Selection of Beauveria bassiana strains against the two spotted spider mite, Tetranychus urticae Koch in laboratory and greenhouse trials

2012 ◽  
Vol 6 (11) ◽  
Author(s):  
M. C. Gatarayiha
2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Cenk Yucel

Abstract Background The two-spotted spider mite, Tetranychus urticae (Koch) (Acari: Tetranychidae), is a widely distributed plant-feeding pest that causes significant yield losses in a wide range of crops. Newly developed or improved environmentally friendly biocontrol agents serve as an alternative to traditional pest control tools. Experiment of the effects of 2 local fungal isolates of Beauveria bassiana (BGF14 and BCA32) was carried out against T. urticae under laboratory conditions. Results Both tested isolates had lethal effect in a short time after application, and this effect increased as time progressed. BGF14 and BCA32 isolates caused T. urticae mortality rates ranging from 25.88 to 61.92 and 32.36 to 62.03% when applied at the concentrations between 1×105 and 1×108 conidia/ml, respectively. According to the Probit analysis performed on the effect of fungi on T. urticae adults, the LC50 values of BGF14 and BCA32 isolates on the 7th day after inoculation were 2.6×106 and 6.3×104 conidia/ml, respectively, and the LT50 values for both fungi applied at a concentration of 108 conidia/ml were 2.14 and 2.23 days, respectively. Conclusions The 2 isolates of B. bassiana (BGF14 and BCA32) had the potentials to suppress T. urticae population and can be recommended as promising biocontrol agent candidates for control of T. urticae.


2010 ◽  
Vol 25 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Slavimira Draganova ◽  
Spaska Simova

Bioassays with five isolates of the entomopathogenic fungus Beauveria bassiana (Bals.- Criv.) Vuillemin were conducted under laboratory conditions with a goal to estimate their virulence to the two-spotted spider mite Tetranychus urticae Koch. (Acari: Tetranychidae). Common bean plants with mites were treated by spraying conidial suspensions of isolates at concentrations of 106, 107 and 108 conidia/ml. Lethal effects of the fungal isolates were evaluated as percentages of cumulative daily mortality due to mycoses, corrected for mortality in the control variant. Virulence of the isolates was estimated based on values of the median lethal time (LT50) calculated by probit analysis for the variants treated with conidial suspensions at the concentration of 106 conidia/ml. The two-spotted spider mite was found susceptible to the examined isolates of the entomopathogenic fungus B. bassiana. Mycosis caused to T. urticae by the B. bassiana isolates 444 Bb and 445 Bb had fast lethal effect after treatment with conidial suspensions even at the concentration of 106 conidia/ ml. The mean mortality values of host individuals were 83.78 ? 3.62% and 68.49 ? 4.28% on the first day, respectively, and up to 100% in both variants on the fourth day. The isolates 426 Bb, 444 Bb and 445 Bb of B. bassiana were highly virulent to two-spotted spider mites with values of the median lethal time varied within overlapped narrow confidence intervals from 0.122 to 1.084 days (average value 0.162 days), from 0.117 to 1.398 days (average value 0.146 days) and from 0.106 to 1.162 days (average value 0.131 days), respectively. Significant differences regarding virulence of the three isolates at p-level < 0.05 could not been proved. The other two examined isolates were distinctly less virulent to T. urticae than these three B. bassiana isolates.


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