Dacus oleae (Gmelin) is a major pest of the olive tree Olea europea causing early fruit drop, ‘sting’ damage to table olives and substantial decreases in the quantity and quality of oil. This review describes the control strategies being developed and in current use—biological, trapping methods, sterile insect release, chemical insecticides, growth regulators and integrated control. Present problems and the implications of the controlling regimes on the disturbance of the agroecosystem are presented. Emphasis is given to newer methods which should be characterized by their specificity and effectivity.

A preliminary taxonomic review of cassava green spider mites, Mononychellus spp., from their South American topotype and from several African countries indicates that the dorsal central body setae is not a reliable and stable diagnostic character as it was found to widely vary. The taxonomie implication of this is discussed.

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.

Motile zoospores, the only infective stage of Pythium species, attached, encysted and infected 100% second instar larvae of Aedes aegypti, Aedes africanus, Aedes simpsoni, and Anopheles gambiae. Motile zoospores variably attached and infected Culex spp. and Eretmopodites but did not attack field collected Toxorhynchites sp. We observed mycelial development within the exposed larvae after exposure indicating that mortality was due to the fungus. The fungus infected 75 ± 10% (SD) second instar larvae of Aedes aegypti, under aseptically reared conditions. It infected 65 ± 12.8% (SD) second instar larvae of Culex quinquefasciatus in aseptic conditions in the laboratory. All field collected larvae were heavily infested with vorticella but after treatment with 5% sodium hypochlorite, control mortalities ranged from 0 to 8.6% (mean = 4.3%).

The fungus was most infective between 20–27.5°C; at 30°C many zoospores were attached to the cuticle but did not infect. Mortality rates were as low as 51.5% at 30°C, with no infection at all at 35°C. pH range from 6–8 was optimum for infection, but pH above 8 inhibited infection. Infection level of 100% was obtained in aseptically reared larvae at higher densities of 1600 larvae of second instar larvae of Aedes aegypti and 97% infection for 1600 second instar larvae of C. quinquefasciatus when exposed to fungal infection. Phosphate, borate and acetate buffers inhibited zoospore production.

Mixed T. congolense and T. brucei appeared in mice when proboscis from 3 field collected G. pallidipes were individually inoculated into mice. One of these flies had earlier been shown by dissection, to have T. congolense and the other two had T. brucei infection. A comparison of the growth rates of T. congolense and T. brucei in mice revealed that T. brucei always overshadowed T. congolense. These observations highlight the significance of multiple trypanosome infections in the epidemiology of African trypanosomiasis.

An ecological study was conducted in two pools, one temporary and one semi-permanent at the Kenya coast to determine the relationship between infection levels of Coelomomyces indicus Iyengar in larvae of Anopheles gambiae Giles, and the species and density of copepods found in these sites. Microcyclops minutus Claus, an intermediate host of Coelomomyces indicus, was the predominant species in both pools. Other species were, Mesocyclops leuckarti Claus, Mesocyclops leuckarti pilosa Kiefer, and Mesocyclops (Thermocyclops) decipiens Kiefer. Infections occurred during the periods when M. minutus densities were above 12 cyclops per 250 ml of water. A positive relationship was shown between M. minutus density and infection levels in An. gambiae with C. indicus. The r-value for this relationship in the temporary pool was 0.726, and in the semi-permanent pool, 0.639.

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.

Combined effects of constant temperature (15–35°C) and relative humidity (50–90%) on longevity and total duration of life cycle of Tetrastichus pyrillae Crawford, one of the most common egg parasitoids of the sugar-cane leaf hopper, Pyrilla perpusilla Walker were determined and are discussed. Influence of the temperature both on the longevity and the developmental duration of this egg parasitoid was highly significant while the relative humidity did not produce any marked change. Average longevity of males decreased from 5.89 to 1.06 days and that of females from 9.60 to 1.04 days in response to corresponding rise in test temperature from 15 to 35 ± 1.5°C. Mean duration of its life cycle also declined from 40.5 to 9.8 days as the rearing temperature was raised from 15 to 30 ± 1.5°C. Developing parasitoid died, without attaining adulthood within its host eggs, at or above 32.5°C.

The fat body protein content of silkworms increased with 0.5 μg of thyroxine (T4) per gram of body weight and more so with 1 μg/g on days 4 and 8 after injection. Thyroxine with 1 μg/g dose, however, caused an earlier increase in protein content on day 2. The higher doses of T4 (2 and 5 μg/g) decreased the protein content. All T4 treated groups (except with an ineffective dose of 0.25 μg/g) showed reduced protein level in the adult stage in comparison to the control. Thyroxine with a dose of 0.25, 0.5 and 1 μg/g increased the fat body RNA content over the control level which was observed on days 2, 4 and 8. But on day 13, the RNA content in these groups returned to the control level. Higher doses of T4 (2 and 5 μg/g) decreased the RNA content during the developmental period. DNA content was not altered by lower doses of T4 (0.25,0.5 and 1 μg/g), while the higher doses (2 and 5 μg/g) surprisingly caused a reduction in DNA content during the larval, pupal and adult stages.

The increase in protein and RNA contents with lower doses of T4 and decrease with higher doses, indicates a biphasic nature of thyroid hormone action in silkworm fat body.

Brugia pahangi microfilariae obtained from peritoneal washings of jirds (Meriones unguiculatus) were incubated with midgut tissue of Culex quinquefasciatus and Aedes aegypti (susceptible stock), in the presence or absence of blood and also in thoracic tissue and salivary glands in various media. Exsheathment took place in the presence of midgut tissue with or without blood and in thoracic tissue, but not in the presence of salivary glands.

