Manipulating larval rearing media to optimise mass production of the blow fly Calliphora vicina (Diptera: Calliphoridae)

The oviparous blow fly Calliphora vicina has shown potential as a managed pollinator to support honeybee (Apis mellifera) usage in Australian horticulture. A series of three laboratory-based studies reared newly hatched larvae of C. vicina on meatmeal with varying amounts of either whole egg powder, whole eggs (including shells), bran flakes, brewer's yeast, fish paste or milk powder. The objective was to determine the best larval media for quick and efficient production of adult flies in a mass-rearing environment. Pure meatmeal or meatmeal with only brewer's yeast added were the least productive media. Larvae fed meatmeal with either 10% or 20% whole dried egg powder had the fastest development to pupae, the highest pupation rate, the heaviest pupae and the highest subsequent adult eclosion. Larval media containing fish paste had the highest survival through to adult emergence (>85%) of all the media treatments, which suggests that this ingredient is of value when mass rearing C. vicina. In addition, newly hatched larvae (n = 50) were reared on varying amounts of media (i.e., 4, 2, 1, 0.5, 0.25 and 0.125 g per larvae) to determine the minimum amount of media required to produce adults. Reductions in media per larvae resulted in smaller pupae and adults that emerged with no subsequent reduction in adult eclosion, indicating the adaptability of this fly to food deprivation. Replacing whole egg powder with whole eggs reduces the costs of rearing C. vicina larvae significantly. In order to rear 1 million adult C. vicina, these studies showed that 0.5 g of media per larvae is sufficient to produce high numbers of pupae with >95% adult eclosion. Although larval development and pupation are optimal on media containing whole egg powder, its recent rapid rise in costs makes it far less economical compared with the use of discarded whole eggs from egg producers. Sourcing of seafood waste could also reduce media costs and improve production of C. vicina. The costs of each media required to realise 1 million adult C. vicina are between $540 and $1900 depending on the media ingredients.