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.

Behavioural and antennal responses of the sorghum chafer Pachnoda interrupta (Olivier) were tested to the synthetic compounds, such as eugenol, methyl salicylate, methyl anthranilate, isoamyl acetate and butyl butyrate. In the field, all odour-baited traps, except isoamyl acetate applied on cotton dispensers, were significantly more attractive than blank (unbaited) traps and all compounds, except isoamyl acetate, elicited dose-dependent responses in both male and female antennae. Dispenser type (cotton wick or rubber septum), trap location (inside or outside sorghum fields) and season (mating/July or feeding/September) affected the performance of the different compounds as lures. In July, methyl salicylate applied on cotton was the most attractive lure, whereas the most attractive treatments in September were eugenol and isoamyl acetate on rubber septa. Possibly due to odour and visual competition from the sorghum plants, traps placed outside the sorghum fields caught significantly more beetles than traps placed inside the fields. The trapping efficiency of a locally produced trap was found not to be competitive with that of the commercially available Japanese beetle trap. Overall, the results suggest that trapping with semiochemicals has a potential in sorghum chafer management, either for mass trapping and/or as part of an integrated pest management programme.

Female-biased sex ratios in Danaus chrysippus (Linnaeus) (family Nymphalidae, subfamily Danainae, tribe Danaini) populations are attributed to the action of an endosymbiotic ‘male-killer’ bacterium of the genus Spiroplasma. In stark contrast to the extensive geographic range of their host, the Spiroplasma appears to be restricted to East Africa, where four African D. chrysippus subspecies exist sympatrically and form a hybrid zone. In this study, specimens collected at three sample sites within the hybrid zone were screened for Spiroplasma infection. The findings demonstrate that, within the hybrid zone, the frequency of Spiroplasma infection varies both spatially and temporally. Host genotype at three biallelic wing pattern loci, representative of subspecific genetic divergence, is correlated to Spiroplasma infection. Linkage between the frequency of the recessive a allele and Spiroplasma is established, suggesting the presence of a linked allele controlling infection susceptibility. In addition, a negative correlation between D. chrysippus forewing length and Spiroplasma infection is identified, suggesting that infection has a deleterious effect on body size.

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.

The aim of this study was to document what water types were most stimulatory to oviposition by the malaria mosquito, Anopheles gambiae Giles s.s. In laboratory choice tests, dishes of black cotton and red laterite soils from around Kisumu, Kenya, equally stimulated An. gambiae oviposition when saturated with water. When infused into either soil type, water from Lake Victoria was significantly more stimulatory than any other type of water or infusion tested. Water from natural An. gambiae puddle habitats, borehole water, cow dung infusion, Bermuda grass infusion and distilled water followed in declining rank order. Relative to An. gambiae puddle-habitat water and distilled water, Lake Victoria water appears to provide the strongest chemical cues for An. gambiae oviposition recorded to date. This work suggests that this important vector of human malaria may oviposit in and around Lake Victoria, as well as in its usual puddle habitats. Lake Victoria should be explored for its possible contribution to malaria mosquito populations.

The insect fauna of rain-fed rice, Oryza sativa, was assessed using the sweep net and direct count methods. The objective of the study was to provide basic information on the insect pest complex of rice in the area and their natural enemies. One hundred and five insect species belonging to nine orders and 57 families were found. The insect orders in order of abundance were Diptera (45.67%), Coleoptera (12.77%), Lepidoptera (12.23%), Orthoptera (8.44%), Heteroptera (8.23%), Homoptera (7.03%), Hymenoptera (3.25%), Dermaptera (1.95%) and Dictyoptera (0.43%). Diopsis thoracica Westwood (Diopsidae) (69.43%) was the most abundant dipteran followed by the sarcophagids (14.93%) and calliphorids (7.11%). Members of the family Chrysomelidae represented 50% of the coleopterans followed by the coccinellids (17.46%). While 31% of the lepidopterans were noctuids, 60% were pyralids. The pentatomids (50.57%) were the most abundant heteropterans while the acridids (43%) were the most prevalent orthopterans. The homopterans were mainly Cofanaunimaculata Signoret (which represented 79%). The insects were clustered into three groups with D. thoracica alone in group 1, C. unimaculata and Sarcophaga species in group 2 and the rest in group 3. We therefore conclude that D. thoracica is the most important pest of rice in Ekpoma while C. unimaculata may also be very important, but Sarcophaga species appears to be the most important natural enemy in the system.

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.

