Comparative study on two entomopathogenic fungi on larvae of the elm leaf beetle, Xanthogaleruca luteola Muller Col., Chrysomelidae

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عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران

¹Department of Plant Protection, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran,

²Department of Entomology and Plant Pathology, College of Aburiehan, University of Tehran, Tehran, Iran,

The elm leaf beetle, Xanthogaleruca luteola Muller (Col., Chrysomelidae) is one of the most important and key insect pests that causes damage to elm trees. Application of traditional synthetic insecticides in urban area has increased public concerns, therefore, the use of alternative and safe compounds is recommended. Entomopathogenic fungi are important biocontrol agents that have been applied in insect pest management systems. The aim of the current research was to evaluate the pathogenicity of two entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, on the 1st, 2nd and 3rd instar larvae of X. luteola. All experiments were conducted at controlled conditions (25 ± 1 °C, 75 ± 5 RH and a photoperiod of 14:10 h L: D). Concentrations of 105, 106, 107 and 108 spores / ml of the fungi were applied on larvae using immersion and spray methods. Based on the results, no mortality was observed in the first 24 h. The findings showed that LC50 of B. bassiana in immersion and spray methods were 3.88 × 102 and 7.52 × 102 spores/ml while LC50 of M. anisopliae in mentioned methods were 7.05 × 102 and 11.85 × 102 spores / ml, respectively, with significant differences. The highest mortalities in both methods were observed on the 1st instar larvae that were significantly different compared with that in control. Moreover, the highest and lowest mortalities in immersion (42.67 and 21.53%) and spray methods (34.87 and 16.13%) were associated to concentrations of 108 and 105 spores/ml on the 1st and 3rd instar larvae, respectively. Therefore, the 1stand 2ndinstar larvae were more susceptible to the both mentioned isolates compared with 3rd instar larvae. Accordingly, B. bassiana and M. anisopliae were pathogenic to the larvae of X. luteola. It is concluded that these biocontrol agents can be utilized against elm leaf beetle larvae as eco-friendly compounds. Of course, in the field habitat, mortality was considerably lower compared with that in the laboratory which requires comprehensive studies in future.

Keywords: Entomophatogenic fungi, Mortality, Pathogenicity, Xanthogaleruca luteola.
 

Entomophatogenic fungi؛ Mortality؛ Pathogenicity؛ Xanthogaleruca luteola