Larvae of Diloboderus abderus Sturm (Coleoptera: Melolonthidae) is an important wheat (Triticum aestivum L.) pest under no-tillage system in the Southern region of Brazil. This study aimed to evaluate doses of different insecticides applied as seed treatment. The effectiveness of the insecticides were assessed by determining the number of larvae in the soil at 30, 60 and 90 days after emergence, the plant biomass at 90 days after emergence, the number of ears at 120 days after emergence and the grain yield. Significant negative correlations were obtained between doses of insecticides and number of larvae. Significant positive correlations were observed between doses of insecticides and plant biomass and number of ears. Larvae infestations in non-treated plots caused significant yield losses when compared to plots treated with insecticides. Increasing doses of insecticides increased yield. Although imidacloprid was not very effective in reducing larval population, doses above 350, 125, 320 and 42 g a.i. /100 kg of seeds of the insecticides thiodicarb, carbossulfan, furathiocarb and imidacloprid, respectively, were efficient in preventing reductions in grain yields on wheat, under inicial infestations between 18 and 26 larvae/m².
Insecta; Scarabaeidae; chemical control; tillage system
