<I>In vitro</I> Efficacy of Three Species of Entomopathogenic Nematodes on Biocontrol of Cattle Tick <I>Rhipicephalus haemaphysaloides</I> Neumann (Acarina:Ixodidae)

Abstract

A study was conducted to assess three entomopathogenic nematodes (EPNs) viz , Steinernema carpocapsae, Steinernema thermophilum and Heterorhabditis indica on engorged females of cattle tick Rhipicephalus haemaphysaloides. Three concentrations of 1250, 2500 and 5000 infective juveniles (IJs) / Petri dish in triplicates were evaluated. H. indica induced 100% mortality within 48 -72 h at all three concentrations. There was a significant reduction in the egg production i.e. 0.1-14.1mg in R. haemaphysaloides at all three concentrations whereas 255.25 mg of eggs were produced by untreated control ticks. The egg mass weight was reduced by EPNs and infertile eggs were produced (no hatchability) S. carpocapsae induced 100% mortality in R. haemaphysaloides, within 72-96 h. There was no significant difference in the egg production but infertile eggs (1% hatchability) were produced. S. thermophilum induced 100% mortality within 72-144 h. There was a significant reduction in the egg production i.e. 12-98.4 mg in R. haemaphysaloides, at all three concentrations in contrast to 255.25 mg of eggs produced by untreated control ticks. 41% hatchability was found in the control group. Among the three EPNs H. indica was highly pathogenic at a concentration of 1250 IJs/petri dish, inducing 100% mortality within 48-72 h when compared to S. carpocapsae and S. thermophilum.