Depth of initial penetration of two aqueous termiticide formulations as a function of soil type and soil moisture.
The initial penetration of two termiticide formulations, Premise 75 (imidacloprid) and Termidor SC (fipronil), were tested in four soils at three moisture levels (5, 10 and 15% by weight) in a laboratory study. Within each soil type and moisture combination, the highest concentrations of active ingredient were found in the top 1 cm of soil and decreased with increasing depth. As soil moisture increased, active ingredient concentration in the top 1 cm decreased while active ingredient concentration in lower depths, especially 2 to 5 cm, increased. For each compound, the effect of soil type on active ingredient penetration depended on the soil moisture and soil depth, with few effects at low moisture and greater depth. Soil type had little overall effect on the penetration of either compound, however, as both compounds were contained in the top 5 cm in each situation. Both compounds were the most toxic to termites in soils with low organic matter.