## 1 Introduction  
Insect juvenile hormone (JH), a multifunctional hormone secreted from the corpora allata (CA), plays a role in multiple physiological events including diapause, pheromone production, polyphenols, growth, molting, metamorphosis and reproduction [1; 2; 3; 4; 5; 6; 7]. The JH biosynthetic pathway was conventionally divided into two phases: early steps (the upstream mevalonate pathway, MVAP) and late steps (the isoprene branch pathway, JH-branch) [8; 9]. The early steps follow the mevalonic acid pathway to form farnesyl pyrophosphate (FPP) and involve several enzymes. Initially, three units of Acetyl-CoA are condensed into mevalonate through three sequential steps involving acetoacetyl-CoA thiolase (_AACT_), 3-hydroxy-3-methylglutaryl-CoA synthase (_HMG-S_) and 3-Hydroxy-3-methylglutaryl-CoA reductase (_HMG-R_). Then, mevalonate is converted to isopentenyl diphosphate (IPP) through three enzymatic reactions catalyzed by mevalonate kinase (_MK_), phosphomevalonate kinase (_PMK_), and mevalonate diphosphate decarboxylase (_MPDC_) [10]. Isopentenyl diphosphate isomerase (_IPPI_) catalyzes the conversion of isopentenyl pyrophosphate (IPP) to dimethylallyl pyrophosphate (DMAPP); subsequently, IPP and DMAPP were condensed head-to-tail manner to produce geranyl diphosphate (GPP); this head-to-tail condensation can be repeated by the further reaction of GPP with IPP, yielding the JH precursor farnesyl diphosphate (FPP) [11]. The expressions of eight enzymes of the mevalonate pathway have been previously examined in _Dendroctons armandi_[12; 13]. During the late steps proceeding from farnesyl diphosphate to JH, FPP is transformed sequentially to farnesol, farnesol, farnesoic acid, methyl farnesoate and JH [10; 14; 15; 16]. The juvenile hormone acid O-methyltransferase transferase (_JHAMT_) is a key regulatory enzyme in the isoprene branch pathway that is essential for insect growth and reproduction [17; 18]. For example, silencing the _TcJHAMT_ gene in the larval stage of _Tribolium castaneum_ resulted in premature larva-pupa metamorphosis [19]. In particular, the genes encoding enzymes for the mevalonate pathway and the last two steps of the JH branch pathway (farnesoic acid (FA) epoxidase and _JHAMT_) have been identified in multiple species [10; 17; 18; 19; 20; 21; 22; 23; 24]. Different factors are involved in the regulation of JH synthesis [14]. These include allatoregulatory neuropeptides, biogenic amines [25; 26], nutritional signals [27] and nuclear receptors [28]. In insects, one of the largest groups of neuropeptides is the group of allatostatins (_ASTs_). _ASTs_ have been identified in beetles, cockroaches, crickets, flies, moths, stick insects, and termites [29; 30; 31; 32; 33; 34; 35; 36; 37]. _ASTs_ were first divided into three distinct families: Type A [37], Type B [33] and Type C allatostatin [29; 38; 39]. However, because the classification of families did not address either the biological properties of these peptides or the structure of the amino acid chains of these peptides, [PERSON] & [PERSON] (2011) systematized the nomenclature of these neuropeptides [40]. They proposed that A Type allatostatin should be named FGL/AST because of the presence of an FGL sequence at the C-terminal end, Type B should be named MIP/AST because of the myoinhibitory properties of these peptides on the visceral muscles, and Type C should be named PISCF/AST, because there is an uncommon PISCF-OH sequence at the C-terminal end [40]. In coleopteran species, in vitro studies showed that the _Tribolium castaneum AS-B3_ peptide inhibited CA activity, while _TcAS_-C inhibited or stimulated JH biosynthesis [41]. Furthermore, the injection of double-stranded RNAs (dsRNAs) targeting _TcAS_-C and _TcAS_-B into young _T. castaneum_ pupae prolonged pupae duration and resulted in the production of approximately 50% of deformed adults. The other 50% were intact in shape [42]. Moreover, in _Leptinontarsa decemlineata_, the mRNA levels of _LdJHAMT_ were significantly increased and the larval growth and delayed development of _L.