Toxic and repellent effects of 2′-acetonaphthone on Coptotermes formosanus (Isoptera: Rhinotermitidae)
2′-Acetonaphthone was evaluated for its toxicity and repellency on Coptotermes formosanus. In topical application assays using 2′- acetonaphthone on termites from four different colonies, the 24 h-LD 50s ranged from 1.75 to 7.24 μg/worker and 2.16 to 5.12 μg/soldier and the 48 h LD90s ranged from 3.09 to 12.32 μg/termite. For each colony, soldiers and workers responded similarly with no significant difference between 24 h and 48 h toxicity data. Termites from one colony showed a 2- to 4-fold increase in tolerance to 2′-acetonaphthone compared to the other 3 colonies. In no-choice assays, filter paper impregnated in 2′-acetonaphthone solutions at ≥ 0.05% (% AI in ethyl alcohol) was toxic to workers and soldiers at 24 h and resulted in 100% mortality by day 5. In two-choice assays with treated and untreated filter paper, 2′-acetonaphthone was repellent at ≥ 5 μg/cm2 and resulted in a significant reduction in food consumption at ≥ 20 μg/cm 2. In two-choice assays, the survival rate of termites exposed to 40 μg/cm2 for 15 d was not different from the control. The same concentration resulted in 100% mortality within 8 h in no-choice assays. In sand barrier assays using 2′-acetonaphthone at 8 mg (AI)/kg sand, the presence of 10% soldiers increased the repellency compared to assays where workers were without any soldiers.