Weaver ants (Oecophylla smaragdina and O. longinoda) are famous for their impressive nest constructions where they weave together living leaves on their host plants. Also, they are known to protect tropical tree crops against insect pests and are thus being utilized for biological control. To optimize their use, nest numbers have been used to track weaver ant abundances in plantation, assuming the number of nests reflects ant numbers. In this study we compared nest size, the density of ants and the proportion of workers in nests between three host plants (cashew, citrus and mango) and between two seasons (rainy and dry). Nest size, ant density and worker proportion all differed between host species, whereas only nest size and worker proportion showed seasonal differences and only on mango and citrus, respectively. On hosts with smaller nests (in increasing size order: cashew, citrus mango), ant densities in the nests were higher, and the proportion of workers in the nests seemed to increase during seasons where food production on host trees decreased, or on hosts where more trophobionts were cultured inside nests. These results have implications for the development of methods used to estimate ant numbers and they raise interesting questions about the function of weaver ant nests.

Cereals are increasingly attacked by Sitotroga cerealella, a highly destructive and economically important insect pest.The need to control this micro Lepidoptera to reduce its pressure on rice stocks is therefore acute.Today, the use of plant extracts, particularly essential oils, is a promising natural alternative to synthetic insecticides in the fight against crop pests.The objective of this study was to evaluate the acute oral toxicity of Premna angolensis in rats in order to propose an effective means of controlling S. cerealella in rice stocks without adversely affecting human health.The toxicity of this essential oil was assessed in male Wistar rats at a single dose of 2000mg/kg.The animals' behavior was observed for 14 days.The results showed that the lethal dose 50% (LD50) is strictly higher than 2000mg/Kg bw and that this extract does not influence the normal weight growth in the treated rats.Also, the evaluation of biochemical parameters of rats proved that P. angolensis essential oil is not toxic to the liver, kidneys and did not disturb lipid metabolism in rats at 2000mg/kg bw.Haematological analyses showed no significant difference from the control (p>0.05),however, the blood platelet count was significantly increased in treated rats compared to the control at the 5% threshold.Thus, essential oil treatments that could be applied at much lower doses to rice stocks could not be harmful to humans.It could therefore be used without risk by the rice industry to control S. cerealella.

Abstract Today the use of plant extracts, in particular essential oils, is a natural alternative to synthetic insecticides in the fight against crop pests. The purpose of this research is to determine the chemical composition of the ylang-ylang Cananga odorata (Lam.) Hook. F. & Thomson leave essential oil and to evaluate on the one hand its ovicidal, larvicidal, insecticidal, anti-oviposition and insect repellent properties, and on the other hand its effectiveness in preserving the weight of the grains and the germination power of rice seeds against the Angoumois grain moth Sitotroga cerealella O., a major pest of rice in Benin. The essential oil from the leaves of the C. odorata (Lam.) Hook. F. & Thomson was obtained by hydro-distillation, and analysed by gas chromatography-mass spectrometry (GC-MS). The analysis showed that the oil contains 32 main compounds, the major ones being α-pinene (7.01%), lavandulyl acetate (7.19%), caryophyllene (30.33%), α-humulene (13.42%) and germacrene D (8.99%). Based on the findings of fumigation bioassays, the Cananga odorata (Lam.) Hook. F. & Thomson essential oil showed high toxicity against adult of the S. cerealella with values CL50 of 0.094μl/mL and CL90 of 0.46μl/mL. Similarly, our work has demonstrated that this oil has ovicidal and larvicidal or egg development retardant properties. It also caused strong oviposition inhibition activity of more than 97% in female of the S. cerealella O. and subsequently developed very good repellent or deterrent properties, with an average repellence rate of 75.7% against the S. cerealella O. insect. These insecticidal effects preserved grain weight, with weight losses of at most 0.38% and a paddy rice seed germination rate of more than 80% at the lowest applied dose of 0.2µL/mL.The essential oil from the leaves of the C. odorata (Lam.) Hook. F. & Thomson can be used as an alternative to modern toxic synthetic chemicals, for protection against this important pest of grains in storage in Benin.

