NHA Choice test: Feeding dilemma for Reticulitermes flavipes (Kollar)
F Green III, S N Kartal, P K Lebow, R A Arango
An AWPA laboratory choice test was performed with Reticulitermes flavipes (Kollar) to determine the role of feeding stimulation or aggregation by N’N napthaloylhydroxylamine (NHA). Pine blocks were vacuum treated with aqueous concentrations of NHA ranging from 250-10,000ppm and exposed to one gram R. flavipes workers in the dual block choice test which included one treated and one untreated block per modified AWPA laboratory test (E1-97) jar. At the end of four weeks, all test blocks were removed and replaced by either filter paper or untreated pine or aspen to observe long-term mortality/survival. Removed blocks were evaluated for mass loss and statisitical evaluation. Mass loss was consistently greater in the untreated-pair blocks and ranged from 18-35%. Weight loss in the NHA-treated blocks was highest at low concentrations (18%) and decreased to < 5% at 10,000ppm. Termite mortality at the end of four weeks was observed nearly zero, however, over the next 12 weeks worker mortality reached 100% in certain groups. Filter paper or control pine was supplemented after the 4 week test period. We hypothesize that exposure to untreated pine during exposure to the NHA blocks delayed the 100% mortality previously observed in similar no-choice test using similar NHA concentrations of NHA, possibly by reduction below toxic levels. Modest accelerated feeding (stimulation) of the control blocks was observed only in the 2600ppm group. Overall, NHA treatment in pine behaves like a typical repellent wood preservative: as the concentration of preservative increases, feeding and mass loss decreases, however addition of an untreated pine block abrogates the high toxicity of NHA to R. flavipes (100%) as previously seen in several no-choice tests.