Acaricidal Activity and Transcriptional Modulation Induced by Randia aculeata Seed Extract in Rhipicephalus microplus

Area of Science:

• Veterinary Entomology
• Molecular Biology
• Natural Product Chemistry

Background:

• Cattle tick Rhipicephalus microplus resistance to synthetic acaricides drives demand for plant-derived alternatives.
• Randia aculeata seed extract shows acaricidal potential, but its molecular mechanisms are unclear.
• This study investigates the acaricidal activity and molecular effects of R. aculeata extract on R. microplus larvae.

Purpose of the Study:

• To evaluate the acaricidal activity of Randia aculeata hydroalcoholic seed extract against Rhipicephalus microplus larvae.
• To investigate the molecular mechanisms underlying the extract's activity by analyzing gene expression.
• To identify potential new targets for tick control strategies.

Main Methods:

• Larval packet test used to assess acaricidal activity.
• Probit regression analysis to determine LC50 and LC90 values.
• Quantitative real-time PCR to analyze the expression of acetylcholinesterase 2 (AChE2) and glutathione S-transferase (GST) genes after exposure to LC50 concentration.

Main Results:

• The R. aculeata extract exhibited significant acaricidal activity with LC50 of 2.84 mg/mL and LC90 of 5.67 mg/mL.
• Exposure to the LC50 concentration led to a significant reduction in AChE2 gene expression (0.41-fold).
• Significant downregulation of GST gene expression (0.48-fold) was observed in treated larvae compared to controls.

Conclusions:

• Randia aculeata hydroalcoholic extract possesses acaricidal properties.
• The extract's activity is linked to the transcriptional suppression of genes involved in neurotransmission (AChE2) and detoxification (GST).
• Findings suggest potential disruption of cholinergic regulation and xenobiotic response pathways in ticks, warranting further investigation with characterized tick populations.