In many parts of Africa, field sorghum is attacked by a number of insect pests, notable among them being the sorghum shootfly, a range of lepidopterous stem borers, midge and a complex of head bugs. Studies on yield losses caused by these insects are scanty, yet such information is essential in formulating an IPM strategy for the crop. This study, therefore, describes the various methods of assessing and quantifying the on-farm (pre-harvest) yield losses caused by the above insect pests.

Data on the populations of larval and pupal stages of Aedes africanus, an important sylvan vector of arboviruses, were collected from tree-holes which are its natural breeding sites in forests. Comparable data were also simultaneously collected from bamboo pots stationed in the Zika Forest to simulate the natural breeding sites. Survivorship curves and time-specific life-tables were constructed. It was observed that the immature stages of A. africanus in both tree-holes and bamboo pots suffered very high mortality rates (an average of 91% in tree-holes and 83.2% in bamboo pots). It was further observed that mortality rates varied monthly. The survivorship curves constructed for the immature stages collected on a daily basis tended to show that a large proportion of the mortality rate was confined to the early instar stages, but the survivorship curves based on the combined data for the 2 years indicated constant mortality rates for all the stages. The high mortality rates of the immature stages of A. africanus appear to be attributed to predation by larvae of Toxorhynchites brevipalpis, with which it shares the same breeding places.

Neomachilellus scandens (Machiloidea; Wygodzinsky, 1978) is a litter inhabitant of inundation forests in the Rio Negro valley, which are annually flooded for 5–6 months. At the beginning of the non-inundation period, juveniles hatch from previously submerged eggs on the forest floor and reach maturity after 3–4 months. Adults propagate in the litter where females deposit their eggs which are subjected to the next flooding. Both sexes subsequently migrate into the trunk/canopy area and perish. In nearby primary and secondary dryland forests N. scandens has no defined reproduction period and juvenile stages are found throughout the year.

The legume pod-borer, Maruca testulalis was reared in the laboratory for 10 successive generations using a semi-synthetic diet. The diet was composed of locally available soybean flour and cowpea flower powder as basal ingredients. The artificial medium was as suitable as the cowpea host plant for M, testulalis in supporting larval growth and development. Fecundity increased with advancing generations on the artificial medium. Field collected pupae were heavier than diet-reared pupae. However, the fecundity, fertility, adult life span, and sex ratio did not differ between the two rearing regimes. The laboratory-reared insects were of acceptable uniform quality and predictable performance even after 10 successive generations of laboratory rearing. Adult emergence ranged between 70–90%. One litre of diet produced on average 400 pupae or adults with a mean fecundity of 200 eggs per female. One person working 8 hr/day can produce a minimum of 1000 healthy pupae or adults daily. The laboratory rearing management protocol is described.

From August 1988 to January 1997, natural enemies were reared from 335 colonies of Plnnococcus citri Risso (Homoptera: Pseudococcidae) sampled for 87 months from 225 randomly selected cocoa farms in the six cocoa-growing regions in Ghana. A total of 20,408 P. citri individuals was recorded, comprising adult females, third instar nymphs and mummified individuals harbouring parasitoids. Observed predators were larvae of Coccodiplosis coffeae Barnes (Diptera: Cecidomyiidae), nymphs and adults of Hyperaspis egregia Mader and Scymnus (Pullus) sp. (Coleoptera: Coccinellidae), as well as an unidentified lepidopteran. Twelve parasitic Hymenoptera were also reared, including Aenasius abengouroui (Risbec), Leptomastix dactylopii Howard, Anagyrus beneficions Compere, Tropidophryne melvillei Compere, Anagyrus amoenus Compere and Chryptochetum (Lestophonus) spp. Also recorded were a hyperparasitoid, Cheiloneurus carinatus Compere, parasitising Coc. coffeae, Xyplugaster pseudococci Risbec and six rare, undetermined parasitoids. Coccodiplosis coffeae was the commonest parasitoid, occurring throughout the year and infesting 72.8% of the P. citri colonies. Parasitism levels were generally low, the highest mean being 4.6 ± 2.6% for Aen. abengouroui. Simultaneous parasitism by more than one species was common and this gave rise to mean monthly parasitism levels ranging from 0.8 to 4.5%. Aenasius abengouroui, Ana. amoenus and H. egregia are being reported for the first time in P. citri on cocoa in Ghana, and the recovery of L. dactylopii suggests its establishment in the country, where it was introduced in 1949.

