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We evaluated, in a laboratory experiment, the susceptibility of 10 tomato cultivars to the attack by the tomato red spider mite Tetranychus evansi, an invasive pest of this crop in Benin. Among the 10 cultivars tested, six were imported (i.e. Roma VF, Tima, Rio Grande, Buffalo, Petomech, and TLCV15) and four local (i.e. Akikon, Tounvi, TomL4, and Kekefo). Leaf disks (2.5 cm diameter) excised from leaves of tested cultivars, and placed upper side down on top of water-soaked cotton wool laying in 9.5 cm diameter Petri dishes (6 leaf disks per Petri dish), served both as experimental units and feeding source for the mites. Mites were individually placed on leaf disks of each cultivar and several biological parameters – development, reproductive parameters and longevity – were assessed. The experiments were performed at 27 ± 1 °C, 65–70% RH, and 12:12 h (L: D) photoperiod. Our results revealed significant effects of tomato cultivars on several biological parameters of T. evansi, especially the developmental time of the egg stage (P ˂ 0.0001), and the larval stage (P = 0.0113), as well as female oviposition period (P = 0.0002). Likewise, female longevity (P = 0.0095) and fecundity (i.e. egg/♀, P = 0.0055) were significantly affected. The sex-ratio of the progeny was generally similar for all the cultivars except for Buffalo and Tounvi on which most juveniles did not develop beyond the larval stage. These two cultivars appeared as potential tomato cultivars for implementation of IPM strategies for the control of T. evansi.

Continuous coverage of vegetables with nets under different climate conditions in Benin and Kenya proved effective in prot ecting vegetable nurseries and main fields against key lepidopteran and dipteran pests. However, netting did not effectively protect the vegetables against small insects such as aphids and whiteflies, although a visual barrier could delay outbreaks. Hence, opening the nets during the day could be an alternative option to conserve the natu ral enemies for small insects. Moreover, the efficacy of the visual barrier may be complemented by a repellent compound impregnated in the net. The small-holder growers adopting the nets in Benin and Kenya have reduced the number of pesticid e applications required by 70-100%. They have also increased the yield in quality and quantity of production due to microclimate modification. Cost-benefit anal yses of the technology showed that with insect proof nets profitability rates of up to three times could be achieved when compared to the farmers' practices observed in the real environment. Hence, this technology could be a promising way to develop an agro-ecological approach for sustainable management of key horticultural crop pests. (Resume d'auteur)

Onion is the third most important vegetable after tomato and pepper for income generation by farmers in Benin, West Africa (Agossou et al ., 2001; MAEP, 2006). Since 1995, a serious disease of onion has been reported by farmers…