Mohammad Saaid Dayer Kayhan Karvandian Department of Parasitology and Medical Entomology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Department of Biotechnology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Arthropods ISSN 2224-4255 http://www.iaees.org/publications/journals/arthropods/online-version.asp 2016 5 3 114 124 International Academy of Ecology and Environmental Sciences Hong Kong 13 April 2016 22 May 2016 1 September 2016 German cockroach Metarhizium anisopliae boric acid synergism biological control probit analysis German cockroach is an important urban pest of worldwide distribution which harbors food poisoning and infectious organisms as well as allergens. In spite of the fact that insecticide application provides solution in severe cockroach infestation, it is associated with resistances development, pollution and economic lost. Integrated pest management (IPM) has been reported to be the best strategy for controlling such a nuisance pest. The main components of a successful IPM programme are biological agents and chemicals of reduced toxicity to non-target species. One of the biological agents which showed promising check on cockroaches is Metarhizium anispoliae (Metschnikoff) Sorokin. Also, boric acid has been traditionally used as a safe inorganic insecticide against many pest of agricultural and health importance. Boric acid and M. anisopliae showed not only compatibility, but also synergism in killing Blattella germanica, when applied as dust or liquid baits. However, incorporation and efficacy of both agents in semi-solid baits remains to be documented. This study revealed that boric acid incorporated at 8 gr/kg in semi-solid baits has no side effect on M. anisopliae but enhance its virulence causing higher mortality in adult males of German cockroaches. This study, also, showed that boric acid can be used at higher dosages without any harm to the fungal pathogen if allowed to be up-taken by the pest through cutaneous contacts and/or grooming. DOI 10.0000/issn-2224-4255-arthropods-2016-v5-0012 http://www.iaees.org/publications/journals/arthropods/articles/2016-5(3)/toxicity-of-Metarhizium-anisopliae-and-boric-acid-against-Blattella-germanica.pdf