A brief description is given of the tick species, their distribution, the diseases they transmit and the control methods used in Botswana. Most of the country is unsuitable for the permanent establishment of the more important ticks so that the diseases they transmit are confined mainly to the eastern part of the country. Among the tick-borne diseases, cowdriosis is the most important although sporadic cases of anaplasmosis and babesiosis also occur. Canine erhlichiosis is established in the urban areas. The presence of theileriosis as a clinical disease has yet to confirmed in Botswana.

The blue biliverdin pigment in the haemolymph of Schistocerca gregaria Forskål (Orthoptera: Acrididae) was shown to be associated with all the stages and ages of the solitary-reared (solitarious) insects, irrespective of their origin or diet. The pigment was absent or present in very small quantities in the crowd-reared (gregarious) insects. The ratio of absorbance at 460 nm and 680 nm, the former representing the λmax for the carotenoid pigment and the latter for the biliverdin, provides a clear-cut index for partitioning the phases. The mean value of the index for the gregarious group fell in the range 3.69 to 4.78. That of the solitarious group ranged from 0.64 to 1.67. The absorbance ratio at 460/680 nm appears to represent a simple and convenient means of differentiating the two phases of the desert locust, Schistocerca gregaria.

Field surveys along the Lake Basin and the Coastal regions of Kenya were carried out to assess the natural incidence of pathogenic microorganisms associated with the legume pod-borer, Maruca testulalis Geyer on the cowpea crop. A regular sampling regime was maintained on plots planted with four varieties of cowpea: T VX 66–2H, Vita 3 (TVU 1190), Ex-Luanda and Nyar-Milambo. Larvae of M. testulalis were recovered from the flowers and pods of the crop, and subjected to routine laboratory disease diagnosis including: tissue examination, culture incubation, microscopy and pathogen identification. The main groups of pathogenic microorganisms found to act as natural mortality factors to M. testulalis larvae include: protozoa, bacteria, fungi and a virus. A higher level of disease incidence and diversity on M. testulalis larvae occurred in the lake basin region of Kenya than the coastal part.

Among several species of insect pests that attack the millet crop, the earhead caterpillar, Raghuva albipunctella de Joannis and Acigona ignefusalis Hmps., are considered the major pests. The constraints against the successful implementation of an integrated pest management programme of these insects are examined. The relative importance and significance of host plant resistance in such a programme is compared against other modalities.

The use of insecticides is negated by lack of cash value returns, water supply, trained personnel and poor delivery system. Cultural practices, such as the synchronisation of early planting, destruction of harvest residues and end-of-season ploughing, have the potential for reducing carry-over populations. However, the difficulties in their implementation range from farmer education and efficiency to changes in traditional practices and introduction of new labour intensive practices after harvest. While it appears that natural enemies are taking a gradual toll on R. albipunctella, they appear inefficient in controlling A. ignefusalis. A range of plant characters have been identified: tillering in certain varieties as a form of tolerance to borers; maturity cycles that result in escape (pseudo-resistance) from Raghuva infestation, hairiness in relation to preference for oviposition and head compactness in deterring larval penetration into millet heads. Most of these characters are common in landrace types. The real problem appears to be one of incorporating and utilising the identified resistance into germplasm sources which possess other desirable agronomic characters that the farmer requires. This implies multi-disciplinary effort which is the basis for integrated pest management. In most of Africa, and in the Sahel in particular, this basis is remotely present.

Ovipositional nonpreference and larval development of stalk-borer, Chilo partellus Swin., on leaf-whorl and stem of 70 sorghums comprising of released varieties and hybrids, experimental high-yielding varieties, lines selected for stalk-borer resistance and local cultivars were studied in the laboratory. Data on oviposition of egg-masses as well as on number of eggs, larval duration, larval mortality and pupal weight on leaf-whorl and stem of individual variety were separately recorded. These characters were also correlated with number of holes, number of tunnels and per cent tunnelling observed in the field.

The egg-masses per seedling ranged from 0.32 to 2.25, while eggs per seedling varied from 2.25 to 20.80 on different varieties. These were highly correlated (0.92**) characters. The varieties SPV nos 35, 101, 110, 232, 257, 289, 291, 309 and 311, E 302, E 701, CSV nos 3, 6 and 8R and Aispuri were relatively less preferred for oviposition. Larval development took 17–32 days on leaf-whorl and 33–62 days on stem of the various varieties. The larval duration on leaf-whorl as well as on stem were more than average on SPV nos 35, 103, 107, 110 and 310, E 302, E 701, CSV-8R, IS 2312 and Aispuri. The larval mortality ranged from 1.7 to 95.0% on leaf-whorl and 13 to 95% on stem. Significantly higher larval mortality on leaf-whorl of SPV nos 35, 101, 292 and 311, E 302, CSV nos 3, 6 and 8R was recorded. It was 11.5 and 29.6% higher on SPV-35 and CSV-8R respectively than the most resistant variety, IS 2312. Larval mortality on leaf-whorl of early maturing varieties was 8.1% more than late varieties. The mean pupal weight was 65.55 ± 3.82 mg on leaf-whorl and 51.65 ± 4.93 mg on stem. The pupal weights were 47–75 mg on leaf-whorl and 33.5–47.7 mg on stem of local varieties.

