Beauveria bassiana . [Descriptions of Fungi and Bacteria]

A description is provided for Beauveria bassiana . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS & SUBSTRATA: All stages of insects of all groups; lungs of wild rodents, nasal swab of horse; man; giant tortoise. The fungus overwinters in vegetable matter and is found in the soil. DISEASE: The fungus has been known since 1835 as the cause of the muscardine disease of silkworms. Although B. bassiana has multiplied in bees in laboratory tests it has so far not been recorded from bees in nature (Bailey, 1971). According to Wasti & Hartman (1975) penetration of the cuticle of gypsy moth ( Porthetria dispar [Lymantria dispar] ) larvae takes place 24 h after 2nd instar larvae have crawled over a culture of B. bassiana and within 64h the interior of the insect is completely filled with hyphae. These authors also note penetration of the gut wall. Fargues & Vey (1974), who sprayed conidia on to 3rd instar larvae of Leptinostarsa decemlineata (Colorado beetle), showed that conidia germinate on the surface of the integument, penetrate the loosening skin, and blastospores develop in the moulting fluid, infecting the new integument as it forms. Some individuals cannot finish the moult, in others the delicate new skin ruptures and hyphae enter the haemolymph. GEOGRAPHICAL DISTRIBUTION: World wide.