Efficacy of five Slovenian natural quartz sands admixed with wheat grainsagainst Sitophilus oryzae

Abstract: The efficacy of Slovenian quartz sands admixed with stored wheat was examinedagainst rice weevil (Sitophilus oryzae) in laboratory conditions. Five different samples of quartzsand of different age were tested: from location Raka-Ravno (with admixture and clean), locationMoravče (with admixture and clean) and commercially available cleaned quartz sand (Plantella)from Puconci locality, each at six concentrations: 100, 300, 500, 900, 1200 and 1500ppm. Theamount of SiO2 in all sand samples is high and varied from 91.52 to 99.24%. For each dose rate,the treated wheat grains were placed at two temperatures (25 and 30°C) and at 55% relativehumidity level. Dead adults were counted after 7, 14 and 21 d of exposure. After 21 d counts allthe exposed adults were removed and progeny production on treated grains was estimated after60 d. All samples showed some insecticidal effect on adults of rice weevil. Commercial quartzsand formulation showed the most promising results with approx. 90% mortality of rice weeviladults at 1500ppm and at 30°C. At this conditions the progeny production was the lowest (7adults per treatment) in experiment.