Desenvolvimento de metarhizium anisopliae em ninfas de periplaneta americana durante a invasão
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2015-03-27
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Universidade Federal de Goiás
Resumo
The susceptibility of cockroaches to infection with pathogenic fungi can be
associated to the host species and their stage/instar. The high resistance of elder
nymphs of Periplaneta americana, a synanthropic species in tropical and
subtropical regions, against Metarhizium anisopliae is still poorly understood and
can be connected to behavioral, physiological and mechanical mechanisms.
Fourth and fifth instar nymphs (N4 or N5), treated topically with conidia, removed
mechanically part of the conidia from the cuticle, antennae and legs, immediately
after treatment and in the following days. A small number (< 5%) of the conidia
on the cuticle germinated in the first 24 hours, and quantitative germination of the
remaining conidia reached 80% within the next 7 days. In most of the treated
nymphs, the fungus failed to reach the hemolymph during the 10 days of the test,
and in the others, the number of hyphal bodies ranged from 500 to 8 x 107 per μL
hemolymph. Few nymphs (30%) died within 10 days after inoculation, and M.
anispoliae developed in 50% of the cadavers. The results confirmed the high
resistance of elder P. americana nymphs to M. anisopliae and highlighted the
importance of the early stages of the infection during the contact and insect
invasion by the fungus. Subsocial behavior patterns and specific physiological
factors in the cuticle, not elucidated in this study, are resistance key issues and
need to be considered when developing mycoinsecticides for P. americana and
other cockroach control.
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MACHADO, J. A. Desenvolvimento de metarhizium anisopliae em ninfas de periplaneta americana durante a invasão. 2015. 61 f. Dissertação (Mestrado em Biologia da Relação Parasito-Hospedeiro) - Universidade Federal de Goiás, Goiânia, 2015.