LEAF ESSENTIAL OIL FROM Croton pulegiodorus Baill SHOWS INSECTICIDAL ACTIVITY AGAINST Sitophilus zeamais Motschulsky

The present study aimed to assess the effects of the essential oil of Croton pulegiodorus Baill on eight populations of Sitophilus zeamais Motschulsky with different patterns of susceptibility to synthetic insecticides. Populations of S. zeamais were obtained from Sete Lagoas-MG, Jacarezinho-PR, Bom Conselho-PE, Garanhuns-PE, Jupi-PE, Lajedo-PE, Sao Joao-PE and Serra Talhada-PE. To estimate the lethal concentrations (LC50 and LC90) of oil for each population, fumigation tests were performed. The susceptibility of S. zeamais to the essential oil varied among populations. Garanhuns and Bom Conselho was considered the susceptibility patterns, presenting the lowest LC50 (3.40 mu L L-1 of air) and LC90 (9.60 mu L L-1 of air) for the essential oil, respectively. The population from Jupi exhibited the highest LC50 (14.49 mu L L-1 of air) and LC90 (19.60 mu L L-1 of air) for C. pulegiodorus. The resistance ratio ranged from 1.84 for the Sao Joao to 4.26 for the Jupi population. Thus, the essential oil of C. pulegiodorus showed fumigant activity, causing mortality in all S. zeamais populations used.