Extrato hidroalcoólico de mandioca (Manihot esculenta Crantz) no controle de carrapatos

Abstract

Cattle ranching has gained economic prominence in recent decades due to the growing global demand for food and the increasing demand for sustainable practices. However, the productivity of the sector depends on the health management of the herd, particularly in combating parasites. Among the main parasites, the bovine tick Rhipicephalus (Boophilus) microplus is responsible for significant economic losses. The reliance on synthetic pesticides for controlling these parasites poses a considerable public health risk, which has driven research into natural alternatives. In this context, the present study evaluated the potential adulticidal, ovicidal, and repellent effects of the hydroalcoholic extract of cassava (Manihot esculenta Crantz), cultivar MEcu 72, on the bovine tick. Using the adult immersion test, mortality, oviposition, and egg production indices were determined. Additionally, larvicidal and repellent activity tests were carried out. A total of 120 adult ticks were randomly subjected to the following treatments: EHEF and EHEFC (at 6%, 17%, and 20%), along with the control treatments: negative (distilled water) and positive control (amitraz 12.5%). Furthermore, the total phenol and tannin contents were determined. Regarding the mortality of adult ticks, both extracts induced mortality in a dose-dependent pattern. However, only EHEF was effective, causing 93.33% mortality at 17%, while EHEFC at 20% resulted in 80% mortality. Both extracts did not show any inhibitory effect on the oviposition index, and although they inhibited egg production, a low deleterious effect was observed. As for the larvicidal effect, EHEFC 6% and EHEF 17% caused low mortalities of 46.3% and 50.7%, respectively. In contrast, EHEFC showed a high repellent rate (95.23%), while EHEF exhibited a moderate repellent effect (88.02%), approaching the results obtained by the positive control treatment (amitraz). Regarding phenolic compounds and total tannins, EHEF and EHEFC at concentrations of 17% and 20% showed the highest concentrations of total phenols (1.2552 mg/mL and 1.2523 mg/mL, respectively), and similarly, the highest tannin contents were observed in the EHEF 17% (2.7798 mg/mL) and EHEFC 20% (2.3566 mg/mL) treatments, in a dose-dependent manner. The results obtained regarding phenols and tannins are directly related to the acaricidal effects observed, suggesting that these compounds may be partly responsible for the efficiency of the extracts in tick mortality and repellency. In conclusion, the hydroalcoholic extract of cassava genotype MEcu 72, especially the leafderived extract, demonstrates adulticidal, ovicidal, and repellent effects on bovine ticks, highlighting its potential as an alternative in controlling this parasite, thus justifying the continuation of in vivo studies.