1999 Volume 34 Issue 4 Pages 501-505
An auto-infection system consisting of a modified sex pheromone trap and a bottle with exit holes containing conidia of the fungus Beauveria bassiana (9.3×1010/1g medium) was designed and tested to control the sweet potato weevil, Cylas formicarius (Fabricius) (SPW). Male weevils were attracted to the system by the phero-mone and exited the bottle after infection. In the sweet potato field where the systems were placed, the highest mortality of males by the disease was 96.2% on 21 days after treatment and that of females was 33.0% on 49 days. Rates of fungus carrier were 57.9% in males and 31.6% in females. In the treated field, the sex ratio of the SPW population was greatly skewed to females. Females seemed to be infected through mating with fungus carrier males. The advantages of this system are : 1) Attracted males are efficiently auto-infected with the fungus ; 2) only SPW is infected by this system ; 3) the fungus is easy to mass-produce ; 4) the cost of this system is low as compared with conventional field sprays ; 5) once attracted and infected, males can be expected to return to their habitat, which accelerates dispersal of the fungus.
