The citrus industry is of significant economic importance to the US, so when any potential pest appears on the horizon there is cause for concern. When the lime swallowtail (Papilio demoleus) was found in the Caribbean in 2006, scientists realised that it may only be a matter of time before these strong fliers appear in America. To try and keep one flight ahead of this zesty pest, scientists have come up with a rather neat solution.
Researchers from the University of Florida have found that the ingestion of the amino acid methionine is fatal to giant swallowtail caterpillars (Papilio cresphontes), a close relative of the lime swallowtail. Once ingested, methionine disrupts an ion channel in the gut, preventing normal nutrient absorption from occurring and eventually leading to the death of the caterpillar. Due to strict laws regarding importing invasive species, the effects of methionine on the lime swallowtail have not yet been tested. However, the alkalinity of the intestine of both the giant and lime swallowtails means that scientists are confident that the method will work in both species.
But methionine isn’t just any insecticide. Unlike many pesticide sprays which are often toxic to mammals and birds as well as the target pest, methionine is an essential part of our diets and even added to some livestock feeds to increase the build-up of protein in muscle. It’s also cost efficient and could act as a fertilizer as it biodegrades on the ground afterwards.
These traits make methionine a ‘green pesticide’, something that many will see as a step forward in improving crop productivity without increasing the negative effects of pest control on the environment and human health. The development of methionine as a commercial product is still a work in progress, but as it is already produced in large quantities for the farming industry, a final product could be available relatively soon. It shouldn’t be long before citrus farmers can use this ‘sublime’ solution to get all the ‘lemon aid’ they need!
Not quite quenched your thirst for knowledge? Celebrate citrus and try this recipe for limeade!
2/3 cup white sugar
8 cups of cold water
1. Squeeze all the juice out of the limes into a pitcher
2. Add the sugar and stir until dissolved
3. Add the water, stir again, and chill.
Once cold, serve with lime slices or mint.
ScienceDaily, ‘Green’ Pesticide Effective Against Citrus Pests, 17 Jan 2012