The effect of CO2 and N2 gases on different stages of Ephestia cautella (Walker) Lepidoptera: Pyralidae

Ephestia cautella (Walker) (Lepidoptera: Pyralidae) causes severe damage to dates held in storage. Losses may increase up to 100% if the pest is not properly controlled. In present study, we evaluated the effect of CO₂ and N₂ gas on eggs, larval, and pupal stages of E. cautella at 5 and 25 ºC temperatures. 

A day old eggs, 15-days old larvae, and 1-2days old pupae of E. cautella used in the experiments were obtained from the mass culture maintained in the laboratory on artificial diet (1 kg diet containing (375g broiler diet + 375g layer diet + 250g wheat flour ) + 100ml Glycerin) at 25 ºC with 65± 5% RH and a photoperiod of 15:9 (L:D) in incubator.

The experiments were laid out in Complete Randomize Design (CRD) with 6-treatments : 1. Co₂ (0%) + N (100%), 2. Co₂ (25%) + N (75%), 3. Co₂ (50%) + N (50%), 4. Co₂ (75%) + N (25%), 5. Co₂ (100%) + N (0%), 6. Control (Atmospheric air),  4- times of exposures (5, 24, 48, and 72) and 2- temperature regimes (5 and 25 ºC) while 70% relative humidity and 15:9 (L:D) photoperiod were remained constant.

The results indicated that CO₂ gas at higher concentrations significantly affected eggs, larval and pupal stages at both temperatures. Promising results were recorded at 100 and 75% CO₂ concentrations for 48 hours and above exposure times. Below 50% CO₂, even for the longer exposure time did not show required results. There was 100% larval mortality when exposed to 100% CO₂ gas for 24 hours and above at 25 ºC. Stage wise comparison of E. cautella mortality revealed that larval stage was more vulnerable to gases followed by pupal and egg stages. Results also indicated significantly greater mortality with increased exposure time. Our results also indicated that temperature did not have significant effect on the efficacy of gases. It is concluded that CO₂ gas can be used successfully for the control of E. cautella in dates under storage and can be a potential alternative to methyl bromide.