Research on insecticidal efficacy of three different wood ashes against maize weevil (Sitophilus zeamais Motschulsky, Coleoptera, Curculionidae) adults under laboratory conditions

Abstract: The effectiveness of three different wood ashes from black locust (Robinia pseudoacacia), beech (Fagus sylvatica), and Norway spruce (Picea abies) were evaluated on maize weevil (Sitophilus zeamais) regarding adult (2-4 weeks old) mortality. Diatomaceous earth served as positive control. We have tested wood ashes as surface treatment (10 and 20 g/m2) and as admixtures (2.5 and 5 w%). Mortality of weevils, when wood ashes were applied as surface treatment was evaluated every day till 7th day of application, and every day till 14th day of application (as delayed mortality). When wood ashes were admixed, we have evaluated mortality after 7, 14 and 21st day. Research was performed at two different relative humidty values (55 and 75%) and at three different temperatures (15, 20 and 25 °C). Based on the results of our survey we conclude that mortality of Sitophilus zeamais adults was influenced by wood ash species, air temperature and relative humidity. As surface treatment, 99.69 ± 0.31% mortality was achived at treatment with Norway spruce on day 7 at 25 °C. When admixed, 100% mortality was achieved on day 14, when Norway spruce’s wood ash has been applied at 25 °C.Use of wood ash as stored product protectant proved to be efficient in our survey, although additional reseach should be made.