Initial test of a semiartificial diet for the thistle biocontrol beetle, Cassida rubiginosa

• DOI: 10.30843/nzpp.2022.75.11758
• Publication Date: 2022-07-14T11:25:30Z
• Authors: Michael Cripps; Jonty Mills; Laura Villamizar; Chikako Van Koten
• Keywords: Cirsium arvense

The thistle biocontrol beetle, Cassida rubiginosa is established in New Zealand, but often not sufficiently abundant to achieve control of the weed, Cirsium arvense (Californian thistle). Mass production beetle could enhance efforts through supplemental and inundative releases. We carried out an initial test a semiartificial diet (containing host plant material) designed for laboratory mass beetle. Larval survival rates were tested on diets with three different concentrations preservatives (full, half, no preservative), compared positive (leaf disc arvense), negative (water). Only larvae leaf developed adult stage. Of diets, longest time was full preservative diet, mean mortality 8.8 ± 0.6 days, maximum 21 days. Although completed development some important progress achieved: (1) Neonate mobile diet; (2) fed (3) there adequate microbial contamination without being acutely toxic larvae. Further should focus nutritional components larval development.