The performance of the Bombyx mori Linnaeus bivoltine hybrid, Shaanshi BV-333, was evaluated on six mulberry cultivars of Morus spp. based on economic characters in rearing and mulberry leaf quality. The growth rate and morphological characteristics for all the cultivars were studied using several parameters. Specific characters such as disease resistance, survival percentage, cocoon weight, cocoon shell weight and single cocoon filament length were recorded during the rearing of silkworm larvae. Tested cultivars significantly differed in all parameters. Cultivars Kanva-2/M5, Thailand, Thika and S-36 exhibited superiority in rearing performance over other tested cultivars. Silkworms fed with cv. Thailand had the highest survival percentage of larvae in the short (S1) and long (S2) rainy seasons as compared with other cultivars. However, cv. Embu produced the lowest mortality during the dry season (S3), while S-41 produced the lowest survival rate in all seasons. Embu had significantly higher filament length and cocoon yield compared with the other cultivars during S3. However, S-41 performed poorly in survival percentage, cocoon yield, silk reeling and cocoon shell weight.

The reproductive behaviour of a generalist aphidophagous ladybird beetle Cheilomenes sexmaculata (Fabricius) was studied in detail. The males first mated at an age of about 2 days, while females mated at 1 day after their emergence. Mate recognition was displayed in five steps, viz. approach, watch, examine, mount and copulatory attempt. Being provided with four dummy models, the male appeared to recognize the female through visual and other possible cues, maybe chemical. The duration of mating was maximum (mean ± SE; 133.0 ± 2.8 min) when an unmated male copulated with a virgin female and minimum (95.0 ± 4.2 min) when a mated male copulated with a mated female. Mating duration seems to be influenced more by the change in male sexual status, thus revealing it to be male dominated. The maximum oviposition period (46.0 ± 1.2 days), fecundity (861.0 ± 2.2) and hatching percentage (64.0 ± 0.6) in C. sexmaculata were noticed after multiple matings, while these parameters were minimum (15.0 ± 1.0, 70.0 ± 2.8 and 37.0 ± 1.0, respectively) after single mating. Thus, multiple matings enhanced the total egg output and percentage of hatchability.

The effect of visual and olfactory stimuli from leaves of two maize cultivars, Basilocal (susceptible) and Kisan (resistant), in eliciting orientational responses by first instar Chilo partellus (Swinhoe) larvae was investigated in the laboratory. The polar and non-polar chemical constituents of these cultivars were extracted in methanol and hexane, respectively. Orientational preference of the larvae for the leaf whorls and hexane extracts of Basilocal leaves was significantly greater than that for Kisan. The methanol extracts of the two cultivars were, however, equally effective in eliciting larval attraction. These observations imply that the non-polar fraction of maize leaves is more effective than the polar fraction in eliciting larval orientation in C. partellus. Moreover, certain chemicals of Kisan leaves, extractable in hexane, elicited larval repulsion whereas those of Basilocal leaves elicited larval attraction. Identification of the chemicals eliciting attraction or repulsion would be valuable in a management programme for this economically important insect pest of gramineous crops.

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.

Sitophilus zeamais Motschulsky is an important field-to-store pest of maize in several parts of Africa including Cameroon. Although synthetic insecticides are effective at controlling the pest, the environmental and health hazards of these chemicals are of increasing concern. This study assesses the efficacy of ashes of local plant material against S. zeamais in the western highlands of Cameroon as an alternative to synthetic insecticides. Laboratory studies on toxicity against F1 progeny of S. zeamais were conducted using leaf ashes of Cupressus arizonica, Eucalyptus grandis, Ocimum gratissimum and root ash of Vetiveria zizanioides at the rates of 0.1, 0.25, 0.5 and 1.0 g/25 g maize grains in Kilner jars. Toxicity of E. grandis ash extract was also evaluated. The ashes of E. grandis and O. gratissimum at the rate of 0.25 g/25 g grains significantly reduced the number of emerged weevils. Eucalyptus grandis ash showed toxicity (1.0 F1 progeny emerging at 0.25 g/25 g grains compared with 16.5 for the control). Eucalyptus grandis ash at 20 g/2 kg grains significantly reduced grain weight loss and protected grains for 6 months without adversely affecting the germination of the seeds. Ethanolic E. grandis ash extracts at rates of 50,000 and 100,000 ppm significantly (P < 0.05) reduced the number of emerged F1 progeny of S. zeamais.

