Plant Allelochemicals as Sources of Insecticides

SIMPLE SUMMARY: Due to the banning of many synthetic pesticides, current intensive farming systems require us to develop new approaches to integrated pest management. Devastating pests rarely occur in the wild and medicinal plants because of effective defense mechanisms. In contrast, only some of these defense mechanisms are found in cultivated crops. Biocidal compounds, derived from various wild and medicinal plants, are bioactive, biodegradable and constitute an ecological method for the successful management of insect pests. Therefore, an extensive study of various wild crops and some weeds is essential to identify new and potential plant species with insecticidal compounds. ABSTRACT: In this review, we describe the role of plant-derived biochemicals that are toxic to insect pests. Biotic stress in plants caused by insect pests is one of the most significant problems, leading to yield losses. Synthetic pesticides still play a significant role in crop protection. However, the environmental side effects and health issues caused by the overuse or inappropriate application of synthetic pesticides forced authorities to ban some problematic ones. Consequently, there is a strong necessity for novel and alternative insect pest control methods. An interesting source of ecological pesticides are biocidal compounds, naturally occurring in plants as allelochemicals (secondary metabolites), helping plants to resist, tolerate or compensate the stress caused by insect pests. The abovementioned bioactive natural products are the first line of defense in plants against insect herbivores. The large group of secondary plant metabolites, including alkaloids, saponins, phenols and terpenes, are the most promising compounds in the management of insect pests. Secondary metabolites offer sustainable pest control, therefore we can conclude that certain plant species provide numerous promising possibilities for discovering novel and ecologically friendly methods for the control of numerous insect pests.