Breakthrough in natural control of cotton pest in Pakistan
CABI South Asia has reported initial success in a government-funded project controlling Pakistan’s most damaging cotton pest, the mealybug.
Two natural agents have shown successful results in controlling the pest in field studies taking place across the country. The agents are an insect with parasitic larvae and an Australian beetle known as the mealybug destroyer.
The cotton mealybug is a small, sap-sucking insect, about four millimetres in length, first recorded in Pakistan in 2005.
Over the past three years this bug has caused massive economic loss to cotton crops and as a result, the Pakistani government has cited mealybug as a high priority threat to the nation’s agriculture. In 2007 the Ministry of Food, Agriculture and Livestock approved and funded a CABI-led project to look at natural ways to combat the bug.
Facts at your fingertips
• Pakistan is the fourth largest producer of cotton in the world and the third largest consumer.
• Cotton is one of the main exports for Pakistan making up 60% of the total export revenue.
• 55% of Pakistan’s domestic cooking oil comes from cotton seeds.
• 3.1 million bales of cotton have been ruined by cotton mealybug (a bale of cotton weighs 500lbs or 227 kg)
• Farmers have been spending 1500 Pakistani rupees (just over US $20) per acre (approximately equivalent to 3700 rupees or $50 per hectare) each year on pesticides in an attempt to control the pest.
“One of the most worrying characteristics of mealybug is that it is an extremely unfussy eater,” said Riaz Mahmood, Project Manager. “It has attacked about 160 species of plants in Pakistan including crops such as tomato, aubergine, okra, chilli, wheat and tobacco.”
Three five-acre plots have been established at Multan, Tando Jam and Lasbela to act as natural reservoirs to help identify indigenous mealy bug enemies, and to develop mass rearing techniques for mealybug enemies. These have proved very successful so far.
A newly discovered mealybug parasitoid was recorded for the first time in August 2008 at Tando Jam and was identified as Aenasius sp. nov. nr. longiscapus Compere by the Natural History Museum in London, UK.
“This discovery will go a long way in controlling the pest on cotton and other plants,” said Riaz Mahmood. “Already the parasitoid is causing more than 50% mortality of the pest on cotton and other plants. It is also spreading fast in areas of land adjacent to the plots.
“Surveys are also being carried out in Punjab to detect the parasitoids on the mealybug. This parasitoid will be distributed throughout the country for mass production and release in farmers’ fields. Follow-up research will then be carried out.”
A predator Cryptolaemus montrouzieri, known as the mealybug destroyer, is also showing promising results. Following government approvals, this beetle was imported to Pakistan in December 2007. It is now being mass produced and releases have been taking place across Pakistan since March 2008.
“Over time the mealybug destroyer will acclimatise to Pakistani conditions allowing it to build up its population and contribute substantially to controlling the pest,” said Riaz Mahmood.
The overall project will involve the establishment of three insectaries, one each in the provinces of Sindh, Balochistan and Punjab, for the primary purpose of mass production of native and introduced parasitoids and predators of mealybug and other cotton pests.
It is hoped that the establishment of these centres will greatly contribute to the management of this serious issue and enable Pakistani farmers to enjoy profitable yields from their cotton crops.
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