Pheromones to entrap the Fall Army Worm | Sunday Observer

Pheromones to entrap the Fall Army Worm

Research to control the spread of the Fall Army Worm (FAW), has been undertaken by many institutions in collaboration the Department of Agriculture (DoA). According to studies, the use of insect pheromones (a chemical produced and released into the environment by the insect) to trap the adult male and use the same technique to estimate the density of the pest population have been successful, Professor, Weed Science, University of Peradeniya and Chairman- National Invasive Species Specialists Group of the Ministry of Environment, Buddhi Marambe told the Business Observer, last week.

Based on initial observations the DoA recommended 15 pesticides last December, but subsequently recommended only five of them, he said. Following the initial screening, the DoA has placed orders to import 20,000 pheromone traps, and has identified four naturally occurring parasitoids and predators who feed on the larvae of FAW, and research is now underway to check their effectiveness. Depending on the results, the predators could be reared for release on a mass scale. “The Ministry of Agriculture has already imported a FAW-specific virus from USA as a biological control agent. Experiments are underway to test its efficacy and the persistence of the virus prior to its release. These are time consuming studies and we have to ensure that the bio-control agent will not survive and become yet another menace after the FAW is controlled,” Prof. Marambe said, adding that research has also commenced to investigate the presence of egg parasites and to see how the adult female can be trapped, which would be a better option than trapping the adult male.

The DoA, according to Prof. Marambe has invited all those who have developed their own control measures, especially the locally-produced plant-based pesticides or pest repellents to collaborate in the studies so that they could be scientifically evaluated for their efficacy, prior to making recommendations.

“The Universities have joined the bandwagon. The Faculty of Agriculture (FoA) at the University of Peradeniya (UoP) has initiated a study aimed at rapid and precise identification of FAW using molecular techniques. This is important as many practitioners and even scientists have misidentified the caterpillar on several occasions, while claiming that the pest had attacked many other crop species, which was not the case,” he said.

Some research carried out at the Uva Wellassa University has revealed that some locally produced ‘pesticides’ have not killed the caterpillar but has ‘doped’ it for hours, and the caterpillar becomes active again. Experiments are on-going to test the efficacy of other locally available techniques to see how effectively they can be used in overcoming the FAW threat. No technology will be left out, unless proven ineffective. Studies have also been initiated to use electrostatic spraying technology as a possible future control measure.

“The pest enters its pupae stage while being in the maize cob. The pupae of FAW are usually found on the ground. Scientists, such as Dr. Rohitha Prasantha of the FoA, UoP have raised the issue of whether the FAW suspends its development in an unfavourable environment (this is known as Diapause). These warrant further studies on the life cycle of the pest under Sri Lankan conditions. Survey studies have also started to identify the alternate hosts such as weeds and to estimate the actual crop losses caused by the pest,” Prof. Marambe said.

However, he said it is difficult to put a timeline on when the country could be completely free from the pest. “Based on the experience of other countries, the pest has come to stay, and we have to live with it in the future. But this is not to say that we have to give up. The fight against this invasive alien pest will continue vigorously.” 

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