Cowpea Vigna unguiculata (L.) Walp. is an important component in mixed cropping systems that are appropriate to the agro-ecological characteristics of the West African savannah. However, the contribution of cowpea to overall productivity of the systems is reduced by a number of insect pest species. Compared with the humid zone, important features of insect pests in the savannah region include: (i) a tendency towards higher pest incidence during the limited growing period, (ii) a more advantageous situation for generalist and migratory pests in the scanty and unstable vegetation and (iii) lower mortality inflicted by parasitoids on the pest populations. The key pests of cowpea of importance in the West African savannah are the legume flower thrips Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), the legume pod borer Maruca vitrata (Fabricius) (Lepidoptera: Crambidae) and the pod-sucking bug Clavigralla tomentosicollis Stål (Hemiptera: Coreidae). To control these insects in a sustainable manner, pest management practices such as the use of resistant cowpea varieties, mixed cropping systems, botanical and reduced risk insecticides, and biological control assisted by pest monitoring have been developed. Nevertheless, no single component is effective when used alone, but specific combinations can work synergistically. This paper highlights recent progress in integrated pest management strategies for cowpea in cereal-based cropping systems in the West African savannah.

A study on the spatial distribution of the silkmoth Anaphe panda (Boisduval) cocoon nests, egg clusters and the host plant Bridelia micrantha (Hochst) Baill. was conducted in two different habitats of the Kakamega Forest of western Kenya: Ikuywa (indigenous forest) and Isecheno (mixed indigenous forest). The mean densities of cocoon nests, egg clusters and B. micrantha were significantly different in the two blocks and were not semi-randomly distributed in the two habitats. The host plants were underdispersed in the indigenous forest, whereas they were overdispersed in the mixed indigenous forest. The cocoon nests were overdispersed and the silkmoth egg clusters were underdispersed in the two blocks of forest. This study reveals that A. panda tends to distribute its egg clusters uniformly over the lower and middle crown of B. micrantha with a preference to eastern localization and confirms the insufficient presence of populations of this silkmoth in a mixed indigenous forest compared with an indigenous forest. Consequently, indigenous forests should be managed in a sustainable way and more indigenous tree species should be used in reforestation campaigns.

Differentiation of bloodstream-form trypanosomes into procyclics in tsetse flies (Diptera: Glossinidae) is a crucial step in the establishment of midgut infections. A number of factors have been implicated in the transformation process, including enzymes and lectins or lectin-like molecules. Recently, Glossina proteolytic lectin (Gpl) gene, which encodes a protein with both lectin and trypsin activities has been shown to stimulate transformation of bloodstream-form trypanosomes into procyclics in vitro. Using RT-PCR, we show that the induction of Gpl gene expression by blood meal occurs only in Glossina fuscipes fuscipes Newstead, Glossina austeni Newstead, Glossina pallidipes Austen, and not in the Anopheles gambiae Giles sensu stricto, Phlebotomus duboscqi Neveu-Lemaire, Rhipicephalus appendiculatus Neumann and Stomoxys calcitrans (Linnaeus). The expression means of Gpl mRNA in G. f. fuscipes following a blood meal were significant (P < 0.05) with low expression in teneral flies and reaching a maximum between 48 and 72 h (P < 0.05), suggesting time-dependent regulation of the transcription. The expression of the Gpl gene was significantly lower (P < 0.05) in G. f. fuscipes fed on blood meal infected with Trypanosoma brucei brucei as compared with G. f. fuscipes fed on uninfected blood meal. This suggests some form of interaction of T. b. brucei or the parasite products with Gpl within the tsetse midgut leading to down-regulation of the Gpl gene. Additionally, refractory G. f. fuscipes expressed higher (P < 0.05) transcript abundance than the susceptible G. pallidipes.

Protecting vegetables with a screen in peri-urban areas of tropical countries could reduce or even prevent often indiscriminate insecticide applications by small-scale farmers. The advantages of such an approach are protection of human health by reducing insecticide sprays, reducing environmental pollution from insecticide residues and increasing effectiveness of crop protection. Tunnel screens are well adapted to farmers cultivating intensively on small plots. Two trials were conducted to test the ability of screened tunnels to protect Brassica oleracea crops. The first was carried out on-station and the second in partnership with three farmers in Cotonou, Benin, West Africa. Tunnel screens impregnated with deltamethrin were found to be particularly well adapted to protect young plants in seedling nurseries against infestations by the aphid Lipaphis erysimi (Kaltenbach). The number of diamondback moth Plutella xylostella (Linnaeus) and borer Hellula undalis (Fabricius) on cabbages protected with the tunnel screen was significantly lower than that of plots conventionally treated with insecticides. The tunnel screen was not efficient against the armyworm Spodoptera littoralis (Boisduval) which laid eggs on the screen. After planting out, the use of a temporary screen from 1700 to 0900 h gave better control against pests than the use of a permanent screen possibly due to the impact of natural enemies during the day. The field trials showed that the protection of cabbage with a tunnel screen could be an economically viable method. The costs of pesticides are on average US$ 45 per 100 m2 for one crop cycle compared with US$ 24 per 100 m2 for tunnel screen material (assuming that this material can be used for 10 consecutive crop cycles). In addition, there are environmental benefits from a reduction of pesticide use. Farmers will have to cope with the initial investment for the screen material, which is, however, very cost-effective and locally available. Tunnel screens for vegetable protection can be easily combined with other integrated pest-management techniques.

