Controlling this pest is one of the biggest challenges faced by the agriculture scientists of the country for the past four years. Its impact on crops,mainly cotton,has been devastating,making the scientists wonder how the pest became so rampant when it had no previous record. They,therefore,decided to crack what has come to known as the mealybug phenomenon. When a group of scientists at the Central Institute for Cotton Research (CICR) here,led by V S Nagrale,conducted a thorough molecular study of the deadly pest,they concluded in December 2008 that the mealybug specie was an exotic (alien) pest that was originally noticed in America. There were,however,not many takers for this. B ut a recent paper by Aligarh Muslim University taxonomist (an expert in identification of species) Mohammad Hayat,too,has confirmed the finding. The paper is already online on the prestigious Biosystematica journal published from the US. Hayat mentions that the exotic nature of the wrecker mealybug species Phenacoccus solenopsis has been confirmed by two expert scientists R K Varshney (Aligarh) and D J Williams (London) who have said that the species did not originally belong to India. India,incidentally,has its own mealybug species called pink hibiscus mealy bug (Maconellicoccus hirsutus),but its impact on cotton was insignificant. Hayat has also established that the parasitoid,Aenasius,which he studied,is also alien to India. But why is it so important to find out if the pest is an exotic species? Because it has to be officially declared as an exotic pest to be able to come out with a pest management regimen for it, says CICR Acting Director and an award-winning cotton scientist Keshav Kranthi. The exotic mealybug variety is known to spread fast since a wax-like coating on its back protects it from pesticides,has a high reproduction rate,can hide easily in soil,cracks and crevices of the plants and has the ability to spread quickly via natural carriers like animals,humans,water,rains etc. The bug badly called for a control regimen to be put in place,especially against the observation that if sprayed with pesticides,it only grows due to the wax-like coating on its back. The study by CICR team led by Nagrale has confirmed that the growth can be attributed to the decimation of the parasitoids feeding on the pest. So,last year,we issued an advisory that no pesticides be sprayed on the cotton crop,at least in the initial stages of crop growth,to let the parasitoids live on as it is they who would naturally eliminate the bug, says Kranthi. Kranthi claims if left without pesticide spray,the mealybug would get decimated due to the parasitoid in a couple of years. CICR has evolved a management package for controlling the mealybug. The package is mainly an advisory about symptomatic control like not spraying pesticides at early crop stage,continuous monitoring of infestation,destruction of cotton stalks after picking and use of botanical and biological control formulations like neem seed kernel extract and biopesticides at different stages. How did US mealybug come to India? In 2004,there was a sudden invasion on Bt cotton in Gujarat of mealybug,which spread to almost entire country and even in neighbouring Pakistan in the next two years. Such was its havoc that in 2007,the total damage to cotton in north India was estimated to be around Rs 2.5 crore. Infestation also increased pest control input costs by about Rs 10,000 per acre. It also brought a bad name to Bt since it is also easily affected the transgenic variety. Activists started crying foul against Bt cotton whose votaries had been claiming it doesnt require pesticides. This has been a matter of intense speculation with no definite conclusion reached till date,but its first appearance was noticed somewhere around 1999. While some feel that it came along with the cotton bolls some Gujarati farmers stealthily brought from US,some doubting Thomases also felt they were a part of sly pest introduction into the country as part of an international conspiracy to weaken Indias growing prowess in the field of cotton.
