The potential immune alterations in insect pests and pollinators after insecticide exposure in agroecosystem

Abstract

Agroecosystems are the habitat of pests and beneficial insects from different orders, which are exposed to agro-practices, especially treatments with chemicals. Insecticides are a wide group of chemicals used in agroecosystems that affect insect ecology and physiology in different ways. Among physiological components affected by insecticides, the immune system (IS) is an important one, enabling insects to resist against invading microorganisms and parasitoids thanks to the action of hemocytes and humoral components. So the determination of any immune alterations should be considered as a critical ‎issue in insecticide application within agroecosystems. ‎Insecticides of synthetic or natural origin, e.g. insect growth regulators (IGRs) and botanicals, are frequently cytotoxic and alter hemocyte morphology and number, impairing cellular-based immune responses in addition to humeral responses. Exposure of pollinators to neurotoxin insecticides like neonicotinoids may inhibit the immune-related transcription factor, NF-B, with a negative impact on the expression of antimicrobial peptides, melanization and clotting. In contrast, some IGRs may have enhancing effects on hemocyte spreading mainly plasmatocytes and cellular-based immune responses. Chemical insecticides have several impacts on the physiology of insects in which immune modulation‎ is one of the most important cases because any alteration may alter their ability to respond toward invading pathogens and directly their survival. This is more severe once pollinators are in contact with chemicals because of the presence of several pathogenic agents that directly influence their performance.