Two mark-release-recapture experiments were carried out on a female population of A. africanus in the Zika Forest, in Uganda, to estimate density, survival rates, dispersal range and duration of the gonotrophic cycle. Marking was achieved using powdered fluorescent pigments and wet paint. In the first experiment, unfed A. africanus female mosquitoes were marked and released. A high overall recapture rate of 17.6% was recorded consisting mainly of first recaptures (up to 85.6%). The highest recapture rate was recorded during the first 4 days after release. Using Jolly's Stochastic Model, daily population estimates ranged from 1386 to 8406 during the first 7 days of release. The daily average population estimated over the first 10 days was 3591. Using the Simple Lincoln Index, population estimates ranged from 1104 mosquitoes to 16,320 with an average daily estimate of 3706. Of interest was the fact that the average daily population estimates using the two methods were not statistically significant. The 24-hr survival rate averaged over 9 days was 0.9228. Dispersal was rather random, and appeared to be of a limited range with an average distance of 50 m. In the second experiment, which involved marking only fully engorged mosquitoes, an overall recapture rate of 7.1% was recorded, with an average daily survival rate of 0.8209 averaged over the first 4 days. The pattern of recaptures indicated a gonotrophic cycle of 5–6 days with a small proportion of mosquitoes seeking secondary feeds during the first 48 hr. It was generally observed that marking and handling did not have any marked effect on mosquitoes during the first 8 days.

Stripe (st+) is a dominant trait on chromosome 3R in region 33B on the cytological chromosome map of Anopheles albimanus. It is expressed as a white longitudinal stripe in fourth stage larvae and pupae, and marks a Y-autosome translocation stock T(Y; 3R)3. Pseudolinkage analysis of the available markers to the translocation breakpoint showed complete absence of recombinant progeny between T(Y;3R)3 and st+. The two loci most likely either overlap or are very closely linked. This translocation strain can be genetically sexed by selection of the stripe marker.

Establishment and maintenance of a laboratory colony of Phlebotomus argentines are described which presently is in the nineteenth generation. Larvae were reared in modified plastic vials and were fed with a newly prepared food. Emerged flies were kept in adult holding cages at 50–90% r.h. and 25–26°C and provided with 30% sucrose solution. The average development time (egg to adult) of each generation in the laboratory was about 32 days at 28–31°C. Adult females were fed blood on hamsters, humans and white mice. Observations were made on mating behaviour, host preference, oviposition, effect of temperature, etc.

The vectors of Leishmania major were investigated in Marigat, Baringo District, Kenya, a focus of both visceral and dermal leishmaniases. These studies resulted in the discovery of the resting sites of Phlebotomus duboscqi, a known vector of L. major, and of alternate principal resting sites of Phlebotomus martini, a known vector of visceral leishmaniasis. Furthermore, Sergentomyia ingrami was incriminated as a possible vector of L. major among susceptible rodents inside burrows. Trapping methods which have resulted in the discovery of the resting sites of these phlebotomine sandflies are presented in this paper.

The ovipositional orientation of an aphidophagous ladybird beetle, Propylea dissecta (Mulsant) (Coleoptera: Coccinellidae) in terms of geo- and photo-taxis, colour and texture of substrates was studied. The beetle exhibited a high preference for negatively geotactic substrates for oviposition. There was no clear preference for positively or negatively phototactic substrates. When studied in combination, it was observed that substrates that were negatively geotactic were preferred over other substrates regardless of the phototaxis. Red was highly preferred over the other 5 colours tested, and plastic was the substrate of choice for P. dissecta oviposition.

The effect of mixed cropping cow pea with maize on general predators' abundance and their influence on population density of Megalurothrips sjostedti (Trybom) on cowpeas was investigated in the field and in exclusion cages. Populations of predatory ladybird beetles, Orius sp. and earwigs (Dermaptera) were not significantly influenced by mixed cropping. The density of spiders, however, was significantly higher in the cowpea sole crop than in the cowpea/maize mixture. The population density of M. sjostedti was significantly less in the cowpea/maize mixture than in cowpea sole crop, both inside cages, where predators were excluded, and outside. We concluded that this reduced population density was not the result of enhanced predators’ population in the mixture.

We studied the distribution of wild Mediterranean fruit flies, Ceratias capitata (Diptera: Tephritidae) in different environments of trimedlure-baited Jackson traps during high fall season populations in Southern Egypt. We found that 98% of females attracted to within aim radius of standard trimedlure (TML)-baited Jackson traps remained on the surrounding foliage without approaching the trap. Also about 30 % of males aggregated there, calling and competing for matings with approaching females. The closest mating occurred 25 cm from a standard trap. The nearest lek formation away from a trap was observed at a distance of 2 m on the same trap tree. The highest captures of males were recorded in the morning after male calling on the foliage reached its daily peak. Jackson traps baited with both protein hydrolyzate and TML on cotton wicks caught as many males, but significantly more females than traps with TML only.