The feeding traces in fossil ginger leaves and the conserved phylogenetic relationships seen today in certain clades of hispine beetles on their monocot hosts point towards a long and intimate plant–insect evolutionary relationship. Studies in the 1970s and 1980s documented the rich fauna of rolled-leaf hispine beetles and their association with the Neotropical monocot family Heliconiaceae in Central America. In this report, the taxonomic breadth of these early studies is expanded to include species in the families, Marantaceae, Poaceae, Arecaceae and Costaceae, all with species occurring sympatrically with the Heliconiaceae in lowland Panama. Additionally, the analysis is widened to include open-leaf scraping and internal leaf-mining clades of hispoid Cassidinae. The censuses add more than 5080 Cassidinae herbivore occurrence records on both open and unfurled new leaf rolls of 4600 individual plants. Cluster analysis reveals that while many Hispinae species tend to group with plant species in only one of the three monocot orders, 9 of 16 Hispinae species on Zingiberales hosts were recorded in substantial numbers on both the Heliconiaceae and the Marantaceae, indicating an underlying pattern of feeding flexibility at the host plant family level.

Recent unusual high damage of finger millet Eleusine coracana (L.) Gaertn. and wheat Triticum spp. by Busseola fusca (Fuller) in Ethiopia prompted the initiation of this study that has involved comparing the host status of these crops with the main host, maize Zea mays. One improved variety and one local land race each of wheat, finger millet and maize were grown with and without fertilizer in a randomized complete block design to evaluate the effect of nitrogen and phosphorous fertilizers and varietal differences on the suitability of these host plants for the development of borer larvae. The results indicated that B. fusca larvae managed to survive up to the adult stage in the stems of finger millet and maize, while wheat failed to support larval development to pupation. The stems of fertilizer-treated crops hosted more larvae than those of untreated ones and these were significantly longer and heavier. Improved varieties tended to be more suitable for B. fusca development. Furthermore, irrespective of the crop species, improved varieties grown with fertilizer were more suitable for the development of B. fusca. An improved finger millet variety, KNE No. 1098, grown with fertilizer was as suitable as the improved maize variety A-511, grown without fertilizer. For wheat, however, immature mortality was 100% irrespective of variety and fertilizer level.

The life cycle of the African wild silkmoth Gonometa postica Walker was studied between September 2000 and September 2001 in the Uasin Gishu District of western Kenya with Acacia mearnsii de Wild and Acacia hockii de Wild as host plants. The initial population of G. postica was set up from healthy live pupae in cocoons collected from host plants in the study area. Oviposition was carried out in net sleeves and small plastic cages. Moth emergence and oviposition were bimodal, occurring between September and October 2000 and between March and April 2001, respectively. Larvae were reared in semi-captivity by using net sleeves on the branches of the two host plants. Larvae passed through six developmental instars. The pupal stage lasted from December to February during the short rains and from June to September during the long rains. Moth fecundity in the net sleeves was higher than that of those kept in plastic cages and fewer eggs hatched in the plastic cages compared with the net sleeves. Larvae reared on A. mearnsii had a shorter developmental period compared with those reared on A. hockii. Male larvae spun cocoons earlier than females but moths of both sexes emerged simultaneously. Sexual dimorphism was exhibited in both pupal and adult stages, females being larger and heavier than males. The importance of the semi-captive rearing technique for sustainable utilization of wild silkmoths for mass production of cocoons is discussed.

Host-plant resistance is one of the major components of integrated pest management programmes against the noctuid pod borer Helicoverpa armigera (Hübner) in chickpea. Survival and development of H. armigera on nine chickpea genotypes were compared using two food substrates, namely fresh leaves and pods, and artificial diets containing lyophilized leaf or pod powder of the same genotypes. Among the genotypes used, six showed different levels of resistance to H. armigera, while three were used as susceptible checks. Using leaves and pods, five of the resistant genotypes yielded lower larval weights compared to one of the susceptible checks used. Significant differences between four of the resistant and two of the susceptible genotypes were also observed when using artificial diets containing leaf or pod powder, but the rankings were different from that on the fresh leaves and pods. On both substrates, four resistant genotypes resulted in lower larval survival, pupation, adult emergence and fecundity when compared to one of the susceptible checks. A similar trend was also observed for larval survival and development when using F1 hybrids based on four of the resistant genotypes. Survival and development of H. armigera on the two food substrates, fresh leaves and pods and artificial diets with lyophilized leaf or pod powder, were highly correlated, suggesting that incorporation of lyophilized leaves or pods into the artificial diet can be used to assess antibiosis to H. armigera in chickpea.

