At 25°C and 70% r.h. larvae of Spodoptera exempta develop faster and pass through five instars on star grass, Cynodon dactylon (L.); Pers. maize, Zea mais L.; and Kikuyu grass, Pennisetum clandestinum Chiov. whereas on guinea grass, Panicum maximum Jacq.; and Setaria plicatilis (Hochst.) Hack, the development is not only slower, but the larvae pass through six and seven instars, respectively. Samples of larvae reared on the former grass species suffer high mortality only at the first and the last instar stages so that the distribution of per cent mortality is U-shaped. On the latter host plants, the mortality during the first instar stage is equally high and continues through the subsequent instars with no obvious peak towards the end of the larval life. The samples on C. dactylon and Z. mais had much higher growth indices than those on P. maximum and S. plicatilis. C. dactylon is a preferred natural food plant of S. exempta in the field, and these investigations demonstrate its value and importance.

The special circumstances of plant protection in tropical developing countries, particularly in Africa, are considered within the context of the needs of the preponderant rural farming community, and in respect of food production. The problems are exacerbated by the existence of complex cropping systems (intercropping), the abundance and diversity of pests, the meagre knowledge of the plant-host-pest relationships, and the poor availability of the scientific understanding of the components of pest control and inputs essential for integrated pest management. Institutional innovations, including stepped-up professional training of experts in the field of plant protection, are required to usher in a more sustained effort in efficacious plant protection in these regions. Attempts in this direction are briefly discussed.

Although pesticides provide benefits in our battle to control pests that destroy more than a third of all food, the use of pesticides also results in significant costs to public health and the environment. As many as 500,000 humans are poisoned annually by pesticides in the world; the United States alone reports about 45,000 human pesticide poisonings.

Pesticides have also caused many detrimental effects on agroecosystems and natural ecosystems. These include: (i) reducing and sometimes eliminating beneficial natural enemies that keep pest populations at low densities; (ii) increasing or decreasing reproduction in various animal populations; (iii) altering decomposition rates of soil organic matter; (iv) developing insecticide resistance in pests, which results in increased pesticide use and additional crop losses; and (v) eliminating honey bee and other bee populations in certain regions thus reducing crop yields and quality. Pesticides also have had major impacts on fish, bird and mammal populations.

The importance of rice in West Africa and the problem posed by pests were highlighted. Stem-borers are regarded as major insect pests of rice and available information on yield losses attributable to insect pests in general and stem-borers in particular, was reviewed. Damage caused by stem-borers usually results in “dead hearts” and “white heads” though other effects including a synergistic interaction between stem-borers and rice blast have been recorded. Survey methods and sampling of rice stem-borers were discussed and brief descriptions on distribution, behaviour and biology of the major rice stem-borers namely, Chilo spp., Maliarpha separatella, Scirpophaga spp., Sesamia spp. and Diopsis spp. were given. Current control tactics under investigation in West Africa include chemical, cultural and biological methods.

About 20 species of borers are rice pests. Of these, five—yellow borer, striped borer, white borer, dark-headed borer, and pink borer—are of economic importance. Yellow borer and striped borer occur most widely in Asia and cause serious yield losses.

Varietal resistance to these two species has been investigated during the last 30 years. Field and greenhouse screening techniques have been developed and numerous germplasm entries have been evaluated for resistance. Several hundred varieties with low to moderate levels of resistance have been identified. Except for several wild species of Oryza, germplasm with a high level of resistance has not been found.

Information available to date indicates that the resistance is under polygenic control. Moderate levels of resistance from several donor parents have been incorporated into improved varieties. Some of these moderately resistant varieties, for example, IR20, IR36, IR50, Ratna and Chandina, are widely grown and play an important role in integrated pest management programs for stem-borer control. Efforts to develop cultivars with levels of resistance higher than presently grown varieties are under way using the diallel selective mating system and the male sterile facilitated recurrent selection schemes.

Journal citations in Bibliography of entomological research in Nigeria: 1900–1973 were subjected to Bradford analysis with the view of evaluating the completeness of the bibliography and determining the core journals and core authors. As to the completeness of the bibliography, it was inferred that the bibliography is 93% complete in terms of journals and 84% complete in terms of articles. On further testing the law for its applicability on author distribution, it was observed that the observed value for total number of authors was just a little above 50% of the actual figure. This may suggest that as in a similar study Bradford's law may not be as applicable to author distribution as it is for literature although the verbal formulation of the law has been found to be applicable to users distribution of periodical literature in a library. On the other hand, the investigation revealed that only three journals (i.e. 1.4% of the total number of 216 listed in the bibliography) form the core, while out of 650 authors, 21 constitute the core. The analysis also reveals an interesting phenomenon with the parameters (a measure of subject breadth being negative).

A wide range of objects have been designed to attract tsetse, such as simple cloth screens, or to both attract and catch them, traps of varying degrees of complexity. The shape and size of these objects affect the number of flies that are attracted to their vicinity and those that actually alight on them or, in the case of traps, are caught by them. Studies on the spectral responses of male Glossina morsitans morsitans, using electrophysiological and behavioural techniques, have shown response maxima in the u.v. and in areas of the visible range. Preliminary field studies are described, in which performances of traps covered in different coloured materials of known spectral reflectance were assessed. The most important colour determinant of trap score is the proportion of attractive blue (400–500 nm) to unattractive green-yellow (500–600 nm) in the reflectance of the material used. Reflectivity of red (above 600 nm) is also a positive factor in trap attractiveness. Optimising the visual attractiveness of targets is particularly important if odour is not employed to effect the initial attraction of tsetse to their vicinity.

