It is well recognized that the quality of host plants affects the development and survival of plant-feeding arthropods. The effects of two leafy vegetable crops, amaranth, Amaranthus cruentus L. (Caryophyllales: Amaranthaceae) and nightshade, Solanum macrocarpon L. (Solanales: Solanaceae) were examined on the development and demographic parameters of the spider mite, Tetranychus ludeni Zacher (Acari: Tetranychidae). This mite was recently identified as a pest of the two leafy vegetables which are widely used in West Africa. The experiments were conducted at the International Institute of Tropical Agriculture, Benin, West Africa, in a growth chamber at 27°C, 70% ±10% RH and 12:12 (L:D). Immature development of T. ludeni was shorter on A. cruentus than on S. macrocarpon, whereas female longevity was the same on the two vegetable crops. Total fecundity per female was higher on A. cruentus than on S. macrocarpon, largely due to longer survival of adult female T. ludeni on the former; however, no differences were observed in the daily fecundity of T. ludeni on the two plant species. The comparison of intrinsic rates of natural increase (rm), the net reproductive rates (Ro) and the survival rates of adult stage of T. ludeni on the two vegetable crops suggests that T. ludeni performs better on S. macrocarpon than on A. cruentus. Reasons for the lower rate of population growth observed on amaranth should be studied in more details as this could be used in IPM strategies such as intercropping to reduce pest density and in developing biopesticides for use against T. ludeni in vegetable farms in Africa.

Maize production in Benin, especially in resource-poor farmers' fields, is constrained by stemborers among other factors. One of the major stemborers in southern Benin is Sesamia calamistis Hampson (Lepidoptera: Noctuidae). African farmers cannot afford to use commercial insecticides for controlling stemborers - they are expensive and unsuitable for durable pest management systems due to eco-toxicity. There is therefore a need for cheaper and environmentally friendly methods and botanicals offer an attractive alternative. The bushmint, Hyptis suaveolens (L.) Poit. (Lamiales: Lamiaceae), was compared with the commercial insecticide Furadan (carbofuran) for the control of S. calamistis on maize Zea mays L. (Poales: Poaceae). Trials were conducted in the screenhouse and in the field during the minor cropping season in 2004 at the International Institute of Tropical Agriculture (IITA)-Benin station. The variables measured included numbers of egg masses per plant, eggs per egg mass (in the screenhouse study), population density of S. calamistis, percentage of infested plants and/or ears, and deadhearts in the field. Irrespective of the variable considered, the aqueous extract of H. suaveolens compared favorably with Furadan while maize surrounded by live H. suaveolens plants had lower S. calamistis densities.

In an attempt to set up habitat management strategy against Eldana saccharina Walker, an economically important graminaceous stem and cob borer, two laboratory experiments were carried out. The first experiment was designed to assess oviposition preference of E. saccharina for growth stages, plant parts and freshness of different host plants and between host plants species. Zea mays L., Sorghum arundinaceum (Desv.) Stapf, Andropogon gayanus Kunth, Panicum maximum Jacq., Pennisetum polystachion (Linn.) and Cyperus papyrus L. were assessed. Results showed that E. saccharina preferred wild grasses to maize for oviposition. More than 94% eggs were laid on wild grasses. Of all tested grasses, P. polystachion was the most attractive with more than 30% of collected eggs. For all plant species, posttasseling stage was more attractive than the tasseling and pre-tasseling ones. More than 90% of total eggs were laid on dry leaves and sheaths and less than 10% on fresh leaves. Different characteristics relating to population dynamics of E. saccharina were assessed in the second experiment. Larval survival rate was 10% on Z. mays, 0.50% on S. arundinaceum and around 0% on the other wild grasses. Larval development length was longer on S. arundinaceum than on Z. mays. Females reared on Z. mays were three times more fecund than those reared on S. arundinaceum. Complete life table of females from larvae reared on Z. mays was studied.