Larval duration was positively correlated with larval mortality on both leaf-whorl and stem and negatively with pupal weight on leaf-whorl. Larval duration and mortality on leaf-whorl were negatively correlated with per cent ‘dead hearts’, and number of tunnels per plant. Larval duration and mortality on stem were also negatively and significantly correlated with holes per peduncle and per cent tunnelling. The magnitude of correlations of larval duration and mortality with tunnelling parameters were higher than that of oviposition. Though ovipositional nonpreference and antibiosis act together to determine the degree of resistance, antibiosis has a greater effect on Chilo resistance than the effect of ovipositional nonpreference.

The antibiosis factor(s) affecting larval development exists in leaf or in stem or in both the plant parts. Short peduncle varieties were less preferred for oviposition.

In olfactometer assays, the predatory mite Amblyseius ciicumeris (Oudemans) recorded a significantly higher response to volatiles from chrysanthemum, Denranthemct morifolium plants infested with western flower thrips (WFT), Frankliniella occidentalis (Pergande) than to volatiles from healthy plants. This increased attraction was attributed to the presence of higher amounts of Germacrene-D in WFT-infested plants. In choice experiments using synthetic volatiles, the predator remained longer in the olfactometer treated with 50 ng Germacrene-D and made many entries at 500 mg.

Preferential attraction of WFT to healthy chrysanthemum flower buds was observed, and attributed to the significantly higher amounts of (E)-β-farnesene found in the buds compared to leaves and open flowers. This attraction peaked at 100 ng/μl (E)-β-famesene. In greenhouse experiments, blue sticky traps with 500 ng (E)-β-farnesene or 1000 mg p-anisaldehyde attracted 32.3% and 27.5% more WFT than the untreated controls, respectively.

The prospects of using Germacrene-D in improving the attraction of A.cucumeris to whole chrysanthemum plants and (E)-β-farnesene in monitoring WFT, are discussed.

Some aspects of flight behaviour in the triatomine bug Triatoma sordida were investigated. A strong link between flight initiation and nutritional status as expressed by weight: length ratio was shown. Flight activity was strongly nocturnal and unimodal, commencing with the onset of darkness. A capacity to lay eggs after flight initiation was noted.

A new 6a-hydroxylated pterocarpan, named hildecarpin, has been isolated from the healthy roots of Tephrosia hildebrandtii. It has been assigned the structure (−)-3, 6a-dihydroxy-2-methoxy-8, 9-methylenedioxypterocarpan on the basis of its spectroscopie data, optical rotation and chemical transformations. Hildecarpin has exhibited insect antifeedant activity against the legume pod-borer Maruca testulalis, an important pest of the cowpea (Vigna unguiculata), and antifungal activity against Cladosporium cucumerinum. This finding suggests that the pterocarpan phytoalexins formed as a result of microbial infection of the cowpea plant may constitute a basis for induced resistance in the plant against M. testulalis.

Lepidopteran stemborers are major limiting factors in the production of maize and sorghum in Africa and Asia. Host-plant resistance and biological control are important components of an IPM programme and can effectively maintain pest populations below economic threshold levels, especially in low-input subsistence farming systems. When damaged by herbivores, plants produce allelochemicals which can attract natural enemies of the pest. These volatiles occur systematically throughout the plant and are different from those emitted in response to mechanical damage. We report evidence of plant volatiles-mediated differential reaction of parasitoid activity to sorghum genotypes. These volatiles could have a positive impact on the efficacy of stemborer parasitoids, leading to increased host finding or increased searching efficiency, thereby enhancing the suppression of stemborer populations. In a single-season case study, parasitoid activity was higher in stemborer-resistant genotypes than in susceptible ones and varied with crop age. Knowledge of such interactions should be explored and intensified by plant breeders and chemical ecologiste aiming at producing plant materials possessing appreciable levels of resistance to stemborers and able to encourage natural enemy activity in cereal-based ecosystems.

