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Insect pest infestations and damage can limit the production of vegetables in the farming systems in Nigeria. This review looks at integrated insect pest management as a possible panacea for resolving insect pest issues in vegetable crops. The main vegetable crops which include okra, tomatoes, chilli peppers, cucumbers, green amaranth, carrots and onions are highlighted. The major insect pests of the various vegetables which include foliage beetles, caterpillars, aphids, fruit flies, stink bugs, and grasshoppers are also mentioned. The various control measures that have been empirically verified for the mitigation of the impact of these insect pests, including the application of synthetic insecticides, modification of agronomic practices, use of resistant varieties, application of botanicals, biological and mechanical controls, are discussed. Studies which have been carried out attempting to integrate two or more of the control strategies for better insect pest control are also reviewed. Strategies that can be put in place for the integrated pest management of vegetable insect pests in Nigeria are considered. Among the IPM (Integrated Pest Management) practices instituted for the mitigation of pest infestations on vegetable crops in Nigeria, intercropping of suitable vegetables in combination with the application of aqueous extracts of Azadirachta indica and Piper guineense seeds under good farm hygiene and sanitation proved to be most successful.

This study investigated the effect of plant extracts (Azadirachta indica and Piper guineense) on the growth and yield of jute (Corchorus olitorius L.) (Cor) under sole and mixed cropping with Amaranthus hybridus (Ama) and Celosia argentea (Cel). The highest percentage increase in plant height, number of leaves, number of branches and stem girth (130.6, 865.0, 220.4 and 114.0%, respectively) was found in untreated Cor + Cel, cypermethrin treated Cor + Ama, cypermethrin treated Cor and A. indica extract treated Cor + Ama, respectively. The highest percentage increase in shoot weight (71.0%), marketable yield (53.9%) and total biomass (51.5%) was in A. indica treated C. olitorius. Extract treatment had no effect on the number of branches at four, five and seven weeks after planting (WAP) in Cor + Ama + Cel; four, five and six WAP in Cor + Cel; four and six WAP in Cor + Ama; as well as four and five WAP in Cor. The highest percentage increase in leaf fresh weight was obtained in cypermethrin treated Cor (53.3%) and Cor + Ama + Cel (52.2%), while the smallest increase was in P. guineense treated Cor (1.1%) and Cor + Ama (2.5%). The activity of A. indica was independent of time of application while P. guineense was not. Among the extract treated groups, the highest percentage increase in shoot weight (71.0%), marketable yield (53.9%) and total biomass (51.5%) was in A. indica treated Cor. The activity of the extracts against insect pests of sole cropped Cor increased significantly (p < 0.05) with increasing extract concentration. The highest efficiency with the use of P. guineense was 250 g dm -3 at four, five and six WAP (94.0, 92.7 and 90.3%, respectively) and 200 mg dm -3 at seven WAP (81.7%). In the case of A. indica extract, the highest efficiency was found with the use of 200 g dm -3 at four, six and seven WAP (92.7, 85.3 and 100%, respectively). A. indica extract (250 g dm -3 ) treatment gave the highest efficiency at five WAP (100%).

The study was conducted in the farming communities of Akure North and South Local Government Areas of Ondo State, Nigeria using pre-tested questionnaire/interview schedule, Key Informant Interview (KII), Focus Group Discussions (FGDs) and observation technique to generate data on: the types of vegetables grown, the major pest species, farmers control method in the field with emphasis on plant-based formulations and farmers' perceived efficacy of the plant botanical formulation on field crop pests. The data were analysed and results presented with descriptive statistics. Results indicate that Telferia occidentale (Ugwu) ranked first among vegetable grown for food (85%) and income generation followed by Amaranthus hybridus (African spinach) and Okra in that order. The major field pests identified were leaf borers (Dysdercus superstitiosus), webbers (Sylepta derogate), leaf hoppers (Zonocerus variegatus), sting bug (Aspavia armigera), weevils, leaf caterpillar (Psara bipunctalis) and flea beetles (Podagrica spp.). The most prominent among the materials used in the preparation of some of the identified botanical formulations are Azadirachta indica (Neem) leaves, Piper guineense (Black pepper), and Nicotiana tobaccum (tobacco). These plants were combined together in the preparation of botanical formulations to prevent and/or control pest in the field. It was ascertained from our FGDs that 75.8% of the farmers were of the opinion that indigenous control methods were as effective as synthetic pesticides. Vegetable farmers in the study area were found to create habitat for insect/bird predators as insect pest control strategy. It is evident from the result that the critical challenge of almost all the farmers was inability to estimate what proportion the ingredients used in plant-based formulations should be combined. As a result, standardized techniques of preparation, bio-safety and environmental guideline for efficacy should form important consideration in formulating botanicals for pest control methods.

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