The global biodiversity crisis emphasizes our need to understand how different stressors (climatic,
chemical, parasitic, etc.) interact and affect biological communities. We provide a comprehensive
meta‑analysis investigating joint effects of chemical and parasitic stressors for 1064 chemical‑parasitic
combinations using the Multiplicative model on mortality of arthropods. We tested both features
of the experimental setup (control mortality, stressor effect level) and the chemical mode of action,
host and parasite phylogeny, and parasite‑host interaction traits as explanatory factors for deviations
from the reference model. Synergistic interactions, defined as higher mortality than predicted,
were significantly more frequent than no interactions or antagony. Experimental setup significantly
affected the results, with studies reporting high (> 10%) control mortality or using low stressor effects
(< 20%) being more synergistic. Chemical mode of action played a significant role for synergy, but
there was no effects of host and parasite phylogeny, or parasite‑host interaction traits. The finding
that experimental design played a greater role in finding synergy than biological factors, emphasize
the need to standardize the design of mixed stressor studies across scientific disciplines. In addition,
combinations testing more biological traits e.g. avoidance, coping, and repair processes are needed to
test biology‑based hypotheses for synergistic interactions.