The coffee berry borer, Hypothenemus hampei, which originates from Africa, is one of the most serious pests of commercial coffee and is now present in most of the major coffee growing parts of the world. Quite recently, this beetle spread into Mexico and Ecuador and is now causing serious economic losses in these two countries. In 1985, a classical biological control programme was started to control the pest using the bethylid, Prorops nasuta and other hymenopterous natural enemies from Africa. During the programme, various studies were conducted in Kenya on P. nasuta and H. hampei including their field distribution and life history. A technique of rearing and screening P. nasuta against plant diseases was developed and several shipments have now been made to Ecuador and Mexico. In 1988 a continuous laboratory culture of P. nasuta had been established in Ecuador and the wasp was also reported to be reproducing in sleeves cages in the field.

In a screen cage study, the pattern of flower and pod development at the various flowering nodes of three cowpea varieties with known susceptibility to the pod-borer Maruca testulalis, was mapped out. The period of flower opening over the whole plant spanned an average of 13 days in TVu946, 17 days in ICV-2 and 18 days in Vita-1 with 85–100° of the pods retained to maturity coming from flowers opening within 8 days of anthesis. The efficiency of pod production from open flowers was highest in TVu 946 (54°), lowest in Vita-1 (11°) and median in ICV-2 (31°). However, as a consequence of the individual pod size, the overall pod and seed characteristics in decreasing order were Vita-1, ICV-2 and TVu 946. The bulk of flowers and pods on the plants were produced at the basal plant nodes where primary branches were developed.

Pod elongation and enlargement were initially rapid in all varieties, but the TVu 946 pods reached physiological maturity 2 days before the other two varieties. The eventual pod size and rate of pod growth appear to be important factors in the susceptibility of cowpea to the pod-borer attack.

Several species of Chilo occur on sugar-cane, out of which five have major pest status. Infestation by these pests causes losses in cane yield and sugar recovery. There are constraints involved in the use of cultural, mechanical and chemical control measures on a large scale, but the nature of the crop facilitates adoption of biological control. Many species of natural enemies occur in the sugar-cane agro-ecosystem, which is relatively less disturbed. They play a significant role in maintaining the pest populations at reasonably low level.

In biological control, the egg parasite, Trichogramma spp., has been widely used with varying results. Among the larval parasites, Apanteles flavipes (Cameron) and Sturmiopsis inferens Townsend have been used on a limited scale and need further testing in other countries. The exotic tachinids introduced, failed to establish against Chilo spp. Not much work has been done on the predators, though the native predators play a significant role in reducing the pest densities. Among the entomopathogens, granulosis virus infecting Chilo infuscatellus Snellen has shown promise in the control of this pest and needs further evaluation in other agro-climatic regions. Future thrust for biological control of Chilo spp., in sugar-cane has also been indicated.

An experiment to examine the effects of four agrometeorological factors on population fluctuations in legume pod borer, Monica testulalis (Geyer) in two cowpea varieties was carried out under field conditions in Ibadan, Nigeria. Plots, 5 x 10 m each, of cowpea varieties IT84S-2246–4 and Dan ilan were planted fortnightly between 5 May and 5 October 1988 (12 plantings in all for each variety). Three peaks of the pod borer populations were observed on the cowpeas. There were smaller peaks on crops planted between 5 May and 1 June and again between 29 June and 13 July and a larger one on those planted between 24 August and 7 September. These two peaks coincided with the peaks of the rainfall.

Significant relationships were obtained between pod borer counts and (a) cumulative rainfall (R2 = 0.41; P = 0.004) (b) number of rainy days (R2 = 0.17; P = 0.04) from plant emergence to 50% flowering. These results suggest though, the distribution of rainfall over time is more crucial than the total amount in determining the fluctuations of pod borer populations. Thus, the adjustment of planting dates is suggested as an IPM tactic to avoid the development of damaging levels of pod borer infestations.

