Involvement of glucose transporter 4 in ovarian development and reproductive maturation of Harmonia axyridis (Coleoptera: Coccinellidae)

Abstract

Glucose is vital to embryogenesis, as are glucose transporters. Glucose transporter 4 (Glut4) is one of the glucose transporters, which is involved in rapid uptake of glucose by various cells and promotes glucose homeostasis. Although energy metabolism in insect reproduction is well known, the molecular mechanism of Glut4 in insect reproduction is poorly understood. We suspect that Glut4 is involved in maintaining glucose concentrations in the ovaries and affecting vitellogenesis, which is critical for subsequent oocyte maturation and insect fertility. Harmonia axyridis (Pallas) is a model organism for genetic research and a natural enemy of insect pests. We studied the influence of the Glut4 gene on the reproduction and development of H. axyridis using RNA interference technology. Reverse transcription quantitative polymerase chain reaction analysis revealed that HaGlut4 was most highly expressed in adults. Knockdown of the HaGlut4 gene reduced the transcript levels of HaGlut4, and the weight and number of eggs produced significantly decreased. In addition, the transcript levels of vitellogenin receptor and vitellogenin in the fat bodies and the ovaries of H. axyridis decreased after the interference of Glut4, and decreased the triglyceride, fatty acid, total amino acid and adenosine triphosphate content of H. axyridis. This resulted in severe blockage of ovary development and reduction of yolk formation; there was no development of ovarioles in the developing oocytes. These changes indicate that a lack of HaGlut4 can impair ovarian development and oocyte maturation and result in decreased fecundity.

Insights from different reproductive gene knockdowns via RNA interference in the lady beetle Eriopis connexa: Establishing a new model for molecular studies on natural enemies

“…As stated before, RNAi‐mediated silencing has been applied to agricultural pests and human disease vectors, but few studies have focused on the functional genomics of natural enemies, such as predators and parasitoids (Castellanos et al, 2022; Yan et al, 2023). Most related work on predators is related to ladybird beetles, such as H. axyridis (Han, Han, et al, 2022; Li et al, 2022; Tian et al, 2022; Tsuji et al, 2018)a. Furthermore, studies on the potential effects of pest‐designed RNAi on nontarget organisms are scarce, with only a few involving ladybird beetles.…”

PxTret1-like Affects the Temperature Adaptability of a Cosmopolitan Pest by Altering Trehalose Tissue Distribution

“…were hydrolyzed to supplement this [ 55 , 56 ]. Glucose levels were elevated in mutant female adults; the reason for this may be that female mutants need energy to maintain normal life activities, such as mating and spawning [ 57 ]. Studies have shown that many insects need to use proteins and carbohydrates to synthesize sufficient lipids; as a result, insects can reach sexual maturity and lay eggs [ 58 , 59 , 60 ].…”