Efficacy of two microbial insecticides in combination with carbon dioxide for the control of Trogoderma granarium in stored wheat grains

The potential of individual and combined treatments of two microbial insecticides, abamectin (AB) and emamectin benzoate (EM), and carbon dioxide (CD) for controlling Trogoderma granarium Everts on wheat grains was investigated. The effects of single and combined treatments on larval mortality after 7, 14 and 21 days, F₁ progeny after 30 days, F₂ progeny and weight loss of wheat after 80 days of treatment were measured. Results revealed that the mixtures of CD and two MIs were more effective in the controlling T. granarium than CD or MIs alone. The two mixtures, CD (40 %) + AB (1.0 mg/kg) and CD (40 %) + EM (1.0 mg/kg) achieved a maximum larval mortality (97.2 and 90.5 %, respectively) 21 days post treatment. Furthermore, AB alone and its combinations with CD caused a strong inhibition of emerged adults during two generations (≤ 1.0 adults). Treatments with EM produced the greatest decrease of adult production and the complete inhibition of F₁ and F₂ adult production when applied as the mixture of CD (40 %) + EM (1.0 mg/kg). Similarly, all MIs alone or their mixtures with CD caused a full protection of grains (weight loss ≤ 1.0 %) against khapra beetle damage for 80 days.