Between 1984 and 1988, a survey of fruit-infesting ceratitid fruitflies was conducted in 11 agricultural districts in Kenya. Samples of up to 18 different fruit crops were examined for infestation. The four species of fruitfly found were Ceratitis capitata, C. rosa (Pterandrus rosa), C. nigra (Trirhithrum coffeae) and C. cosyra (Pardalaspis cosyra). The first three were sympatric infestants of coffee, while the latter was exclusively found in mangoes. In addition, C. rosaalso infested loquat, guava and custard apple. C. capitata infested commercial orange cultivars. This species was predominant in the main arabica coffee growing areas in the central highlands. C. rosa and C. nigra were more widespread, occurring in high proportions in most parts of the country. Generally, the proportions of the three species per coffee sample, and the mean number of each species per kg of coffee, tended to vary considerably over time and space.

The study of the population dynamics of Helicoverpa armigera (Hübner) in Cicer arietinum (chickpea), Lycopersicon esculentum (tomato), Abelmeschus esculentus (okra) and Zea mays (maize) crops revealed that the insect passed through five overlapping generations in a year. The growth of the population of H. armigera and its generation survival were maximum in second generation followed by fourth, third, fifth and first generations. Parasitoids, predators, fungal and viral diseases and abiotic factors were among the various observed mortality factors, although the role of predation was not specifically investigated. The key mortality factor within generation was an unidentified pupal parasitoid. The key mortality factor operating between generations was the variation in natality (log of ratio of maximum potential natality and actual eggs). In spite of the biotic mortality factors operating on H. armigera populations, the number of eggs laid is the most important factor that governs the trend of the population growth in all generations. Therefore, a powerful control measure is necessary by either trapping the adult moths or by cultivating trap crop to distract egg laying for those crops to be protected.

A study was undertaken to test the hypothesis that the quality of host plant parts determines the nutritional quality of herbivorous insects feeding on it to their parasitoids. A Gossypium hirsutum-Helicoverpa armigera-Campoletis chlorideae tritrophic system was evaluated. The superior nutritional quality of bolls and young leaves of Gossypium hirsutum (MCU-5 variety) contributes to more efficient feeding, growth and reproduction of the bollworm, Helicoverpa armigera (Hübner) and better survival of its larval parasitoid, Campoletis chlorideae Uchida. Longer total developmental duration and decrease in adult longevity were observed in H. armigera reared on senescent leaves than in those reared on bolls. Consumption, growth rate and efficiency measures were significantly lower in parasitised H. armigera larvae than in unparasitised larvae. Percentage parasitism was highest (84.1%) in H. armigera fed on bolls. The parasitoid C. chlorideae displayed shorter developmental duration and improved survival on H. armigera fed on bolls.

The predacious mite, Pachylaelaps aegyptiacus Hafez & Nasr completed life cycle when fed on eggs of housefly, Musca domestica (L.) at 25 ± 2°C and 70–80% r.h. in the laboratory. The durations of the immature stages and of the adult stage were determined. Immature stages of P. aegyptiacus consumed in total an average of 16 eggs of housefly, whereas each day throughout her life, the adult female consumed an average of 7.6 eggs of housefly. Daily rate of single and multiple mating was 0.93 and 1.0 eggs/female respectively. Description of immature stages of the predatory mite was given.

The sternal gland shows significant differences in size and activity in different instars of the worker caste of Trinervitermes bettonianus. Gland size (volume and surface area) was not significantly different between instars 1 and 2, and 2 and 3; but was significantly different between these age groups and instars 4–7. The potential trail-laying activity of the gland of a worker increased from zero to 50 trail units in the course of development from the first to seventh instar. The relatively high biological activity of the gland in the older instars 5–7 may be of ecological significance, since these stages were found to constitute over 90% of foragers under field conditions.

The purpose of this study is to elucidate the production dynamics, growth characteristics and trends of African trypanosomiasis research (ATREP) literature between 1900 and 1985 through graphical methods.

