Worldwide, food grain is lost due to damage by insects, mites and micro-organisms. Any additional approaches towards preventing farm-storage losses could contribute to saving more grain. In one paper of this issue, the authors assess the effect of a lectin-like protein on lepidopteran larvae causing loss in stored food.

Stem and cob borers cause substantial damage to maize and affect the quality and economic value of maize in West Africa. Manipulation of planting dates is considered a possible mechanism for averting the overall impact of borers and their damage to the crop. Experiments were carried out in southern Benin to evaluate the effect of various planting dates on the incidence and damage to maize by Sesamia calamistis (Hampson). The trials were conducted at the Benin station of the International Institute of Tropical Agriculture (IITA) at Abomey-Calavi and at Sèhouè, located 70 km north of the IITA, Benin station. The planting dates were: early planting (the day following the first rains), intermediate planting (2–3 weeks after the early planting) and late planting (4–5 weeks after the early planting). The experiments were carried out in the main and minor cropping seasons, respectively, during two successive years in 2003 and 2004. The variables measured included population density of S. calamistis, percentage of infested plants and cob damage. In the main cropping season, incidence of stemborers and percentage of infested plants were higher in the late planting than in the early planting and intermediate planting treatments. The manipulation of planting dates for the control of S. calamistis during the minor maize growing season is not recommended.

Cowpea (Vigna unguiculata (L.) Walp) is an important food staple in sub-Saharan Africa. The legume pod borer Maruca vitrata Fabricius is one of the key pests of cowpea as the larvae feed on the tender parts of the stem, peduncles, flower buds, flowers and on pods of the plant, causing significant yield losses. Understanding the seasonal and geographical patterns of M. vitrata is essential for the establishment of effective pest management strategies. Sites in three ecological zones in Burkina Faso were sampled for the presence of M. vitrata adults and larvae both during and outside of the cowpea-growing season. Our data suggest that M. vitrata do not maintain a permanent population in the Sahelian or Sudano-Sahelian zones, but emigrate from the Sudanian zone where M. vitrata populations evidently may occur throughout the year.

Cotton leaf curl disease, a viral infection vectored by the whitefly Bemisia tabaci (Gennadius), is a major threat to the cotton industry in India and Pakistan. We examined the settling preferences of B. tabaci adults on infected versus healthy cotton plants under choice conditions. For experiments with plants at 20 and 35 days post-inoculation (DPI), whiteflies preferentially settled on healthy cotton plants after 8 and 1 h of release, respectively. Whiteflies, however, were unable to discriminate between virus-infected and healthy cotton plants at 5 DPI. Our results suggest that whiteflies' preference for healthy plants compared with diseased plants can lead to rapid virus spread in the field, resulting in higher crop losses.

Pollinators are important natural agents for fruit and seed formation in most tree crops and the use of appropriate sampling methods is fundamental in studying their population. A study to develop surveying and monitoring protocols for cocoa pollinators was undertaken in Ghana. Yellow, white and blue UV-bright painted pan traps (UVPPT), McPhail traps and motorized aspirators were used to sample pollinators of cocoa for 13 successive months, after 6 days assessment of the effectiveness of the traps and diurnal active period of the pollinators. The peak pollinating period of cocoa by ceratopogonid midges was between 07.00 and 12.00 h, as previously reported. All three methods were effective in sampling ceratopogonid midges with the UVPPT being the most efficient in terms of sampling effort. The number of ceratopogonid midges caught by the yellow-UVPPT was significantly higher than that by blue- and white-UVPPT. The diversity of midges caught could not be determined due to taxonomic difficulties, and thus all the three colours of UVPPT should be used until efficiency in terms of diversity is determined. It is reported here that the meliponine bee Liotrigona parvula Darchen visits cocoa flowers and thus their effectiveness in cocoa pollination should be investigated.