In the Chitwan valley, Nepal, Chilo partellus preferred maize and sorghum over rice, teosinte, finger millet and sugar-cane. Infestation on young maize plants produced “dead hearts” and on older plants reduced growth and sometimes prevented cob formation. The yield reduction in some maize cultivars reached 60% and stem infestation levels reached 98%. Borers produced “dead hearts” in young and “whiteheads” in older rice plants.

The egg, larval and pupal periods from April through September lasted 4–5, 16–41 and 4–8 days, respectively. A complete generation took 28–48 days under summer field conditions and 192–233 days from October to May. Of the one egg, four larval and two pupal parasitoids, all hymenopterans, which were reared from C. partellus, the two most important were Trichogramma chilonis (70% egg parasitism) and Apanteles flavipes (30% larval parasitism).

Glossina pallidipes, a widely but discontinuously distributed African savanna species, is one of the economically important tsetse flies because it is a vector of trypanosomiasis, a lethal disease of cattle and other domestic animals. DNA sequences of ribosomal (r16S2, 249 bp) and cytochrome oxidase I (COI, 421 bp) concatenated mitochondrial genes were analysed in 23 geographically diverse samples of G. pallidipes from Ethiopia, Kenya, Tanzania, Zambia and Zimbabwe. Among 873 flies, we detected 181 composite haplotypes and found that their spatial diversities and frequency distributions were heterogeneous. Haplotype and nucleotide diversities were greatest in Ethiopia and least in southern Africa. We observed little haplotype and nucleotide diversity among regions, and detected severely limited maternal gene flow among the sampled populations (ΦST= 0.42). Tests for demographic stability and analysis of mismatch distributions revealed regionally contrasting demographic histories. The Ethiopian populations were phylogenetically the oldest and genetically the most diverse, and exhibited successive waves of contraction and expansion. The southern African populations were phylogenetically the youngest and genetically the least diverse, and showed only a single, recent expansion. Likely ecological correlates of historical tsetse fly demography include population suppression trials in East Africa and recurring rinderpest epizootics in southern Africa, beginning in the late nineteenth century that reduced host mammalian populations.

Host searching, slit making, egg deposition and protection are distinct sequences of one event, which lead to oviposition on the lower surface of rice leaves by the rice hispa Dicladispa armigera (Olivier). Females spent an average of 8.05±1.35 min in selecting an oviposition site, 6.40±0.25 min in preparing a triangular slit, and 1.17±0.07 min in laying and protecting a single egg. An egg measuring 0.85×0.42 mm in size was partially inserted inside a slit of 1.95×0.84 mm. The female exhibited ovipositional preference among the leaves of a rice plant, as 67.5% of eggs were deposited in the first leaf. On the first, second and third leaf, the female deposited her eggs mostly in the middle part of the leaf blade, avoiding the area between 4.15–4.89 cm from the tip and 12.72–14.25 cm from the base of the leaf.

Okra, Abelmoschus esculentus (L.) Moench, is an important vegetable crop grown throughout the tropical and temperate regions of the world. Spotted bollworm, Earias vittella (Fab.), is one of the most important insect pests of okra. The effects of insecticides (cypermethrin, imidacloprid, carbaryl and neem oil) were studied on the fitness of the F1 generation of E. vittella by a demographic method. Life table was constructed from the eggs obtained by the surviving individuals that had ingested insecticides. Survivorship and expectancy was highest with the commencement of age and gradually decreased with the progression of age in the treatment groups and control. However, it was reduced in the treatment groups in comparison to control groups. Highest numbers of unhatched eggs (17%) were recorded with imidacloprid and cypermethrin treatments, whereas all the eggs hatched in control groups. Larval mortality was high in the initial instars as compared to late instars. Potential fecundity was significantly reduced to 94 females/female/generation treated with cypermethrin as compared to 256 in the untreated females. Developmental time of pre-pupa and pupa was significantly decreased with cypermethrin treatment. The intrinsic rate of increase was reduced to 0.0201 females/female/day in cypermethrin groups as compared to 0.046 in the control groups. The generation time was 33.27 days in the control, which was reduced to 26.78 days with carbaryl treatment and was increased to 37.5 days with neem oil. Insecticides cause adverse effect on the surviving generation of E. vittella, and may be incorporated as a valuable component in the integrated management of E. vittella on okra.

