Artificial diets for rearing Euseius scutalis (Acari: Phytoseiidae)

Mass rearing of the predatory mite Euseius scutalis (Athias-Henriot) using natural prey is costly and labor-intensive, limiting its application in biological pest control. Artificial diets may serve as alternative food sources; however, some studies should be previously conducted, to evaluate the possible biological consequences of their adoption. In this study, we compared the suitability of eight artificial diets, including a basic artificial diet (A) consisting of a combination of 10% honey, 10% sucrose, 5% tryptone, 5% yeast extract, 10% egg yolk, and 60% distilled water (w/w), along with seven other diets, each consisting of 80% of diet A enriched with date palm pollen (B), Typha pollen (C), Ephestia kuehniella eggs (D), Helicoverpa armigera hemolymph (E), a mixture of date palm pollen and E. kuehniella eggs (F), Tetranychus turkestani adults (G), and hen's liver (H). The data showed that E. scutalis was able to complete its development on all tested diets. Oviposition of the predator was observed on all diets, except for diets E and H. Females reared on diets B and F had the shortest adult pre-oviposition period (APOP), while those on diet B had the shortest total pre-oviposition period (TPOP). Furthermore, the number of oviposition days and fecundity were highest on diets B, D and F. Diets B and F resulted in significantly higher intrinsic (r) and finite (λ) rates of increase than the other diets, with values statistically similar to those obtained on D. The lowest values of r and λ were recorded on diet G. Based on our results, date palm pollen, E. kuehniella eggs or their mixture added to the basic diet A are more beneficial than other options for use in artificial diets for the mass rearing of E. scutalis.