Laboratory investigation on virulence of three entomopathogenic fungi against the larvae of Aeolesthes sarta (Col.: Cerambycidae)

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Abstract

Sart longhorn beetle, Aeolesthes sarta Solsky (Col.: Cerambycidae) is one of the most destructive borers attacking many tree species in Iran and some Asian countries. Despite its high economic importance, little information is available on its biological control agents. In this research, pathogenicity of entomopathogenic fungi Lecanicillium muscarium (strain DAOM 198499), Metarhizium anisopliae (strain DEMI-001) and Beauveria bassiana (strain PTCC5197) were tested in the laboratory for the pathogenicity to A. sarta larvae. The survey was conducted to determine the efficacy of various treatments (105, 106, 107, 108 spore/ml) against the larvae of A. sarta. Larvae of the same age were individually treated with conidial concentrations of fungi for 30 sec. and placed in hand-made grooves (diameter of 1.5 cm and length of 10 cm) in the sapwood of poplar trunks (Populus nigra, Colon 56/32). After 15 days, the trunks were chopped and the mortality of larvae was determined. Furthermore, Probit analyses were conducted calculate LC50 and LC90 values for each fungus. The results indicated significant differences between treated and untreated individuals (p < 0.01). Estimated LC50 for L. muscarium, B. bassiana and M. anisopliae were 8.53 × 106, 3.65 × 107, and 8.7 × 104 spore/ml, respectively. There were significant differences among the mortalities of fungi and concentrations (p < 0.01). M. anisopliae with the mean of 50.99% and B. bassiana with the mean of 30.41% had the highest and the lowest mortality, respectively (p < 0.05). Also, the treatments 108 and 105 spore/ml caused the highest (68.57%) and lowest (38.64%) mortality, respectively. Finally, the comparison of means of interaction (treatment × fungus) showed that M. anisopliae treatment (108 spore/ml) with 78.9% had the highest and B. bassiana treatment (105 spore/ml) with 16.66% had the lowest mortality.

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Journal of Entomological Society of Iran
Volume 28, Issue 1
September 2008
Pages 19-34

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