Optimizing diet thickness and egg density for economic mass rearing of Ephestia kuehniella Zeller, 1879 (Lepidoptera: Pyralidae): A laboratory host for biological control agents

Abstract

BackgroundMediterranean flour moth [Ephestia kuehniella Zeller, 1879 (Lepidoptera: Pyralidae)] (MFM hereafter) is a significant pest of stored products, particularly flour and causes significant economic damages. However, its eggs are important laboratory host for mass rearing of biological control agents of important agricultural pests. However, diet thickness and eggs’ density to be used in a specific area for economic mass rearing are not fully understood. MethodsThis study optimized the diet thickness and eggs’ density to be used in a specified area for harvesting higher number of MFM eggs with low cost. The MFM was reared under dark environment, i.e., 25 ± 1 °C temperature and 60–70% relative humidity in 32×26×6 cm plastic tubs. The diet consisted of wheat flour and wheat bran in 2:1 ratio by weight, respectively. Three diet thicknesses [i.e., 0.5 cm (thin), 1.5 cm (medium) and 2.5 cm (thick)] and three egg densities [i.e., 25 mg (low), 50 mg (medium) and 75 mg (high)] were tested to determine the most economic and productive combination. ResultsLife history traits, i.e., moths’ production, moths’ ratio and egg production were significantly altered by individual an interactive effect of diet thickness and egg density. The highest number of moths was obtained for medium diet thickness and high egg density. Medium diet thickness with low egg density resulted in the lowest number of moths. The highest number of eggs were produced by thin and medium diets and high egg density combinations, and these combinations proved the most economic for mass production of 100 g eggs. ConclusionThe results of the current study indicated that combination of medium and thin diet thicknesses with high egg density are the most economic for mass production of MFM. Interestingly, the study revealed that terminating moths’ collection at 2nd week after first moth emergence and egg collection at 4 days after the moths are placed in egg laying containers is the most suitable time for the economic mass rearing of MFM. However, egg densities >75 mg need further testing on thin and medium diet thicknesses to explore whether they are more economic than recommended densities in this study.