature of most of the ants recorded, and considering the feeding behaviour observed in the field, it is suggested that they can have considerable effect on C. testaceus populations in the grassland ecosystem at Kaazi.

Mussidia nigrivenella Ragonot is the main cob borer of maize in Ivory Coast. An accurate description of male and female genitalia is given. Rearing in the laboratory has permitted determination of the number and duration of the pre-imaginal instars, fecundity of adults and fertility of eggs as also the sex-ratio. An artificial diet has been elaborated which provides conditions of similar development to those observed in the field: The insect has 5 to 6 larval instars and the total duration of development from the egg-laying to the adult emergence is 46 days for the male and 49 days for the female.

Investigations were carried out on the seasonal population fluctuations of the moth Cydia ptychora. The population increased from May to September and declined from November to April. Increasing temperatures and decreasing r.h. appeared to be associated with population decline, while the reverse seemed to favour population increase.

From light trap catches, sex ratios of adults showed considerable variation from month to month. The overall ratio was 2:1, in favour of the males, but there was a tendency for adjustment towards an apparently female-biased ratio from March to August.

Bracon (?) hancocki was found to be a major parasite. Other biotic factors contributing to population regulation included 13 hymenopterous parasites and three predators (Philodicus temerarius, Bactria sp. nr. guineensis and Chrysopa sp.)

Parasitization of P. brassicae L. by A. glomeratus L. was found to be between 63.79 and 76.52% in Farm 1 and 92.68 and 93.43% in Farm 2. Population density of the parasitoids ranged between 35.16 ± 6.05 and 57.76 ± 13.20. The developmental period of the parasitoids within the host was 21 days and the pupal period 9 to 10 days. The population of the parasitoid showed a steady increase during November–December. The rate of pupation of P. brassicae showed a decline from 36.21% in mid-November to 23.48% in later November in Farm 1 with an early crop. In Farm 2 with a late crop the pupation rate dwindled from an already low 7.32 to 6.57% by late December.

The immature stages of the predaceous mite Typhlodromus talbii Athias-Henriot are described. The mite was reared on different prey species and pollen in the laboratory, and its developmental parameters calculated. Tydeus californicus (Banks) was found to be the most suitable and nourishing diet, giving a shorter life cycle and higher female fecundity (8.8 days and 33.4 eggs respectively), than the scale insect Coccus acuminatum (Gennadius) (10.0 days and 24.8 eggs respectively) at 25 °C. Other associates of Typ. talbii, the eriophyid Cesaberoptus kenyae Keifer, the tetranychid Oligonychus mangiferus (R. & S.) as well as date palm and castor oil pollen, were unsuitable diet. When reared on moving stages of Tyd. californicus (Banks) at 70 ± 5 % RH, 16:8 (L:D) h photoperiod and temperatures of 15,20,25,28,30,32 and 35 °C, the total developmental time of Typ. talbii averaged 21.3, 12.4, 8.8, 7.6, 7.1, 5.8 and 11.6 days respectively. The intrinsic rate of natural increase (rm) and the net reproduction (Ro) reached maximum values of 0.299 individuals per female per day and 28.06 times respectively, at 32 °C.

A headcage technique to screen for resistance to sorghum head bug, Eurystylus immaculatus Odh. (Hemiptera: Miridae) was standardized for use in West Africa. Panicles infested at the half-anthesis to complete-anthesis stage had greater population build-up and suffered maximum grain damage, loss in grain mass, grain hardness and seed germination. Panicles with higher grain damage also showed greater severity of grain mould incidence. Maximum population build-up and grain damage was recorded in panicles infested with 20 pairs of adults. Panicles infested with 30–40 pairs of bugs generally showed a decrease in population build-up, possibly because of crowding. Head bug numbers decreased with a decrease in panicle size, while the extent of grain damage increased. To screen for resistance to head bugs, data should be recorded both on head bug numbers and grain damage. Fifty nymphs (third to fourth instar) or 40 bugs collected at random can also be used in the headcage to screen for resistance to head bugs.

