Biological control of the black weevil (Scyphophorus interstitialis Gyllenhal) with entomophatogenic nematodes and fungi in agave in Oaxaca, México

This research was carried out under laboratory and field conditions. The laboratory experiments were carried out in the CIIDIR-IPN-Oaxaca in 2005. The field experiments were located at Tlacolula, Oaxaca during 2006. Besides, the negative effect of the bacterium Erwinia carotovora against fungi and entomopathogenic nematodes was evaluated. In the laboratory phase there were evaluated two species of fungi and four of entomopathogenic nematodes while in the field one fungus and four species of nematodes were evaluated against black weevils Scyphophorus interstitialis Gyllenhal. Bacterium E. carotovora did not present negative effects against entomopathogenic agents. In the experiments with larvae, the nematodes only needed 12 days to eliminate 100 % of the larvae and the fungi only needed 21 days to eliminate 100 % of the larvae of the third stage. Within 50 days, in the experiments with adults, there were found three treatments with nematodes that controlled 100 % of adults with a dosage of 9000 nematodes/individual and other two combined treatments with fungi + nematodes which controlled 90 % of the adult black weevils. On the basis of the field experiments of 2006, there were found three excellent treatments: native nematode (4500 nematodes/insect) with 90.31 % of efficiency, the second best was Steinernema feltiae (9000 nematodes/insect) with 84.23 % and the third one was Heterorhabditis bacteriophora (9000 nematodes/insect) with 78.23 % of efficiency.