Action of Heterorhabditis indica (Rhabditida: Heterorhabditidae) strain LPP1 on the reproductive biology of engorged females of Rhipicephalus microplus (Acari: Ixodidae)

Abstract

The aim of this study was to evaluate the effect of different concentrations of the entomopathogenic nematode (EPN) Heterorhabditis indica, LPP1, on the reproductive biology of engorged females of Rhipicephalus microplus. For this purpose, 240 females were divided into eight groups with statistically similar weights (p>0.05). Each group was divided into six subgroups with five females distributed in Petri dishes and exposed to concentrations of 0, 375, 750, 1500, 3000, 6000, 12,000 and 24,000 EPNs/dish. The following biological parameters were evaluated: egg mass weight (mg), egg production index (%EPI), hatching percentage (%) and percentage of control. The action of the nematodes resulted in a significant reduction (p<0.05) in egg mass weight, hatching percentage and EPI in all treatments groups. The percentage of control in all groups was above 97%, reaching 100% at concentrations of 3000 and 12,000 EPNs/female. Comparison of these results with those reported in other articles evaluating the in vitro pathogenicity of different EPN species against R. microplus shows that under laboratory conditions H. indica LPP1 is the one of most virulent species.