Cocoa (Theobroma cacao L.) is an important foreign exchange earner for Ghana. However, production is constrained by a high incidence of pests and diseases. Based on farmers' needs, this study focused on the control of capsids, mainly Sahlbergella singularis Haglund and Distantiella theobroma (Distant) (both Hemiptera: Miridae). Annual crop loss caused by capsids is estimated at 25–30%. To control capsids, formal research recommends application of synthetic insecticides four times between August and December. However, farmers hardly adopt this recommendation, which they consider unsuitable for their conditions and context. Three alternative control methods were tested with farmers: mass trapping, using sex pheromones; applying crude aqueous neem Azadirachta indica A. Juss. (Meliaceae) seed extract (ANSE) and using the predatory ant Oecophylla longinoda Latreille (Hymenoptera: Formicidae) as a biological control agent. Contrary to most previous reports, studies on temporal distribution of cocoa capsids indicated that the population peaked in March. ANSE was effective against capsids and other cocoa insect pests and did not affect the predatory ant. When O. longinoda occurred in high numbers, capsid incidence was low. Shade did not influence ant or capsid abundance significantly. ANSE caused 100% mortality of capsids in cage and 79–88% in field experiments. The sex pheromone was as effective as ANSE or ants in suppressing capsids. All the three methods were effective and compatible; hence, they can be used in an integrated pest management strategy for cocoa, including organic production in Ghana.

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.

Many pests, especially capsid bugs, infest cocoa and contribute to low yields in producing countries. In Ghana, synthetic pesticides are recommended for controlling the insect pests, and a combination of synthetic pesticides and cultural practices for diseases and weeds. However, the farmers in Ghana are not motivated to adopt these recommendations due to the high cost of pesticides and low producer prices. There is also concern that use of synthetic pesticides on a wide scale can affect both human health and the environment. With the objective of improving cocoa yields through environmentally friendly pest control practices, evaluation of an integrated pest management (IPM) package based on aqueous neem (Azadirachta indica A. Juss.) seed extracts to control the insect pests and cultural practices to manage the diseases, weeds and parasitic plants was undertaken in farmers' fields with their active participation. The IPM package improved yields significantly and was found to be more profitable than the farmers' practices. However, there are two major constraints to adoption of the package by farmers: it is labour-intensive and currently, neem is not readily available to the community. The study recommends that these constraints must be tackled to motivate the farmers to adopt or adapt the IPM package.

Information on termite assemblage in a young eucalypt plantation in Kerala was generated by running a single line transect and monthly sampling for 1 year. Through the transect sampling, 11 species were recorded under two families and four subfamilies. The subfamily Macrotermitinae dominated with eight species while the other three subfamilies were represented by a single species each. A temporal pattern of abundance was observed for the different active foraging species of termites in the monthly sampling. During April–November, a single species, Odontotermes obesus (Rambur), was the most abundant. During December–January, Microcerotermes fletcheri Holmgren & Holmgren was dominant, while Odontotermes feae (Wasmann) dominated during February and March. Rainfall was found to have a negative influence on the diversity of the active/foraging species of termites. Among the 14 species of termites collected, only four were found attacking eucalypt seedlings. Of the total termite samples collected, 40% belonged to the single species O. obesus, which was the major pest species representing 12 out of the 18 recorded incidences of termites feeding on roots of eucalypt seedlings. Among the species recorded, one was a new species and two were new records for Kerala State. The large number of non-pest species of termites indicates the beneficial role of these termites as efficient decomposers.

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 biology of Neoseiulus barkeri (Hughes), Typhlodromus balanites El-Badry and Amblyseius zaheri Yousef & El-Borolossy was studied using Ephestia kuehniella Zeller eggs as food source. For N. barkeri, the development was faster and reproduction was higher than for A. zaheri. Survival of immatures of T. balanites was low on eggs of E. kuehniella and all failed to develop to adulthood. A total of 50.4 and 41.0 eggs per female were obtained when N. barkeri and A. zaheri were fed on moth eggs, respectively. A diet of E. kuehniella eggs provided the highest female longevity and mean total fecundity, which resulted in the highest net reproductive rate (Ro = 32.88), intrinsic rate of natural increase (rm = 0.139) and finite rate of increase (λ = 1.149) for N. barkeri. The mean generation time ranged between 24.65 and 25.03 days for A. zaheri and N. barkeri, respectively. The sex ratio of the progeny was strongly female biased (female/total = 0.69 and 0.58) when eggs of E. kuehniella were provided for N. barkeri and A. zaheri.

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.