Ethyl formate as a fumigant to control the stored date insects in a prototype and its impact on date fruit quality

Abstract

The date fruits contribute significantly to food security and population livelihoods, providing a wide range of products. Thus, the present study aimed to conduct a survey over a year, from September 2020 to August 2021, to explore the most common insect species infesting the date fruits of 11 varieties in storehouses. The 11 varieties comprised nine dry date varieties collected from Aswan Governorate and Siwa Oasis, along with two semi-dry date varieties obtained from New Valley Governorate, Egypt. In a prototype, the efficacy of the EF/CO₂ (16.7%/83.3%, w/w) at 270, 420, and 670 g/m³ was evaluated against the most common insect species found in the date varieties. Moreover, the impact of fumigation by the EF/CO₂ (670 g/m³) on the quality parameters of Ghazali as dry and Elwadi-I as semi-dry date varieties was studied. The almond moth, Ephestia cautella, was the most abundant insect species, followed by the saw-toothed grain beetle, Oryzaephilus surinamensis, and the red flour beetle, Tribolium castaneum. The highest infestation percentage (43.7%) of E. cautella was recorded on Shamia variety, while the lowest infestation percentage (9.8%) was on Elwadi-Ⅱ variety. The Malkabi variety had the highest infestation percentage of O. surinamensis at 23.6%, while the Elwadi-Ⅱ variety had the lowest infestation percentage at 5.4%. The infestation percentages of T. castaneum were the lowest among insect species, ranging from 0.2 to 1.0%. The EF/CO₂ mixture was highly toxic to all life stages of the three insect species at all application rates, giving complete control at 420 and 670 g/m³. No significant differences in the quality parameters have been observed between untreated and treated samples of Ghazali and Elwadi-I varieties with EF/CO₂ at 670 g/m³. The present study suggests that the EF/CO₂ mixture could be a promising alternative fumigant to protect the date fruits in storehouses from insect pests.