Pest Management Science (2018) 74, 2488-2495

Nicolai V. Meyling, Samuel Arthur, Kathrine E. Pedersen, Suraj Dhakal, Nina Cedergreen and Brian L. Fredensborg (2018)
Implications of sequence and timing of exposure for synergy between the pyrethroid insecticide alpha-cypermethrin and the entomopathogenic fungus Beauveria bassiana
Pest Management Science 74 (11), 2488-2495
Abstract:
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.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Nicolai Vitt Meyling

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
control - general
Research topic(s) for beneficials or antagonists:
application technology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
Beauveria bassiana (entomopathogen)