Indicators of diversity (population density, relative number of species and evenness) in ground beetles (Carabidae) and rove beetles (Staphylinidae) in upland rice fields were assessed between 1995 and 1999 at Garoua in the Benue valley in North Cameroon. A total of 4369 beetles belonging to 45 carabid species and 2109 beetles belonging to 31 staphylinid species were caught in pitfall traps. Among the carabid beetles, five species Scarites (Orientolobus) lucidus strigiceps Quedenfeldt, Chlaeniostenus denticulatus elatus (Erichson), Lissauchenius venator (LaFerté), Pheropsophus marginatus (Dejean) and Abacetus crenulatus Dejean, in decreasing order, were dominant. In the staphylinid group, Paederus sabaeus Erichson was the most common, followed by Stenus ravus Puthz and Stenus (Mendicus) senegalensis Bernhauer. The Shannon–Weiner and evenness indices varied slightly from year to year. Diversity values remained relatively low among the staphylinid beetles, revealing that rice fields were underpopulated by this group of polyphagous predators. The features of predatory soil-surface beetles and the role they play as an IPM component in West African rice ecosystems are discussed.

The ovipositional responses of the stem-borer, Chilo partellus, to the susceptible maize genotype, inbred A, are higher than to the resistant genotype, ICZ1-CM. These responses are elicited by certain characters of the plants that are perceivable prior to the moths' arrival on the plants (distance-perceivable) as well as those perceivable after arrival on the plant (contact-perceivable). Distance-perceivable characters were not found to be responsible for the differences in the oviposition on the two genotypes tested.

The contact-perceivable characters of the two genotypes differ markedly in eliciting oviposition by moths. Contact with the resistant ICZ1-CM elicits much less oviposition than with the other genotype.

Austracris guttulosa in northern Australia is similar to Nomadacris septemfasciata in the southern half of Africa in having one generation per year, mainly in tall grass plains that are seasonally flooded by rainfall and flooding rivers. Locusts survive the dry season as adults and after the early rains of the wet season, oviposit in bare areas. Young offspring nymphs hatch out and feed on adjacent short ephemeral grasses while older nymphs and young adults are in taller vegetation. While locusts usually do not breed well outside tall grass plains of the source area, rain is critical to overall population increase of A. guttulosa, allowing egg and nymphal survival in the normally dry open plains south of the source area. When such rain falls, a preventive control programme is instituted, which begins with forecasts of population increase in areas receiving rain for offspring survival; any high populations found are delineated for control. While swarms within the source areas are often not controlled, those further south nearer cropping areas usually are. Austracis guttulosa does not form bands, so control is usually left until the adult stage when swarms form. Current practice involves the use of chemical insecticides, though promising research indicates that the entomopathogenic fungus Metarhizium anisopliae may form part of an integrated pest management programme in the future.

With N. septemfasciata, outbreaks seem to be related to dry periods, but the precise factors leading to outbreaks are not well understood. Until further research that allows accurate forecasting is undertaken, regular monitoring of outbreak areas and control of any bands and swarms that form will be an essential part of any preventive control programme. Both bands and swarms are present for long periods, giving ample opportunity for preventive control particularly in localities where crops are grown near outbreak areas.

The effects of larval population density and food quality on the velvetbean caterpillar, Anticarsia gemmatalis Hübner, were compared with investigations of other migratory noctuids. Crowded larvae of the velvetbean caterpillar responded with: (1) an increase in the degree of dark pigmentation; (2) a decrease in larval, pupal and adult size; (3) a prolongation of the larval stage and a decrease in weight gain in the ultimate stadium; and (4) low juvenile hormone and juvenile hormone esterase haemolymph titres.

The effects of flight, throughout a 4 hr flight period, on the haemolymph titres and whole body contents of carbohydrate and lipid are presented for the velvetbean caterpillar and discussed relative to other noctuid moths. Total carbohydrate concentration decreased during the first 30–45 min of flight, and total fatty acid concentration increased during the first 30–60 min of flight, after which it declined and stabilized at preflight levels. Lipid reserves and the small amount of lipid depletion after long periods of flight indicated that velvetbean caterpillar adults are capable of making long distance movements in which lipid is the principal flight fuel.

Juvenile hormone regulated the effect of density on larval colour, size and growth rate. Applications of juvenile hormone to crowded larvae increased the proportion of the lighter (green), larger and faster developing phase. This hormone action suggests that the juvenile hormone titre of crowded larvae is lower than that of uncrowded larvae.

Genetic differentiation among populations of velvetbean caterpillars suggests that south-central United States populations originate from overwintering populations in Mexico or south Texas. A system has been developed, using pheromone-baited bucket-type traps, to investigate the population dynamics and migration of the velvetbean caterpillar in Louisiana and Texas.

