# Proteomic Evaluation of Insecticidal Action of Phosphine on Green Peach Aphids, _Myzus persicae_
## 1 Introduction  
Tablets of various phosphine (PH3)-containing chemicals, including aluminum phosphide, release PH3s, which have been extensively used as fumigants for the control of insect pests, thereby minimizing trading risks and protecting stored agricultural products [1]. In addition, PH3s have been introduced as an alternative to methyl bromide for controlling adult greenhouse thrips (_Heliothrips haemorrhiodalis_), adult aphids (_Myzus persicae_), and light brown apple moth larvae (_Epipayas postvitana_), in cut flowers [2]. Based on the trials, the most effective formulation for aphids was 1000 uL/L PH3 + 33% CO2 for 4 h, while all tested insects were killed within 36 h of exposure [2].  
Furthermore, _M. persicae_ can be controlled by Brassicaceae ethyl ester oils [3], a certain wavelength of light-emitting diodes [4], and biologically using banker plants with _Aphidius colemani_[5]. Recently, ethyl formate (EF) was used to control _M. persicae_ by fumigation and this fumigant induced2-fold cytochrome c oxidase (COX) activity in comparison with the control [6]. [PERSON] and [PERSON] [7] introduced the use of EF fumigation to protect film-wrapped lettues from _M. persicae_.  
Interestingly, PH3 and EF have been combined for use in the control of insect pests. The combination of PH3 and EF effectively killed _Aphis gossypii_, the cotton aphid [8], whereas individual treatments with PH3 fumigation over short periods of time or at low EF concentrations provided relatively low eradication rates. The combination may also completely control the eggs of _Planococcus citri_ (Hemiptera: Pseudococcidae) on pineapples, when applied at concentrations of 25.1/1.0 (EF/PH3) mg/L at 8 \({}^{\circ}\)C for 4 h [9].  
This combined fumigation has been used to eradicate _M. persicae_ efficiently and may hinder the development of PH3 and/or EF resistance in _M. persicae_. PH3 resistance in various insect pests have been reported throughout the world in various insect species, including _Rhyzopertha dominica, Tribolium castaneum_, and _Cryptolestes ferrugineus_[10; 11; 12], leading farmers and fumigators to explore new fumigation tools to control PH3-resistant insect pests in storage facilities [13; 14].  
This study assessed the acute toxicity in _M. persicae_ caused by PH3 to determine its lethal concentration LC10 and LC50 values. Regarding the acute toxicity, activities of two enzymes such as acetylcholinesterasecholinesteraseterase (AChE) and cytochrome c oxidase (COX) were measured to know the actual target sites of PH3. AChE and COX have been known to be the target site of an organophosphorus insecticide and PH3, respectively. Besides, expression levels of six genes responsible for expressing cytochrome P450 6 CY3 (_cypccy3_), farnesyl diphosphate synthase 1 (_fps1_), acetylcholinesteraseinesterase (_ache_), voltage gated sodium channel subunit 1 (_para_), nicotinic acetylcholine receptor alpha 3 subunit (_ni-arc_), and ecdysone receptor (_ecr_) were also measured to understand effects of PH3 on metabolism, neurotransmission system, and growth in _M. persicae_. Finally, overall protein expression levels were compared between the PH3-treated adults of _M. persicae_ and the control using liquid-chromatopy tandem mass spectrometry (LC-MS/MS) to find further biochemical reasons for the explication of the toxic effect by PH3.