"The Last of Them": Entomopathogenic Effect of Akanthomyces muscarius on the Scale Insect Pest Toumeyella parvicornis Under Laboratory Conditions, a Potential Biological Control Candidate.

Entomopathogenic fungi are valuable alternatives to traditional agrochemicals, providing more sustainable crop protection. Akanthomyces spp. is acknowledged in biocontrol practices, especially in controlling aphids, thrips, whiteflies, and mites; however, its efficacy on soft scale insects is still poorly known. This study investigates the potential use of Akanthomyces muscarius on the soft scale insect Toumeyella parvicornis, a new invasive pest for European stone pines (Pinus pinea). The strain of A. muscarius tested in the experimentation has been isolated from Parthenolecanium corni, a soft scale insect on which the fungus seems to be highly infective. After molecular identification and characterization, bioassays were conducted to compare the performances of the different conidial concentrations of A. muscarius isolate and commercial formulations on T. parvicornis overwintering females and nymphs. Results showed a promising colonization and higher pathogenicity of A. muscarius on T. parvicornis in all the trials, compared with the other commercial formulations, in some cases showing a quick infection and death of the host. Our results pave the way to further field uses where A. muscarius is applied as a biological control method to reduce infestations of T. parvicornis.