Polyacrylamide gel disc electrophoresis of the salivary secretion from the tsetse, Glossina morsitans morsitans Westwood, showed 11 protein bands, four of which were characterized as glycoproteins. Sixteen amino acids and four sugars in the hydrolysates of saliva were identified. Thin layer chromatography showed five lipid classes and three phospholipids. The secretion is a clear, transparent, viscous fluid with a pH between 7.00 and 7.5. These findings are discussed in relation to the nutritional requirements of the metacyclic forms of trypanosomes that may be found in the salivary glands.

Non-setting adhesives available were assessed for catching insects of medical and veterinary importance. Physical, chemical and handling properties are described. The results of tests are given using the most suitable adhesives against Glossina spp. (tsetse), Aedes aegypti (mosquito), Lutzomyia longipalpis (sandfly), triatomid bugs and cockroaches. Details are given of a formulation suitable for the capture of most insects in a variety of climatic conditions. The manufacturer's addresses are given to prevent difficulties in ordering and obtaining these products.

Upsurges in the populations of the migratory locust Locusta migratoria (L.) occurred in July 2011 at the airport and in sugarcane fields on Shimoji Island, Okinawa, Japan. In sugarcane fields and pathways, dark-coloured nymphs at early instars marched and infested sugarcane leaves. The number of locusts was estimated as approximately 1.4 million. After prompt control by spraying insecticides, the locust populations decreased remarkably in size at the airport and in sugarcane fields. The locust populations at the airport restored gradually and dark-coloured nymphs similar in appearance to typical gregarious forms were found marching on paved roads at the end of August. Insecticides were sprayed again in early September over those areas at the airport where nymphs were abundant. The locust populations rapidly declined and only a few locusts were observed thereafter on the island before winter. These observations indicate the importance of constant monitoring and prompt action for the control of locusts. The seasonal life cycle of this locust species on this island was studied by regularly sampling the locusts in the field, which revealed that this locust species produces three generations per year with different overwintering stages.

The African root and tuber scale Stictococcus vayssierei Richard is the only known hypogeal species of the family Stictococcidae. Its wide range of host plants together with concurrently field observed differences in host preference provided evidence of polyphagy or the involvement of more than a single-scale species. To establish the baseline information for future taxonomic studies, newly emerged larvae were collected from infested cassava from three sites in the humid forest zone of southern Cameroon. A glass binocular magnifier was used to observe morphological changes of live individuals and slide-mounted individuals of all developmental stages were examined with a compound microscope. Stictococcus vayssierei females went through three developmental stages—two larval instars and an adult stage. The first and second instars were purple-red, while the adult was brown. Body size and the degree of sclerotization of the dorsal line increased in each developmental stage. White waxy secretions on the basal periphery of the second instar, and both dorsum and periphery of the adults, distinguished them from the first instar, which lacks the white waxy secretions. On slide-mounted specimens, certain aspects of the anal complex (i.e. number of opercular plates and -setae) were found to be the most discriminating features of S. vayssierei life stages. These results are useful for further studies on the diversity of subterranean stictoccocid scales.

Forest loss has caused fragmentation and destruction of habitats, and thereby presents serious extinction risk to many endemic species in Madagascar. Among many other arthropod groups, carabid beetles are poorly known in Madagascar as regards their distribution, habitat requirements and taxonomy. The aim of this study is to document community composition, distribution patterns and habitat preferences of carabids in the forest-dominated Ranomafana National Park, south-eastern Madagascar. Carabids were collected by hand and trunk traps from secondary forest, primary forest and nearby village areas. In total, 4314 individuals representing 125 species, including 38 new species, were collected. Almost 70% of the species were recorded in very low abundances. Furthermore, there were only a few species in intermediate abundance classes, while the three most abundant species represented ~36% of the total catch. The carabid community seems to be very species rich, consisting mostly of species in low abundances. A positive correlation was found between abundance and occupancy despite high variation among species distribution patterns. Small population sizes of endemic species with nearby habitat destruction make the species especially vulnerable to extinction and increase the importance of protecting Ranomafana National Park.

Insect-enhanced diets of Periplaneta americana (L.), in separate combinations with Zea mays L. and starter mash/finisher, were fed to 4-week-old birds, Gallus gallus domesticus L., over a period of 13 weeks to identify alternative and relatively cheaper sources of protein for poultry birds. Within the first 3 weeks of feeding, the body weight of the birds was not significantly (P>0.05) different from each other, whereas a significant (P = 0.009) trend arose at week 8. This preliminary study shows that insect-enhanced meals could be used as an alternative feed within the formative stage of development of G. domesticus.