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Time and concentration dependent interactions of Beauveria bassiana with sublethal rates of imidacloprid against the aphid pests Macrosiphoniella sanborni and Myzus persicae
Author(s) -
YE SUDAN,
DUN YUHUI,
FENG MINGGUANG
Publication year - 2005
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.2005.040147.x
Subject(s) - myzus persicae , beauveria bassiana , imidacloprid , aphid , biology , bioassay , bassiana , biological pest control , horticulture , aphididae , botany , ec50 , toxicology , homoptera , pest analysis , pesticide , agronomy , ecology , in vitro , biochemistry
Summary A series of laboratory bioassays with each consisting of low, medium and high concentration treatments of the fungal biocontrol agent Beauveria bassiana alone or supplemented with an increasing sublethal rate of imidacloprid were conducted to quantify the fungal and chemical interactions on chrysanthemum aphid Macrosiphoniella sanborni (0.01‐0.05 a.i. μg mL −1 ) and green peach aphid Myzus persicae (0.05‐0.5 a.i. μg mL −1 ). During one week after exposure to a 1 mL spray onto a 95 cm 2 area in a Potter Spray Tower, M. sanborni was either more susceptible to B. bassiana or more sensitive to imidacloprid than M. persicae . The time–concentration–mortality (TCM) responses of each aphid species in each of five bioassays fit well to a TCM model, indicating a strong dependence of the fungal and chemical interactions on both concentration and post‐spray time. Adding imidacloprid to B. bassiana sprays at the rates of 0.025–0.05 μg mL −1 against M. sanborni or 0.1–0.5 μg mL −1 against M. persicae significantly enhanced or accelerated the fungal action. Based on the LC 50 or LC 90 estimates and their variances determined by the fitted TCM relationships for each aphid species, the relative potencies of an imidacloprid‐inclusive bioassay over those with B. bassiana alone or together with a lower sublethal rate ranged from a few to hundreds of times and varied over days after spray. These results suggest an alternative tactic for practical control of the aphid pests by a combined formulation or application of B. bassiana and imidacloprid and manage aphid resistance to the chemical insecticide.