The effect of modified atmospheres on the developmental stages of Sitotroga cerealella in stored wheat

Abstract

The efficacy of modified atmosphere with CO₂ gas in three concentrations (20, 40 and 80%) for seven exposure times against different stages of Sitotroga cerealella were assessed. Mortality percent of life stages, adult emergence, F₁ progeny, and chemical components in wheat grains were evaluated. The complete egg mortality (100 %) was achieved by 80% CO₂ and exposure time (48 h) with LT₅₀ value (2.5 h), 40 %CO₂ and exposure time (96 h) with LT₅₀ value (6.9 h) and 20% CO₂ and exposure time (120 h) with LT₅₀ value (18.8 h). The present study showed also, that larvae and pupae of S. cerealella were more tolerant than eggs. These two stages affected with increasing CO₂ concentrations resulted reduction in adult emergence. Furthermore, the full mortality of adults was obtained by 20% CO₂ after exposure time 96 h with LT₅₀ value (26.9 h) and 40% CO₂ after exposure time 72 h with LT₅₀ value (12.8 h), respectively. The modified atmosphere affected progeny and reduced the adult emergence and the F₁ generation more than half of resulted offspring from all life stages of S. cerealella. Also, the modified atmosphere caused slightly reduction in chemical components of wheat grains. These findings suggest that modified atmosphere may be a useful method for the management of this insect pest.