The red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier), a concealed tissue borer, is a lethal pest of palms and is reported to attack 17 palm species worldwide. Although the weevil was first reported on coconut Cocos nucifera from South Asia, during the last two decades it has gained a foothold on date palm Phoenix dactylifera in several Middle Eastern countries from where it has moved to Africa and Europe, mainly due to the movement of infested planting material. In the Mediterranean region, RPW also severely damages Phoenix canariensis. Currently, the pest is reported in c. 15% of the coconut-growing countries and in nearly 50% of the date palm-growing countries. Infested palms, if not detected early and treated, often die. However, palms in the early stages of attack respond to chemical treatment with insecticide. RPW has been managed in several countries employing an integrated pest management (IPM) strategy including the use of food-baited pheromone traps. Early detection of infestation in the field is important for the success of any RPW-IPM programme. Ideally, movement of planting material from infested plantations within the country and also from one country to another needs to be stopped. Wherever this is not possible, it is essential to implement strict pre- and post-entry quarantine regimes, wherein only pest-free and certified planting material can be transported. The existing pheromone-based IPM programme can be strengthened by intensifying the search for effective natural enemies, coupled with the introduction of resistance in palms to RPW. This article reviews the work done during the last 100 years on various aspects of RPW viz. life history, damage and symptoms of attack, seasonal activity, spatial distribution, host range, IPM and its main components, including trapping adult weevils and chemical control, besides biological control, host plant resistance and male sterile technique.

A survey was conducted in Tororo, Bugiri and Kapchorwa districts in eastern and northeastern Uganda on farmers' perceptions of constraints in maize production. Farmers in Tororo and Bugiri consistently ranked stemborers and striga as the major production constraints in maize growing, while those in Kapchorwa ranked stemborers and lack of capital as the most important. Approximately 35 and 40% of the farmers in Tororo and Bugiri, respectively, identified stemborers as the ‘caterpillar’ that destroys their maize. In Kapchorwa, 50% of the farmers identified stemborers. Pesticide application was the most common control measure while the use of indigenous and cultural control measures was limited. Less than 50% of the farmers were aware of the existence of alternative plants/grasses on which stemborers feed. This study identified the need for creating farmers' awareness on the biology and ecology of stemborers. Empowering farmers by letting them learn and experiment will facilitate the development of innovative control measures.

The antifeedant activities of Piper guineense Schum et Thonn (Piperaceae), Aframomum melegueta (Rosk) K. Schum (Zingiberaceae), Aframomum citratum (Pareira) K. Schum (Zingiberaceae) and Afrostyrax kamerunensis Perkins and Gilg (Huaceae) seed extracts were investigated in laboratory dual- and no-choice bioassays using third-instar Spodoptera littoralis (Boisduval) larvae. In the dual-choice test, the hexane and methanol extracts of A. melegueta showed potent dose-dependent antifeedant activity at concentrations of ≥300 ppm and the water extract at ≥500 ppm, as illustrated by significantly lower leaf consumptions. Aframomum citratum methanol and water extracts exhibited antifeedant activity at ≥300 and ≥1000 ppm, respectively, but the hexane and ethanol extracts did not affect feeding at any concentration. Piper guineense ethanol and water extracts showed dose-dependent antifeedant effects at ≥300 and ≥500 ppm, respectively, and the methanol extract was active only at 1000 ppm. None of the extracts of the highly aromatic A. kamerunensis exhibited antifeedant activity at any of the tested concentrations. In the no-choice bioassays, extracts with antifeedant activity in the dual-choice tests also showed dose-dependent feeding inhibition. The hexane and methanol extracts of A. melegueta were effective in the no-choice tests at ≥100 and ≥500 ppm, respectively, and the water extract at ≥300 ppm. Similarly, the A. citratum water and methanol extracts were active at ≥500 ppm and the P. guineense water and ethanol extracts at ≥100 ppm. GC/MS chromatography of A. melegueta hexane and methanol extracts revealed volatile constituents with known anti-insect activity. The hexane and methanol extracts of A. melegueta, the methanol extract of A. citratum and the water and ethanol extracts of P. guineense may have potential for use by subsistence farmers.

Investigations were conducted to establish the magnitude and pattern of differential expression of proteins due to generational selection of third instar Anopheles gambiae s.s. Giles larvae by cadmium, copper and lead heavy metals, the three possible common urban pollutants.

