Knockout of tyramine receptor 1 results in a decrease of oviposition, mating, and sex pheromone biosynthesis in...

Mating and oviposition are essential and closely coordinated events in the reproduction of moths. Although tyramine, a biogenic amine, can affect insect reproduction by binding its receptors, the specific regulatory mechanism has not yet been fully elucidated.

Plutella xylostella mutant with tyramine receptor 1 (TAR1) knockout (homozygous mutant with 7-bp deletion, Mut7) was developed by the CRISPR/Cas9 system to investigate the effect of TAR1 knockout on the reproduction of the moth. Compared with wild-type (WT), the egg yield of Mut7 female (Mut7^F ) was significantly lower, no significant difference was observed in the egg size and hatching ratio between the groups. Further analysis showed that TAR1 knockout adversely affected ovary development, characterized by shorter ovarioles and fewer mature oocyte. Additionally, TAR1 knockout significantly reduced the occurrence of mating, resulting in a decrease in egg yield in Mut7^F . The amounts of sex pheromones were quantified using gas chromatography-mass spectrometry. Results showed that the amounts of sex pheromone released by Mut7^F were significantly lower before mating. Correspondingly, the messenger RNA (mRNA) levels of sex pheromone biosynthesis enzymes, including acetyl-CoA carboxylase (ACC) and desaturase (DES), were significantly lower in the Mut7^F pheromone gland. The decreased sex pheromone biosynthesis in Mut7^F , especially before re-mating, may be related to the underexpression of pheromone biosynthesis-activated neuropeptide (PBAN).

Overall, this study investigated the effect of PxTAR1 on oviposition and mating of P. xylostella. We report for the first time that TAR1 knockout could reduce the sex pheromone biosynthesis. These findings provide insights for developing a novel integrated pest control strategy based on mating interference. © 2023 Society of Chemical Industry.