Recording of electroantennographic (EAG) responses from tsetse, Glossina pallidipes and G. morsitans morsitans (Diptera: Glossinidae) has been used to detect olfactory stimulants in volatiles from cattle. The most potent stimulant in cattle odours collected on Porapak resin has been identifiedas 1-octen-3-ol by gas chromatographic retention data and mass spectrometry. The rate of production of 1-octen-3-ol by a normal ox was estimated to be 0.043 mghr−1, and the natural material was shown to be predominantly the (R)-(−)enantiomer. No 1-octen-3-ol was collected under the conditions used in the absence of an ox. EAG dose-response curves to 1-octen-3-ol showed it to be about 106 times more potent than acetone, a known attractant for tsetse, with the maximum response of about 1 mV occurring to approx. 1 ng at source. 1-octen-3-ol caused increased upwind flight by tsetse in a wind tunnel bioassay, and in the field it was attractive to tsetse by itself and also increased the attractiveness of both ox odour and of mixtures ofcarbon dioxide and acetone.

Field data of counts of eggs and larvae of Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) in 12 uncultivated plants in Tolima, Colombia, were used to conduct analyses of variance of the relative importance of the 12 for the insect. Analyses were based on the number of eggs and larvae found per terminal and per 5 g of terminal material of each host.

Regardless of the analysis, more eggs and larvae of H. virescens were found on Desmodium tortuosum (Sw) DC (Papilionaceae) than on the other 11 hosts. In general, more eggs were found on pubescent plants, especially those with glandular trichomes.

A relatively high ratio of larvae:eggs for Ipomea triloba L. (Convolvulaceae) was interpreted to mean that larvae of H. virescens migrated to this plant from eggs laid on other hosts.

The removal rate of eggs from seven hosts due to unknown reasons was estimated to differ between the seven.

A comparison of the metabolic rates of different castes and instars was estimated by measuring the biological half-life of the radioisotope I131. The metabolism in the soldier caste was not only higher than alates and dealates, but also pre-soldiers. The rate of metabolism increased with an increase in the age of the nymphs. The termites which were provided with food had slow metabolism compared to those kept under starvation. The studies are helpful in understanding the phenomenon of ‘temporal polyethism’ among termites.

Sandflies caught from termitaria at Tseikuru (Kitui District) and Masinga (Machakos District) were dissected and examined for the presence of Leishmania. Leishmanial parasites were found in the guts of 12 out of 112 Sergentomyia garnhami from Tseikuru and in 2 out of 48 S. antennatus from Masinga. Five of the 12 S. garnhami and 1 of the 2 S. antennatus had leishmanial parasites in the malpighian tubules. Electron microscopic investigations revealed that in the malpighian tubules of S. garnhami the parasites were either free in the lumen or in close contact with the basement membrane.

The ecology of the red locust, Nomadacris septemfasciata Serv. in its outbreak areas plays an important part in the survival of all its developmental stages. Some of the important ecological factors affecting the multiplication and formation of red locust swarms are described briefly. Different methods of controlling the red locust are discussed including ecological, biological and chemical methods. It is concluded that the various control methods play some part in regulating the locust population but at present, when the populations are high, only the chemical method is capable of reducing the population to acceptable levels. The ‘preventive control’ now used to control the red locust is effective and takes advantage of the biology and the ecology of the red locust in the outbreak areas.

Chemical pesticide technology has spread much more quickly in the developing world than has the capability to ensure its effective and safe use. Use of pesticides in developing countries is rapidly increasing, and pesticide exporters from the industrialized nations are increasing their sales to the developing countries. Many pesticides considered too dangerous for unrestricted use in the western nations are being exported from these nations to the developing world. Yet under current law it is perfectly legal for companies to export them. Some developing countries have not enacted legislation to govern the importation, domestic use and disposal of these or other pesticide materials. Even with the laws, the governments frequently lack the infrastructures required to enforce them. Further, the developing countries seldom have the medical personnel and facilities required for diagnosing and treating cases of pesticide poisoning, and programmes to train farmers on the correct use of pesticides and alternative methods are often inadequate.

This paper discusses ways that governments at national and international levels influence the spread and use of pesticides in the developing countries through legal action, policies on export and import, aid, research and extension, pest control programmes, and other means.

Studies on G. m. morsitans clearly indicate that the foundations for acoustic communication among tsetse exist. Tsetse produce sound in connection with the important physiological activities of feeding, mating and larviposition. The possible role of these acoustic emissions in the complex behaviour patterns of tsetse is discussed.

Both free and sessile haemocyte counts in Alphitobius piceus showed wide variations between 06.00 and 22.00 hr. Variations in the haemogram appeared to be related to sex related cycles of activity, presumably with special reference to feeding patterns. Males showed higher total haemocyte counts during the day in comparison to females. In both sexes, the percentage of prohaemocytes and spherule cells and only in males, plasmatocytes increased during the early hours of night. In females, the percentage of granular haemocytes decreased notably between 18.00 and 20.00 hr. Number of adipohaemocytes and oenocytoids did not vary significantly. Heat treatment caused release of sessile haemocytes into the circulation resulting in a notable increase in total haemocyte counts during the day. This increase was comparatively high in females in comparison with males. Altered photoperiod had little effect on these haemocyte variations. Blood volume was slightly higher in the night than in the day in both sexes. The variation of blood volume was insignificant under both heat treatment and altered photoperiod conditions.