Conidia production of Isaria fumosorosea (Hypocreales: Cordycipitaceae) in organic substrates through two propagation techniques

In the last decades, the use of entomopathogenic fungi for the control of pest insects has increased globally, however a key step to achieve the successful application of fungal propagules as biocontrol agents depends of various factors, inoculum production being one of the essential stages for these microorganisms to be used in pest management programs. The objective of this study was to evaluate the production of conidia by solid fermentation and biphasic culture in different sporulation matrices for four native isolates and a strain of Isaria fumosorosea that have been shown potential for the control of various insects at the laboratory level. The experimental design was completely randomized, two propagation methods were used with six treatments and ten repetitions per treatment; the data were analyzed using an analysis of variance and the means were compared using the Tukey test (p≤ 0.05). In the production by solid fermentation the minimum value of 5.30 × 105 conidia g-1 was registered with the pericarp of peanut and the maximum of 2.35 × 107 conidia g-1 in the corn grain; in the biphasic culture the minimum of 7.60 × 105 conidia g-1 was observed in birdseed and the maximum of 2.07 × 107 conidia g-1 in rice. The differences were significant (p ≤ 0.05) in the production by method and by substrate, in solid fermentation 6.84 × 106 conidia g-1 and in biphasic culture 8.85 × 106 conidia g-1. In the production by substrate, the rice showed 1.75 × 107 conidia g-1 and the lesser canary seed concentration (7.80 × 105 conidia g-1). The average production per isolate and / or strain was of the order of 106 and significant difference was registered (p ≤ 0.05) among the fungi, the isolate HIB-9 showed concentration in average higher in the production (7.90 × 106 conidia g-1) and the isolated HIB-19 was the least effective, with only 1.08 × 106 conidia g-1. The results obtained show marked differences between the isolates with respect to their capacity to use the different substrates used as propagation media to obtain conidia of I. fumosorosea

Optimization of Pathogenicity Tests for Selection of Native Isolates of Entomopathogenic Fungi Isolated from Citrusgrowing Areas of México on Adults ofDiaphorina citriKuwayama (Hemiptera: Liviidae)

Huanglonbing (HLB), es considerado una de las más letales enfermedades de los cítricos alrededor del mundo, y ha alcanzado las principales áreas de producción de limón Mexicano (Citrus latifolia Tanaka) en la costa del pacifico de México. Los productores han iniciado el uso de insecticidas para controlar las poblaciones del psílido asiático de los cítricos, Diaphorina citri Kuwayama (Hemiptera: Liviidae), el vector del patógeno ‘Candidatus Liberibacter asiaticus’ asociado con el HLB. Actualmente los costos de los insecticidas y los efectos secundarios de su uso son las principales preocupaciones, ya que podrían perjudicar la estrategia de manejo contra el vector; y por lo tanto, alternativas ecológicas y económicamente viables a los insecticidas convencionales serian necesarias a corto plazo. Por tanto, el objetivo de este estudio fue evaluar la patogenicidad de 27 aislados nativos y 3 cepas de hongos entomopatógenos para determinar su potencial como agentes de control biológico sobre Diaphorina citri usando 2 diferentes métodos de bioensayo. Los bioensayos fueron realizados bajo condiciones de laboratorio (26 ± 2 °C, 60 ± 5% H.R y 16:8 h L:O) mediante la exposición de insectos adultos a una concentración de 1 × 108 conidios por mililitro utilizando 2 diferentes métodos de aplicación, es decir, por asperjado de esporas en las plántulas de cítricos y por asperjado directo a los psílidos adultos. Los resultados mostraron que para el asperjado directo a los adultos los aislados HIB-24 (B. bassiana) y HIB-32 (I. fumosorosea) mostraron el mayor porcentaje de mortalidad (60.66%). Respecto al asperjado de plántulas el aislado HIB-19 (I. fumosorosea) mostró el mayor porcentaje de mortalidad (62.02%). Los resultados de este estudio demuestran el potencial para el uso de hongos entomopatógenos en el manejo de D. citri en México. ABSTRACT Huanglongbing (HLB), considered one of the most lethal diseases of citrus worldwide, has reached the main areas of Mexican lime (Citrus latifolia Tanaka) fruit production on the Pacific coast of México. Growers have initiated intensive use of insecticides in order to control populations of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), the vector of the pathogen, ‘Candidatus Liberibacter asiaticus’ associated with huanglongbing. Presently, costs of insecticides and the side effects of their use are major concerns, because they could impair the management strategy against the vector; and thus, ecologically and economically viable alternatives to conventional insecticides are required in the short term. Therefore the goal of this study was to evaluate the pathogenicity of 27 native isolates and 3 strains of entomopathogenic fungi and determine their potential as biological control agents of D. citri by using 2 different bioassay methods. Bioassays were performed under laboratory conditions (26 ± 2 °C, 60 ± 5% RH and 16:8 h L:D) by exposing adult insects to a concentration of 1 × 108 conidia per milliliter using 2 different application methods, i.e., spraying the spores onto the citrus seedlings and spraying the spores directly onto the adult psyllids. The results showed that by direct spraying the adults, HIB-24 (B. bassiana) and HIB-32 (I. fumosorosea) isolates showed the highest mortality (60.66%). Regarding spraying of the seedlings, HIB-19 (I. fumosorosea) showed the highest percentage of mortality (62.02%). The results from this study demonstrate potential for using entomopathogenic fungi in the management of D. citri in México