Laboratory trials were conducted in Uganda at the Kawanda Agricultural Research Institute to determine attraction, eclosion success and larval survivorship of the banana weevil Cosmopolites sordidus (Germar) on crop residues of different ages. In the first experiment, studies focused on different types and ages of residues of one susceptible highland banana clone ‘Nabusa’ (genome group AAA-EA). Corms attracted 65% of the test weevils, pseudostems 30%, while 5% were non-respondents. Oviposition levels and the number of eggs per female were higher on young than old corms. Eclosion rates of < 1-day-old eggs inserted into corm pieces of residues (cultivar ‘Kisansa’, genome group AAA-EA) declined from 66% in residues collected < 2 days after harvest (DAH) to 58% in residues collected >30 DAH. To assess immature survival, < 1-day-old 1st instar larvae were put on banana corms of suckers and crop residues of the cultivar Kisansa in single rearing chambers. The number of surviving individuals was recorded at 3-day intervals until adults emerged. Survivorship was 12% on sword suckers, 10% on maiden suckers and 7% on flowered plants; and 12% on residues collected < 2 DAH and 5% on residues collected >30 DAH. Larval duration and mean days taken for adult emergence increased with plant and crop residue age. Females emerging from the different plant and residues treatments were similar in weight. The data suggest that all aged residues are suitable hosts for C. sordidus, suggesting that sanitation practices should be implemented soon after harvest.

Tree-hole phytotelmata encompass the internodal water pools that form in many species of bamboo (Gramineae). Using bamboo traps, we sampled macroinvertebrate communities in a habitat within the subtropical cloud forest of Henri Pittier National Park, Rancho Grande, north-central Venezuela, and quantified the temporal differences in their abundance and composition. In total, 1024 invertebrates were collected during the 7 months between February and August 2008. The insect orders Diptera and Coleoptera were abundant, particularly Culex (Anoedioporpa) conservator Dyar & Knab, Culex (Culex) mollis (Dyar & Knab), Wyeomyia (Wyeomyia) arthrostigma (Lutz) and Toxorhynchites (Lynchiella) theobaldi (Dyar & Knab). The traps also contained predators, detritivores and collectors (filtering and gathering). Macroinvertebrate abundance in the traps was higher during the rainy season. This observation was attributed to a greater abundance of Ephydridae, Blattaria and Culicidae during wetter months, and an increased availability of potential new breeding sites in the environment, which resulted in increased adult eclosion, and higher rates of oviposition in the bamboo traps. Temporal differences in pH and dissolved oxygen levels of trap water were observed.

Crop pollination by wild pollinators is an ecosystem service of immense value to modern agriculture. Pollination by wild insects is under-researched in the tropics, where many crops may require or benefit from wild pollinators. Papaya is a dioecious tree crop widely cultivated throughout the tropics. In East Africa, papaya is an important component of rural smallholder farming systems. Traditional agricultural systems are currently under stress due to landscape degradation. These trends are of special concern with respect to pollination services provided by wild insects. Investigation of the role of hawkmoths as pollinators of papaya on subsistence farms in Kenya was conducted over a period of 3 years. Hawkmoths were the most abundant and reliable visitors to both ‘female’ pistillate and ‘male’ staminate papaya flowers. Hawkmoths accounted for >95% of legitimate visits and xenogamous pollination of papaya flowers. Hippotion celerio, Nephele comma and Agrius convolvuli were the main pollinators. Sites in two districts with similar climates and natural vegetation, but different levels of habitat degradation were chosen for comparison of pollinators and pollination services. Hawkmoth abundance and visitation rates declined sharply with increasing distance of natural habitat patches from the crop. Fruit set was also reduced at sites with high levels of disturbance/poor agricultural practices. Natural habitat containing larval food plants and other nectar resources for hawkmoths therefore supports adjacent cultivated papaya with pollination services. Understanding the links between wild biodiversity, in this case pollinating hawkmoths, and agricultural productivity can help bridge the gap between agricultural development and biodiversity conservation.