Female sexual receptivity was studied in F1 laboratory-reared Glossina pallidipes Austen, 1903 originating from Nguruman in the Rift Valley of Kenya. Females mated as early as 6 days old but reached peak receptivity at 9–13 days old (60–80%). Females did not immediately mate with more than one male. The mean spermathecal value (MSV) was highest between 7 and 14 days of age, and declined thereafter. The duration of copulation was comparatively short (mean = 24 min), and did not vary significantly with age. High female receptivity corresponded with maturity of ovariole A, which reached maximum length at an age of 10 days. These results are discussed in relation to mass rearing of G. pallidipes.

Pyrethrins I and II were extracted from five seasonal Compositae herbs collected from semi-arid and hilly areas of North India. The relative toxicity of natural pyrethrins were evaluated against Mesocyclops leuckarti sensu lato. Based on the LC50 values, the extract of the plants could be arranged as follows: Tagetes minuta > Pulicaria crispa > T. patuia > T. minuta > P. angustifolia.

The ultrastructural changes in the ejaculatory duct epithelium in Glossina morsitans morsitans Westwood was examined for special features related to spermatophore formation; special attention was paid to the cytoplasmic organelles and the plasma membrane specializations (apical infoldings and space formation). Internally, the transportation system is characterized by a cuticle-lined lumen bordered by cuboidal cells. The endoplasmic reticulum is scarce, while mitochondria are distributed throughout the cytoplasm. At the cuticular surface of the cells, extensive apical infoldings are associated with numerous mitochondria. Glycogen granules are found only in the cytoplasm of teneral flies. Apically, adjacent cells are tightly apposed; however, prominent intercellular spaces develop (1 to 7 days), permeate most of the epithelium and connect to the basal surface of the cells. These are features characteristic of transporting cells believed to have an absorptive function. As the adult fly ages, the ultrastructural characteristics of the epithelium change and are typified by the disappearance of glycogen granules and the formation of intercellular spaces. The features of the ejaculatory duct are discussed briefly in terms of their role in spermatophore formation.

Insect pests are major yield reducers in sorghum under traditional farming practices in Africa. The use of resistant varieties in an integrated pest management scheme provides the most cost effective and practical means of sorghum insect control. Corneous grain sorghums are more weevil resistant than their softer endosperm counterparts. A wide range of sources of resistance to shootfiy, stem-borer and greenbug are known. Breeding for resistance to sorghum insects has been practised with varying degrees of success. Greenbug resistance breeding in sorghum has been successful in the U.S.A. Stem-borers are perhaps the most serious group of sorghum insects in Eastern Africa and further efforts are needed in breeding for resistance to these pests. In an effective pest resistance breeding work, the breeder and the entomologist must work as a team to make the fastest possible progress. Where several pests are of concern in an area, genotypes with multiple resistance in good agronomic backgrounds are needed.

Preferences of Maruca vitrata (Fabricius) (Lepidoptera: Pyralidae) larvae to flowers, flower buds and pods of three different varieties of cowpea (IT 82E-666, IT 82D-716 and Botokpoyi) were studied in the laboratory using a four-branched olfactometer. For each plant part, fourth instars of M. vitrata were individually exposed to a set of three odours obtained from the cowpea varieties with pure air serving as the control. Movements of the larvae in the exposure chamber were followed at two levels of choice. Results from the first level of choice showed that the attractiveness of a particular plant part to M. vitrata larvae was not significantly influenced by variety. At the second level of choice a weakly significant preference was found for flowers (P = 0.1218) compared to pods (P = 0.7530) and flower buds (P = 0.6172). In all cases, no significant difference was found between the control (pure air) and the varieties.

Injection of antiserum prepared against accessory reproductive gland (ARG) secretions of the male desert locust, Schistocerca gregaria, disrupted the normal growth and function of the ARG complex in sexually maturing adults. Male locusts were injected with either antiserum or normal guinea-pig serum on days 3, 7 and 10 after adult ecdysis. When the injection of ARG antiserum began as early as day 3 of adult development a marked inhibition of ARG growth was accompanied by the suppression of other characteristics of sexual maturation (yellow body coloration and mating behaviour). Inhibition of ARG growth, while significant, was less pronounced when antiserum injections began on day 7 of adult development, and the injected males did not exhibit normal mating behaviour when placed with virgin females. When single antiserum injections were administered on day 10 of adult development, the males still attained their yellow body coloration by day 19 and copulated normally with virgin females, although their ARGs were only equivalent in size to those 13-day-old males.