Virulencia de blastosporas de Isaria fumosorosea nativas del noreste de México sobre Anastrepha ludens (Diptera: Tephritidae)

Anastrepha ludens is one of the pests that seriously affects fruit production in Mexico and other Neotropical countries. The aim of this study was to evaluate the virulence and effects of four native isolates and a collected strain of Isaria fumosorosea on the metamorphosis of A. ludens through the use of bioassays under laboratory conditions [25 ± 2 °C; 60 ± 5 % (HR); 12:12 h (L: O)]. Larvae and pupae were exposed to 1 × 108 blastospores/ ml using two different methods: direct spraying and spraying of soil. The isolates HIB-23 and HIB-30 showed the highest mortality on A. ludens when applied using the direct spraying method on larvae (84 %), while the isolate HIB-19 showed the highest percentage of interruption of the metamorphosis (43 %) of A. ludens when applied through the method of direct spraying on pupae. The results show that A. ludens is susceptible to the attack of I. fumosorosea, which causes the disruption of its life cycle.Anastrepha ludens es una de las plagas que afectan severamente la producción de frutas en México y otros países neotropicales. El objetivo de este estudio fue evaluar la virulencia y el efecto en la metamorfosis de cuatro aislados nativos y una cepa de colección de Isaria fumosorosea sobre A. ludens mediante bioensayos bajo condiciones de laboratorio [25 ± 2 °C; 60 ± 5 % (HR); 12:12 h (L: O)] exponiendo larvas y pupas a una concentración de 1 × 108 blastosporas/ml mediante dos diferentes métodos, asperjado directo y asperjado de suelo. Los aislados HIB-23 e HIB-30 mostraron la más alta mortalidad sobre A. ludens mediante el método de asperjado directo sobre larvas (84 %) mientras que el aislado HIB-19 tuvo el más alto porcentaje de interrupción de la metamorfosis (43 %) sobre A. ludens por el método de aspersión directa sobre pupas. Estos resultados sugieren que A. ludens es susceptible al ataque por I. fumosorosea y esto puede influir en la terminación de su ciclo de vida

Virulence of blastospores of Isaria fumosorosea natives of northeastern Mexico on Anastrepha ludens (Diptera: Tephritidae).

Anastrepha ludens is one of the pests that seriously affects fruit production in Mexico and other Neotropical countries. The aim of this study was to evaluate the virulence and effects of four native isolates and a collected strain of Isaria fumosorosea on the metamorphosis of A. ludens through the use of bioassays under laboratory conditions [25 ± 2 °C; 60 ± 5 % (HR); 12:12 h (L: O)]. Larvae and pupae were exposed to 1 × 108 blastospores/ ml using two different methods: direct spraying and spraying of soil. The isolates HIB-23 and HIB-30 showed the highest mortality on A. ludens when applied using the direct spraying method on larvae (84 %), while the isolate HIB-19 showed the highest percentage of interruption of the metamorphosis (43 %) of A. ludens when applied through the method of direct spraying on pupae. The results show that A. ludens is susceptible to the attack of I. fumosorosea, which causes the disruption of its life cycle