Hexane and acetone extracts of Trichilia connaroides leaves were evaluated for their biological activity against the Bihar hairy caterpillar Spilosoma obliqua Walker, a destructive pest of crop, medicinal and ornamental plants. Fresh caster (Ricinus communis) leaves treated with a range of concentrations (1–10%) of the extracts were offered to 2nd instars for 120 h, followed by untreated leaves until pupation. Acetone extracts exerted better growth-regulatory properties than hexane extracts, shown by morphogenic malformation and adverse effects on the insect's larval duration, pupal duration, adult emergence and fecundity.

Antheraea assamensis (Helfer, 1837) is a sericigenous insect with distinct coloration, namely green, blue, orange and yellow in their larval stages and these are multivoltine in culture. However, wild morphs with diapause are found in dense forests. In this study, the wing venation and its variation in A. assamensis were analysed using traditional as well as landmark-based morphometric methods. The venation patterns are reviewed and significant changes in veins recorded. The samples were analysed using geometric morphometric methods and other conventional statistical methods. Landmark-based data were measured among selected veins and the centroid sizes, procrustes to tangent distance of different veins were analysed. Results show significant differences in some of the veins among the intraspecies of A. assamensis. The results suggest that both visual comparison as well as a quantitative approach in A. assamensis may lead to unsound taxonomic conclusions at intraspecies level.

The abundance and distribution of Ceratitis capitata (Wiedemann) in Late Valencia citrus orchards and other alternative host crops was investigated using trimedlure-baited traps at the University of Ghana's Agricultural Research Centre in the Eastern region of Ghana. The effect of some climatic factors on the population dynamics of the pest was also studied. The population of C. capitata increased from September to October 2006 and from February to March 2007, when Late Valencia citrus fruits were ripening or ripened. The fruit fly population was the lowest from November 2006 to January 2007 when citrus fruits were in the immature green stage. Ceratitis capitata was not trapped in mango, pawpaw and pepper fields and did not emerge from fruits of these crops. Multiple regression analyses also revealed that rainfall and temperature significantly influenced the pest population. The results of this study have important implications on the decision-making process for the safe, effective monitoring and management of C. capitata in Late Valencia citrus orchards in the study area in Ghana and probably in other areas as well.

Pyrethroids are the insecticides of choice for the treatment of bednets for malaria control. Pyrethroid resistance in Anopheles spp. vectors may adversely impact malaria control measures, and therefore it is important to know the initial level of pyrethroid resistance before pyrethroid-treated bednets are introduced. Furthermore, a search for replacement insecticides is necessary to manage any eventual high-resistance levels to pyrethroid insecticides that may affect the effectiveness of treated bednets. This study reports on the susceptibility of Anopheles gambiae s.s. exposed for 1 h to the pyrethroid insecticide permethrin and the carbamate insecticide propoxur, at eight localities in the Greater Accra region of Ghana. The observed mortality rates ranged between 21–92% and 92–100% to permethrin and propoxur, respectively. The results also showed a reduction in the knockdown time (KD50 and KD95) in propoxur (mean KD50 = 20 min and mean KD95 = 31 min) when compared with permethrin (mean KD50 = 47 min and mean KD95 = 87 min). The results suggest that permethrin may not be effective in all areas. Where pyrethroid resistance is a problem, propoxur could be an alternative for indoor residual spraying and for insecticide-treated materials such as curtains and eave screens.

The effects of sublethal concentrations of the insect growth regulators (IGRs) diflubenzuron and methoprene on some fitness components of an Aedes aegypti (L.) population in south-eastern Brazil were investigated. The fourth instar larvae of the mosquito were exposed to 20 ppb methoprene and 3 ppb diflubenzuron, and adult survivors were evaluated for fitness parameters, including body size and biomass, fecundity, fertility, longevity and symmetry. The sublethal concentrations had negative effects on longevity, but biomass, fecundity and fertility were not affected by either IGR. In separate experiments, A. aegypti individuals' surviving concentrations of 2, 3 and 3.5 ppb diflubenzuron and 5, 10 and 20 ppb methoprene were used for morphological analyses (size and symmetry). Diflubenzuron had negative effects on the mosquito's body symmetry. The observed decreases in longevity and symmetry may have negative impacts on the population dynamics of A. aegypti.

