Herbivory and Pathogens

Aconitum is well defended against herbivory from animals through high concentrations of alkaloids, which can be fatal if ingested. These alkaloids are found in all parts of the plant except the nectar. The highest concentrations are found in the roots and pollen (Gosselin et al, 2013). The absence of the alkaloids in the nectar, and the high concentration in the pollen suggests a chemical defense against excessive pollen harvest by the pollinators. 
There are a few pathogens that are known to attack Aconitum. Crown rot, stem rot, and wilt are all caused by fungi, and they mainly cause damage to the vascular tissues. There are also some insects that attack Aconitum. The four lined plant bug and larkspur leaf miner attack the leaves of the plant, and are not deterred by the alkaloids (Pirone, 1978). 

http://www.ces.ncsu.edu/depts/ent/notes/Ornamentals_and_Turf/flowers/note09/ColLeafminer.jpg

http://bygl.osu.edu/content/fourlined-plant-bugs-2

Works Cited

Frank, Steven. "Leafminer Flies." Ornamentals and Turf. North Carolina State University, Jan. 2011. Web. 9 Apr. 2014.

Gosselin, Matthias, Denis Michez, Maryse Vanderplanck, Dorothee Roelants, Gaetan Glauser, and Pierre Rasmont. "Does Aconitum Septentrionale Chemically Protect Floral Rewards to the Advantage of Specialist Bumblebees?" Ecological Entomology 38 (2013): 400-07. Zoologie.umh. The Royal Entomological Society, 20 May 2013. Web. 9 Apr. 2014.

The Ohio State University Extension. "Fourlined Plant Bugs." Buckeye Yard & Garden Online. The Ohio State University Extension, 9 May 2013. Web. 9 Apr. 2014.

Pirone, Pascal. Diseases and Pests of Ornamental Plants. 5th ed. N.p.: John Wiley & Sons, 1978. Google Books. Web. 9 Apr. 2014.