Biological control of subterranean termites (Isoptera: Termitidae) with soil bacteria
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Date
2014
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Publisher
CCSHAU
Abstract
Selected ten bacterial strains having termite killing ability along with two control strains was
studied for antagonistic interactions with local soil termites. Live bacterial cells, heat killed cells and
culture supernatants were tested for termiticidal activity. Different bacterial strains showed more than
80% killing of termites at 5 days of incubation. Four bacterial strains KBM79, KPM35, PPM147 and
PBM195 caused 100% killing at 10 days of observation. The cell free culture filtrate studies of these
antagonistic cultures showed that antagonistic substance is extracellular. Termite mortality percentage
increased when culture supernatants were used as compared to whole cell broth of bacterial strains. The
killing frequency of the culture supernatants obtained from different bacterial strains varied from 78.0
to 96.0% at 2nd day of observation. Termicidal activity was lost on treatment of whole cell broth and
culture supernatant of bacterial strains by incubation at high temperature (1000C for 10 minutes).
Bacterial strains KBM79 and KPM35 possessed proteolytic, lipolytic and chitinolytic enzyme activities
and caused 100% killing of termites at 10 days. Partial purified proteins caused 100% killing of
termites within half an hour. The SDS–PAGE analysis of selected bacterial strains showed four
common protein/polypeptides having molecular weight 129 KDa, 37.1 KDa, 28.7 KDa and 26.3 KDa
in all the ten bacterial strains. These proteins/polypeptides were missing in control bacterial strains
WPS73 and KPM31. Plasmid-cured strain KPM35 lost the protein band having molecular weight 129
KDa. Termiticidal activity was also decreased in plasmid-cured strain KPM35 indicating that some of
the termiticidal genes were located on the plasmid. Moreover, crude preparation and partial purified
protein of bacterial strains KBM79 and KPM35 when treated with proteinase K lost the antagonistic
activity indicating that extracellular protein could be involved in termite mortality. Combination of
different chemical compounds with efficient bacterial strains showed high termite mortality than
individual insecticides. Application of bacterial strain KPM35 and dexamethasone (50 ug/ml) caused
100% mortality even at 12 hours of incubation. Dexamethasone alone was found more lethal than boric
acid and sodium citrate, and caused 90% mortality at 48 hours of incubation. Bacterial strains KBM79
and KPM35 were identified as Bacillus subtilis and Pseudomonas synxantha. These bacterial strains
could be further tested for termiticidal activity under field conditions.
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Keywords
biological phenomena, bacteria, proteins, enzymes, insecticides, productivity, poultry equipment, fungi, plasmids, selection