A susceptible strain of A. gambiae s.s. third instar larvae was separately placed under selection pressure with cadmium, copper and lead at LC30 and controls through five generations. First, third and fifth generation selection survivors were screened for differentially expressed proteins relative to non-exposed control by two-dimensional gel electrophoresis. Distribution patterns of the spots were analyzed by χ2 or Fishers' exact test and variations in expressions between and within generations by ANOVA. Most differentially expressed spots were acidic and of low molecular weight among all metals and generations. Type of heavy metal and generation were the main indicators of variations in differential expressions. Variation between generations was most significant among cadmium-selected populations of which the most number of spots were induced in the fifth generation. Most spots were induced in the copper-selected population in the third generation. The induced protein spots may be the products from respective genes that respond to heavy metals and counter their toxicity, thus building A. gambiae s.s. tolerance to these pollutants. The differential pattern and magnitude of expressed spots have potential application as molecular markers for assessment of anopheline adaptation status to heavy metals, and provide insight into the extent of environmental pollution.

A field experiment was conducted to track the daily population trends and occurrence of the flower thrips Megalurothrips sjostedti Trybom and Frankliniella occidentalis (Pergande), and their indigenous natural enemies Orius spp. and Ceranisus menes (Walker), infesting French beans. French beans in monocrop or interplanted with six companion crops (Zea mays L., Coriandrum sativum L., Tagetes erecta L., Brassica oleracea var. acephala L., Daucus carota L. and Capsicum annuum L.), and two chemical insecticides, methiocarb (Mesurol 500SC) and L-cyhalothrin (Karate 1.75% EC), were evaluated for their effects on the abundance of flower thrips, throughout the day, at 1-h intervals. The average population peak of thrips was found to occur at around 1300 h, but each species had different peak periods. Adult F. occidentalis populations peaked at midday and adult M. sjostedti populations at 1500 h, while the larvae of the two thrips species peaked at around 1300 h. Orius spp. were the most abundant natural enemies and their populations peaked at around 1400 h. Ceranisus menes population also peaked at around 1400 h.

A survey of the mite fauna associated with Amaranthus cruentus L. (amaranth), Solanum macrocarpon L. (Gboma) and S. aethiopicum L. (African eggplant), three major indigenous vegetables produced in Benin, was carried out from August to October 2004 both at IITA-Benin station and on a vegetable farm at Togba in Abomey-Calavi area. Thirty-three mite species belonging to 12 families were found on the three vegetables. These species included phytophagous mites, predatory mites of the family Phytoseiidae, and another group whose feeding habits were not clear. The following phytophagous mites were found: Tetranychus urticae Koch and T. ludeni Zacher, in the family Tetranychidae; Polyphagotarsonemus latus (Banks) and another unidentified mite species, in the family Tarsonemidae. The two Tetranychus species were present on all three vegetables whereas tarsonemids were found only on the two solanaceous plants. Polyphagotarsonemus latus was the most dominant pest during the course of the experiments. It is the major mite pest on solanaceous plants, especially on Gboma in vegetable farms, where broad-spectrum pesticides harmful to natural enemies are used. The phytoseiids group was the most diversified with 16 species out of the 33 identified and more predominant in IITA plots where no pesticides were applied, compared to Togba plots where pesticides were regularly applied on nearby plots. They seem to better control P. latus on Gboma than on African eggplant. Other mites identified on the three vegetables belong to the following families: Acaridae, Tydeidae, Erythraeidae, Cunaxidae, Anystidae, Ascidae, Bdellidae, Uropodidae and Oribatidae.

Domestic cockroaches Blattella germanica were trapped from various homes in Gaborone, Botswana using ‘Dyroach’ traps. Isolations of bacteria, yeasts and moulds were done on external body parts and on the faecal pellets using various selective media. Body parts of cockroaches were also fixed with OsO4 vapour for 24 h, sputter coated with gold under special conditions and examined in a Phillips (1) XL30 ESEM in low vacuum mode. A wide spectrum of bacteria including common food spoilage and pathogenic organisms, such as Bacillus spp., Staphylococcus spp., Escherichia coliPseudomonas spp., Enterobacter spp., Klebsiella spp., Erwinia spp. Salmonella sp., Shigella sp. and Serratia spp. were isolated. Yeasts commonly associated with food spoilage, such as Pichia sp., Candida sp. and Torulopsis spp. were found on many cockroaches. In addition, various groups of moulds, some associated with food spoilage and others known to produce mycotoxins, such as Aspergillus flavusAspergillus fumigatus and Aspergillus parasiticus were isolated. Antimicrobial sensitivities of bacterial isolates revealed resistance patterns to various agents. Since cockroaches are prevalent in homes, particularly in food preparation areas and since their body parts and faecal pellets have been found in food storage areas, concern about their impact on food quality and safety is raised and possible control measures including education of communities on proper sanitation are suggested.

