Fly to head off the weed in­va­sion

Hy­drel­lia agent re­leased as SA’s first bio­con­trol for the Brazil­ian me­nace

Daily Dispatch - - News - TYLER RIDDIN

The first bio­con­trol agent in SA in­va­sive Brazil­ian wa­ter­weed was into the Na­hoon River on Fri­day.

Rep­re­sen­ta­tives from var­i­ous or­gan­i­sa­tions, in­clud­ing Amath­ole Wa­ter and the de­part­ment of en­vi­ron­men­tal af­fairs, were in at­ten­dance.

Pro­fes­sor Julie Coet­zee of the Cen­tre for Dis­ease Con­trol (CDC), said a bi­o­log­i­cal con­trol is es­sen­tially the re­lease of the nat­u­ral preda­tor of an­other species into the en­vi­ron­ment.

In this case, the “preda­tor” be­ing used as the bio­con­trol agent for the wa­ter­weed is the Hy­drel­lia fly from Ar­gentina.

Rhodes Univer­sity PhD stu­dent Ros­ali Smith has been cred­ited as the head re­searcher whose blood, sweat and tears cul­mi­nated in Fri­day’s his­toric re­lease.

Smith told the Daily Dis­patch she and a team of re­searchers had been work­ing on the fly and test­ing its vi­a­bil­ity in bi­o­log­i­cal con­trol for about four years.

She said that due to the species be­ing only re­cently dis­cov­ered, time had to be taken to learn about them and run risk as­sess­ments in quar­an­tine. for the re­leased

Smith ex­plained the Hy­drel­lia lar­vae are what would eat and de­stroy the sub­merged plant.

The young PhD stu­dent as­sured the Daily Dis­patch that this new fly species would not turn its hunger onto other plants, but in­stead it would die out when the Brazil­ian wa­ter­weed did.

Smith ex­plained that were the wa­ter­weed al­lowed to grow unchecked, it would even­tu­ally choke up the wa­ter­way, re­sult­ing in dam­ag­ing the lo­cal eco­log­i­cal sys­tem and putting an end to wa­ter-based hob­bies in the area, such as fishing.

Coet­zee said that bio­con­trol is a long-term so­lu­tion which is en­vi­ron­men­tally friendly but re­quires pa­tience.

The species be­ing in­tro­duced into a new en­vi­ron­ment needs time to build up and “get happy” be­fore it heads to work.

Coet­zee added that this method was a su­pe­rior so­lu­tion to herbacides, which would re­sult in poi­son­ing the rest of the ecosys­tem as well, and me­chan­i­cal meth­ods, which would be ex­pen­sive and are not guar­an­teed to per­ma­nently erad­i­cate the in­va­sive plant species.

Pic­ture: MICHAEL PINYANA

HANDY HELPERS: Rhodes Univer­sity PhD stu­dent Ros­ali Smith and Ahmed Khan, of the de­part­ment of en­vi­ron­men­tal af­fairs re­lease the first bio­con­trol for the Brazil­ian wa­ter­weed in SA into the Na­hoon River.

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