Agricultural research in the 21st century has become a collaborative effort. Research on crop pests like Spodoptera frugiperda (J.E. Smith), commonly known as the fall armyworm (FAW), can involve international collaboration because it is a pest not only in the southern United States, but also in Latin and South America. Our interest to study the genetic variation of 24 subpopulations of FAW from the southern United States, Mexico, Puerto Rico, Brazil and Argentina required insect collection procedures that preserve the integrity of DNA for molecular genetic analysis. The samples were collected primarily from maize (Zea mays L.), but also included outliers collected from pigweed (Amaranthus sp.), Royal Paulownia (Paulownia tomentosa (Thunb.) Sieb. and Zucc. ex Steud.), lemon tree (Citrus limon (L.) Burm) and Bermuda grass (Cynodon dactylon (L.) Pers.). A common insect preservation technique is to place individual insects in 95% ethanol (ETOH). However, various regulations for shipping and the size of this insect often prevent large sample sizes stored in ETOH from being imported. Genomic DNA from samples preserved in 95% ETOH, lyophilized and fresh insects was extracted and evaluated using DNA quantification and polymerase chain reaction–amplified fragment length polymorphism (PCR–AFLP). All three treatments yielded high-quality/high molecular weight (c. 70–150 μg) DNA. No differences in quality of genomic DNA for AFLP analysis were observed. Lyophilization is a reliable tool to preserve FAW samples, which yields high-quality DNA for use in AFLP genetic analysis.

Aqueous extracts of Tephrosia vogelii and Hyptis suaveolens, and of oils of Azadirachta indica and Jatropha curcas, as well as the pesticide Furadan 5G were evaluated for their insecticidal activity against the maize cob borer Mussidia nigrivenella Ragonot in laboratory and field experiments. In general, treated plants had a strong deterrent effect on ovipositing M. nigrivenella. The oviposition deterrence index was highest with neem oil at both concentrations, J. curcas at 5% and H. suaveolens at 20%. In addition, neem and Jatropha oils adversely affected egg hatch; it decreased with an increase in concentrations of oil emulsions and varied between 3 and 25.5% for neem and 6 and 16% for J. curcas. The lethal concentration 50 values calculated were 1.3 and 0.8%, respectively, for neem and J. curcas. By contrast, larval survival was not affected by the oil treatments. In the field, Furadan, neem and J. curcas oils significantly reduced the number of M. nigrivenella larvae by 16–49.2%, while aqueous extracts of T. vogelii and H. suaveolens were similar to the emulsified water control. The treatments did not significantly influence cob weight, and only neem oil at both concentrations and Furadan significantly reduced cob damage and consequently grain losses. These results showed that oil emulsions of A. indica and J. curcas oils act not only as an oviposition deterrent but also as ovicides. The prospects for possible inclusion of botanicals into integrated M. nigrivenella control in maize cropping systems are discussed.

Three gregarious, endoparasitic braconids, a Kenyan strain of Cotesia sesamiae, and the exotic Cotesia flavipes and Cotesia chilonis were imported into Benin as candidates for biological control of stem- and cob borers of maize and stemborers of millet. Host acceptability and host suitability of six gramineous borers occurring in western Africa, the noctuids Sesamia calamistis, Sesamia poephaga, Busseola fusca, the crambid Coniesta ignefusalis, and the pyralids Eldana saccharina and Mussidia nigrivenella, to these parasitoids were evaluated to test the hypothesis that new associations were superior over old association parasitoid–host relationships. All hosts were accepted by all Cotesia spp., except M. nigrivenella, which was not attacked by C. chilonis. Parasitoid progeny developed successfully in S. calamistis, S. poephaga and C. ignefusalis. S. calamistis was the most suitable host in terms of duration of developmental time, brood size and mortality of parasitoid progeny. It was concluded that because of its host specificity, the old association parasitoid C. sesamiae would have the highest chance of establishment in cereal systems in West Africa.