Objective: Synthetic insecticides have long been used for cotton protection, resulting in pest resistance, toxicity and environmental pollution. Biopesticides have been suggested as alternatives to synthetic pesticides. Both field and laboratory experiments were conducted to evaluate the effectiveness of neem oil in controlling Syllepte derogata (Fabricius), a cotton phyllophagous pest.Methodology and Results: In the field trials, effect of neem oil was compared to that of conventional insecticides; while in the laboratory direct larval immersion and leaf dip method using EMA SUPER 56DC and neem oil were tested. Decrease in damage by S. derogata for about 63 and 86% was recorded with neem oil and synthetic insecticides. In the laboratory, the mortality of S. derogata after 24 hours exposure to neem oil and Ema Super was significantly higher (2.5 to 100%) than that of the control. The mortality of larvae of S. derogata was positively correlated with the concentration of neem oil and exposure time. Lethal Concentration (LC50) after 24 hours exposure of larvae was respectively 4.03 104 ml/l and 51.13 ml/l forleaf dipping method and larval immersion.Conclusion and application of results: Overall, these results showed the efficacy of neem oil in controlling S. derogata, as a biopesticide. This oil could also constitute a successful alternative to synthetic pesticides. However, the effectiveness of neem oil appeared to be weakened by the rapid degradation of the active substances, azadirachtin in particular. Indeed, azadirachtin, the main active ingredient of neem is photo and heat labile. It easily degrades under high solar radiations and high temperatures, hence the need for stabilization.Keywords: Phyllophagous pest, integrated pest management, leaf-dipping method, larval immersion, Lethal Concentration.

Weaver ants are used for biological control of insect pests in plantation crops. To obtain proper pest control, ant densities need to be high. Food availability and nesting facilities on host plants and management practices may affect ant performance. In the present study, we tested the effect of two host plant species (mango and cashew) and three different management practices (ants only, ants fed with sugar and ants combined with the soft chemical insecticide Spinosad) on weaver ant performance. Performance was assessed over a 22 month period, as an index value based on the number of ant trails per tree and as the number of ant nests per tree. A total of 216 trees (72 per treatment) were observed in each crop. In all treatments, the ants performed better in mango compared to cashew. Using the index based performance measure, ants also performed better in the sugar treatment as compared to the two other treatments, whereas this was not the case in cashew. We conclude that sugar feeding can be used to increase ant populations in mango. We also found that the treatment with Spinosad in combination with ants showed performance equal to the treatments with only ants, suggesting that Spinosad did not negatively affect ant populations. We therefore conclude that Spinosad is compatible with the use of weaver ants in integrated pest management programs.

The article synthesises the experiences of innovation platforms (IPs) that engaged in open-ended experimental action to improve the institutional context for smallholder farm development in West Africa. The IPs sought change at the level of the institutional regime covering an entire agricultural domain (such as cocoa, cotton, oil palm or water management). Their purpose was therefore not to ‘roll out’ farm-level technologies across rural communities. The IPs's outcomes were documented and analysed throughout by means of theory-based process tracing in each of seven of the nine domains in which regime change was attempted. The evidence shows that by means of exploratory scoping and diagnosis, socio-technical and institutional experimentation, and guided facilitation IPs can remove, by-pass, or modify domain-specific institutional constraints and/or create new institutional conditions that allow smallholders to capture opportunity. The article describes the 5-year, €4.5 million research programme in Benin, Ghana and Mali, covering theory, design, methods and results. It is the sequel to Hounkonnou et al. in AGSY 108 (2012): 74–83.

