Efficacy of a synthetic amorphous zeolite against five species of stored-grain insects on wheat and concrete

Two different particle sizes (Coarse :Dv= 155 µm; Fine: Dv= 47.0 µm) of a synthetic zeolite (Odor-Z-Way®, sodium aluminum silicate) were tested for their ability to control adults of stored-grain insects on wheat and on concrete Petri dishes used to simulate floors of empty bins. Insect species included unsexed adults of the lesser grain borer, Rhyzopertha dominica (F.); rice weevil, Sitophilus oryzae (L.); maize weevil, Sitophilus zeamais (Motschuslky); red flour beetle, Tribolium castaneum (Herbst), and sawtoothed grain beetle, Oryzaephilus surinamensis (L.).

On concrete, arenas in 9-cm diameter Petri dishes were sprinkled with the synthetic zeolite to provide deposits of 0 (control), 5 and 10 g/m². Mortality was assessed from 10 minutes to 24 hours post-exposure followed by 48 hours recovery on wheat. Efficacy of the zeolite was dependent on the particle size and rate and duration of insects’ exposure. Adults of R. dominica were most susceptible.

On wheat, bioassays were conducted using rates from 0.05 to 3.0 g/kg. Mortality was assessed 7 days post-infestation. Efficacy was not related to particle size. A rate of 0.75 g/kg achieved 100% mortality in adults of S. zeamais, T. castaneum, and O. surinamensis. All adults of S. oryzae were killed using 0.50 g/kg. Adults of R. dominica were least susceptible: maximum application rate (3.0 g/kg) was required for 100% mortality.

This is the first study showing the efficacy of a synthetic zeolite against adults of stored-grain insects on concrete and wheat. Synthetic zeolites could be viable alternatives to currently used chemical pesticides.

Keywords: Stored-grain insects; Synthetic zeolite; Concrete surfaces; Wheat; Pest management; Efficacy assessment.