Effect of short neuropeptide F signaling on larval feeding in Mythimna separata

Mythimna separata is a notorious phytophagous pest which poses serious threats to cereal crops owing to the gluttony of the larvae.Because short neuropeptide F(sNPF)and its receptor sNPFR are involved in a diversity of physiological functions,especially in functions related to feeding in insects,it is a molecular target for pest control.Herein,an sNPF and 2 sNPFRs were identified and cloned from M.separata.Bioinformatics analysis revealed that the sNPF and its receptors had a highly conserved RLRFamide C-terminus and 7 transmembrane domains,respectively.The sNPF and its receptor genes were distributed across larval periods and tissues,but 2 receptors had distinct expression patterns.The starvation-induced assay elucidated that sNPF and sNPFR expression levels were downregulated under food deprivation and recovered with subsequent re-feeding.RNA interference knockdown of sNPF,sNPFR1,and sNPFR2 by injection of double-stranded RNA into larvae not only suppressed food consumption and increased body size and weight,but also led to decrease of glycogen and total lipid contents,and increase of trehalose compared with double-stranded green fluorescent protein injection.Furthermore,molecular docking was performed on the interaction mode between sNPFR protein and its ligand sNPF based on the 3-dimensional models constructed by AlphaFold;the results indicated that both receptors were presumably activated by the mature peptide sNPF-2.These results revealed that sNPF signaling played a considerably vital role in the feeding regulation of M.separata and represents a potential control target for this pest.

Chord error constraint based integrated control strategy for contour error compensation

As the traditional cross-coupling control method cannot meet the requirements for tracking accuracy and contour control accuracy in large curvature positions, an integrated control strategy of cross-coupling contour error compensation based on chord error constraint, which consists of a cross-coupling controller and an improved position error compensator, is proposed. To reduce the contour error, a PI-type cross-coupling controller is designed, with its stability being analyzed by using the contour error transfer function. Moreover, a feed rate regulator based on the chord error constraint is proposed, which performs speed planning with the maximum feed rate allowed by the large curvature position as the constraint condition, so as to meet the requirements of large curvature positions for the chord error. Besides, an improved position error compensation method is further presented by combining the feed rate regulator with the position error compensator, which improves the tracking accuracy via the advance compensation of tracking error. The biaxial experimental results of non-uniform rational B-splines curves indicate that the proposed integrated control strategy can significantly improve the tracking and contour control accuracy in biaxial contour following tasks.