The effects of methanol extract of Peganum harmala L. seeds were evaluated against Tribolium castaneum (Herbst). Larval growth was inhibited and food intake reduced when the extract was incorporated into the diet at concentrations of 2.5, 5 and 10%. All doses caused an increase in the duration of larval period and completely inhibited F1 progeny production. The main body metabolites were determined in last-instar larvae after feeding for 8 days on the diet treated with different doses. Protein and lipid contents were decreased with concentrations >2.5%. Glycogen content was reduced at a concentration of 10%. Tribolium castaneum larvae possessed two major and one minor α-amylase isoforms as determined by gel assays. Larvae fed the treated diet presented less activity of the major isoforms, while activity of the minor isoform was totally inhibited. The activity of this enzyme is not inhibited in vitro by seed extracts. Histological studies showed that P. harmala extracts caused a severe cytotoxicity on the epithelial cells of the midgut resulting in marked vacuolization of the cytoplasm and a large intercellular space. These findings suggest that seed extracts of P. harmala exert their toxic effect by severely damaging the midgut epithelial cells. This naturally occurring plant extract could be useful for control of T. castaneum.

A survey to establish the distribution of tsetse flies (Diptera: Glossinidae) in southern Sudan was conducted using biconical traps. Only Glossina fuscipes fuscipes was caught. The results obtained revealed a further northern advance of G. f. fuscipes of c. 29 km along River Bahr el Jebel and 48 km along River Luri, and a southern contraction of Glossina morsitans submorsitans belt from Lewis' distribution limit. Glossina f. fuscipes was encountered in gallery forest along water courses with no significant differences in sex ratios and proportions of tenerals and non-tenerals between trap catches (P>0.1). Flies were absent from villages and open savanna woodland forests away from water courses. Trap catches were significantly higher during wet than dry season (t = 2.681; P < 0.025), although flies could be caught in any one location during both seasons. These results are discussed in relation to the current epidemic of human African trypanosomosis (HAT) in southern Sudan.

The antibiotic effects of 12 different cotton genotypes on Bemisia tabaci (Gennadius) were studied during June–July and August–September 2003, with the objective to determine the biological parameters which are important to study the mechanism of antibiosis and to identify the genotypes in which antibiosis is operating. The detailed biology of whitefly, i.e. developmental period, survival, fecundity, longevity and sex ratio were studied under ‘no choice’ conditions, by confining the whiteflies in leaf cages. The study revealed that incubation period, nymphal developmental time, total developmental time, nymphal survival, total survival, fecundity and female longevity are the most important biological parameters for detecting the presence of antibiosis in resistant cotton genotypes against whiteflies. On the other hand, pupal period and survival, male longevity and sex ratio do not seem to play important roles in antibiosis. The combined effect of these parameters indicated that Gossypium arboreum genotype PA 183 was the most resistant while Bt 6304, TX Maroon 2–78 and F846 were the most susceptible ones. Other genotypes with moderate resistance include Supriya and LD 694.

Three transgenic maize hybrids, viz. Prabal YG, Hishell YG and Double YG, producing Bacillus thuringiensis (Bt) Cry1Ab protein (event Mon 810), were evaluated under field and laboratory conditions for their resistance to spotted stemborer Chilo partellus (Swinhoe). The Bt maize hybrids suffered less damage than their non-Bt iso-hybrids with respect to per cent plant infestation (0.0–0.6), leaf injury rating (1.0–1.1) and per cent stem tunnelling. These hybrids also resulted in significantly higher larval mortality (79.4–100.0%) in laboratory bioassays. The toxin protein produced in leaves was equally effective against neonates and 15-day-old larvae. Neonate larvae consumed less leaf area (5.0–13.8%) in case of Bt hybrids than their non-Bt iso-hybrids.

Neem products are often perceived as harmless to natural enemies, pollinators and other non-target organisms. For this reason, several integrated pest management (IPM) programmes have adopted neem as one of the prime components. This study revealed toxic effects of neem on soil-inhabiting and aerial natural enemies in chickpea to an extent of 41 and 29% population reduction, respectively, compared with 63 and 51% when using a conventional insecticide (endosulfan). Neem also affected the parasitization of Helicoverpa armigera (Hübner) larvae by Campoletis chlorideae Uchida up to 20%. The natural enemy population started building up from the vegetative phase and reached their peak during the reproductive phase, and there was a gradual decline from pod formation to pre-harvest phases of the crop. Adapting the currently used IPM system in chickpea using neem during the vegetative phase, followed by an application of Helicoverpa nuclear polyhedrosis virus (HNPV) at flowering and need-based application(s) of chitin inhibitors like novaluron or flufenoxuron instead of endosulfan during pod formation would strongly augment natural enemy populations. This paper discusses the relative toxicity of neem and other IPM components on soil-inhabiting and aerial natural enemies in the chickpea ecosystem.

A new aspirator is proposed for the collection of springtails (Collembola) and other small arthropods. It is hand operated, safe and efficient to use.