The data analysed comprised 5139 articles from Tropical Diseases Bulletin and Tsetse and Trypanosomiasis Information Quarterly. Counting technique was employed in sorting the articles according to yearly production and respective subject disciplines. The bibliometric ranks of the disciplines were determined based on (1) the total output and (2) the average decennial relative changes (Rc) in publications between 1936 and 1985 using 1936/45 as the base decade.

The results show that the growth is neither linear nor logistic but exponential with an average 39.5-year doubling time. A marked feature is the occurrence of high “epidemic” peaks between 1910–1914 and 1979–1985, a state in which publications were produced at relatively high level probably due to new discoveries or research orientation; and hence capable of quickly infecting a large number of scientists enhancing productivity. There was also a low level of activity from 1914 which lasted for about 22 years.

The foundation disciplines for African Trypanosomiasis Research Programme (ATREP) are entomology and parasitology. Entomology had the highest bibliometric rank followed by parasitology. However, the Refactors indicate that greater attention, as depicted by publication outburst, was given to physiology, immunology, biochemistry, and epidemiology between 1976–1985 than had been before.

In spite of its consistently higher output, entomology exhibited the greatest fluctuating growth trend than all the other components. A possible explanation for this behaviour was ventured.

The biophysical characters of the mosquito, Culex quinquefasciatus, a dreaded vector of bancroftian filariasis was investigated. The data represents the “system” in bioaerodynamics which comprises the adult mosquito and induced air, and constitutes “action-reaction pair” for the hovering flight. Hence the static and dynamic parameters of this species are determined. An expression for moment of inertia of the flight surface (wing) is deduced considering wing design and geometry. Further aerodynamic requirements in relation to flight performance of the insect are elaborated. It is concluded that this study provides useful information on the hovering flight behaviour of the mosquito C. quinquefasciatus.

Cytogenetic studies in indoor resting An. gambiae s.l. complex in five selected localities from east, south, and southwestern parts of Ethiopia were conducted. An. arabiensis was the only cyto-species found. Close examination of the inversion polymorphisms revealed the existence of two more polymorphisms in the 2Ra and 2Rd inversions, in addition to those previously reported viz. 2Rb and 3Ra, by Mekuria et al. (1982) and White (1974). The study covered wide ecological and altitudinal ranges and the karyotype frequencies were in agreement with the Hardy-Weinberg expectations. However, it was not possible to correlate the relationship between the 2Rb inversion and altitude as has previously been reported by Mekuria et al. (1982). The adaptive value of the 2Rb to increase in altitude (Mekuria et al., 1982), in view of diverse ecological and climatic conditions in An. arabiensis in Ethiopia is open to question.

Although biconical traps are now widely used for the sampling of tsetse populations, they provide only relative population estimates determined by the fly density, activity and trap response. Studies were therefore undertaken to convert such biconical trap indices into unbiased absolute population density estimates. The first step was to determine the range of attraction of such traps for the main trypanosome vector in Kenya, Glossina pallidipes, although some data were also obtained for G. brevipalpis. Two different techniques were used. Firstly traps were placed at varying distances apart, resulting in competition and consequent reduction of catch sizes per trap when ranges of attraction overlapped. Secondly, the catches in grassland at varying distances from a forest edge were compared with two predicted functions relating catch size to distance. Results from the competition experiments showed a marked decline in catch per trap when the intertrap distance was less than 30–40 m. The resultant estimate of maximum range of attraction of 15–20 m for G. pallidipes was compatible with the observed pattern of decline of catches at increasing distances from the forest edge. The range for G. brevipalpis was tentatively estimated as up to 10–15 m.

