Azadirachtin inhibits the development and metabolism of the silk glands of Spodoptera frugiperda and affects spinning behavior

Abstract

Spodoptera frugiperda is a major agricultural pest, and the 1st -3rd instar S. frugiperda have spinning behaviour and can drift to adjacent plants with the help of the wind. The present study found that azadirachtin can affect this behaviour, and the mechanism by which azadirachtin affects the spinning behaviour of S. frugiperda has been studied. In this study, the 3rd instar larvae were exposed to azadirachtin, and the pathological changes in the silk glands of S. frugiperda and the differences in their metabolites were analysed by pathological sectioning, transmission electron microscopy, metabolomics and other experimental methods. The results showed that azadirachtin can affect the silk gland of S. frugiperda. After 48 h of treatment with azadirachtin, the silk gland lumen of S. frugiperda appeared vacuolated, and KEGG showed that 31 different metabolites were identi ed, of which 12 were upregulated and 19 were downregulated. These metabolites were enriched in 15 different metabolic pathways, which pathways indicated that the silk gland of S. frugiperda was closely related to the formation of fatty acids and to energy metabolism in the process of silk formation. This research can further explain the spinning mechanism of insects and provide a research basis for determining the spinning, cocooning, and transfer damage mechanisms of many agricultural and forestry pests. Key MessageThe 1st -3rd instar Spodoptera frugiperda can spit and drift to neighbouring plants.Azadirachtin causes a decrease in the amino acids histidine, glycine, and leucine in the silk glands of Spodoptera frugiperda.Azadirachtin causes insect silk to break more easily.Feeding with azadirachtin for 72 h reduces Spodoptera frugiperda spinning.Azadirachtin can affect the development of the silk glands of Spodoptera frugiperda and thus affect silking behaviour.

Dispersal Behavior Characters of Spodoptera frugiperda Larvae

“…Des on a silk thread is an important mechanism by which FAW larvae disperse dow usually within the same plant. Such behavior allows larvae to rapidly reach lowe and thereby locate new food sources and avoid cannibalism [42]. Similarly, larva grapevine moth (Lobesia botrana; Tortricidae) move downward mainly by silk desc Vertical descent on silk threads is likely responsible for the observed distribution of FAW larvae within individual corn plants.…”

“…Descending on a silk thread is an important mechanism by which FAW larvae disperse downward, usually within the same plant. Such behavior allows larvae to rapidly reach lower leaves and thereby locate new food sources and avoid cannibalism [ 42 ]. Similarly, larvae of the grapevine moth ( Lobesia botrana ; Tortricidae) move downward mainly by silk descent [ 43 ].…”

Novel Synthetic 2-Cyano-N-(3-(N-(Thiazol-2-yl) ‎Sulfamoyl) Phenyl) Acetamide Derivatives against ‎Spinning Silk Threads in Spodoptera frugiperda ‎

“…When the strength and length of the silk are reduced, the insect's hanging silk migration may be curtailed. Silk formation is linked to the growth of silk glands and the synthesis of silk protein (Zhao et al, 2022).…”

A comprehensive review of azadirachtin: physicochemical properties, bioactivities, production, and biosynthesis

“…Midgut damage resulting from apoptosis can lead to disruptions in digestive enzyme function, subsequently affecting the digestion and absorption of nutrient metabolites and impeding the growth and development of insect larvae. Furthermore, Zhao et al [63] revealed that azadirachtin can influence the formation of silk glands and fatty acids, as well as affect energy metabolism in Spodoptera frugiperda. Additionally, studies have shown that azadirachtin administration leads to the inhibition of cell proliferation and RNA synthesis in protozoa, specifically Tetrahymena thermophila, along with the explicit blockade of malarial microtubule formation in a critical stage of the Plasmodium berghei parasite [64][65] .…”