Scientia Agricola (2002) 59, 267-273

Alcides Moino Jr., Sérgio Batista Alves, Rogério Biaggioni Lopes, Pedro Manuel Oliveira Janeiro Neves, Roberto Manoel Pereira and Solange Aparecida Vieira (2002)
External development of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae in the subterranean termite Heterotermes tenuis
Scientia Agricola 59 (2), 267-273
Abstract: The subterranean termite Heterotermes tenuis is one of the main pests of sugarcane and eucalyptus in Brazil, and the use of entomopathogenic fungi, alone or associated to chemicals, is an efficient and environmentally favorable method for its control. Studies related to the fungal development on these insects are important due to the effect of insect behavior on entomopathogens. The objective of this work was to describe the external development of Beauveria bassiana and Metarhizium anisopliae on H. tenuis using Scanning Electron Microscopy (SEM), determining the duration of the different phases of fungal infection. Two fixation techniques for preparing SEM samples were also evaluated. Worker specimens of H. tenuis were inoculated with a 1 x 10⁹ conidia mL^-1 suspension of the fungi and maintained at 25±1^oC and 70±10% relative humidity. Insects were collected from 0 to 144 hours after inoculation and prepared on SEM stubs for each of the two fixation techniques. The results obtained with the two techniques were compared and duration of the different phases of the infection process were estimated from SEM observations and compared for three fungal isolates. B. bassiana and M. anisopliae have similar development cycles on the termite, but some important differences exist. The penetration, colonization and conidiogenesis phases are relatively faster for M. anisopliae than for B. bassiana, which results in a faster rate of insect mortality. The fixation technique with OsO₄ vapor is suitable for preparation of insects to be used in SEM observation of the developmental stages of entomopathogenic fungi.
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Database assignments for author(s): Roberto M. Pereira, Sérgio Batista Alves, Alcides Moino Jr.

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Heterotermes tenuis	Sugarcane (Saccharum officinarum)	Brazil (south)
	Heterotermes tenuis	Eucalypt (Eucalyptus)
Beauveria bassiana (entomopathogen)	Heterotermes tenuis
Metarhizium anisopliae (entomopathogen)	Heterotermes tenuis