Effects of natural and synthetic zeolites against maize weevil (Sitophilus zeamais Motschulsky, Coleoptera, Curculionidae) adults under laboratory conditions

Abstract: Laboratory experiment was carried out to evaluate the impact of zeolites of different origin on the mortality of the maize weevil (Sitophilus zeamais Motschulsky) adults. We have tested the efficacy of natural zeolites (Slovenian and Serbian) and synthetic zeolites (‘Asorbio’). Diatomaceous earth (product SilicoSec® was used as positive control). We have applied zeolites as surface treatment (at concentrations 10 and 20 g/m2) and as admixtures (at concentrations 450 and 900 ppm). Mortality of weevils, when zeolites were applied as surface treatment was evaluated everyday till 7th day after application, and everyday till 14th day after application (as delayed mortality). When zeolites were admixed, we have evaluated mortality after 7th, 14th and 21st day. Research was performed at two different relative humidty values (55 and 75%), and at three different temperature (15, 20 and 25 °C). We conclude that mortality of maize weevil adults was influenced by higher temperature values and lower relative humidity value. When we have applied ‘Zeolite Slovenia’ (at 900 ppm, 15 °C, 55% Rh) as admixture we have recorded 69.69 ± 7.04% after day 21, meanwhile mortality reached 83.66 ± 3.21% after day 21, when ‘Zeolite Slovenia’ was applied at 25 °C. 100% mortality of maize weevil adults was recorded, when ‘Zeolite Slovenia’ (after day 7 at 25 °C) was applied at surface. There was no impact of zeolite’s dose on mortality of maize weevils. Mortality of weevils was alike in two natural zeolites (Slovenian and Serbian), meanwhile mortality of maize weevils was the lowest in treatments with ‘Asorbio’. Use of natural zeolites proved to be efficient as stored product protectant in our research, although additional surveys should be made.