In Vitro Evaluation of Essential Oils Derived from Piper nigrum (Piperaceae)‎ and Citrus limonum (Rutaceae)‎ against the Tick Rhipicephalus (Boophilus)‎ microplus (Acari: Ixodidae)‎

الملخص EN

The present research aimed to study the chemical composition and acaricidal activity of Citrus limonum and Piper nigrum essential oils against the cattle tick Rhipicephalus microplus.

GC-MS analysis of C.

limonum essential oil showed limonene (50.3%), β-pinene (14.4%), and γ-terpinene (11.7%) as the major components; P.

nigrum oil was mainly composed of β-caryophyllene (26.2%), σ-ocymene (5.8%), and α-pinene (5.5%).

Acaricide activity was evaluated at concentrations of 2.5, 5.0, and 10.0% (v/v) of each plant oil, as well as 1 : 1 combination of both oils (5% : 5%, 2.5% : 2.5%, and 1.25% : 1.25% each), by immersing engorged R.

microplus females for one minute.

The LC90 of oils from C.

limonum, P.

nigrum, and the combination were 4.9%, 14.8%, and 5.1%, respectively.

C.

limonum essential oil caused 100% mortality of engorged females at the highest concentration (10%).

P.

nigrum essential oil inhibited egg-laying by up to 96% in a concentration-dependent manner, suggesting it reduces tick fecundity.

When combined, the oils presented toxicity as to C.

limonum oil alone, but with stronger inhibition of oviposition (5% : 5%), indicating a possible additive effect against R.

microplus.

The present data provide support for further investigation of novel natural products to control bovine tick infestations.