# The Industrial Residue of Andiroba (Carapa sp.): A Promising Source of Natural Acaricides Against Dermacentor nitens (Acari: Ixodidae)

## TL;DR

A waste product from andiroba oil extraction in the Amazon can kill tropical horse ticks, offering a natural alternative to chemical acaricides.

## Contribution

The industrial residue of andiroba is identified as a novel source of natural acaricides against D. nitens.

## Key findings

- A 5% concentration of andiroba extract killed 100% of D. nitens larvae in tests.
- Lower concentrations (2.5% and 10%) showed reduced but still significant larval mortality.
- The residue from andiroba oil production has potential for developing natural acaricides.

## Abstract

Andiroba is an Amazonian seed that is pressed for oil extraction. Andiroba residue is usually discarded, but it may still contain substances with biological value. Here, we tested an extract of this residue to see if it can kill tropical horse ticks. We found that the andiroba extract at a 5% concentration can kill all the ticks in the test used. This Amazon plant waste has potential for the development of a natural acaricide.

Dermacentor nitens (tropical horse tick) is a tick species commonly found parasitizing horses and other equids in the Amazon region, causing economic losses. Currently, tick control is based on chemical acaricides, usually in a power formulation for topical use. However, its indiscriminate use results in the emergence of resistant tick lineages. Several plant compounds have been tested for their acaricide activity. In the Amazon, several plants are used for oil extraction, resulting in the production of solid residue (waste) that may contain chemical molecules with biological activities. Thus, we aimed to test the in vitro acaricidal potential of the ethanolic extract of the industrial residue of andiroba (Carapa sp.) against D. nitens. In a larval immersion test (LIT), D. nitens larvae were tested with 2.5%, 5%, and 10% andiroba extract concentrations in three replicates. Subsequently, the envelopes were kept in a BOD chamber (28 °C ± 1 °C; 80% ± 5% humidity) for 24 h. At the end of this period, live and dead larvae were counted, and efficiency was calculated from the mortality rate caused by the extract and corrected by the Abbot formula. In the three repetitions, the andiroba extract at a concentration of 5% caused the death of 100% of the larvae. At concentrations of 2.5% and 10%, they caused the death of, respectively, 12.38% (±3.5%) and 69.79% (±7.98%) of the larvae. These results indicate that the extract from the industrial residue from the production of andiroba oil has acaricidal activity. It is concluded that the solid waste from industrial andiroba oil extraction has the potential for the development of natural acaricides against D. nitens.