TY - JOUR
T1 - Implications of sequence and timing of exposure for synergy between the pyrethroid insecticide alpha-cypermethrin and the entomopathogenic fungus Beauveria bassiana
AU - Meyling, Nicolai Vitt
AU - Arthur, Samuel
AU - Pedersen, Kathrine Eggers
AU - Dhakal, Suraj
AU - Cedergreen, Nina
AU - Fredensborg, Brian Lund
PY - 2018
Y1 - 2018
N2 - BACKGROUND: Combining low doses of chemical insecticides with entomopathogens constitutes a sustainable pest control method, but the significance of the timing and sequence of exposures needs clarification. We studied lethal effects of combinations of the entomopathogenic fungus Beauveria bassiana (KVL03-122) and the pyrethroid alpha-cypermethrin on the beetle Tenebrio molitor under varying timing and sequence of exposure. Synergy over time was evaluated in relation to the model of independent action (IA). We expected that increased progression of disease caused by B. bassiana would make beetles more susceptible to the insecticide, leading to enhanced synergy.RESULTS: Synergistic effects between B. bassiana and alpha-cypermethrin were observed when B. bassiana was applied first, but only when the interval between applications was >48 h. With 72 h between exposures, mortality had increased to 100% after 8 days, in contrast to the 60% mortality expected. No synergy was observed when the insecticide was applied prior to fungal exposure within 24 h.CONCLUSION: The sequence and timing of exposure do matter to achieve synergistic mortality by combining B. bassiana and alpha-cypermethrin, and the IA model proved to be a strong tool with which to evaluate the interactions of the two stressors over time. Pest control strategies could include B. bassiana followed by low-dose exposures to alpha-cypermethrin after 2-3 days. © 2018 Society of Chemical Industry.
AB - BACKGROUND: Combining low doses of chemical insecticides with entomopathogens constitutes a sustainable pest control method, but the significance of the timing and sequence of exposures needs clarification. We studied lethal effects of combinations of the entomopathogenic fungus Beauveria bassiana (KVL03-122) and the pyrethroid alpha-cypermethrin on the beetle Tenebrio molitor under varying timing and sequence of exposure. Synergy over time was evaluated in relation to the model of independent action (IA). We expected that increased progression of disease caused by B. bassiana would make beetles more susceptible to the insecticide, leading to enhanced synergy.RESULTS: Synergistic effects between B. bassiana and alpha-cypermethrin were observed when B. bassiana was applied first, but only when the interval between applications was >48 h. With 72 h between exposures, mortality had increased to 100% after 8 days, in contrast to the 60% mortality expected. No synergy was observed when the insecticide was applied prior to fungal exposure within 24 h.CONCLUSION: The sequence and timing of exposure do matter to achieve synergistic mortality by combining B. bassiana and alpha-cypermethrin, and the IA model proved to be a strong tool with which to evaluate the interactions of the two stressors over time. Pest control strategies could include B. bassiana followed by low-dose exposures to alpha-cypermethrin after 2-3 days. © 2018 Society of Chemical Industry.
KW - Animals
KW - Beauveria/physiology
KW - Insect Control/methods
KW - Insecticides/pharmacology
KW - Larva/drug effects
KW - Pest Control, Biological
KW - Pyrethrins/pharmacology
KW - Tenebrio/drug effects
KW - integrated pest management
KW - insect immune response
KW - combination effects
KW - independent action modelling
KW - Tenebrio molitor
U2 - 10.1002/ps.4926
DO - 10.1002/ps.4926
M3 - Journal article
C2 - 29603560
SN - 1526-498X
VL - 74
SP - 2488
EP - 2495
JO - Pest Management Science
JF - Pest Management Science
IS - 11
ER -