PELLETS MADE FROM PLANT STRUCTURES AND ESSENTIAL OIL OBTAINED FROM LEAVES OF Ageratum conyzoides L. AFFECTING THE DEVELOPMENT OF Sitophilus oryzae

Abstract

The objectives of this study were to evaluate the effect of pellets, made from either vegetative and reproductive plant structures powder or essential oil obtained from leaves of billy goat weed, on the development of Sitophilus oryzae (L., 1763) (Coleoptera: Curculionidae), as well as to determine the period in which they could be stored without losing their insecticidal action. Pellets made from powders of different billy goat weed structures (root, leaf, inflorescence, and seeds) were stored for 2, 60, 120, and 180 days, and those made from essential oil were stored for 2 and 60 days. The billy goat weed presents insecticidal activity on S. oryzae, depending on the plant structure and concentration in the pellet. Pellets made from leaves and seeds, at the concentration of 0.5%, provided a better S. oryzae control, affecting more the emergence of insects than their development cycle. Pellets made from any plant structure, except for root, at 5.0%, can be stored for up to 180 days without losing their insecticidal action, while, at 0.5%, the storage period should be less than 60 days. Pellets made from essential oil of billy goat weed leaves can not be stored under uncontrolled conditions and reduce the S. oryzae population, but do not eliminate it, at concentrations of up to 0.5 µg L^-1.

KEY-WORDS: Insecta; biopesticide plant; weevil; billy goat weed.