title: New insights into the infection of the American cockroach Periplaneta americana nymphs with Metarhizium anisopliae s.l. (Ascomycota: Hypocreales).
abstract: OBJECTIVE
  To study the marked resistance of Periplaneta americana to entomopathogenic Metarhizium anisopliae.
  
  
  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 × 104hyphal bodies (HB) nymph-1and reduced the survival of nymphs ≤50%. Most nymphs (>70%) survived after injection of 6 × 103and 2 × 103HB nymph-1.
  
  
  CONCLUSIONS
  Findings emphasize a distinct resistance of nymphs of the American cockroach to infections by M. anisopliae.
  
  
  CONCLUSIONS
  Our findings provide support for the development of biological control of this synanthropic cockroach pest.
authors: Instituto de Patologia Tropical e Saúde Pública, IPTSP, Universidade Federal de Goiás, Goiânia, Brazil.|Centro de Estudios Parasitológicos y de Vectores, CEPAVE (CONICET Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de La Plata), La Plata, Argentina.
authors: A C
authors: AC
authors: Gutierrez
authors: Instituto de Patologia Tropical e Saúde Pública, IPTSP, Universidade Federal de Goiás, Goiânia, Brazil.|Centro de Estudios Parasitológicos y de Vectores, CEPAVE (CONICET Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de La Plata), La Plata, Argentina.
authors: J A R
authors: JA
authors: Machado
authors: Instituto de Patologia Tropical e Saúde Pública, IPTSP, Universidade Federal de Goiás, Goiânia, Brazil.
authors: R
authors: R
authors: Hubner-Campos
authors: Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, CICBA, La Plata, Argentina.
authors: M A
authors: MA
authors: Pennisi
authors: Instituto de Patologia Tropical e Saúde Pública, IPTSP, Universidade Federal de Goiás, Goiânia, Brazil.
authors: J
authors: J
authors: Rodrigues
authors: Centro de Estudios Parasitológicos y de Vectores, CEPAVE (CONICET Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de La Plata), La Plata, Argentina.
authors: C C
authors: CC
authors: López Lástra
authors: Centro de Estudios Parasitológicos y de Vectores, CEPAVE (CONICET Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de La Plata), La Plata, Argentina.
authors: J J
authors: JJ
authors: García
authors: Instituto de Patologia Tropical e Saúde Pública, IPTSP, Universidade Federal de Goiás, Goiânia, Brazil.
authors: É K K
authors: ÉK
authors: Fernandes
authors: Instituto de Patologia Tropical e Saúde Pública, IPTSP, Universidade Federal de Goiás, Goiânia, Brazil. wchrisluz@hotmail.com.
authors: C
authors: C
authors: Luz
mesh_terms: D000818:Animals; D005227:Fatty Acids / Q000737:chemistry; D052981:Metarhizium; D009758:Nymph / Q000737:chemistry / Q000382:microbiology; D010526:Periplaneta / Q000737:chemistry / Q000254:growth & development / Q000382:microbiology*; D010572:Pest Control, Biological; D013172:Spores, Fungal
chemical_list: D005227:Fatty Acids
keywords: behaviour; cockroach; cuticular fatty acids; entomopathogenic fungus; haemolymph