Fire ants to the rescue! Venom could be a natural fungicide
August 2, 2013
• USDA sees potential in ants’ venom
• Might be used to combat “damping-off”
(Photo by Stephen Ausmus/ARD)
There might actually be a use for those nasty red imported fire ants that plague much of the southern reaches of the nation, including portions of the Central Valley, with their serious bites and stings.
Now, the same venom that packs such a painful wallop may actually do some good for a change, according to scientists with the U.S. Department of Agriculture.
Studies by USDA scientists in Stoneville, Miss., have shown that certain alkaloid compounds in the venom—piperideines and piperdines—can hinder the growth of the crop pathogen Pythium ultimum.
Chemical fungicides, delayed plantings and crop rotation are among methods now used to control P. ultimum, which causes damping-off diseases that decay the seed or seedling of vegetable, horticultural and cucurbit crops.
Despite such measures, damping-off remains a costly problem, and new approaches are needed, says Jian Chen, an entomologist with USDA's Agricultural Research Service.
Mr. Chen is investigating the potential application of fire ant venom to manage soilborne pathogens like P. ultimum in collaboration with ARS microbiologist Xixuan Jin, and Shezeng Li of the Institute of Plant Protection in Baoding, China.
For their studies, conducted at the ARS Biological Control of Pests Research Unit in Stoneville, the researchers used sophisticated extraction techniques to obtain purified amounts of piperideine and piperidine from the venom glands of both red and black imported fire ants, which are considered invasive pests and a dominant species on more than 320 million acres in the U.S.
In petri dish trials, the researchers exposed P. ultimum's threadlike growth form, called "mycelium," to various concentrations of the alkaloids and monitored the effect on the pathogen's colony size. Its spore-forming structures, called sporangia, were similarly exposed.
The results include significant reductions in the growth and germination of the pathogen's mycelium. Both alkaloids performed equally well and retained their activity against P. ultimum for up to 12 weeks when stored at room temperature.
Additionally, more than 90 percent of sporangia failed to germinate when exposed to the alkaloids at concentrations of 51.2 micrograms per milliliter.