The effect of temperature on [ 14 C]Þpronil uptake and transfer from donor (D) to recipient (R) Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae) workers was evaluated. Test chambers used in the Þpronil uptake study were constructed from petri dishes containing autoclaved soil treated with 1 ppm [ 14 C]Þpronil (1.14 Ci of total radioactivity per petri dish), distilled water, and R. flavipes workers. Test chambers were held in environmental growth chambers preset at 12, 17, 22, 27,

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... 32ЊC. For the Þpronil transfer study, donor termites stained with Nile blue-A were exposed to soil treated with 1 ppm [ 14 C]Þpronil for 2 h. Donors were then combined with unexposed recipient termite workers at either 1D:5R, 1D:10R, or 1D:20R ratios. Test chambers consisted of a nest and feeding chamber connected by a piece of polyethylene tube and held in growth chambers at 12, 17, 22, 27, and 32ЊC. Worker termites were sampled over time and the amount of [ 14 C]Þpronil present was measured by scintillation counting. Some degree of uptake and transfer occurred at all temperatures and ratios in this study. The highest level of uptake occurred by termites held at 22Ð32ЊC, followed decreasingly by 17 and 12ЊC. Maximum transfer of [ 14 C]Þpronil occurred at the higher ratios (1:5 Ͼ 1:10 Ͼ 1:20) of donors to recipients. Data presented in this study suggest that temperature is one of the key factors affecting the rate of uptake and subsequent horizontal transfer of [ 14 C]Þpronil in subterranean termites. 30 35 J F M A M J J A S O N D Month Soil temp. (°C) at 10 cm depth Average Maximum Minimum Fig. 2. Average daily soil temperatures (Celsius) from 1995 to 2005 at 10-cm depth in Lincoln, NE.