Evaluation of the efficacy of strains of Steinernema carpocapsae Santa Rosa and ALL (Steinernematidae: Rhabditida) to control engorged female Anocentor nitens (Acari: Ixodidae)

Abstract

In view of the need to combat the generalized spread of resistance in ticks to commercial acaricides, the objective of this study was to evaluate the action of entomopathogenic nematodes (Steinernema carpocapsae, strains Santa Rosa and ALL) on engorged female Anocentor nitens. Five ticks per Petri dish were exposed to concentrations of 500, 5,000, or 25,000 infective juveniles of S. carpocapsae for 72 h. After transferring the ticks to clean plates, biological parameters were analyzed. Related to strains Santa Rosa, the period of pre-oviposition (p = 0.0001), oviposition (p = 0.041), and the mass weight of eggs (p = 0.005) showed significant differences between the control group and treated group. When the strain ALL was tested, the control and treated groups differed between the periods of pre-oviposition (p = 0.001), oviposition (p = 0.001), and egg mass weight (p = 0.01). The egg mass conversion was less significant in the groups when exposed to strains Santa Rosa (p = 0.002) and ALL (p = 0.001) relative to the control. The efficacy of both entomopathogenic nematode strains used in this study was comparable to other biological control agents, showing their potential against A. nitens in the laboratory.