Fast breeding insect devastates Java’s rice

Author: James J. Fox, ANU

Java could lose up to six million tons of rice in 2014, unless something is done immediately to regulate and reduce pesticide use.

An Indonesian farmer carries a sack of rice crop at a paddy fields in Kerawang, Indonesia, 26 January 2011. (Photo: AAP)

Brown planthopper populations have exploded due to the overuse of insecticides that destroy the planthopper’s natural enemies. This is a serious threat to Java’s rice production for 2014.

On 13 January, the Department of Plant Protection at Indonesia’s prestigious Institut Pertanian Bogor (Bogor Agricultural University) issued a press release to call attention to this threat, which was identified by intensive field research in Java’s 2013 cropping season — a litany of Java’s main rice producing areas particularly in East and Central Java were affected.

The brown planthopper, Nilaparvata lugens Stal, is a miniscule, fast breeding insect that lodges in the stalks of rice plants. It feeds directly on the rice plant and in large numbers is capable of sucking the life out of extended fields of rice, causing what is called ‘hopperburn’. The brown planthopper is also a carrier of two destructive rice viruses: ragged stunt virus and grassy stunt virus, either of which can be as devastating to a rice crop as the brown planthopper directly feeding on it.

With the onset of the rainy season, planthopper populations are forecast to explode in number, spread and become even more devastating.

Brown planthoppers are exceedingly difficult to predict and control as populations increase. It can produce both fully winged forms and partially winged forms. The partially winged forms are enormous breeders, each producing up to 350 eggs in roughly two weeks. Fully winged forms, though they produce fewer eggs, are exceptionally mobile and can migrate considerable distances. This produces a potent combination of local super breeders and equally remarkable migrants. Still, scientists have identified nearly 100 natural enemies that prey on the brown planthopper. These natural enemies range from hunter spiders that are easily observed to the tiniest of parasitoids that effectively prey on brown planthopper populations. But they, rather than the planthopper, are especially vulnerable to a great variety of general and systemic pesticides.

Indonesia has suffered a number of increasingly serious outbreaks of brown planthopper since the uptake of new rice technologies in 1967. Its first serious infestation occurred during the 1974–75 planting season, followed by a succession of further outbreaks culminating in a particularly severe outbreak in 1985–86. In response, President Soeharto issued a presidential order that banned 57 organophosphate pesticides used at the time. For a period of some 20 years thereafter Indonesia enjoyed substantially reduced pesticide use and a steady uninterrupted increase in its rice production — with only limited and localised outbreaks of the brown planthopper.

But in 2002, a time of reformation, pesticide policies were changed and the country was opened up to a flood of pesticides, many originating in China. As pesticide use increased, the brown planthopper returned with a vengeance. A build-up of brown planthopper populations that began in 2009 led to the loss of more than 1.96 million tons of rice across Java in 2011. Java is now facing an even more intensive and widespread build-up, which is the reason for the urgent press release by the Department of Plant Protection at the Institut Pertanian Bogor.

The press release summarises field evidence that shows a direct correlation between the number of pesticide applications and the damage to rice fields caused by the brown planthopper in infected areas. The more farmers spray, reducing natural predators, the greater the extent of ‘hopperburn’.

During the New Order, pesticides for rice were limited to a few chemical formulations, mainly organophosphates. Now the situation is vastly different. Dozens of chemical formulations are available to farmers, including varieties of neuro-active insecticides or neonicotinoids, numerous synthetic pyrethroids and even a range of organophosphates that are technically prohibited for rice. These different chemical formulations are sold under thousands of catchy brand names and actively promoted by suppliers’ agents. Many farmers mix a cocktail of different pesticides and some spray their field up to nine times in a single season.

Major rice producers like Vietnam have forbidden many pesticides, reduced the use of others and introduced biological methods to encourage the increase of the brown planthopper’s natural predators. But Indonesia has seen only an increase in the use of pesticides on rice.

So, another bold presidential order is needed to regulate pesticide use in the country and to promote modern biological technologies that effectively control brown planthopper populations.

James J. Fox is Professor Emeritus in the Resource Management in Asia-Pacific Program, Crawford School of Public Policy, the Australian National University.