Insect growth regulators play an important role in integrated pest management strategies.The FGLa–allatostatins(ASTs)are a family of neuropeptides that can inhibit juvenile hormone(JH)biosynthesis by the corpora allata(CA)of Diploptera punctata in vitro,are regarded as insect growth regulator candidates.In the search for new potential mimics and to explore the effect of linker length on inhibiting JH biosynthesis,a series of AST analogs were synthesized by modifying the linker of K24,which was found to have a significant effect on JH biosynthesis in vitro in our previous study.Functional evaluation demonstrated that all the target compounds can activate the Dippu-Ast R,albeit with different potencies.Analog L6 with the longest linker(n=5),exhibited not only a promising effect on inhibition of JH biosynthesis both in vitro and in vivo,but also good activity in inhibiting basal oocyte growth.Structure–activity relationships(SAR)studies showed that longer linkers provided greater contribution to activity. Insect growth regulators play an important role in integrated pest management strategies. The FGLa-allatostatins (ASTs) are a family of neuropeptides that can inhibit juvenile hormone (JH) biosynthesis by the corpora allata (CA) of Diploptera punctata in vitro, are advertised as insect growth risers. In the search for new potential mimics and to explore the effect of linker length on inhibiting JH biosynthesis, a series of AST analogs were synthesized by modifying the linker of K24, which was found to have a significant effect on JH biosynthesis in vitro in our previous study. Functional evaluation of that the target compounds can activate the Dippu-Ast R, albeit with different potencies. Catalog L6 with the longest linker (n = 5), not only a promising effect on inhibition of JH biosynthesis both in vitro and in vivo, but also good activity in inhibiting basal oocyte growth. Structure-activity relationships (SAR) studies showed that longer linkers provided greater cont ribution to activity.