Assessment of a liquid larval diet for rearing Dacus species and Bactrocera dorsalis (Diptera: Tephritidae)

Species of the genus Dacus are important insect pests of fruits and vegetables. Two Dacus species, Dacus punctatifrons Karsch and Dacus vertebratus Bezzi, as well as Bactrocera dorsalis (Hendel), were reared on a liquid artificial diet, a carrot (Daucus carota L.)-based solid artificial diet, and a natural fruit host to assess the suitability of the liquid diet for small-scale rearing of these species. Egg hatch, pupal production, adult emergence and F-1 productivity were recorded to evaluate performance of the three species on each diet. Egg hatch on the three diets was more than 50% for D.punctatifrons and B.dorsalis, but for D.vertebratus, egg hatch was less than 40% when they were introduced to the liquid artificial diet. Pupal production for both Dacus species was very low or nil on the liquid artificial diet and the carrot-based artificial diet, respectively. Adult emergence was low for D.punctatifrons and nil for D.vertebratus on the liquid artificial diet. This study showed that the two Dacus species did not develop well on either the liquid or solid carrot-based artificial diet whereas B.dorsalis performed well on the liquid diet. Cucumber, the natural host of both Dacus species, was better for small-scale rearing of these species than the liquid and carrot-based artificial diets. Nutrients found in cucumber need to be identified to formulate alternative rearing media for Dacus species that are economical and easy to use.