The nonparasitic phase of Dermacentor nitens under field conditions in southeastern Brazil

Abstract

Dermacentor nitens is a one-host tick that uses domestic equids as main hosts. Herein, the nonparasitic phase of D. nitens was evaluated under field conditions in Pirassununga, São Paulo state, Southeastern Brazil. By exposing engorged females of D. nitens to field conditions (grass plots) for 24 consecutive months, this tick species was able to complete its nonparasitic phase by producing host-seeking larvae in the pasture throughout the year. Preoviposition and egg incubation periods were longer during autumn and winter months than during the other months. The number of larvae generated by engorged females was in most of the times lower during autumn and winter months, as demonstrated by lower egg hatching values. Such conditions could be linked to lower mean temperatures and rainfall. Larvae with the longest longevity hatched from the eggs with the shortest incubation periods. An apparent synchronism of larval hatching during spring was observed from the eggs laid by females during late winter and autumn, which is consistent with the phenomenon of “spring rise”. The results indicate that D. nitens can complete up to five generations per year in southeastern Brazil, providing baseline data to develop future protocols for the appropriate control of D. nitens on horses.

Unusual parasitism site of Dermacentor nitens (Acari: Ixodidae) on a horse

“…

Dermacentor nitens Neumann is the most common tick found parasitizing horses in the main Brazilian biomes, such as Amazon, Atlantic Forest, Cerrado (savannah), semiarid Caatinga, Pantanal (wetlands) (LABRUNA & FACCINI, 2020). This ixodid species became widely distributed in South America during the 20 th century through the movement and distribution of domestic equids (NAVA et al, 2017) and D. nitens has never been reported from a site without the presence of equids (LABRUNA & FACCINI, 2020).Dermacentor nitens is a one-host ixodid tick, its parasitic phase on horses has an average duration of 25 days, the pre-oviposition period an average of 5 days and the average incubation period near 26 days, totaling a mean of 56 days of life cycle (RODRIGUES et al, 2017).

…”

“…Dermacentor nitens Neumann is the most common tick found parasitizing horses in the main Brazilian biomes, such as Amazon, Atlantic Forest, Cerrado (savannah), semiarid Caatinga, Pantanal (wetlands) (LABRUNA & FACCINI, 2020). This ixodid species became widely distributed in South America during the 20 th century through the movement and distribution of domestic equids (NAVA et al, 2017) and D. nitens has never been reported from a site without the presence of equids (LABRUNA & FACCINI, 2020).…”