By Dr. K. Sogawa
A planthopper entomologist who has been doing research on rice planthoppers for more than 35 years in Japan, China and Indonesia.
Recently I have read an interesting book published in Japanese, entitled (in English) Neonicotinoids, Devilish Novel Pesticides and subtitled Silent Summer Without Bees, 235pp, Sangokan, Tokyo. It is written by a Japanese reporter, Syunsuke Funase, who writes on industrial pollution issues. He said in the book that he has been motivated at a young age by Rachel Carson’s “Silent Spring”.
Neonicotinoids are the class of neuro-toxic insecticides modeled after the botanical, nicotine. One such chemical is imidacloprid, a long residual insecticide used widely in rice, which is sold numerous trade names, like Admire, Confidor and Gaucho. See fact sheet.
Mr Funase paid a special attention to the colony collapse disorder (CCD) of honeybees that is affecting pollination activities and how imidacloprid may be playing a significant role in this. CCD is used to describe the abrupt and large scale collapse of beehives by massive disappearance or dying in the USA and EU where imidacloprid is commonly used in agriculture. The book discusses the loss of bees as a sign of disorders in ecosystems and the effects on human health attributed to neonicotinoid insecticides because of the long-residual and easy contamination of food and water.
The organo-phosphorous insecticides, that caused insecticide resistance in and insecticide-induced pest problems in the 1970s and 1980s are being replaced with the neonicotinoid insecticides in the 1990s. Imidacloprid had been introduced with its so called “labor-saving, environment friendly and IPM-compatible” properties and now widely adopted in Asia.
Imidacloprid was first launched as “Admire” to prevent hopperburn by brown planthopper (BPH) in Thailand as early as 1991. Since then, imidaclopriod has been widely used in the paddy fields in the Indochina Peninsula, China and Japan. Today rice planthoppers have developed multiple fold resistance to this chemical.
Imidacloprid (Chinese trade name is Pi-Chong-Lin) has also been an essential component of technical packages for high-yielding hybrid rice technologies in China. In many places, hybrid rice is being commercialized by pesticides/seeds companies together with routine insecticide applications. IRRI will need to pay attention to the ecological impacts of hybrid rice and the use of long-lasting insecticides.
The use of hybrid rice coupled with prophylactic insecticide applications can have dangerous consequences that will repeat the problems of the Green Revolution and is threatening sustainable rice production and IPM-based pest management achieved so far. Although imidacloprid has been introduced as an “IPM-compatible insecticide”, its long-lasting broad spectrum residual effects can have detrimental effects on both pollination and bio-control services.