Abstract
The present study was carried out to evaluate the efficacy of three different conidial concentrations (1 × 104, 1 × 105, and 1 × 106 conidia/ml) of five isolates (TR-04, TR-05, TR-07, TR-08, and TR-10) of Lecanicillium muscarium, one isolate (TR-01) of Simplicillium lamellicola, a commercial bioinsecticide Verticillium lecanii, and a synthetic insecticide (Imidacloprid) against the black bean aphid, Aphis fabae Scopoli (Hemiptera: Aphididae) under laboratory conditions. Bioassays were conducted in Petri dishes, and insect mortality rate was recorded daily. The LT50 values (days) of the isolates at 1 × 106 conidia/ml were 2.96 (TR-05), 3.08 (TR-10), 3.21 (TR-07), 3.45 (TR-01), 3.73 (TR-04), and 3.83 (TR-08), while they were 4.37 and 0.73 for the commercial bioinsecticide and insecticide, respectively. The LT90 values (days) of the same conidial concentrations of the isolates attained 4.30 (TR-07), 4.35 (TR-05), 4.80 (TR-10), 5.15 (TR-04), 5.25 (TR-01), 6.06 (TR-08), 6.72 (commercial bioinsecticide), and 2.36 (insecticide). The 1 × 105 and 106 conidia/ml concentrations of all the entomopathogenic fungal isolates tested against A. fabae caused > 90% mortality by the end of the seventh day. It is concluded that both conidial concentrations of these isolates had significant potential to control black bean aphid.
Highlights
Aphids (Hemiptera: Aphididae) are one of the most significant threats to agriculture and forests (Blackman and Eastop 2007)
The objective of the present study was to evaluate the pathogenicity of five different entomopathogenic fungi (EPF) isolates of L. muscarium and one isolate of S. lamellicola against A. fabae and compare the results with one commercially bioinsecticide and a synthetic insecticide under laboratory conditions
Among the different fungal isolates tested in the present study, TR-08 with 1 × 104 conidia/ml showed the highest efficacy (95.65%) against A. fabae at the end of the seventh day, followed by TR-07 (92.31%), TR-10 (90%), TR-05 (82.67%), TR-04 (69.57%), and TR-01 (67.14%) (Fig. 1)
Summary
Aphids (Hemiptera: Aphididae) are one of the most significant threats to agriculture and forests (Blackman and Eastop 2007). Aphis fabae Scopoli (Hemiptera: Aphididae), known as the black bean aphid, is one of the most important species causing yield losses in several cultivated crops, including broad bean and sugar beet (Volkl and Stechnann 1998). The aphids are predominantly controlled by synthetic insecticides; their use has raised serious environmental problems (Scorsetti et al 2007). The overuse of pesticides resulted in insect resistance and forced many countries to reduce pesticide use through alternative methods, including biological control in wake of the increasing consumer tend to prefer pesticide-free food as well as environmental concerns (Kim et al 2001).
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