Dietary RNAi mediated silencing of HvPP2A affects the survival and reproduction of the 28-spotted ladybeetle, Henosepilachna vigintioctopunctata

This study investigated the impacts of silencing the serine protein phosphatase 2A (PP2A) gene on the survival and reproductive capabilities of the 28-spotted ladybeetle, Henosepilachna vigintioctopunctata, through a dietary RNA interference (RNAi) method.

The expression patterns of HvPP2A were analyzed during different developmental stages (egg, 1^st ~4^th instar larvae, and adult) and in various tissues (cuticle, fat body, midgut, and Malpighian tubules) of the 4^th instar larvae using RT-qPCR. The impact of the HvPP2A gene on larval survival, development, and gene expression was evaluated by feeding the 1^st instar larvae with different concentrations of dsHvPP2A. Moreover, the effects of HvPP2A on the developmental and phenotypic characteristics, as well as the physiological functions of both the 3^rd instar larvae and female adults, were evaluated following treatment with dsHvPP2A.

The study highlighted varying expression levels of HvPP2A across various developmental stages of H. vigintioctopunctata, with the highest expression detected in females. Notably, HvPP2A was predominantly expressed in the midgut among the analyzed tissues. The findings revealed a significant dose-dependent effect of dsHvPP2A on the mortality of the 1^st instar larvae. Specifically, at a concentration of 50 ng/μL dsHvPP2A, the mortality rate of the 1^st instar larvae reached 82.5%, escalating to 100% at higher concentrations of 100 ng/μL, 200 ng/μL, and 500 ng/μL. Furthermore, administering 100 ng/μL dsHvPP2A to the 3^rd in instar larvae resulted in failure to molt and subsequent death. Additionally, feeding female adults with 1000 ng/μL dsHvPP2A inhibited ovarian development and egg production compared to the control group, preventing normal egg-laying.

This investigation emphasizes the essential role of HvPP2A in the survival and reproduction of H. vigintioctopunctata, suggesting HvPP2A could be a promising target gene for RNAi-based management strategies in this species.