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 cerealbased cropping systems in the West African savannah.

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Effect of heating on Callosobruchus maculatus (Fabricius) in Vigna angularis (Willd.), Ohwi & Ohashi, seed was assessed using an 1188 obtuse base angle solar box heater. The box heater was constructed with 1.2 mm thick sheet metal, glued inside with aluminium foil and insulated on the outside by fixing 1 cm thick polystyrene and glazed with 0.15 mm thick clear plastic sheet. Electric energy from a solar simulator panel adjusted to simulate heat trapped from natural solar energy was used. Exposure of the various developmental stages of C. maculatus infesting adzuki bean seed to heat for 45 min and more raised the temperature between and within the seeds well in excess of the lethal level (. 60 8C) and resulted in complete control. Heating at 608C of up to 3 cm adzuki bean seed (seven to eight seed layers) took about 1 h and resulted in complete control of the pest. This would enable this heater to treat large amounts of seed at a time compared with solar heaters demonstrated so far in which only a single layer of seed can be treated. Therefore, solar heating of infested adzuki bean seeds using the aforementioned box heater around noon, for 1 h, gives effective control of C. maculatus. Results of the effect of heat treatment on seed viability and moisture content showed that adzuki bean seed germination is affected by heating; hence seed meant for planting should not be heat treated to control storage insect pests. Heat treatment also did not affect seed moisture content.

The work was carried out at a location (11 0 58`N and 8 0 26`E) in Ungogo Local Government area of Kano State, Nigeria with objective of identifying an unfamiliar larva feeding on Moringa leaves and to describe its nature of damage. The leaf feeding larvae were sampled and reared through to pupation and to adulthood in the Entomology laboratory, Crop Protection Department, Faculty of Agriculture, Bayero University, Kano, Kano State. The adults that emerged were identified to be Ulopeza phaeothoracica Hampson. On the larval feeding, it was observed that damage caused was very severe on a heavily infested young Moringa tree at the study location. In conclusion, the study revealed that U. phaeothoracica is a leaf feeding pest of M. oleifera and that its activity could be of serious concern especially on young trees of Moringa, kept under poor management conditions.

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