A B S T R A C TAleurodicus cocois (Curtis, 1846), the coconut whitefly, is a very damaging pest in Peru, mainly in avocado trees (Persea americana Mill.). It has been determined that entomopathogenic fungi can infect and kill white flies and can be used as biological control agents. The object of this research was to determine if there is any synergic action of the entomopathogenic fungi Paecilomyces fumosoroseus (Wize) Brown & Smith 1957 and Verticillium lecanii (Zimmerman, 1892) Viégas 1939, in controlling A. cocois. Plastic sterile dishes were prepared where 5 mL 2% agar were used for each stage; leaves infested with A. cocois were placed upon these. Three different treatments were applied by sprinkling: P. fumosoroseus (P), V. lecanii (V) or the mixture of the two fungi. These treatments were evaluated at one, two and seven days in the case of nymph I and eggs, and after four, eight and 12 days for nymph II, NIII and NIV. The lethal effect of V. lecanii on the second nymph instar of A. cocois was better than that of P. fumosoroseus and than the mixture of both fungi; the highest mortality percentage appeared from day eight to day 12. A small increase was observed in the effect of the mixture of the two entomopathogenic fungi on the IV nymph instar, and the effect of P. fumosoroseus was the lowest.
RESUMENEl moho foliar Cladosporium fulvum (Cooke 1883) produce una enfermedad que ataca el cultivo de tomate en invernadero en el Perú. Como alternativa al control de este patógeno se probó la eficiencia bajo condiciones in vitro e invernadero de cuatro hongos antagonistas: Hansfordia pulvinata (Berk y Curt 1958), Trichoderma harzianum (Rifai 1969), T. viride (Persoon 1821) y T. virens (Miller, Giddens y Foster 1963). El cultivo y crecimiento de los hongos se realizó en Agar Sabouraud para Trichoderma spp. y en Agar Jugo V 8 para H. pulvinata. El bioensayo empleado fue el de placas precolonizadas propuesto por Krauss. En condiciones in vitro se observó que a 24 ºC y 72 h, el crecimiento de T. harzianum fue estadísticamente diferente de las otras tres especies ensayadas, y a 28 ºC fue similar a T. viride. A 24 ºC y a las 120 h, T. virens fue diferente de todas las especies evaluadas. A las 168 h el crecimiento de las tres especies de Trichoderma fue estadísticamente similar, diferenciándose de H. pulvinata. A 28 ºC a las 120 h y 168 h los resultados fueron estadísticamente similares para las tres especies de Trichoderma, pero diferentes de H. pulvinata. El mecanismo de acción más común para los hongos antagonistas fue el micoparasitismo. Finalmente, T. harzianum fue más eficiente debido a que redujo la severidad de la enfermedad en un 19,35 % bajo condiciones de invernadero.Palabras clave: Cladosporium fulvum, control biológico, Hansfordia pulvinata, tomate, Trichoderma harzianum, Trichoderma viride, Trichoderma virens. ABSTRACT BIOCONTROL OF LEAF MOLD OF TOMATO CLADOSPORIUM FULVUM (COOKE 1883) EMPLOYING FOUR ANTAGONISTIC FUNGILeaf mold Cladosporium fulvum (Cooke 1883), produce a tomato crop disease under greenhouse in Peru. As an alternative to control this pathogen the efficiency under in vitro conditions and greenhouse conditions of four antagonistic fungi was probed: Hansfordia pulvinata Berk y Curt 1958, Trichoderma harzianum (Rifai 1969), T. viride (Persoon 1821) and T. virens (Miller, Giddens y Foster 1963). Fungal culture and growth was performed in Agar Sabouraud for Trichoderma spp. and in Agar Juice V 8 for H. pulvinata. The bioassay employed was precolonized plates proposed by Krauss. In in vitro conditions was observed that at 24°C and 72 h growing of T. harzianum was statistically different than the other three species tested, and at 28°C was similar to T. viride. At 120 h and 24°C growing of T. virens was different from all species evaluated. At 168 h growing of the three species of Trichoderma, were statistically similar, varying from H. pulvinata. At 28°C and at 120 h and 168 h the results were statistically similar to the three species of Trichoderma, but different to H. pulvinata. Micoparasitism is the most common-action mechanism. Finally, T. harzianum was the most efficient antagonistic fungus because reduced disease in 19.35% under greenhouse conditions.
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