Mycopathologia (2007) 163, 233-240

Adão Valmir Santos, Bruno Lorenz de Oliveira and Richard Ian Samuels (2007)
Selection of entomopathogenic fungi for use in combination with sub-lethal doses of imidacloprid: perspectives for the control of the leaf-cutting ant Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae)
Mycopathologia 163 (4), 233-240
Abstract: In the first part of this study, four isolates of the fungus Beauveria bassiana (Bals.) Vuillemin (LPP1, LPP2, CG05 and CG24) and one isolate of Metarhizium anisopliae (Metsch.) Sorokin (CG46) were tested against adult foragers of Atta sexdens rubropilosa. Ants were allowed to walk on filter paper discs, inside Petri dishes, previously impregnated with 1 ml of a conidia suspension (2 × 10⁷ conidia ml⁻¹), maintained at 80% RH and 26°C for 24 h and subsequently, transferred to sterile Petri dishes, maintained at 23°C, 80% RH, 24 h dark. The mean values of LT₅₀ for LPP2, LPP1, CG46, CG24 and CG05 were 3.5, 3.7, 3.8, 4.2 and 4.4 days, respectively. Control insects for all tests in this study showed less than 10% mortality. Experiments were carried out to test the toxicity of imidacloprid (IMI) to A. sexdens rubropilosa. Mortality was evaluated 10 days following a 24 h exposure to the insecticide. Percent mortality caused by 500, 200, 100 and 10 ppm IMI was 77.8, 56.7, 45.5 and 5.5 respectively. Insects treated with 10 ppm IMI were observed to have reduced locomotor activity 24 h after exposure to the insecticide. The LC₅₀ of IMI was 154.3 ppm. Subsequent tests were carried out to evaluate the combination of a sub-lethal dose of IMI (10 ppm) and infection by CG24 (1 × 10⁷ conidia ml⁻¹). Mortality due to fungal infection alone was 43.3%. Mortality of insects treated with IMI followed by exposure to the fungus was 64.3%. These results indicate that IMI significantly increases the susceptibility of ants to infection by B. bassiana CG24.
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Link to article at publishers website
Database assignments for author(s): Adão Valmir Santos

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
application technology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Atta sexdens
Beauveria bassiana (entomopathogen)	Atta sexdens
Metarhizium anisopliae (entomopathogen)	Atta sexdens