Inhibition of acetyl-CoA carboxylase by spirotetramat causes growth arrest and lipid depletion in nematodes

Abstract

Plant-parasitic nematodes pose a significant threat to agriculture causing annual yield losses worth more than 100 billion US$. Nematode control often involves the use of nematicides, but many of them including non-selective fumigants have been phased out, particularly due to ecotoxicological concerns. Thus new control strategies are urgently needed. Spirotetramat (SPT) is used as phloem-mobile systemic insecticide targeting acetyl-CoA carboxylase (ACC) of pest insects and mites upon foliar application. However, in nematodes the mode of action of SPT and its effect on their development have not been studied so far. Our studies revealed that SPT known to be activated in planta to SPT-enol acts as a developmental inhibitor of the free-living nematode Caenorhabditis elegans and the plant-parasitic nematode Heterodera schachtii . Exposure to SPT-enol leads to larval arrest and disruption of the life cycle. Furthermore, SPT-enol inhibits nematode ACC activity, affects storage lipids and fatty acid composition. Silencing of H. schachtii ACC by RNAi induced similar phenotypes and thus mimics the effects of SPT-enol, supporting the conclusion that SPT-enol acts on nematodes by inhibiting ACC. Our studies demonstrated that the inhibition of de novo lipid biosynthesis by interfering with nematode ACC is a new nematicidal mode of action addressed by SPT, a well-known systemic insecticide for sucking pest control.

Exposure to fluopimomide at sublethal doses causes oxidative stress in Caenorhabditis elegans regulated by insulin/insulin‐like growth factor 1‐like signaling pathway

“…Similarly, many studies showed that several environmental toxicants such as nanoparticles decreased lifespan of C. elegans 43,44 . Furthermore, pesticides including paichongding and spirotramat interrupted life cycle and shortened lifespan of nematodes 45,46 . These findings implied that exposure to environmental xenobiotics such as fluopimomide adversely affected survival of C. elegans .…”

“…43,44 Furthermore, pesticides including paichongding and spirotramat interrupted life cycle and shortened lifespan of nematodes. 45,46 These findings implied that exposure to environmental xenobiotics such as fluopimomide adversely affected survival of C. elegans. An increase in ROS accumulation indicated that the nematodes were under oxidative stress, which was considered to be an important factor leading to aging.…”

Spiro Derivatives in the Discovery of New Pesticides: A Research Review

“…28,29 Spirotetramat degrades readily in soil, 59 and moderate application protects plants without affecting their growth. 60 It also effectively controls pests such as Psyllidae, Aleyrodidae, Coccoidea, Lygus lucorum, Caenorhabditis elegans, 29 and Frankliniella occidentalis 61 and has long-lasting efficacy, providing control for up to 8 weeks.…”

“…The most commonly used presently are spirodiclofen, spirotetramat, and spiromesifen (developed by Bayer), which target acetyl-CoA carboxylase (ACC) in pests, by inhibiting lipid synthesis, resulting in efficient, rapid insecticidal activity (Figure ). − As a result, global sales of these three insecticides have risen since their launch. Spirodiclofen sales have soared since it was first listed in 2003.…”

“…Spirotetramat is a common systemic insecticide used to control sucking pests. It enters the plant, hydrolyzes into its spirotetramat-enol form, and exerts its insecticidal effect by inhibiting secondary lipid synthesis in the pest via interference with its ACC. , Spirotetramat degrades readily in soil, and moderate application protects plants without affecting their growth . It also effectively controls pests such as Psyllidae, Aleyrodidae, Coccoidea, Lygus lucorum, Caenorhabditis elegans, and Frankliniella occidentalis and has long-lasting efficacy, providing control for up to 8 weeks.…”