The palaeotropical, gregarious, endoparasitic braconids Cotesia sesamiae, Cotesia flavipes and Cotesia chilonis were recently imported into Benin as candidates for biological control of stem and cob borers of maize. Host acceptability and host suitability of six gramineous borers occurring in western Africa, namely the noctuids Sesamia calamistis, Sesamia poephaga, Busseola fusca and the pyralids Coniesta ignefusalis, Eldana saccharina andMussidia nigrivenella, to these candidate parasitoids was evaluated in order to gain insight into the physiological suitability of the natural and factitious hosts. All hosts were accepted by all Cotesia spp., except M. nigrivenella which was not attacked by Co. chilonis. Parasitoid progeny development was successful in S. calamistis, S. poephaga and Con. ignefusalis. Sesamia calamistis was the most suitable host for Cotesia spp. development, in terms of duration of developmental time, brood size and mortality of parasitoid progeny.

The present article is one of a series of papers in preparation in which an ecological approach to developing a sound biocontrol programme for cereal stem borers is proposed and outlined. The proposed approach involves detailed population estimation and analysis in relation to crop phenology to determine the role of local natural enemies, evaluation of biocontrol potential of promising biocontrol agents, developing mass rearing and release technology and monitoring the impact of the biocontrol programme. In the example used to illustrate the first step in such a programme, life table analysis of data from a 2-year study on Chilo partellus on maize and sorghum under subsistence agriculture in Western Kenya, showed local predators (and unidentified factors) to contribute up to 97.6 % of generation mortality of the borer in the age interval from egg to early instar larva, while parasitoids and pathogens contributed less than 1 % mortality in the various life stages. Hence, a programme involving conservation and augmentation of local predators and introduction of selected exotic parasitoids of this borer seems appropriate. This represents an attempt to apply life table analysis, taking into account plant phenology, in studying interacting populations under subsistence farming conditions.

The concept and practice of IPM has emerged over the past two decades or more. The primary impetus for its development has come from developed countries. IPM technology transfer to developing countries has followed the earlier pattern of the ‘green revolution’. The technology being proposed requires high energy inputs and an intensive infrastructure to support it. These conditions simply do not exist in most developing countries. IPM programs for developing countries must be based on their own socioeconomic situation rather than on simple technology transfer. Better understanding of cropping systems must be the keystone to development of IPM programs. Chemical control should play a secondary role. Cultural and bioligical control and plant resistance adapted to subsistence farming holds the greatest promise. Little attention has been given to the reciprocal feature of studies of traditional agriculture. These practices embrace a wealth of time-honoured ecological wisdom which if unravelled could provide useful leads for modern agriculture. The sequence of steps contributing to this process are proposed.

Stability of resistance to corn planthopper, Peregrinus maid is (Ashmead), was studied over three plant growth stages in 56 sorghum germplasm accessions. Genotype x stage interactions were significant. Plant age exerted a profound influence on the rate of oviposition, establishment of nymph, macropterous and brachypterous adult populations and plant damage. Resistance to corn planthopper was stable over three growth stages in IS 18557, IS 18677 and PJ 8K(R), which also supported low colonization of nymph and adult populations; IS 12308 was unstable due to high deviation. Significantly low rate of oviposition on resistant as compared to susceptible genotypes and the positive and significant correlation between oviposition and plant damage illustrated that antixenosis for oviposition is the primary mechanism of resistance. As a consequence the genotypes preferred for oviposition showed susceptibility due to higher plant damage. Establishment of nymphs was affected on the genotypes, IS 1054, IS 1082, IS 2194, IS 3992, IS 12308, IS 18676 and IS 19349 which may be due to the factors involved either in reduced hatchability of eggs and/or deterrence or poor feeding preference of nymphs.

Experiments were carried out to determine the factors that influence the feeding behaviour of Culex tigripes, a mosquito whose larvae are predators of other mosquito larvae. The results indicated that the efficiency of predatory activities of Cx tigripes larvae increased as they developed from 1st to 4th instar with regard to the number of mosquito prey larvae they consumed in a given period of time. Fourth instars of Cx tigripes are the most voracious of all the stages and are better adapted for catching and consuming all stages of mosquito larvae. The mean number of mosquito larvae consumed in 24 hours increased with increasing prey density. When offered a mixture of different prey species and larval stages, Cx tigripes larvae consistently selected 4th instars of mosquitoes over pupae and preferred Aedes aegypti larvae to the larvae of Cx quinquefasciatus and Anopheles gambiae. Prey size, density and mobility were also found to influence prey selection by Cx tigripes.