Many insect, pests, and diseases destructive to field crops, horticulture, floriculture and forests are present in the world, but luckily all are not present in a particular country or geographical region. Pakistan is fortunate not to have many of the pests and diseases yet that are highly destructive to its crops, horticulture and forest. However, with the rapid development of quick means of transport, increased trade relations and establishment of new air, land and sea routes, the movement of plants and plant material have increased manifold, particularly after the implementation of WTO regime. The regime has mobilised tremendous increase in trade and travel among member countries, and has enhanced the chances of introduction and spread of alien pest and diseases, which is a global ecological time bomb, the explosive potential of which has just started to get full attention.
The impact of alien or exotic pests in the country can be gauged from the introduction of the Banana Bunchy Top Disease (BBTD) in Pakistan, back in 1989. Initially this virus appeared on a banana plantation in a small area in Ghorabari, in district Thatta. Despite the fact that BBTD was an exotic disease, no efforts were made for its eradication, nor were any quarantine measures taken to restrict its spread to other banana growing areas. As a result, the very deadly menace managed to spread to the entire banana growing regions of the country, causing economic loss worth millions of rupees annually.
Unfortunately, now we are again under threat of an alien insect pest, called the Tutaabsoluta or the South American Tomato Leaf Minor, which is an invasive virus that can prove to be deadly for tomato crops. Though it is native to South America, it managed to cross in to Spain from Chile in 2006 and managed to spread around Europe, the Mediterranean and Africa. It is estimated to have arrived in India in 2014 and was reported in Nepal in 2016. Defying quarantine barriers, it has also managed to enter into Bangladesh, Iran, Turkey and most of the Middle East. In a nutshell, we can say this menace is practically knocking at our door and if concrete steps are not taken by the Pakistani authorities, then the result might be disastrous for the tomato growers of the country.
Literature review has suggested that Tutaabsoluta arrived in Turkey in 2010, but in the absence of tomato crop it shifted to potato, causing huge economic loss. Besides potato, its alternate host plants are egg plants, datura, chenopodium and many species of the Solanaceae family. This aspect of this menace is immensely haunting, as abundance of alternate host plant species will make its control difficult once it enters in to the country from India or Iran, from whom Pakistan imports tomatoes and other fruits by the tons, every year.
The impact of alien or exotic pests in the country can be gauged from the introduction of the Banana Bunchy Top Disease (BBTD) in Pakistan back in 1989. Despite the fact that BBTD was an exotic disease, no efforts were made for its eradication. As a result, the very deadly menace managed to spread to all the banana growing regions of the country, causing economic loss worth millions of rupees annually
Tutaabsoluta is a micro Lepidoptera. The adult moth has grey brown colour and is about 6mm in size. Moth has life cycle of 29 to 30 days depending upon temperature. Under favourable climatic condition 8 to 10 generations can occur in a single year. The female can lay 260 eggs in their entire life. The larva feeds voraciously upon tomato plants producing large galleries in leaves, burrowing stalks and consuming terminal buds and green and ripe fruits. The pest is capable of causing devastation to the entire crop with 100 percent yield loss.
To control the tomato leaf minor, there are several pesticides which are used as a foliar spray, but because of the peculiar nature and high fecundity rate of this pest, frequent sprays are required that are neither cost effective nor safe for the humans or the environment. However, use of sex pheromones has been proved to be effective in suppressing the Tutaabsoluta population and keeping it within the economic threshold. In India “Pest Control of India” provide lures (pheromones) to farmers for control of this potent pest.
So what should we do moving forward? One, since prevention is better than cure, the Federal Department of Plant Protection in Karachi, which comes under the jurisdiction of the Ministry of National Food Security & Research in Islamabad, and are in charge of maintaining Plant Quarantine Regulatory Service in the country, must keep a vigilant watch on the import of tomato consignments from abroad. In case evidence of Tutoabsoluto infestation is found then the consignments should be confiscated and destroyed.
Two, at present, pheromones that provide safe and effective control of tomato leaf minor as well as Pink Boll Worm of cotton, is very costly and beyond the means of the financially constrained farmers, particularly of Sindh and Balochistan. It is suggested that the Federal Government should provide adequate subsidy on pheromones in order to control the spread of these dangerous viruses.
The writer is a former Entomologist of the Plant Protection Department, Government of Pakistan, Karachi. He can be contacted on his E-mail: [email protected]
Published in Daily Times, July 14th 2018.