The gelechid bud borer Anarsia achrasella (Latreille) has become an increasingly serious pest of sapodilla Manilkara zapota Van Royen in India. The objective of the present study was to estimate the pest damage potential and determine the influence of abiotic factors and plant phenology on the pest incidence. The results indicate that each larva of A. achrasella could damage up to 36.9–46.6 buds before reaching pupation. Correlation analysis indicates that the pest incidence is not influenced by plant phenology and that the effect of abiotic factors is minimal. Of all weather parameters studied, only minimum temperature and wind speed correlated significantly with bud borer infestation. The linear and non-linear analyses showed that, in the case of minimum temperature, polynomial model order (2) Y=0.4108x2−11.95x+92.329 was found to explain 46% of the variability in bud borer incidence. However, in the case of wind speed, none of the tried models could explain variability in A. achrasella incidence beyond 53%. The implications of these results are discussed.

Experiments were conducted during the rainy seasons in 2003 and 2004 in central Burkina Faso to assess the importance of the African rice gall midge Orseolia oryzivora Harris & Gagné in relation to the planting date under irrigated conditions. The young midge larva feeds at the growing point of the rice tiller, which stimulates the plant to produce an oval hollow gall that prevents the plant from heading. Experiments consisted of three treatments arranged randomly within each of the four replications. Treatments were planting dates separated by 7 days. The rice cultivar planted in the experiment was FKR 14, which matures in 120 days. Nine entomological evaluations (assessment of the number of galls per hill) were performed for each planting date, starting at 25 days after transplanting (DAT) and ending at 81 DAT. Evaluations were conducted on 20 randomly selected hills and consisted of counting the total number of tillers and galls per hill. These hills were identified on one of the two diagonals of each treatment. At the rice maturation stage, 20 randomly selected hills were harvested and the grains from each hill were weighed and recorded. Yield loss was estimated for each treatment from these data. Results showed that the later the planting date, the higher the damage caused by O. oryzivora. The damage was low ( < 10%) during the vegetative phase but increased dramatically (>20%) during the reproductive phase of the rice plant, regardless of the planting date. Yield losses were correlated to the observed damage: In 2003, for the first planting date, 1% of galling was associated with 1% yield loss, while the same level of damage was associated with 1.3% yield loss for the second planting date.

Preliminary screening of germplasm from the International Institute of Tropical Agriculture (IITA) showed that a number of cowpea Vigna unguiculata (L). Walp. cultivars have potential for resistance to the flower bud thrips, Megalurothrips sjostedti (Trybom). In an earlier study, 10 cultivars from this germplasm were selected and the mechanisms of resistance determined. Therefore, in this study, the basis of resistance operating in the cultivars was elucidated during the first and second planting seasons of 1998. Cowpea cultivars were analysed for primary metabolites (total protein content and glucose contents) to study their relationship with resistance parameters of M. sjostedti under field conditions. Total protein and glucose contents varied significantly (P<0.01) in floral buds and flowers of the different cultivars, while in racemes there were little or no significant differences. Highly significant negative correlation coefficients were obtained between total protein contents in reproductive structures and resistance parameters, especially during the second season, regardless of cowpea cultivar, indicating that quality of total protein content plays a significant role in cowpea resistance to M. sjostedti. Significant (P<0.05) correlation between damage indices and glucose content in Vita 7 and Kpodjiguegue is responsible for their susceptibility to M. sjostedti damage. Furthermore, presence of a unique protein band (20.1 kDa) in Moussa local, Sanzibanili and Sewe cultivars could be associated with resistance to flower bud thrips, regardless of quantity of total protein content in these and other test cultivars. Similarly, the specific band just above the 94 kDa in Vita 7 could be responsible for its susceptibility to M. sjostedti.

