Tropical and Subtropical Agroecosystems (Mar 2020)
EVALUATION OF THE EFFECT OF THE COMBINATION OF DIBENZYL DISULFIDE, DIBENZYL TRISULFIDE AND OCTADECENOIC ACID METHYL ESTER ON THE PROCESS OF OVOGENESIS IN ACARICIDE-RESISTANT RHIPICEPHALUS MICROPLUS
Abstract
Background. The aromatic compounds of P. alliacea are a good alternative for the control of Rhipicephalus microplus resistant to acaricides; however, there are not reports evaluating the effect of these compounds on the reproductive system of R. microplus. Methodology. In the present work, the effect of the combination of three compounds: dibenzyl disulfide (63.1%), dibenzyl trisulfide (32.5%) and octadecenoic acid methyl ester (0.7%), on mortality and the oogenesis process was evaluated on Rhipicephalus microplus ticks resistant to acaricides. To evaluate the effects of this combination of compounds, the adult immersion test (AIT) was used, where mortality values, inhibition of oviposition and inhibition of hatching were obtained. Histopathology (HP) was used to evaluate the effect on oogenesis of the reproductive system. Results. In the AIT, non-significant mortalities (26.4 ± 9.8%) were obtained, high efficiency in percentages of oviposition inhibition (85.6 ± 3.7%) and moderate efficacy in the inhibition of hatching (57.0 ± 4.0%). In HP, the uteri of ticks subjected to immersion in the mixture of benzylsulfur compounds (1%) for one minute showed changes in the normal structure of their oocytes: morphological alterations that appear as deformed and heterogeneous cell masses. Implications. These compounds do not affect adult mortality; however, they have a high impact on larval progeny, breaking the R. microplus cycle. Conclusion. The mixture of the studied compounds exerts an inhibiting effect on the process of oogenesis in R. microplus, which is promising for the control of this ectoparasite.
