Interrelationships of the agave weevil Scyphophorus acupunctatus (Gyllenhal), Erwinia carotovora (Dye), entomopathogenic agents and agrochemicals

Abstract

Several chemical based methods for control of the bacterium Erwinia carotovorawere evaluated and its hosts and vectors were characterized as well. Besides, the effects of these bacteria on entomopathogenic fungi and nematodes, which are used in agave weevil control, were also evaluated. We also investigated the sensitivity of these bacteria, entomopathogenic fungi and nematodes to different agro-chemicals. We found that streptomycin sulphate and sulfur controlled or inhibited over 90% of the bacterial colonies, that the soil was not a reservoir for these bacteria and that adult insects of E. caratovora acted as vectors; only isolates from fresh agave leaves produced bacterial colonies. We concluded that E. carotovora did not affect the populations of fungi and entomopathogenic nematodes evaluated, but the fungicides tested decreased significantly the percentage of germination of spores of the fungi Beauveria bassiana and Metarhizum anisopliae. Mefenoxam (2 kg/ha) decreased spore germination by 83.5%, while chlorothalonil (2 kg/ha) reduced it to 77.5%. Regarding the insecticides tested, carbofuran (2 L/ha) eliminated 89% of the nematodes, while hexachloro (2.2 L/ha) controlled 76.5% of these. Keywords: Beauveria bassiana, Metarhizum anisopliae, Steinernema feltiae, agave weevil.