This article analyses the development of a system for producing and distributing hybrid oil palm seedlings to small-scale famers. The existing seed system had become so corrupted that the seedlings actually planted were largely of unimproved kinds. The article describes institutional experiments carried out by two Innovation Platforms (IPs) in order to improve the oil palm seed system. Theory Guided Process Inquiry was used to document, evaluate and analyse these interventions. The experiments catalysed changes in interpersonal and inter-organisational power relationships that enabled further co-learning and co-construction of understanding and action among key stakeholders in the oil palm domain. The IPs and those who became local champions of seed system innovation, also triggered change in institutional behaviours, technologies, and practices that further improved the integrity of the seed system. Official nursery holders must now be trained, registered and licensed by local government. Farmers are encouraged to source hybrid seedlings only from licensed nurseries. These achievements were then shared and discussed with officials and higher level government leaders, drawing on IP members' pre-existing professional and personal networks. Improvement of the oil palm seed system was included in the government's latest 5-year development plan.

Weaver ants, Oecophylla spp., are known to positively affect cashew, Anacardium occidentale L., raw nut yield, but their effects on the kernels have not been reported. We compared nut size and the proportion of marketable kernels between raw nuts collected from trees with and without ants. Raw nuts collected from trees with weaver ants were 2.9% larger than nuts from control trees (i.e., without weaver ants), leading to 14% higher proportion of marketable kernels. On trees with ants, the kernel: raw nut ratio from nuts damaged by formic acid was 4.8% lower compared with nondamaged nuts from the same trees. Weaver ants provided three benefits to cashew production by increasing yields, yielding larger nuts, and by producing greater proportions of marketable kernel mass.

This work has objectives to study the chemical composition of volatile extracts obtained from leaves of Polyalthia longifolia and Clausena anisata and to evaluate their ovicide and larvicide effects by fumigation against Sitotroga cerealella, as alternative to the pesticides of synthesis. The analyses of the extracts by GC-MS showed that the essential oil of P. longifolia contains 57 compounds representing 86.1% of oil and 26 compounds corresponding to 97.3% of the essential oil of C. anisata. The main compounds identified for the extract of P. longifolia are the β-Caryophyllene (24.5%), Allo-Aromadendrene (13.5%), the α-Zingiberene (9.4%), the α-Humulene (8.5%) and the α-Selinene (2.6%). The extract of C. anisata mainly composed of methyl chavicol (69.9%) is characterized by the presence of oxygenated monoterpens (1.4%), hydrogenated monoterpens (7.8%), hydrogenated sesquiterpens (16.2%), oxygenated sesquiterpens (1.7%) and of aromatic compounds (69.9%). The biological test results showed that the treatments by fumigation done with the essential oils reduce meaningfully (pu003c0.001) the bursting of the ovums on the paddy rice. The essential oil of C. anisata has completely inhibited the viability of the larvas and the emergence of adult butterflies from the dose 0.5 µl mL-1 contrary to P. longifolia that recorded respectively 10.0±0.3% and 50.0±0.2% at the strong dose 3 µl mL-1. The study has, otherwise, shown that the essential oils delayed the cycle of development “ovums to adult” of S. cerealella (29.0±0.4 to 35.4±0.5 days) in relation to the witness (25±0.1 days). The essential oil of C. anisata proved to be more poisonous for the juvenile stages of S. cerealella. These results provide the scientific basis for potential alternatives to the synthetic fumigants in subsistence and commercial agriculture.

This paper discusses external influences on innovation platforms(IPs) and the options for effective responses. The platforms examined in this paper were conceived as vehicles for facilitating institutional change in support of innovation that benefits smallholders, in selected agro-enterprise domains in Benin, Ghana and Mali. They were designed and implemented in a manner that enabled experimentation with processes of change in the selected domains. A Research Associate in each case facilitated the work of the IPs and applied Theory-Guided Process Tracing (TGPT) methodology to document the innovation processes pursued by platform members. The recorded data allow analysis of the external influences on the IPs. This paper first presents a typology as derived from literature of the main external influences on the domains of interest, and then uses the typology to analyse the influences on and responses of the IPs. The main influences were found to emanate from global, sub-regional and national levels. The IPs' responses were diverse but generally included reconstitution of the membership, lobbying, capacity-building among smallholders, and empowerment of smallholders by organizing provision of new knowledge, skills or financial resources. The paper highlights lessons drawn by the platform members in addressing the challenges involved. It concludes that external influences are important in determining the direction of socio-technical and institutional innovation.

