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Estimation of oral toxicity of boron as a bait toxicant and the trophallactic effects between individual members of termite colonies.
2003 - IRG/WP 03-10495
In recent years, because of the favourable environmental characteristics of boron, researchers in the wood preservation industries have refocussed on the use of boron as a major wood preservative against wood-destroying insects. Currently the greatest use of boron compounds is in remedial treatments. Boron has been found to have slow-acting toxicity against subterranean termites. Because of this characteristic, boron compounds may also be used as termite bait toxicants. The effect of boric acid on an individual donor termite was investigated in laboratory bioassays Trophallactic transfer of boron by these individual termites to other orphaned group of termite workers was conducted and the effects on the recipient groups recorded. It was believed that, this sequence of tests would provide a greater understanding of the carrying ability of ‘bait toxicant’ by individual termites, and allow estimates of the threshold toxicity of boric acid and termite survival rates to be determined. The bait matrix was Eucalyptus regnans F. Muell sawdust impregnated with various formulations of boric acid solutions in the laboratory. The result suggests that the toxicity of boron is dose dependent and it critical for the termites to ingest sufficient amounts of boron. But the mode of toxicity of boron has not yet been fully explained.
B M Ahmed


Transfer of thiamethoxam from exposed to non-exposed workers of Microcerotermes diversus Silvestri (Isoptera: Termitidae)
2012 - IRG/WP 12-10783
Because Microcerotermes diversus (Silvestri), a subterranean termite, is able to attack cellulosic materials, it is destructive to structures and the most economically important wood pest in Iran. Therefore, control or management of the termite is a serious public concern. The use of nonrepellent termiticides such as thiamethoxam (a neonicotinoid compound) has been gaining popularity in recent years. The success of these compounds in managing termite infestations depends primarily on their speed of action and non-repellent characteristics. The current study was designed to determine termite mortality, non-repellency, and horizontal transfer of termiticide by trophallaxis when termites were in contact with treated-filter paper in laboratory choice and no-choice tests. A donor-recipient trial in two ratios was used: 1:1(10 donors: 10 recipients) and 1:5 (10 donors: 50 recipients). In one trial, workers were placed on filter paper previously treated at 5.0, 10.0 or 15.0 ppm thiamethoxam. Exposed workers were then removed from the treated paper, placed in a clean container, and allowed to have side-by-side feeding interactions with previously non-exposed recipient workers for 14 days, after which mortality was assessed. Results indicated that mortality of non-exposed workers contacted by the exposed workers increased with increasing of insecticide concentrations in both donor-recipient worker ratios. Therefore, transfer of lethal insecticide concentrations from the donor to recipients was observed with thiamethoxam.
Z Fathollahi, B Habibpour