Larvae of the Mediterranean flour moth (Anagasta kuehniella Zeller) cause major losses in stored grains throughout the world. In this study, pouterin, a lectin-like protein isolated from Pouteria torta (Mart.) Radlk. seeds, was tested for activity against A. kuehniella larvae. Pouterin did not produce significant effects on survival; however, at c. 1% w/w concentration in artificial diet, it produced a 71.4% reduction in average weight of the larvae. A dietary utilisation assay showed a reduction in efficiency of conversion of ingested food, efficiency of conversion of digested food and approximate digestibility, as well as an increase in metabolic cost. Pouterin increased the level of trypsin in the midgut and faeces of larvae. We conclude that pouterin possesses an insecticidal effect against A. kuehniella larvae and this effect may be mediated by the binding of pouterin to chitin components of the peritrophic membrane, or glycosylated proteins in the insect midgut.

The spatial distribution of Bactrocera fruit flies in the Goa region (west coast of India) was studied using several dispersion parameters between April 2006 and March 2008 in three ecological zones, viz. coastal, midland and upland. These zones are 10, 25 and 50 km to the east from the coastline of the Arabian Sea at an elevation of 15, 70 and 100 m above mean sea level, respectively. The dispersion parameters revealed that the population of all the fruit fly species attracted to methyl eugenol-baited traps, viz. Bactrocera dorsalis, Bactrocera caryeae, Bactrocera zonata, Bactrocera affinis and Bactrocera correcta, followed the negative binomial distribution pattern and was highly aggregated or clumped.

The willingness of a species to leave a forest fragment is a prerequisite for subsequent dispersal across the intervening non-forested landscape. Species with stringent fidelity to the forest patch will be isolated from populations in other fragments and predisposed to factors that promote extinction of local populations. Here, we document which fruit-feeding, forest-dwelling butterflies occur in the farm bush savannah outside an afrotropical forest reserve in order to gain a first approximation of those potentially dispersing across it. Standard fruit-baited traps hung at 80 m inside the forest, the forest edge and 12 and 50 m into the savannah matrix were used to characterize communities in the different habitats. A total of 1616 specimens were collected from the 19 traps, representing 90 species. Rarefied species richness was generally comparable across habitats. Multivariate ordination analyses, which integrate species composition and relative abundance in addition to richness, uncovered two broad community types, i.e. forest (edge plus 80 m inside) and matrix. Relative fidelity to forest habitat was investigated for the 45 species that were represented by at least five individuals. More than half of the forest-associated species showed relaxed fidelity to forest habitat and were commonly trapped in the matrix. Although forest generalists and dry forest species were expected to be more commonly trapped outside the forest relative to wet or moist forest species, there was no relationship between the relative occurrence of species in matrix versus forest habitat and their habitat association category.

The African rice gall midge (AfRGM) Orseolia oryzivora Harris and Gagné is an important insect pest of rice in Nigeria. Studies were conducted at Ogidiga (forest zone) and Edozhigi (southern Guinea savanna) in Nigeria, under rainfed lowland conditions during the 2006 and 2007 rainy seasons, on the population dynamics of AfRGM adults using light trap and random sampling of % tiller infestation (plant damage due to AfRGM) and % parasitism by Platygaster diplosisae Risbec and Aprostocetus procerae Risbec (parasitized larvae and pupae and parasitoid species present in dissected tillers). The results obtained showed that AfRGM populations were relatively low in June and July – the beginning of the 2006 and 2007 rainy seasons, respectively – and increased abruptly from September, reaching a peak in October at both locations. The increase was attributed to the rapid build-up of the pest populations at both locations. There were strong positive correlations between adult populations from light-trap catches and % tiller infestation, and between % tiller infestation and parasitism. The peak period of parasitism by P. diplosisae and A. procerae occurred towards the end of the rainy season in October, coinciding with high level of % tiller infestation. It is concluded that conservation of the parasitoids early in the cropping season (i.e. to improve their synchronization with the host) could become an effective management strategy against AfRGM.