Mode of Action of Plant-Derived Natural Insecticides

Abstract

Most of the chemical insecticides are neurotoxic, acting on targets in the central nervous system such as the membrane ion channels (DDT, pyrethroids), the enzyme acetylcholinesterase (organophosphate, carbamate), and the receptors of neurotransmitters (avermectins, neonicotinoids). The recently introduced diamide group of insecticides target the novel ryanodine receptor in the nervous system. Since pests continue to evolve resistance to compounds currently in use, new compounds with new modes of action are needed. Natural products could be a promising source for novel pest control agents. The origin of many of the important insecticide classes is traceable to a natural source as in the case of pyrethroids, avermectins, spinosads, and neonicotinoids. Although insect control agents acting on targets other than the nervous system such as insect growth regulators (e.g., azadirachtin, JH analogues, ecdysone antagonists) have been developed, due to their lack of contact toxicity, they are not quite successful, but fi nd a place in the integrated pest management. Recent progress in understanding the biology of insect olfaction and taste offers new strategies for developing selective pest control agents. Decalesides, recently discovered natural insecticides, represent a new class of plant-derived insecticides targeting the tarsal gustatory receptors. In this chapter, we focus on the toxicity and mode of action of natural insecticides.

Plant-Derived Pesticides as an Alternative to Pest Management and Sustainable Agricultural Production: Prospects, Applications and Challenges

“…Sabadilla is one of the least toxic plant extracts with pesticide activity, considered a contact and stomach poison with minimal residual activity. However, its major alkaloids, when isolated, are much more toxic to humans, and affect mostly stinks, squash bugs, thrips, leafhoppers and caterpillars [ 11 , 27 ].…”

“…Moreover, most of the synthetic pesticides act against non-target organisms (mammals, fish and plant species), becoming a potential health hazard to consumers. Furthermore, they are too expensive for the farmers in developing countries [ 8 , 9 , 10 , 11 ].…”

“…Among the plant-derived pesticides, there are the insecticides (constituents that kill insects in any stage of development: adults, ova and larvae), which act by several different mechanisms affecting one or more biological systems, including nervous, respiratory and endocrine systems, as well as water balance. Additionally, insecticides can also be classified depending on the mode of its entry into the insect, namely: stomach poisons, contact poisons and fumigants [ 11 ]. A compilation of natural insecticides with their corresponding toxicity and mechanisms of action may be found in Table 1 .…”

Biodegradation of Acetamiprid by both free and immobilized Lysinobacillus macrolides strain MSR-H10 in soil

“…In recent research, neonicotinoids had some delicate dangerous effects on bees (2) and (3) and neonicotinoid residues were detected in surface water (4,5), wetland and soils. AAB causes acute and chronic toxicity in mammals and, moreover, a common method of action: mimicking the action of neural transmitters affecting the central nervous system, resulting in paralysis and death (6). In agricultural, acetamiprid are usually applied as insect controls, principally in seed treatments for crops, like corn, soybean and cereals.…”

Mode of Action of the Natural Insecticide, Decaleside Involves Sodium Pump Inhibition

“…The insect toxicity of decaleside in the contact bioassay based on the symptoms and behaviour indicated neurotoxic nature somewhat similar to that of pyrethroids [ 21 ]. The knockdown effect and mortality and symptoms suggest that decalesides may act on neural/neuromuscular targets via gustatory chemosensilla [ 21 – 22 ]. In insects, the axons of the gustatory receptor neurons from the chemosensilla directly report to the thoracic-abdominal and subesophageal ganglion as in the case of Drosophila [ 23 – 24 ].…”