Effects Of Clay And Trichoderma Spp. On The Foraging And Aggregation Behavior Of Termites

Some subterranean termites live underground,and are closely associated with soil and soil microorganisms.Previous studies showed that many wood-rotting fungi were attracted to termites,however,little attention had been paid to the relationship between termites and soil fungi.In addition,subterranean termites often transport soil into bait stations,but the biological significance of this behavior remained unclear.In the present study,the effects of soil and soil microorganisms on the behavior of the subterranean termites were investigated.(1)Different two-choice tests were conducted to investigate the aggregation,foraging and tunneling behavior of Coptotermes formosanus Shiraki(wood-feeding lower termites)and Odontotermes formosanus Shiraki(fungus-growing higher termites),in response to soil or sand treated with the commercial conidial formulations of Trichoderma harzianum Rifai or Trichoderma viride Persoon ex Fries.In the short-term(1 d)choice tests,the percentage of termites(C.formosanus and O.formosanus)was not significant different between untreated and Trichoderma-treated soil.However,long-term choice tests showed that compared to containing untreated soil,significantly more wood consumtion of C.formosanus in the chambers containing soil treated with the conidial formulation of T.viride(1×10~8 conidia/g)was detected.The tunneling choice tests showed that sand treated with T.harzianum(1×10~6 conidia/g)or T.viride(1×10~6 or 1×10~8 conidia/g)significantly increased length and area of the tunneling of C.formosanus.However,sand treated with T.viride(1×10~6 or 1×10~8 conidia/g)had repellent effects on O.formosanus.(2)In this study,choice tests were conducted in the laboratory to investigate the aggregation and feeding preference(wood consumption)and no-choice were conducted in the laboratory to investigate the survivorship,wood consumption,and body water percentage of termites,in response to food containers(placing a pine-wood block into a bigger plastic box with termite-entering holes on the wall to simulate the bait station)with the void space filled with soil(sandy clay loam),sodium bentonite or remained unfilled.In the choice tests,under low moisture conditions,the percentages of termites(C.formosanus and Reticulitermes guangzhouensis Ping(Blattodea:Rhinotermitidae))was aggregated in the food containers filled with sodium bentonite were significantly more than that food containers filled with soil,or unfilled.Under high-moisture conditions,however,the termites were aggregated in the food containers filled with soil or sodium bentonite were no significantly different,but both were significant higher than unfilled ones.No-choice tests showed that there were the highest survivorship and wood consumption of C.formosanus were detected under high-moisture conditions in food containers were filled with sodium bentonite but the lowest survivorship and wood consumption were detected under low-moisture conditions in food containers were filled with soil.Interestingly,under low moisture conditions,filled with sodium bentonite increased the body water percentage of termites.(3)In the field study,multiple-choice tests(bait stations that were filled with soil treated with the conidial formulations of T.viride,untreated soil,sodium bentonite or remained unfilled)were conducted to investigate the feeding wood bait of termites.Results showed that the percentage of wood consumption and wood damage were not significantly different among these treatments.This study showed that the conidial formulations of T.viride were attractive to C.formosanus and may impore baiting infestation.Also,filled with the bait station may be a practical operation to increase the recruitment and feeding activities of subterranean termites.In the selection of filling materials,bentonite may be a more suitable material than soil,because it can attract termites,regardless of the dry and wet conditions.However,more field studies are needed to investigate the period of rainfall and the rainy season on termite aggregation and feeding under natural conditions.