The leaf miner Coelaenomenodera lameensis Berti and Mariau (Coleoptera: Chrysomeiidae, Hispinae) is the main oil palm pest in Africa. A study of variations in its fecundity, in space and time, was carried out at 7 plantations and 19 sites in Côte d'lvoire. Fluctuations in fecundity, which could vary from almost 300 eggs to just a few eggs per 90-day period, were very similar at the various sites of the same plantation, and at the sites of different plantations, even when these were very far apart from each other. Fecundity increased with temperature, but other climatic factors were also important, with air saturation deficit playing a decisive role. The drier the air, the lower was the fecundity, which could even reach almost zero. As this parameter had a considerable impact on palm leaves' stomatal opening, a highly significant correlation was established between the latter and fecundity. Food supplies for larvae and adults can also affect fecundity, which seems to vary with the potassium content of the leaves.

Desmodium tortuosum (Sw) DC (Papilionaceae) is a preferred wild host of Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) which is an important pest of cotton in Tolima, Colombia. From November 1976 until March 1979, cotton and D. tortuosum were compared and contrasted in the field as hosts of the pest. A very high infestation level of H. virescens in cotton in 1977 was preceded by an extremely low infestation level of the insect in D. tortuosum previous to the cotton-growing season. In 1978 and 1979 moderate infestation levels in cotton were preceded by moderately low infestation levels of H. virescens in D. tortuosum previous to the cotton growing season in both years.

Progressively less eggs were laid on cotton versus D. tortuosum as the cotton plants aged. Peak numbers of H. virescens occurred during the latter part of the cropping season and immediately after. A mean of 13% of first-instar larvae of H. virescens on D. tortuosum were found stuck by the glandular trichomes of the plant. On cotton significantly more eggs were found during the week of full moon than new moon or first quarter. Apparent sterility and pre-hatch mortality of eggs of H. virescens varied between 1–5 and 0 and 7%, respectively, for both hosts combined.

Egg parasitism by Trichogramma sp. (Hymenoptera: Trichogrammatidae) in cotton was 1.5% in 1977, presumably due to excess use of pesticides, and 23.5% in 1978 when pesticides were not used much. Parasitism of eggs on D. tortuosum by the same parasite averaged 1%; the glandular trichomes of D. tortuosum trapped and killed adult Trichogramma.

The fact that infestation levels of H. virescens in cotton were very high in the year that they were very low in D. tortuosum previous to the cotton-growing season, and moderate in cotton during 2 years that they were not as low previously in D. tortuosum suggests that the continued presence of the pest many aid its natural regulation, perhaps by providing a source of hosts to H. virescens specific parasites.

If relative levels of oviposition in cotton could be predicted by lunar cycles this would aid in planning control strategies, such as massive liberations of egg parasites and more intensive monitoring of infestation levels during predicted peak periods.

Screen house studies on the incidence and yield losses in three cowpea (Vigna unguiculata) varieties, TV × 3236, Ife Brown and Ife Bimpe due to the leaf beetle Ootheca mutabilis Sahl were carried out. Artificial infestation was done at two growth stages of cowpea: the 5-leaf stage (2 weeks after emergence) and 4 weeks after emergence. Variety TV×3236 was found to be the least susceptible, while var. Ife Bimpe was the most susceptible to leaf beetle damage. Young plants were more susceptible than older ones.

Flowering was delayed in plants infested with beetles and the extent of defoliation had a pronounced effect on the yield of cowpea.

The percentage grain yield loss ranged from 19.48% to 59.77% depending on level of beetle infestation, variety and age of the plant at infestation.

Riverine tsetse, which are vectors of human and animal vectors, are very difficult to control because of the specific nature of their habitat and behaviour. The problem, however, is not technical, because nowadays entomologists have at their disposal a wide range of efficient methods to eradicate them. The problem is therefore practical, and it is related to the way in which these methods are used.

