Insecticidal efficacy of local diatomaceous earths against adult and larvae of Tenebrio molitor L., 1758 (Coleoptera: Tenebrionidae)

In this study, insecticidal activity of diatomaceous earths (DE) of different particle size (Turco 000, 004 and 020) obtained from domestic sources in Turkey were tested against Tenebrio molitor L., 1758 (Coleoptera: Tenebrionidae) larvae and adults under laboratory conditions. DE were tested against larvae and adults of T. molitor at four different rates (0, 0.001, 0.002, 0.003 and 0.004 mg/cm(2)), and LC50 and LC90 values were calculated. Turco 000 grade DE with the smallest particle size had 100% efficacy at all rates against the adults at 60 h, and after 48 h, LC50 and LC90 values were 0.006 and 0.019 g/cm(2), respectively. After 48 h treatment, the LC50 and LC90 values for Turco 004 were 0.013 and 0.022 g/cm(2), respectively, whereas they were 0.022 and 0.041 g/cm(2)with Turco 020, respectively. The DE applied to the larvae had activity in varying proportions. LC50 values were 0.014, 0.034 and 0.032 g/cm(2) after 72 h for Turco 000, 004 and 020 , respectively. LC90 values were 0.053, 0.089 and 0.075 g/cm(2), respectively. The results obtained in this study are promising for control of this pest with local DE.