Innovation as a policy goal, normative practice, and a conceptual framing of purposeful human activity, has received increasing attention. The question of what kinds of purposeful innovation might benefit smallholders in developing countries has been raised. This issue presents and analyses the work of Innovation Platforms (IPs) established by the COS-SIS (Convergence of Sciences–Strengthening Innovation Systems) programme in nine agro-enterprise domains in West Africa, drawing on Theory Guided Process Inquiry data recorded through 2011-end 2013. Six papers synthesise individual IP experiences, complemented by a cross-case analysis of external influences on the IPs and their responses, a reflection on how well the IPs in Mali dealt with local conflicts, and an analysis of how the work of the IPs in Ghana led to changes in university curricula and in the researching practices of three leading agricultural institutes. An analysis of thirteen case studies from Kenya, Benin, and South Africa supported by the JOLISAA (Joint learning in and about Innovation Systems in African Agriculture) programme, adds further insights. Five general lessons are drawn, expressed as propositions that can be further tested against others’ experiences: (i) IPs can bring about significant socio-technical and institutional changes at a range of levels, and in a wide variety of agro-enterprise domains and contexts; (ii) the IPs are not isolated from nor independent of the networks of influence in which they are embedded; thus they cannot be treated as the sole causal agents of the changes accomplished; (iii) research that tracks the IPs’ work and performance provides evidence that enables the members to learn from experience and adjust activities in the light of effects; (iv) there is no blueprint for what an IP is nor a recipe for the processes by which such changes are brought about; the form, activities, and changes co-evolve with whatever is happening in the wider context; (v) field-based diagnosis of opportunity, evidence-based information-sharing and experimental exploration of pathways of change establish the legitimacy and influence of IPs.

Our study aims to assess the kinetic of the decomposition and nutrient mineralization process of organic manures from pigs’ dejection. A litter bag study was carried out during 12 weeks following decomposition and nutrient release process in ferralitic soil in southern Benin (West Africa). 200 g of pigs’ manures from four groups of pigs fed with four diets were considered as treatments: T1 (recommended diet composition, consisted of 15% Azolla pinnata + 55% provender + 5% coconut copra + 5% oil palm + 5% soybean bran + 10% rice bran + 5% kitchen waste), T2 (partially improved diet with Azolla pinnata, consisted of 30% Azolla pinnata + 65% rice bran + 5% oil palm), T3 (improved diet with Azolla pinnata, consisted of 47.5% Azolla pinnata + 47.5% rice bran + 5% oil palm), and T4 (improved diet with cereal bran, consisted of 15% Azolla pinnata + 40% rice bran + 40% wheat bran + 5% oil palm). Animals of six months age were fed during three months. A randomized complete block design with three replicates was set up for litter bag study. One component exponential decomposition model y = y0e-kt was found for all treatments. Nutrient mineralization was slow in the soil. Less than 50% of the pigs’ manures were decomposed after 12 weeks. In addition, manure from treatment T1 was richer in K, Ca and Mg than manures from treatment T3. High quantity (42.65%) of N was released in treatment T3. Pigs fed with diet enriched with Azolla produce manure which has released high N proportion in the soil. This is an opportunity to sustain food crop production. Key words: Pigs’ diet composition, Azolla pinnata, soil fertility, organic manure, decomposition rate.

In Benin cashew plantations, yields and nut quality are lost mainly as a result of insect pests. In the present study, we investigated the effectiveness of the African weaver ant Oecophylla longinoda as a biocontrol agent against Beninese cashew pests. In a 2-year study, nut yield and quality were compared among: (i) trees with weaver ants O. longinoda; (ii) trees where weaver ants were sugar-fed; (iii) integrated pest management (IPM) trees with weaver ants combined with fruit fly bait spray; and (iv) control trees receiving no control measures. All treatments with ants showed significantly higher yields than the control, with the IPM treatment leading to the highest yield. Compared with the control trees, the ants, ant sugar-fed and the IPM trees produced 78%, 122% and 151% more nuts, respectively. Nuts produced on control trees were of a higher quality on average because they were less damaged by thrips (probably because the fruit fly bait worked as a contact poison on thrips); this was also the case for the IPM treatment. In absolute numbers, however, trees in ant treatments produced more first-quality nuts. To achieve a broader and effective control of both coreid bugs and thrips, a combination of weaver ants and supplementary compatible control measures is recommended.