Percentage exsheathment was variable and not reproducible for each type of tissue. Exsheathment also occurred in the presence of mosquito cells in suspension and in monolayers. In the latter, percentage exsheathment in some cases was higher than that observed in vivo in the midgut of C. quinquefasciatus, which is refractory to B. pahangi microfilariae.

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.

Studies on the peridomestic resting sites of Glossina f. fuscipes were carried out at night and during the day. Flies were caught, marked with fluorescent powders and then released in coffee and banana plantations, Lantana camara thicket and adjoining forest habitat and the potential resting sites subsequently searched.

Leaves, twigs and branches between 0.5 and 1 cm in dia. are the preferred resting sites of G.f. fuscipes. The resting heights ranged from 0 to 3.66 m. Results are discussed in relation to tsetse control in the Busoga sleeping sickness epidemic area.

A sizeable population (60.5%) of muga silkworm (Antheraea assama Westwood, Saturniidae: Lepidoptera) enters pupal diapause in its natural environment in the wild state whereas the development is continuous when reared in the plains (0 to 20 m MSL) under human care (in this practice the larvae are mounted on the food plants with suitable leaves and protected from natural enemies and pass the entire larval stage in the out-door and rest of the development, viz. cocooning, pupation, moth emergence, courtship, copulation, oviposition and embryonic development etc. take place in in-door conditions; the ripe worms are collected from the food plants and put in the cocoonage; after cocoon formation the cocoons are placed in cages for moth emergence; if the moths do not couple naturally, mechanical coupling by gentle rubbing of the genital segments of the opposite sexes is resorted; finally the coupled moths are tied on a straw bundle for oviposition). Inbreeding of diapausing population in plain inhibits dormancy but intercross with the non-diapausing population channels a few pupae (3.5%) into diapause. Low temperature (6–10°C) and short photophase (9 to 10 hr) prevailing in winter in the hills (100 to 450 m AMSL) appear to be the threshold level to induce diapause in muga silkworm.

Moisture content, hardness or consistency, and age of diet were some of the properties studied for their effect on survival, growth and development of Sesamia inferens Walker. Survival of larvae was maximum on diet with 66.1% moisture. Increase or decrease in moisture resulted in excessive stickiness or dryness to the diet. Reduction in moisture content in the artificial diet was dependent on particle size of bulk constituent. Proper consistency or hardness resulting from 1.8 and 2.2% agar permitted higher number of larvae to reach pupal stage. Diet stored for 24 hr and 48 hr provided favourable conditions for the early instar larvae to establish on the diet.

In order to evaluate the migratory potential of the brown planthopper, Nilaparvata lugens, under as near to normal environmental conditions as possible, adult macropterous insects were captured from the field whilst in the process of flight initiation at the times of their natural take-off peaks. The insects were then flight-mounted and flown in the field. Average flight durations following the dusk take-off were 4 hr 55 min for males and 6 hr 17 min for females. However, many insects flew throughout the night and there was a high frequency of flight cessation at dawn. Following a dawn take-off both sexes flew for much shorter periods, an average of 2 hr 00 min for males and 2 hr 04 min for females. Female insects were reluctant to initiate a second major flight. The role of mating and ovary development in female flight willingness is discussed.

Egg distribution on cowpea seeds and the influence of seed population on extent of oviposition by Callosobruchus maculatus (F.) were investigated in this study. Majority of the eggs were laid on the cheek of the cowpea seeds. The number of eggs laid by females increased with increase in seed population. The results are discussed in relation to observations on oviposition behaviour of C. maculatus reported by earlier workers.

Insect growth regulating properties of petroleum ether extracts of 10 indigenous plants were tested against Culex pipiens fatigans (Wied) and Musca domestica nebulo (Fabr) by continuous exposure and topical application methods. Out of the 10 plants, Acorus calamus and Azadirachta indica demonstrated insect growth regulatory (IGR) activity against C. p. fatigans and also against M. d. nebulo. There was IGR activity, but this was observed only when these extracts were used in higher concentration.

Two antifeedants, isopongaflavone and tephrosin have been isolated from Tephrosia elata. Tephrosin displayed high activity against Spodoptera exempta, while isopongaflavone was shown to be very active against Maruca testulalis and Eldana saccharina. Rotenone was found to be active as an antifeedant against S. exempta, E. saccharina and M. testulalis. Insects in the orders Coleoptera, Hymenoptera, Lepidoptera and Diptera, all associated with T. elata seed pods, were identified.

The relative pathogenicity and toxicity of nuclear polyhedrosis virus of the cotton leafworm, Spodoptera litioralis (Boisd.) (SLNPV) and three pesticides, namely DC–702, DC–703 and DC–800, were investigated against the second- and fourth-instar larvae of S. littoralis. Results revealed that the second instar was more susceptible to the action of all treatments than the fourth instar. Among the tested insecticides, DC–703 was most toxic for either instars, followed by DC–800 and DC–702 for the second instar larvae. Fourth-instar larvae were more susceptible to DC–702 and DC–800, respectively. Combination of virus and DC–702 gave increased larval mortality when compared with the effects of either alone. On the other hand, antagonistic effect occurred when DC–703 was combined with NPV. This may be due to the high percentage of diflubenzuron (4.8%) as one of the components of DC–703, while DC-702 contains only 2.4% diflubenzuron. Synergistic interactions of mixtures containing low concentrations of SLNPV and DC–702 or DC–800 may be effective against S. littoralis and more safe for other biotic control agents.