Bemisia tabaci (Gennadius) adults from colonies reared on cassava or sweet potato plants were studied to determine their ability to transmit Indian cassava mosaic virus (ICMV) (Geminiviridae: Begomovirus) from cassava to cassava. Virus acquisition access (feeding) periods (AAP) of 48 h on ICMV-infected cassava leaves and 48-h virus inoculation access (feeding) periods on virus-free cassava seedling leaves were investigated. ICMV was successfully transmitted from cassava to cassava by whiteflies reared on cassava, but not whiteflies reared on sweet potato. Virus-specific primers were designed around conserved regions of the coat protein gene (CP) (771 bases) of the Trivandrum (Tri; GenBank accession number AF423180) isolate and used for virus detection in the whitefly vector after different AAP. The activities of the cyanide detoxifying enzymes rhodanese and β-cyanoalanine synthase in B. tabaci were evaluated and shown to be significantly higher in the cassava-reared whitefly population compared with the sweet potato-reared population suggesting a possible reason for higher mortality of the sweet potato strain feeding on cassava. Mating compatibility studies between cassava and sweet potato colony whiteflies resulted in production of fertile offspring with no evidence for reproductive isolation. Results confirm that only B. tabaci whiteflies reared on cassava transmit ICMV from cassava to cassava in India.

The infectivity and pathogenicity of three native entomopathogenic nematodes (Heterorhabditis (HNI 0100 and sp-CIAT) and Steinernema (SNI 0198)) were evaluated in third instar larvae of Phyllophaga menetriesi (Blanchard) under laboratory conditions. Concentrations of 7000 and 13,000 infective juveniles per millilitre were applied to the coleopteran larval host (individuals) that had been placed in plastic cups with 40 g of sterile sand at 5.8% (w/w) moisture. The evaluations were done 5 and 10 days after treatment. It was observed that both the percentage of infectivity (74.5%, n = 247), measured in terms of percentage of penetration and the percentage of pathogenicity (10.5%, n = 247) of the three native nematodes were significantly different due to the treatments. Steinernema had the highest values of infectivity (>80%), but no pathogenicity. In contrast, the treatments with Heterorhabditis, despite having the lowest degree of infectivity (52.9%), had the highest mortality values (31.6%). Therefore, the Heterorhabditis strains were considered to be the most promising as biological control organisms within an integrated pest management programme due to their higher degree of pathogenicity. Nevertheless, different strains and species of native nematodes should be evaluated in all the developmental stages of the pest.

Neem (Azadirachta indica A. Juss.) has been demonstrated to reduce insect populations in stored products through its toxic and growth-disrupting and other effects on the pests. Grain movement and percussion also help to kill pests in grain. The combination of neem and grain movement on population growth and development of four insect pests is reported in this study. Dried whole neem leaves, neem leaf powder and neem seed kernel oil were combined individually with dried beans and rice in separate experiments, and subjected to varying degrees of gentle grain tumbling. The results showed that the combined treatments were more effective in reducing populations and disturbing growth and development of Acanthoscelides obtectus (Say) (Bruchidae), Sitophilusoryzae (Linnaeus) (Curculionidae), Oryzaephilus surinamensis (Linnaeus) (Silvanidae) and Cryptolestes ferrugineus (Stephens) (Cucujidae) compared to the untreated control or the neem or tumbling treatments alone. This study demonstrates the potential of a simple, effective and cheap method of protecting stored seed or food grain in small-scale storage for resource-poor farmers who do not have access to sophisticated control methods, entoleters or other mechanical devices for grain protection.

Shade-dried, powdered drupes of Melia azedarach L. were selected from three states in India, each representing a different geographical region, viz. Rajasthan (arid), Punjab (open plains), and Himachal Pradesh (hilly). Drupes were extracted in chloroform: methanol (9:1) and evaluated against second instar larvae of Plutella xylostella (Linnaeus) using a ‘leaf-disc dip’ bioassay. The ecotype from the arid region of Rajasthan yielded the lowest LC50 (1.47%), followed by that from the open plains of Punjab (1.79%) and the hilly areas of Himachal Pradesh, which yielded the maximum LC50 (2.29%). The survivors demonstrated various types of sublethal effects such as prolongation of larval period (7.0–7.8 days compared to 6.3–6.5 days in the control), reduction in pupal weight (36.0–38.4 mg/10 pupae in comparison to 54.4–56.0 mg in the control), deformation of pupae (up to 69.7%) and inhibition of adult emergence (up to 92%). A highly pronounced curtailment of fecundity (up to 10.4 against 73.2 in the control), significant reduction in oviposition period of the adults (up to 3.5 days compared to 7.4 days in the control) and longevity (5.5–7.8 days against 8.9–10.3 days in the control), were also recorded. The extracts produced from trees in the arid region of Rajasthan caused both lethal and sublethal effects following treatment of the second instar larvae of P. xylostella. Only 1.0% normal adults survived at the end of the study compared to 3.5 and 5.5% adult survival in the extracts from the open plains and hilly area ecotypes, respectively. An understanding of the bases of these variations in the toxicity of the crude extracts from the M. azedarach ecotypes growing in different climate conditions may open up the possibility of propagation and genetic improvement of the desired traits in the future.