Weaver ants (Oecophylla longinoda Latreille) are used commercially to control pest insects and for protein production. In this respect fast colony growth is desirable for managed colonies. Transplantation of non-nestmate pupae to incipient colonies has been shown to boost colony growth. Our objectives were to find the maximum number of pupae a founding queen can handle, and to measure the associated colony growth. Secondly, we tested if transplantation of pupae led to production of larger nanitic workers (defined as unusually small worker ants produced by founding queens in their first batch of offspring). Forty-five fertilized queens were divided into three treatments: 0 (control), 100 or 300 non-nestmate pupae transplanted to each colony. Pupae transplantation resulted in highly increased growth rates, as pupae were readily adopted by the queens and showed high proportions of surviving (mean = 76%). However, survival was significantly higher when 100 pupae were transplanted compared to transplantation of 300 pupae, indicating that queens were unable to handle 300 pupae adequately and that pupae require some amount of nursing. Nevertheless, within the 60-day experiment the transplantation of 300 pupae increased total colony size more than 10-fold whereas 100 pupae increased the size 5.6 fold, compared to control. This increase was due not only to the individuals added in the form of pupae but also to an increased per capita brood production by the resident queen, triggered by the adopted pupae. The size of hatching pupae produced by the resident queen also increased with the number of pupae transplanted, leading to larger nanitic workers in colonies adopting pupae. In conclusion, pupae transplantation may be used to produce larger colonies with larger worker ants and may thus reduce the time to produce weaver ant colonies for commercial purposes. This in turn may facilitate the implementation of the use of weaver ants.

This work aims to study for the first time the chemical composition and evaluate insecticidal and repellent effects of essential oils of Premna angolensis and Premna quadrifolia leaves, against Sitotroga cerealella, an insect pest of rice stocks as alternatives to synthetic pesticides. The GC-MS analysis showed that essential oil of P. angolensis contains 29 compounds representing 96.1% of the oil and 42 compounds corresponding to 91% for the essential oil of P. quadrifolia. The main constituents regardless of the species were β-caryophyllene (13.1%), (E)-β-caryophyllene (13.5%), octen-3-ol (3.2%–28%), phytol (3.7%–4.9%), β-elemene (1.4%–21%), globulol (11.2%), germacrene-D (8.9%), α-humulene (2.9%–6.4%), α-pinene (5%), sabinene (3.7%), δ-cadinene (0.4%–3.3%), and linalool (3.3%). The results of laboratory tests showed that both essential oils have insecticidal and repellent effects on S. cerealella. Presenting the results, the damage caused by the adults and larvae of S. cerealella was evaluated by calculating the percentage of grains attacked and weight loss thereof. The results suggest that volatile extracts of P. angolensis and P. quadrifolia can be used as alternatives to synthetic chemicals in paddy protection against S. cerealella.

Oecophylla ants are appreciated for their control of pests in plantation crops. However, the ants´ nest building may have negative impacts on trees. In this study we tested the effect of ant densities and nest building on the leaf performance of mango trees. Trees were divided into three groups: trees without ants, trees with low and trees with high ant densities. Subsequently, the total number of leaves, the proportion of leaves used for nest construction, and tree growth was compared between these groups. The percentage of leaves used for nests was between 0.42-1.2 % (mean = 0.7%±0.02) and the total number of leaves and tree growth was not significantly different between trees with and without ants. Further, leaf performance was compared between shoots with and without ant nests and between leaves in or outside ant nests. The number of leaves and lost leaves per shoot, leaf size, leaf condition (withered), leaf longevity and hemipteran infection was compared between groups. In the dry season nest-shoots held more leaves than shoots without nests despite nest-shoots showed more lost leaves. Leaves in nests were smaller than other leaves, more likely to wither and more often infested with scales. However, smaller nest-leaf size was probably due to the ants´ preference for young leaves and the higher incidence of withering resulting as leaves in nests cannot fall to the ground. In conclusion, the costs associated to ant nests were low and did not affect the overall number of leaves per tree nor tree growth.

