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Insect pests cause serious damage through feeding in the process and may also transmit plant diseases. Although most resource-poor farmers rely on the use of synthetic insecticides for controlling insect pests, it is generally considered too expensive for them. Plant products may be a safer alternative approach and play a significant role in insect pest management and crop protection amongst resource-poor farmers. Laboratory and field evaluation of locally available pesticidal plants were evaluated. The study was conducted at Jenda and Nchenachena in Malawi with rape and tomato to assess the efficacy of some selected pesticidal plants for the control of vegetable pests. Largely, the choice of the selected pesticidal plants was based on resource-poor farmers’ knowledge in the area. The results of the tested plant extracts suggested that some plant extracts could reduce the infestation of red mites and aphids below economic threshold levels. Under laboratory experiments, all plant species caused a significant increase in mortality of Trypanosoma evansi after 24 h. However, Dolichos kilimandscarichus, Tephrosia vogelii, Azadirachta indica, and Bedotia madagascarensis had significantly at P<0.05 greater mite mortality than the untreated. This suggests that these pesticidal plants could be an alternative to acaricidal and insecticidal pesticides against vegetable pests. These pesticidal plants caused an impressive reduction of red mites and aphids and protected tomatoes and rapes from serious damage and hence could be incorporated into integrated management for the control of vegetable pests.

Common beans (Phaseolus vulgaris) remain an important dietary protein source in Malawi. However, its production is highly hindered by insect pest and disease attack. The study aimed at evaluating the effectiveness of Tephrosia vogelii and Tephrosia candida extracts against bean aphid (Aphis fabae). The evaluation involved two botanical extracts at three different concentrations (0.5%, 2%, and 5% w/v) against bean aphid. Plant extracts (leaves) were air-dried and milled. Powders were then soaked in a 2-litre plastic bucket of cold water. Results indicated that there was significant difference (P<0.05) among treatments. The effectiveness of the treatments was based on reduction in aphid population per plant, pod length, and bean yield. Pod length and bean yield were higher in T. vogelii and Karate as compared to untreated and T. candida. There was a high mortality rate of aphid on the plots treated with T. vogelii compared to plots treated with T. candida at the same concentration. Though these two plant extracts were not as effective as the synthetic insecticide in reducing aphid population, they were considerably and significantly found to be effective; hence, its use by poor-resource farmers is recommended in the protection of bean against aphid.