In fact, the entomologist is faced with several intractable problems that reduce his scope of action. First of all, because he has to pay due regard to the environment, he is obliged to refrain from taking any action that may be fatal for the tsetse, but harmful for the environment such as cutting down woody, scrub and shrub vegetation, setting bush fires, etc. Furthermore, he is not allowed to tamper with wildlife which is the nutritional source of the tsetse, but is also an important source of foreign exchange through tourism. He also must respect the non-target fauna, especially the aquatic fauna, with the result that this limits: (1) the choice of pesticides that can be used in one way or the other, affecting the chain in the biological cycle, invertebrates, fish, birds, mammals and (2) the method of application of chemical, because he cannot use residual sprays or aerial aerosols everywhere.

The entomologist must also take into account economic considerations. The world economic crisis has considerably reduced the availability of potential sources of donor funds, and most African countries afflicted by sleeping sickness and animal trypanosomiasis cannot individually undertake large-scale eradication campaigns for lack of funds, adequate equipment and trained manpower. Using aeroplanes or hordes of workers is therefore out of question. Similarly, controlling the tsetse through the use of sterile male release technique, which is a complementary control method to attain the 0 density, seems now to be unachievable because of the huge investments that are required.

Finally, many scientists, economists and ecologists have recently begun to wonder if controlling the tsetse is after all a good solution, since their disappearance would lead to the overexploitationofthe land freed, resulting in the destruction of the vegetation and bio-climatic changes and finally total desertification. The challenge therefore is how to control the tsetse under these conditions.

The use of traps seems to be a good solution. Experiments conducted in Africa (and since the discovery of certain olfactive attractants) have shown that it is effective, safe for the environment, easy to use, and especially very cheap, when it is used by the rural communities. But even with trapping, a number of questions are being asked: Is it better to kill the tsetse than to sterilize it? Is impregnating it with an insecticide indispensable? Is there no risk of selecting a “trap resistant strain” of tsetse? Can the use of traps lead to eradication?

In fact, in most cases, eradication is wishful thinking and controlling the fly is the only realistic thing to do; the entomologist has to control, but cheaply and with a less harmful technique. Besides, because of its numerous qualities, trapping is the only method that can be used nowadays as long as it is used wisely.

Cowpea, until recently the major food legume in Ghana (in terms of area under cultivation) has been witnessing a decline in production at the expense of groundnuts. Among the factors leading to the decline are the havocs caused by insect pests and diseases with the former being of major importance.

The paper presents some of the systematic screening and testing procedures of both exotic and indigenous materials with the aim of evolving varieties that are not only high yielding but also resistant to a broad spectrum of these prevalent insect pests.

The susceptibility of 23 cotton genotypes to spotted bollworm, Earias vittella, was studied under natural infestation during 1977 and 1978 rainy season at Delhi, India. There were substantial differences in bollworm damage and larval population in different genotypes. Damage in shed squares and bolls was higher than in green bolls picked up from the plant. The damage/larval population in the less susceptible cultivars (Hindiweed, XG-15, HR-26 # 8XH · HG-6-IN and Sanguineum) was lower than in the susceptible check (BJR) and the trial mean. The differences in susceptibility were more pronounced at the moderate damage levels and that the damage in less susceptible cultivars increased or decreased according to the insect pressure.

There were significant differences in the gossypol, tannins, moisture, phenols and sugar content among the genotypes tested. Gossypol, tannins and moisture content of bolls and squares were negatively correlated with bollworm damage and larval population. Free phenols showed negative, but lower correlation coefficients with bollworm damage. Sugars contributed towards susceptibility while nitrogen content of bolls did not show any effect on bollworm damage. The less susceptible cultivars had higher amounts of gossypol and tannins. Some genotypes showed ovipositional non-preference because of smooth leaves.

Many factors appeared to influence the genotypie susceptibility to spotted bollworm, of which gossypol, tannins and ovipositional non-preference (due to smooth leaves) were the major factors. Gossypol and smoothness are genetically inherited and can be manipulated through crop improvement. The rating of the number and size of pigment glands on the calyx tubes and hairiness on the under surface of leaves can be used as important marker characters in breeding for spotted bollworm resistance.