Evaluation Of Entomopathogenic Effects Of The Fungi, Metarhizium Anisopliae And Beauveria Bassiana For Biological Control Of Rhipicephalus (Boophilus) Decoloratus
Abstract
Rhipicephalus decoloratus causes heavy losses economically in livestock annually. Currently,
control of ticks is done using acaricides but use of other alternatives such as biological control is
being studied. Twelve fungal isolates; seven Metarhizium anisopliae and five Beauveria
bassiana obtained from ICIPE Arthropod’s germplasm were pretested for their germination
potential and conidial viability, results of which indicated that their viability ranged from 96.6 %
for ICIPE 644 to 100% for ICIPE 9, ICIPE 7 and ICIPE 718. The mortality of fungal isolates that
was pathogenic to amitraz-susceptible and amitraz-resistant strains of R. decoloratus larvae,
ranged from 10.0 to 100% and 12.1 to 100%, respectively. For the selected fungal isolates, their
LT50 values ranged between 2.6 to 4.2 days in amitraz-susceptible strains and from 2.8 to 3.9
days in amitraz-resistant strains. Amitraz-susceptible strain showed LC50 values of between 0.4 ±
0.1 and 200.0 ± 60 x 103 conidia ml-1 while, amitraz-resistant strains had LC50 values ranging
from 0.1 ± 0.1 to 200.0 ± 31.0 x 103 conidia ml-1. ICIPE 7, M. anisopliae outperformed the other
eleven isolates and was selected for amitraz compatibility and field studies. It was also shown to
be compatible with amitraz. In the field study, four treatments; control, M. anisopliae alone,
amitraz alone and combination of M. anisopliae and amitraz were applied on cattle. All the
treatments significantly reduced tick numbers significantly on day 7, day 14, day 21 and day 28
in comparison with the control. Results of the present study demonstrated the potential value of
fungal pathogens for tick control; further research is needed to determine the association of
biological products with chemical products and ICIPE 7 should be improved for use as a mycoacaricide
and it can manage the amitraz resistant strains of R. decoloratus
Publisher
University of Nairobi
Rights
Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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