An artificial diet for rearing three exotic longhorn beetles invasive to Europe

Anoplophora glabripennis, Anoplophora chinensis and Psacothea hilaris hilaris are three invasive exotic longhorn species (Coleoptera Cerambycidae) threatening native broadleaf trees in Europe and North America. Field studies on invasive species are somewhat difficult in the areas of introduction due to the application of eradication measures and the activation of quarantine protocols. Rearing these species in standard laboratory conditions would allow specific ecological and biological investigations to be conducted. In this paper, the rearing of these longhorn beetles has been tested on an artificial diet in laboratory conditions. The tested diet can be used to obtain viable healthy adults of each of the three studied species. P. h. hilaris had the best rearing performance with 74% of eggs producing new adults, while A. chinensis and A. glabripennis were poorer with 24.7% and 23.3%, respectively. The low percentage of emerging A. glabripennis and A. chinensis adults was due mainly to a high mortality of their first instar larvae not entering the diet. Moreover, A. chinensis and A. glabripennis had a mean development time, 60.06 and 37.29 weeks, respectively (including the chilling periods required for pupation), longer than P. h. hilaris (16.1 weeks). During development, larval moults varied according to species and within species ranging from 5-7 (P. h. hilaris), 6-11 (A. chinensis) and 7-8 (A. glabripennis) moults, respectively. Adults of A. glabripennis and P. h. hilaris reared on the diet were bigger than wild specimens collected from the same population, whereas A. chinensis adults were smaller. Adult survival was shorter in A. glabripennis (62.9 days) than in P. h. hilaris (119.3 days). According to the different performance of the three species, the rearing costs were about 2.0, 8.1 and 16.1 US dollars per adult beetle for P. h. hilaris, A. glabripennis and A. chinensis, respectively. A laboratory insect population has to be cost effective and self-sustainable over time, and the tested diet provided valuable results for the low-cost mass rearing of these invasive longhorn beetles.