Susceptibility and development of resistance of the mite Tetranychus urticae to aerial conidia and blastospores of the entomopathogenic fungus Beauveria bassiana

2020 ◽  
Vol 25 (3) ◽  
pp. 429-443
Author(s):  
Charbel Al Khoury ◽  
Jacques Guillot ◽  
Nabil Nemer
Keyword(s):  
Tetranychus Urticae ◽  
Beauveria Bassiana ◽  
Resistance Development ◽  
Development Of Resistance ◽  
Different Types ◽  
Aerial Conidia ◽  
Resistant Strains ◽  
Two Spotted Spider Mite ◽  
Tetranychus Urticae Koch ◽  
First Time

The virulence of aerial conidia of the entomopathogenic fungi Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae) has been documented on a very broad range of arthropods; however, the activity of blastospores against the two-spotted spider mite has been seldomly reported. Moreover, studies investigating the activity of blastospores under greenhouse conditions were not found in the literature. In this study, we tested the efficacy of blastospores and aerial conidia of two B. bassiana strains, against all life stages of Tetranychus urticae Koch (Acari: Tetranychidae). The concentration of 109 blastospores/ml of the Lebanese strain was the most efficient in laboratory experiments, and the recorded mortalities were 52, 67.9 and 95.3% in treated eggs, motile juveniles and adults, respectively. In greenhouse experiments, higher T. urticae mortalities were recorded among strawberry plants (Fragaria x ananassa) sprayed with blastospores of B. bassiana. Furthermore, the latter plants also recorded a higher yield (454.92 ± 5 g/plant) compared to infested control plants (144.42 ± 5 g/plant) during the growing season. In addition, this study also investigated for the first time the resistance development of T. urticae to different types of infective propagules of B. bassiana. Under selective pressure for 40 generations, the laboratory yielded aerial conidia (AC-TSM) and blastospores (BS-TSM) resistant strains of the mite recorded 28.8- and 8.4- fold change in LC50 values respectively when compared to the field strain; however, this resistance ratio was minimal when compared to those of chemical acaricides.

scholarly journals Effects of local isolates of Beauveria bassiana (Balsamo) Vuillemin on the two-spotted spider mite, Tetranychus urticae (Koch) (Acari: Tetranychidae)

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Cenk Yucel
Keyword(s):  
Tetranychus Urticae ◽  
Beauveria Bassiana ◽  
Spider Mite ◽  
Lethal Effect ◽  
Probit Analysis ◽  
Plant Feeding ◽  
Wide Range ◽  
Two Spotted Spider Mite ◽  
Short Time ◽  
Tetranychus Urticae Koch

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.

scholarly journals Susceptibility to Acaricides and the Frequencies of Point Mutations in Etoxazole- and Pyridaben-Resistant Strains and Field Populations of the Two-Spotted Spider Mite, Tetranychus urticae (Acari: Tetranychidae)

Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 660
Author(s):  
Hyun-Na Koo ◽  
Jihye Choi ◽  
Eungyeong Shin ◽  
Wonjin Kang ◽  
Sun-Ran Cho ◽  
...  
Keyword(s):  
Point Mutation ◽  
Tetranychus Urticae ◽  
High Frequency ◽  
Spider Mite ◽  
Point Mutations ◽  
Cross Resistance ◽  
Resistance Patterns ◽  
Resistant Strains ◽  
Two Spotted Spider Mite ◽  
Tetranychus Urticae Koch

The two-spotted spider mite Tetranychus urticae Koch is a major agricultural pest worldwide and is known to rapidly develop resistance to pesticides. In the present study, we explored a field strain that was collected in 2000 and 2003 and has been exhibiting resistance to etoxazole and pyridaben over the last 16 years. The resistance ratios of the etoxazole- and pyridaben-resistant strains (ER and PR) to etoxazole or pyridaben were more than 5,000,000- and 4109.6-fold higher than that of the susceptible strain, respectively. All field-collected populations showed resistance to etoxazole and pyridaben. The ER and PR strains showed cross-resistance to several acaricides. Both I1017F and H92R point mutations were detected in 7 out of 8 field groups. Spirodiclofen and spiromesifen resulted in more than 77.5% mortality in the 8 field groups. In addition, the genotype frequency of the I1017F point mutation was 100.0% in the ER strain, and that of the H92R point mutation was 97.0% in the PR strain. All of the field populations were found to have a high frequency of I1017F. These results suggest that the observation of resistance patterns will help in designing a sustainable IPM program for T. urticae.

scholarly journals Susceptibility of Tetranychus urticae koch. (Acari: Tetranychidae) to isolates of entomopathogenic fungus Beauveria bassiana

2010 ◽  
Vol 25 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Slavimira Draganova ◽  
Spaska Simova
Keyword(s):  
Tetranychus Urticae ◽  
Beauveria Bassiana ◽  
Entomopathogenic Fungus ◽  
Spider Mite ◽  
Probit Analysis ◽  
Average Value ◽  
Lethal Time ◽  
Two Spotted Spider Mite ◽  
Tetranychus Urticae Koch ◽  
Fungus Beauveria Bassiana

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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