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Abstract. The bioefficacy of various plant extracts, namely Azadirachta indica A. Juss, Khaya senegalensis Desrousseaux (A. Jussieu) and Hyptis suavuolens (L.) Poit, either alone or in combination with half the recommended dose of synthetic pesticides, was studied with farmers to find a more sustainable strategy for the management of bollworms in cotton. A number of treatments were farmer innovations. The treatments were compared six times during the season to the application of the fully recommended dose of synthetic pesticides and to a control with no pesticide application. Applications of either the fully recommended dose of the synthetic pesticides or the combinations with a neem seed extract (6 kg/ha) were most effective in reducing bollworm incidence and damage. Both the treatments gave the highest yields of cottonseed, the latter being the most costeffective. All the pesticides used, except neem alone, had a toxic effect on bollworm predators. This study has increased farmers' confidence in endogenous technology. The researcher's interaction among the local learning group members, who conducted the experiments, facilitated the introduction of a cost-effective alternative to the standard fulldose synthetic pesticide recommendation.Key words: cotton, plant extracts, synthetic pesticides, bollworms, endogenous technology Résumé. Dans le but de trouver une méthode de lutte durable contre les chenilles ravageuses du cotonnier, I'efficacité biologique de différents extraits de plantes (Azadirachta indica, Kaya senegalensis et Hyptis suavolens) a été évaluée, en milieu paysan, seule ou en association avec des demi-doses d'insecticides de synthèse. Certains des traitements sont le résultat d'innovations paysannes. Les traitements ont été comparés six fois au cours de la saison culturale à des applications normales d'insecticides ou la combinaison de synthèse et á des traitements témoins. Les traitements, avec des doses normales d'insecticides ou la combinaison de I'extrait de graine de neem (6 kg/ha) associé à une demi-dose d'insecticides de sysynthèse, ont été les plus efficaces pour réduire la densité des chenilles et leurs dégâts. Ces deux traitements ont donné les meilleurs rendements avec un ratio coû t/bénéfice plus avantageux pour la mixture insecticide de synthése-exrait de graine de neem. Tous les insecticides utilisés à I'exception de I'extrait de neem utilisé seul, ont eu un effet toxique sur les prédateurs des ravageurs du cotonnier. Cette étude accroît la confiance des fermiers dans les locales. L'interaction entre le *

Methodology and results: The current study was performed in three villages of the cotton growing areas of central Benin (Glazoue municipality). Four treatments consisting of 1) unsprayed control, 2) TopbioMaviMNPV mixture, 3) B. bassiana and 4) Decis were arranged in a randomized complete block design with three replicates. Seventy five grams per ha of B. bassiana (isolate Bb 115) conidia were formulated with peanut oil and applied at a volume of 2 litres/ha-1. Virus MaviMNPV suspension was applied at 2.10 9 OB/ha in a formulation containing neem (TopBio).The Decis and TopBio, 1L /ha. The effects of the different pesticides used on cowpea pests populations' densities (M. vitrata, Megalurothrips sjostedti, Clavigralla tomentosicollis) were evaluated as well as their damage of reproductive organs (flowers buds, flowers and pods). Fruiting bodies organs were collected weekly to monitor alive and dead of M. vitrata larvae, and other key cowpea insect pests and their damage on flower budsl, flowers and pods as well. Cowpea grain yield was evaluated. Although, the great variation in their effects, the biopesticides tested have significantly reduced the population density of M. vitrata and of the other insect species as well as damage level. The overall grain yield was improved in treated cowpea compared to the untreated control. In farmers' cowpea fields, pest control by the various pesticides used, was similar with yields of 933.03 ± 8.7Kg / ha obtained in plots treated with B. bassiana. Conclusion and results' applications: These results showed that the biopesticides used in our study can significantly reduce the densities of different target pests. This study suggested the possibilities of the use of biopesticides as alternatives to chemical insecticides in the control of cowpea pests.

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