Bioassay with two Iranian isolates of Metarhizium anisopliae on eggs, 2th nymphal instars and adults of the sunn pest, Eurygaster integriceps and the effect of EC oil on pathogenicity

Document Type : Pest Management

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Abstract

In this study pathogenicity and virulence of two Metarhizium anisopliae isolates (IRAN 437C and M14) were evaluated against egg (using dipping method), 2nd nymphal instar and summer generation adults (aestivation population) of sunn pest, E. integriceps (Hem., Scutelleridae) using direct spray technique. Different concentrations consisted 103, 104, 105, 106, 107 and 108 conidia/ml and experiment replicated 4 time. Effect of fungal suspensions of 106 and 108 conidia/ml in EC oil was also studied on sunn pest adults (aestivation population) using direct spraying method. Mortality in all of treatments was daily recorded. Results showed that isolate M14 reduced egg hatching by 40%. Estimated LC50 value for each isolates (IRAN 437C and M14) was 4.3×107 and 1.4×106 conidia/ml on adults and 4.8×104 and 2.3×103 conidia/ml on 2nd nymphal instar, respectively. Also, the calculated LT50 value using concentration of 108 conidia/ml for each isolates (IRAN 437C and M14) on adults were 29.64 and 11.9 days, and for nymphal stage were 3.23 and 2.22 days, respectively. The bioassay results showed that M14 isolate was more effective on both stages of the sunn pest. Although, nymphal stage was more susceptible compared to adult. In addition, EC oil (0.3 %) decreased LT50 of M. anisopliae to 54.45 percent compared with distilled water mixed with wetting agent (Tween 80). Adding oil carriers to a fungus suspension increased the pathogenicity.

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Applied Entomology and Phytopathology
Volume 81, No. 2
March 2014
Pages 87-96

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