Five groups of adult Rhipicephalus appendiculatus Neumann, with an average of 98 Theileria parva-infected salivary gland acini per tick, were exposed to four different temperature conditions in the laboratory or to quasi-natural conditions in Kenya. The survival of the infected ticks and T. parva parasites in their salivary glands were determined over time. Ticks kept under quasi-natural conditions survived up to 86 weeks. This period was longer than that of ticks exposed to any of the four laboratory conditions, except the diurnal temperature rhythm of 13–23 °C and 85% relative humidity (RH) to which it was comparable. Theileria parva survived for 82 weeks in ticks exposed to quasi-natural conditions, a period which was much longer than that of the parasites in ticks maintained under any of the laboratory conditions. Survival of the infected ticks and their infections seemed to be adversely affected by higher temperatures in the laboratory or drought in the field. There was an apparent density-dependent influence in parasite survival, with a dramatic fall in infection occurring in the more highly infected ticks before stabilizing at lower levels.

The penetration of adult Sitophilus zeamais Motschulsky through maize grain bulks (0.75 m deep), treated with Protect-It®, a diatomaceous earth (DE) at 0, 0.05, 0.1 and 0.2% (w/w), was determined 12 weeks after weevils were released at the upper surface of the grain. Maize was stored in columns in polyvinyl chloride (PVC) pipes, under controlled conditions of 26±2°C and 70±10% RH. Grain samples were collected from various pre-determined depths and the numbers of S. zeamais adults counted. Differences in insect numbers between treatments and at different depths from which samples were collected were highly significant (P<0.001). The bottom 2–3 layers (0.65–0.75 m deep) had significantly more insects than the upper layers for all the DE concentrations. No significant differences in total insect numbers (live+dead) were found between the DE concentrations. Dead S. zeamais weevils were found at the bottom of grain treated with Protect-It®, indicating that insects can penetrate through DE-treated grain 0.75 m deep but then subsequently die. There was no strong evidence that DEs admixed with bulk grain restrict S. zeamais movement within the grain.

A survey on the geographical distribution of Chnootriba similis (Thunberg), formerly known as Epilachna similis, was undertaken from 2001 to 2003 in the main cereal-growing areas of Ethiopia. The population density of the insect was estimated by sweep netting (100 sweeps/farm). In addition, more detailed studies on seasonal and annual fluctuations in population density of C. similis were carried out in southern Ethiopia between 2002 and 2003 by sampling 10 quadrants of 0.25 m2 per farmer's field. The damage levels were determined using scores of 0–9. The survey revealed that C. similis is widely distributed in different parts of the cereal-growing regions of Ethiopia. It was observed that the beetles had spread to altitudes ranging from 1217 to around 3000 m asl. However, the variations in population densities of C. similis cannot be directly attributed to altitude, as highly differing population densities in similar altitudes of different locations were recorded. Annual and seasonal variations in population density were observed in different areas of the southern part of Ethiopia. These results suggest that C. similis has a sporadic nature and can occasionally build up to outbreak levels. Beetles fed on both cereals (barley, wheat, tef, maize, sorghum and finger millet) and wild grasses (Leersia hexandra (Sw.), Avena abyssinica (Hoechst) and Lolium temulentum (L.)). Population densities and damage levels on the cereal crops varied considerably with the highest densities and damage levels on barley.

Sorghum is one of the most important cereal crops in the semi-arid tropics. Several insect pests damage it. The possibility of identifying genotypes with multiple resistance to these pests and transferring the relevant genes into high-yielding varieties and hybrids has been considered as an attractive approach to reducing yield losses. A set of 12 cytoplasmic male-sterile and maintainer lines, 12 restorer lines and their F1 hybrids were evaluated for resistance to sorghum shoot fly Atherigona soccata Rondani, spotted stemborer Chilo partellus (Swinhoe) and sugarcane aphid Melanaphis sacchari (Zehntner) under field conditions. There were significant differences among the genotypes tested. A total of 50% of male-sterile lines, 41.7% maintainers, 58.3% restorers and 35.4% of the hybrids tested showed moderate to high level of resistance to the three pests. The male-sterile and restorer lines showing resistance to different insects can be exploited for developing hybrids with multiple insect resistance for cultivation by the resource-poor farmers in the semi-arid tropics.