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New insights into the infection of the American cockroach Periplaneta americana nymphs with Metarhizium anisopliae s.l. (Ascomycota: Hypocreales)
Author(s) -
Gutierrez A.C.,
Machado J.A.R.,
HubnerCampos R.,
Pennisi M.A.,
Rodrigues J.,
López Lástra C.C.,
García J.J.,
Fernandes É.K.K.,
Luz C.
Publication year - 2016
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.13254
Subject(s) - nymph , metarhizium anisopliae , biology , periplaneta , cockroach , conidium , botany , cuticle (hair) , metarhizium , germination , microbiology and biotechnology , horticulture , ecology , anatomy
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 days 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 days 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 × 10 4 hyphal bodies (HB) nymph −1 and reduced the survival of nymphs ≤50%. Most nymphs (>70%) survived after injection of 6 × 10 3 and 2 × 10 3 HB nymph −1 . Conclusions Findings emphasize a distinct resistance of nymphs of the American cockroach to infections by M. anisopliae . Significance and Impact of the Study Our findings provide support for the development of biological control of this synanthropic cockroach pest.