A light trap was operated in Samaru, Nigeria between 1973 and 1980 to monitor populations of Coniesta ignefusalis. Two generations of the insect/year were represented by two adult peaks in July and September. In 1974, an early peak in May resulted in three generations. In cages in the field, eggs were laid between the leaf sheath and the stem in batches of 20 to 70 with a mean of 47.5 eggs/batch. Laboratory studies conducted at 25–28°C and 75–85% r.h. showed an average developmental period of 35.5 days. The average duration of the egg, larval and pupal stages were 4.5, 21.9 and 9.2 days, respectively. Unfed adults lived for 5.3 days.

Field investigations were carried out in northern Nigeria to determine the prominent natural habitats of phlebotomine sandflies. Two biotopes, termite hills and rock crevices, were identified as the major habitats with the termite hills being the most significant. All the 12 species (Phlebotomus duboscqi, P. rodhaini, Sergentomyia antennula, S. bedfordi, S. africana, S. schwetzi, S. ingrami, S. adleri, S. clydei, S. buxtoni, S. affinis and S. christophersi) identified in this study came from this source. Only a small number of samples representing a few species were collected from the three other habitats (tree holes, animal burrows and a cave) investigated. The distribution of the sandflies was found to be influenced by the availability of suitable biotopes and physico-chemical composition of the soil.

The biology of Chilo partellus (Swinhoe) was studied on two resistant, IS 2205, IS 5469 and two susceptible, HC 136, ICSV1 sorghum genotypes. Significant differences were observed between resistant and susceptible genotypes in regards to larval mortality in whorl, larval period, larval weight, larval length, per cent pupation, pupal weight, fecundity per female and total life span of this pest. Growth index was also influenced by the resistant genotypes. It has been concluded that high mortality of larvae on resistant lines is due to antibiosis.

The correlations between the characters of the pest biology have been worked out and larval stage was the most important parameter influencing the total pest survival and population build-up in the succeeding generations.

This paper gives an account of the activities of the International Red Locust Control Organisation for Central and Southern Africa (IRLCO-CSA) in the management of the red locust, other locust species and non-locust migratory pests in the 1980s and 1990s. It also analyses the advances made by IRLCO-CSA in implementing a preventive control strategy so as to avoid future plagues and outlines the activities of IRLCO-CSA during periods of locust recession.

There were widespread upsurges throughout the 1980s into the 1990s, with outbreaks being recorded throughout the period 1985–1997. Without doubt, the period 1981 to the present, was the most active since the suppression of the last plague in the 1940s. It is concluded that the threat of red locust plagues is not yet over and that the continued existence of IRLCO-CSA remains key to the food security needs of the region.

Field experiments at the Msekera Regional Research Station during 1988–1990 and at Masumba (Luangwa Valley) Sub-station during 1989–1990 showed that six groundnut genotypes—ICG.485, ICG.2271, ICG-2306, ICG.5041, ICG.5045 and HyQ (cg) S-10 were distinctly less susceptible to the leafhopper, Empoasca dolichi (Paoli). ICG.2271 also appeared to combine low susceptibility to early leaf spot, Cercospora arachidicola Hori and good yield potential. This genotype as well as ICG.5041 and ICG.5045 also are known to be resistant to thrips and/or termites. The scope for their utilization in exploitation of leafhopper resistance in groundnut improvement programme in Zambia is indicated.

The effects of various exposure to irradiation from cesium 137 in nitrogen and air on survival and fecundity of Glossina palpalis palpalis were compared. With doses from 3 to 21 krad in nitrogen atmosphere, male fertility was inversely correlated with dose, above 15 krad male survival was inversely correlated with dose. All males subjected to either 21 krad in nitrogen or 15 krad in air were sterilized. Females appeared to be more sensitive to gamma-irradiation than males; a dose of 6 krad in nitrogen resulted in 100% sterility and arrested further development of the ovaries after the ovulation of follicles A1 and C1. In males, this dose caused 70.3% sterility. Approximately 97 and 98% sterility were obtained when males were treated with 15 krad in nitrogen and 12 krad in air respectively. No fly emerged from irradiated puparia younger than 15 days. Irradiation of 15 or 20 days old puparia killed the insect either before or shortly after eclosion, whereas the normal patterns of emergence, survival and reproduction were observed from puparia that were irradiated when 25 days old or older.