Effects of CO2 dosage and expossure time on the mortality of adult and inmature stages of Sitophilus oryzae.

RICARDO BARTOSIK; DIRK MAIER; JUAN RODRIGUEZ

Sacramento, California, EEUU

Conferencia; Conferencia Anual de la Sociedad Americana de Ingenieria Agricola (ASAE); 2001

An experiment was carried out to determine the effect of CO2 dosage and exposure time on mortality of adult and non-adult stages of Sitophilus oryzae. The design of the experiment included three different CO2 concentrations (40-55-70 %) and four different ct-product dosages (approximately 6000-8000-12000-15000 %hs). The adult mortality was higher than 97.5% at any CO2 concentration and exposure time combination. Non-adult stages were less susceptible, and mortality ranged from 55% to 100%. The data showed that for the same ct-product ratio, except for 15000 %h, the lower the CO2 concentration the better the control. This means that the exposure time had a bigger relative effect than the CO2 concentration in the ct-product ratio. Minimum exposure time requirements for good non-adult control were 170 hours for 40 and 55%, and 220 hours for 70% CO2. The best combination caused 100% mortality with 55% CO2 during 266 hours of exposure (14614 %h).