Laboratory evaluation of insecticidal effectiveness of a natural zeolite formulation against Sitophilus oryzae (L.), Rhyzopertha dominica (F.) and Tribolium castaneum (Herbst) in treated wheat

Inert dusts are increasingly becoming an integral part of programs for protection of cereal grains from stored-product insects.The intention in this study was therefore to conduct preliminary tests of insecticidal potentials of the natural zeolite formulation Minazel SP (66% SiO 2 , particle size ≤ 50 μm) originating from Serbia in controlling S. oryzae, R. dominica and T. castaneum.Dust effectiveness was tested in the laboratory (24±1ºC and 50-55% r.h. for parents and 24±1ºC and 60±5% r.h. for F 1 progeny) by exposing insects to wheat treated with 0.50, 0.75 and 1.00 g/kg of Minazel SP.Mortality was determined after 7, 14 and 21 days of insect contact with threated wheat, and total mortality after an additional 7 days of recovery on untreated broken wheat.Progeny production in F 1 generation was also determined for each insect species after 8-12 weeks.After seven days of exposure and 7 days of recovery of all tested species, the highest efficacy of 62% was observed after the highest application rate of 1.00 g/kg against S. oryzae.The highest efficacy after 14 and 21 days was achieved with the same application rate against T. castaneum (100%), S. oryzae (96-98%) and R. dominica (70-82%).Progeny reduction (IR -inhibition rate) of all tested species depended on the duration of parents exposure to treated wheat.After 7 days of exposure progeny reduction rates were 49-67% for S. oryzae, 42-68% for R. dominica and 47-78% for T. castaneum.After 14 days of exposure, inhibition rates were 55-78% for S. oryzae, 72-81% for R. dominica and 53-90% for T. castaneum, while progeny reductions of S. oryzae were 51-85%, R. dominica 80-96% and T. castaneum 87-99% after 21 days of exposure.