Le présent travail vise à caractériser quatre espèces de feuilles végétales utilisées comme emballages alimentaires en Afrique de l’Ouest. La caractérisation a été réalisée au plan physico-chimique, phytochimique et de la toxicité au moyen de méthodes de références. Il est apparu que les teneurs en protéines, en lipides totaux et en cendres totales sont respectivement de 6,0 ; 4,6 ; 8,7% pour Tectona grandis ; 16,0 ; 4,3 ; 9,1% pour Musa sapientum ; 12,5 ; 4,6 ; 7,0% pour Thalia geniculata et 13,4 ; 2,0 ; 7,2% pour Manihot esculenta. Une diminution significative de ces valeurs a été observée après 3 jours de conservation des produits emballés dans ces espèces de feuilles. Le fer est présent dans toutes les espèces, notamment dans Manihot esculenta (8,4%), Tectona grandis (4,4%) avec une légère diminution après emballage des produits. La teneur en vitamine C est présente uniquement dans les feuilles de Manihot esculenta dans l’ordre de 0,4%. Les tanins, les catéchiques, les anthocyanes, les leuco-anthocyanes, les mucilages, les flavonoïdes et les coumarines ont été identifiés dans toutes les espèces de feuilles analysées. Toutes les espèces de feuilles analysées se sont révélées non toxiques.Mots clés : Emballages végétaux, emballages alimentaires, Bénin, valeur nutritionnelle, toxicité des plantes, caractéristiques phytochimiques.

Weaver ants (Oecophylla spp.) are widely used as effective biological control agents. In order to optimize their use, ant abundance needs to be tracked. As several methods have been used to estimate ant abundance on plantation trees, abundances are not comparable between studies and no guideline is available on which method to apply in a particular study. This study compared four existing methods: three methods based on the number of ant trails on the main branches of a tree (called the Peng 1, Peng 2 and Offenberg index) and one method based on the number of ant nests per tree. Branch indices did not produce equal scores and cannot be compared directly. The Peng 1 index was the fastest to assess, but showed only limited seasonal fluctuations when ant abundance was high, because it approached its upper limit. The Peng 2 and Offenberg indices were lower and not close to the upper limit and therefore showed fluctuations throughout the season. The numbers of nests showed high fluctuations unlikely to reflect ant abundance, but rather reflected nest building behaviour influenced by tree phenology. In conclusion, nest counting is not recommended, whereas the Peng 1 index can track dynamics at low ant abundance and the Peng 2 and Offenberg indices can be used in most situations. (Resume d'auteur)

In the oil palm-based cropping system on the Adja Plateau, land titling plays an important role. Landowners argue that oil palm fallow (dekan) restores soil fertility, but in the long-term it is also an instrument in the struggle for control over land. A land-titling programme in the study area allowed an analysis of the relationship between titling and soil fertility management that showed two different institutional effects with socio-technical consequences. Titling increased land security for landowners and, although this security initially reduced access to land for tenants, a subsequent introduction of witnessed paper-based contracts enhanced tenants' access to land and improved their security of tenure. Improved titling and more secure tenure reduced conflicts over land and opened possibilities for agricultural intensification. This change was associated with a shift from long-term oil palm fallow to shorter-term land-management practices where tenants and landowners increasingly invested in land through rotations between maize and cowpea (rather than maize mono-cropping) and the use of mineral fertilizers, without increased use of household waste. The paper suggests that sustainable agricultural intensification requires institutional changes, based on a mixture of customary and formal rules, in both landownership and rental agreements to access land.