Azadirachtin Affects the Growth of Spodoptera litura Fabricius by Inducing Apoptosis in Larval Midgut

Abstract

Azadirachtin, the environmentally friendly botanical pesticide, has been used as an antifeedant and pest growth regulator in integrated pest management for decades. It has shown strong biological activity against Spodoptera litura, but the mechanism of toxicity remains unclear. The present study showed that azadirachtin inhibited the growth of S. litura larvae, which was resulted by structure destroy and size inhibition of the midgut. Digital gene expression (DGE) analysis of midgut suggested that azadirachtin regulated the transcriptional level of multiple unigenes involved in mitogen-activated protein kinase (MAPK) and calcium apoptotic signaling pathways. Simultaneously, the expression patterns of some differentially expressed unigenes were verified by quantitative real time-PCR (qRT-PCR). In addition, the enhanced terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) staining, the increased expression of caspase family members and apoptosis-binding motif 1 (IBM1) on both gene and protein level and the release of cytochrome c from mitochondria to cytoplasm were induced in midgut after azadirachtin treatment. These results demonstrated that azadirachtin induced structural alteration in S. litura larval midgut by apoptosis activation. These alterations may affect the digestion and absorption of nutrients and eventually lead to the growth inhibition of larvae.

Development Rate and Ultrastructure Changes of Puparia of Megaselia scalaris (Loew) (Diptera: Phoridae) Induced by Azadirachtin.

“…This property adversely affects the ecdysteroid and juvenile hormones thus preventing pest proliferation. Moreover, Shu et al (2018) reported that azadirachtin inhibited the growth of Spodoptera litura larvae by inducing apoptosis and destroying the structure of the midgut.…”

Proteomic Profiling Analysis of Male Infertility inSpodoptera LituraLarvae Challenged with Azadirachtin and its Potential‐Regulated Pathways in the Following Stages

“…The mitochondrial and cytosolic proteins were isolated by mitochondrial protein extraction kit (KeyGEN, Nanjing, China) according to manufacturer's protocol. Western blot analysis for caspase‐3 (Cell signaling technology) and cytochrome C (CYC, Beyotime Biotechnology) were carried out according to our previously described in this paper . DNA fragmentation in the testis of S. litura was detected using the principle of TdT‐mediated dUTP nick‐end labeling (TUNEL), a marker of apoptosis .…”

Pro-Apoptotic Function Analysis of the Reaper Homologue IBM1 in Spodoptera frugiperda

“…The transcript levels of Bm-IBM1 in BmN cells and pupae of Bombyx mori were up-regulated after infection by baculovirus B. mori Nucleopolyhedrovirus [13]. Sl-IBM1 was induced by azadirachtin along with increased apoptosis in the midgut of Spodoptera litura [29]. In this study, we demonstrated that azadirachtin, camptothecin, and UV induced expression of Sf-IBM1 in Sf9 cells along with increased apoptosis.…”

“…The Caspase-3 activity assay was measured using a Caspase-3 Colorimetric Assay Kit (KeyGEN BioTECH, Nanjing, China) as previously described [29]. Cells under different treatments were collected by centrifugation and washed with PBS for two times.…”