# Proteomic Evaluation of Insecticidal Action of Phosphine on Green Peach Aphids, _Myzus persicae_
## 4 Discussion
In addition to this oxidative stress, one of the regulatory proteins, ion protease homolog in mitochondria, was down-regulated and it is involved in maintaining protein quality and controlling the occurrence of misfolded or incompletely synthesized proteins (Figure 4A). We need to further study the role of proteins in PH\({}_{3}\) toxicity in _M. persicae_. During PH\({}_{3}\) treatment, _M. persicae_ experienced induced expression of defense-related proteins including glutathione S-transferase-like (\(\times\)2.26-fold), lysozyme-like (\(\times\)3.14-fold), probable protein phosphatase 2C 6 (\(\times\)2.02-fold), and a cluster of esterase E4-like isoform X1 (Figure 4B). These are involved in chemical detoxification (glutathione S-transferase-like and Cluster of esterase E4-like isoform X1) and antimicrobial properties (lysozyme-like and probable protein phosphatase 2C 6). Glutathione S-transferase-like and a cluster of esterase E4-like isoform X1 are easily found in organophosphorus insecticides (OP insecticides)-resistant _M. persicae_[23]. Therefore, their up-regulation in PH\({}_{3}\)-treated _M. persicae_ is related to the chemical structure of PH\({}_{3}\) and this includes the phosphorus ion. However, they may not be involved with the actual mechanism of PH\({}_{3}\) detoxification in the insect because PH\({}_{3}\) does not have an ester bond for esterase or an electrophilic site for conjugation reaction by glutathione _S-_transferase. However, there was no relationship between the inhibition of AChE activity and PH\({}_{3}\) treatment in _M. persicae_ in our study (Figure 2), even though PH\({}_{3}\) inhibited AChE activity in _Ephestia cautella_ (Lepidoptera: Pyralidae) [22]. This difference may be due to the low (equivalent to LCT10) concentration of PH\({}_{3}\) in the treatments. [PERSON] et al. [24] used a series of concentrations of PH\({}_{3}\) treatments, which could kill the pupae of _Ephestia cautella_. This phenomenon has been corroborated by [PERSON] and [PERSON] [25], who showed that PH\({}_{3}\) toxicity was influenced by concentration, in a study involving fumigation of _Liposciels bostrychophila_. Therefore, at a low PH\({}_{3}\) concentration, AChE activity will not be targeted in insects. Other neurologically related proteins, including neurotransmitter receptors and channels, were not affected by PH\({}_{3}\) fumigation (Figure 3). At low PH\({}_{3}\) concentrations, various regulation signals such as synaptic vesicle membrane protein VAT-1 (negative regulation of mitochondrial fusion), V-type proton ATPase subunit d (regulation of macroautophagy), serine/threonine-protein phosphatase 2A catalytic subunit alpha isoform (positive regulation of apoptotic process), cathepsin B (regulation of apoptotic process), and slit homolog 1 protein-like (positive regulation of apoptotic process, response to cortisol), were turned on in _M. persicae_ (Figures 4 and 5). This suggests that even low PH\({}_{3}\) concentrations induce the apoptotic process in _M. persicae_. Finally, metabolic changes in relation to PH\({}_{3}\) toxicity were also observed with the up-regulation of glucosidase2 subunit beta-like (\(\times\)10.3-fold) and galactokinase-like (\(\times\)2.20-fold), similar to findings by [PERSON] et al. [17]. This may be the first study to show such dramatic increases in glucosidase in relation to PH\({}_{3}\) toxicity.