Secret Site Map
Monday, October 20, 2014

Home News Fire Ant Venom as a Fungicide?

Fire Ant Venom as a Fungicide?

Ants

USDA-ARS studies have shown that certain alkaloid compounds in the venom — namely, piperideines and piperidines — can hinder growth of Pythium ultimum, a top crop pathogen worldwide.

| August 9, 2013

Compounds in the venom of the red imported fire ant could prove promising for managing plant diseases caused by Pythium ultimum.

Studies by scientists at the Agricultural Research Service’s Biological Control of Pests Research Unit in Stoneville, Mississippi, have shown that certain alkaloid compounds in the venom—namely, piperideines and piperidines—can hinder growth of Pythium ultimum, a top crop pathogen worldwide.

Chemical controls, delayed plantings, and crop rotation are among methods now used against P. ultimum, which causes damping-off diseases that decay the seed or seedlings of vegetable, horticultural, and cucurbit crops. Despite such measures, damping-off remains a costly problem, and new approaches are needed, notes Xixuan Jin, an ARS microbiologist. He coinvestigated the potential application of fire ant venom in the management of soilborne plant pathogens with ARS entomologist Jian Chen and Shezeng Li of the Institute of Plant Protection in Baoding, China.

Research groups have studied the insecticidal and antibiotic properties of fire ant venom since the 1950s, including against crop pests such as fruit flies and boll weevils, and bacteria such as Escherichia coli. However, the Stoneville team is the first group not only to identify piperideine alkaloids, but also to demonstrate the properties of both piperideines and piperidines against soilborne plant-pathogenic P. ultimum.

The team demonstrated this on two fronts—in petri dish experiments using P. ultimum colonies and in greenhouse trials with container-grown cucumber seedlings. In the first experiments, the team exposed the pathogen’s threadlike growth form, called “mycelium,” to various piperideine or piperidine concentrations and monitored the effect on the colony size of P. ultimum. The pathogen’s sporangia, or spore-forming structures, were also exposed to the two alkaloids. In the greenhouse trials, the alkaloids were mixed separately in a solution and applied to cucumber seedlings as a drench treatment.

The results, reported in 2012 Pest Management Science, include significant reductions in growth and germination of P. ultimum mycelium. Both alkaloids performed equally well and retained their activity against P. ultimum for up to 12 weeks when stored at room temperature. In petri dish experiments, more than 90 percent of sporangia failed to germinate when exposed to piperideine or piperidine concentrations of 51.2 micrograms per milliliter of solution. Higher amounts (56.5 and 565.2 micrograms/milliliter) were effective in greenhouse experiments. Additionally, cucumber seedlings treated with the alkaloids grew taller than untreated seedlings.

Despite the alkaloids’ promise in managing damping-off diseases caused by P. ultimum, “Further studies on disease-control mechanisms and phytotoxicity are needed,” says Xixuan.

In their experiments, the researchers used sophisticated extraction techniques to obtain purified amounts of piperdeine and piperidine from the venom glands of both red and black imported fire ants. Producing commercial amounts would require considerable scale-up, even though these biting, stinging pests are a plentiful “resource,” infesting over 320 million acres in the South, where they’ve become a dominant species as well as in other states and Puerto Rico.

One approach may arise from the work of a University of Mississippi team, which has succeeded in creating synthetic versions, or “analogs,” that mimic piperideines identified by the Stoneville group. Two of seven synthesized analogs, even when used at especially low concentrations, were effective at inhibiting several cultured human fungal pathogens, raising the prospects for the analogs’ use as novel antifungal agents.—By Jan Suszkiw, Agricultural Research Service Information Staff.

This research is part of Crop Protection and Quarantine, an ARS national program (#304) described at www.nps.ars.usda.gov.


 

Top news

Extreme Spider Infestation Forces Missouri Family to Relocate

A family was driven from their suburban St. Louis home by thousands of venomous spiders that fell from the ceiling and oozed from the walls.

Landscaper Killed by Bee Swarm

One person is dead and several others are recovering from bee stings after a huge swarm of about 300,000 bees attacked landscapers working outside a home in Douglas (Ariz.), TucsonNewsNow.com reports.

UC Survey Asks PMPs What Are Their Biggest Bed Bug Concerns

University of California urban entomologists have launched an electronic survey to gather information from PMPs about what they are doing to manage bed bugs, and to determine what kind of bed bug research is needed.

AMVAC Introduces Nuvan Directed Spray Aerosol

Featuring the active ingredient dichlorvos (DDVP) the product can be used to control bed bugs, cockroaches, fleas and 21 other structural pests.

WCBB Raising Funds to Help Injured Industry Professional

Trade group Wildlife Control Business Builders (WCBB) is raising funds to help ECO Wildlife Solutions' Susan Sims, who suffered serious injuries as a result of a ladder fall.

x