New insights into the infection of the American cockroach Periplaneta americana nymphs with Metarhizium anisopliae s.l. (Ascomycota: Hypocreales)

HUBNER-CAMPOS R.; LÓPEZ LASTRA, C; LUZ C.; HUBNER-CAMPOS R.; LÓPEZ LASTRA, C; LUZ C.; GUTIERREZ A.C.; PENNISI M.; GARCÍA, J.J; GUTIERREZ A.C.; PENNISI M.; GARCÍA, J.J; MACHADO JAR; RODRIGUES J.; FERNANDES EK; MACHADO JAR; RODRIGUES J.; FERNANDES EK

JOURNAL OF APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 121 p. 1373 - 1383

1364-5072

Aims:To study the marked resistance of Periplaneta americana to entomopathogenic Metarhizium anisopliae. Methods and Results: The low susceptibility of 4th instar nymphs applied topically with conidia seemed to be related to an active removal of conidia by the cockroach and to a disabled or retarded germination and subsequent development of conidia on the cuticle (up to 80% germination in the next 7 d after application). Inhibitions or delays of germination were related to the composition of the epicuticular fatty acids (30.1% w/w oleic, 28.3% w/w linoleic, 24.5% w/w palmitic and 11.7% w/w stearic acid) reported here. Propagules invading the nymphs through the cuticle took at least 3 d to reach the haemocoel, and no propagules were found after day 8 post-treatment. Strain IP 46 infected > 50% of nymphs treated with doses ≥ 2 x 104 HB nymph-1 and reduced the survival of nymphs ≤ 50%. Most nymphs (> 70%) survived after injection of 6 x 103 and 2 x 103 HBnymph-1.