Infection of the red palm weevil (Rhynchophorus ferrugineus) by the entomopathogenic fungus Beauveria bassiana: a SEM study.

The Red Palm Weevil (Rhynchophorus ferrugineus) is a devastating pest of palms in the Mediterranean, Middle East, and Eastern countries. No effective control measures are available. R. ferrugineus has been found naturally infected by the entomopathogenic fungus Beauveria bassiana, but its infection process in this host is unknown. We have studied the infection of R. ferrugineus larvae and adults by B. bassiana using dry conidia and conidia suspensions using scanning electron microscopy (SEM). In early stages, SEM revealed acquisition of B. bassiana conidia by cuticle ornamentation in legs, antennae, and elytra of R. ferrugineus adults. Subsequently, conidia germinated and frequent episodes of hyphal/conidial fusion were found. Appressoria, signs of adhesion and cuticle degradation led to penetration (even direct) and colonization of R. ferrugineus hosts by the fungus. B. bassiana conidiophores were found in a R. ferrugineus cuticle, which indicate the completion of the life cycle of the fungus in the insect host. SEM has proven that dry conidia of B. bassiana is an adequate inoculum for R. ferrugineus infection. SEM revealed that conidia of B. bassiana attached to the cuticle of R. ferrugineus can germinate and differentiate appressoria.

Mycobiota of the date palm phylloplane: description and interactions.

We have analysed the mycobiota of date palm (Phoenix dactylifera, L.) leaves using several techniques. Profusely sporulating fungi (Penicillium spp. and Cladosporium spp.) developed when plating leaf fragments and leaf washings. Fusarium oxysporum, was particularly abundant in leaves infested with the red scale insect Phoenicococcus marlatti Cockerell, 1899, but an undescribed Lecanicillium cf. psalliotae was also found. Dual and overlay cultures showed interactions between palm pathogens, entomopathogenic and saprotrophic fungi. The most significant was the strong inhibition of the palm pathogen Penicillium vermoesenii caused by the entomopathogen Beauveria bassiana. No symptoms developed when F. oxysporum isolated from scale insects or the entomopathogens B. bassiana or Lecanicillium dimorphum were wound-inoculated on P. dactylifera petioles.

Mycobiota of the date palm phylloplane: description and interactions

Se ha analizado la micobiota presente en las hojas de la palmera datilera(Phoenix dactylifera, L.) utilizando diferentes técnicas. Tras lavar y cultivar enplacas fragmentos de hoja de palmera se observó una alta esporulación devarios hongos (Penicillium spp. y Cladosporium spp.). Fusarium oxysporum fueparticularmente abundante en hojas infestadas por la cochinilla roja(Phoenicococcus marlatti Cockerell, 1899). Además se detectó un hongoentomopatógeno no descrito: Lecanicillium cf. psalliotae. Los cultivos dualesy las técnicas de sobreposición de membranas mostraron interacciones entrehongos patógenos de la palmera, entomopatógenos y saprótrofos. Lo mássignificativo fue la fuerte inhibición del hongo patógeno de palmerasPenicillium vermoesenii producida por el entomopatógeno Beauveria bassiana.Ni el hongo F. oxysporum, aislado de la cochinilla roja, ni losentomopatógenos B. bassiana o Lecanicillium dimorphum, causaron síntomascuando fueron inoculados en heridas de pecíolos de P. dactylifera(AU)

We have analysed the mycobiota of date palm (Phoenix dactylifera, L.) leavesusing several techniques. Profusely sporulating fungi (Penicillium spp. andCladosporium spp.) developed when plating leaf fragments and leaf washings.Fusarium oxysporum, was particularly abundant in leaves infested with the redscale insect Phoenicococcus marlatti Cockerell, 1899, but an undescribedLecanicillium cf. psalliotae was also found. Dual and overlay cultures showedinteractions between palm pathogens, entomopathogenic and saprotrophicfungi. The most significant was the strong inhibition of the palm pathogenPenicillium vermoesenii caused by the entomopathogen Beauveria bassiana.No symptoms developed when F. oxysporum isolated from scale insects or theentomopathogens B. bassiana or Lecanicillium dimorphum werewound-inoculated on P. dactylifera petioles(AU)