BPH Infestations Building Up in Thailand’s Rice Bowl – Many Areas Remain Highly Vulnerable

Posted on August 27, 2010 by moni

by
Manit Luecha, Director Chainat Rice Seed Center, Chainat, Thailand
K.L. Heong, International Rice Research Institute, Los Baños, Philippines

Hopperburn in Chainat province. Picture taken on August 23, 2010.

In 2009 BPH outbreaks began in July and by December Thailand had lost about a million tons of paddy. Thousands of farmers were affected and many in debt because of loans.  Hopperburn and virus disease infestations continued in early 2010. In June 2010 there were signs of BPH problems declining (Read Wantana et al). However in the next 2 months, BPH problems seem to be picking up again as farmers start planting after the drought and the release of irrigation water.

We travelled about 1500 kilometers from Bangkok to Nakhon Nayok, Phitsanulok, Chainat, Utai Thani, Phichit, Ang Thong, Ayuthaya and Suphan Buri, examining fields, visiting with farmers, policy makers, extension and research officials. Many of the factors that tend to increase vulnerability to planthopper outbreaks remain dominant, despite efforts to initiate change.

Crop intensity

In the dry season from March 2010, while many farmers had stopped planting because of water shortage, many had continued planting the next crop just 2 weeks after harvesting.  Farmers in Phichit for instance pumped underground water to continue planting. With the government’s recent release of irrigation water, more intensive planting in the next 3 months seems likely.

Rice varieties farmers are using

Last year we found that about 75% of farmers plant either Pathum Thani 1 or Chainat 1. Since these 2 varieties have been grown for more than 10 years, it is likely that planthoppers have grown adapted to them. The government started a campaign to change farmers’ varieties to more tolerant varieties, like Phitsanuluk 2 and RD 31.  However less than 10% of the farmers have adopted the new varieties, partly because of the lack of supply of new seeds but in most cases it was because Pathum Thani 1 fetched higher prices.

Insecticide use

Most farmers continue to rely on local pesticide dealers for advice and this had influenced  farmers’ use of cypermethrin, chlorpyrifos and abamectin, which are toxic to natural enemies, particularly hymenopteran parasitoids (Read: Farmers’ insecticide selection). This trend is still dominant. Although the government has recommended buprofezin, a highly planthopper specific compound and has mild effects on natural enemies, most farmers can’t get them from the local stores or are not recommended by the local dealers. In Suphan Buri we found farmers about to use buprofezin, which were free government issues. Most farmers continue to fear leaf folders and start spraying as early as 2 weeks after sowing, often as a prophylactic or on first sight of leaf folder damages. These early season sprays using resurgence causing insecticides continue to disrupt natural biological control and make fields vulnerable to BPH outbreaks (Read: Chien et al – Rice more vulnerable after early sprays).  Insecticide use in Central Thailand this year seems likely to increase. The emergency funds for insecticide purchase released last year were only available this year and loss aversion of most farmers seem higher than before.

Light trap data from Chainat province showing the 3 distinct spikes in BPH caught in 2009 and 2010. The spike in April 10 was higher than April 09 by 4 folds.

The light trap records in Chainat province in 2009 showed 3 spikes which corresponded to the 3 crop seasons in the area. The spikes in August and November were higher than that of April and there were serious hopper outbreaks  and virus infections.  This year the April spike was 4 folds larger than last year and if the fields continue to remain vulnerable there are indications that the 2010 BPH outbreaks could be 4 times more severe than 2009. At this moment, more than 50,000 ha have been recorded damaged in Suphan Buri, Ang Thong, Chainat and Singburi provinces and the Rice Department is closely monitoring its development.  Intensity and extent of damage by BPH and the related virus diseases seem likely to increase in the coming months.

Other reports on the BPH situation in Thailand are found in:

http://www.irinnews.org/Report.aspx?ReportId=90269

http://www.upi.com/Science_News/Resource-Wars/2010/08/25/Thai-rice-crop-faces-infestation/UPI-38121282739884/

http://beta.irri.org/news/bulletin/2010.34/

Posted in Planthoppers, Virus disease management | Tagged | Leave a comment

China Expects Heavy Pest infestations in Rice Areas – Provides Emergency Funds for Insecticides

Posted on August 20, 2010 by moni

by
K.L. Heong
International Rice Research Institute, Los Baños, Philippines

The Ministry of Agriculture (MOA) of the Peoples’ Republic of China issued a report on its website on 17 August 2010 warning farmers to expect higher pest infestations in the coming months (Read:  Ministry of Agriculture rice pest prevention and control). In many rice growing areas in China, planthopper populations seem to have increased markedly about 2 to 4 times that of last year. Areas damaged by hoppers were reported to be about 2.1 million mu (~ 140,000 ha) and the southern rice black streak dwarf virus carried by the white back planthopper (WBPH) has spread to more provinces and areas infested increased by 50%. The abnormally high pest and disease attacks to be expected might be due to the recent floods and elevated summer temperatures.  In 2005 elevated summer temperatures brought about heavy planthopper outbreaks that destroyed some 7 million ha of rice.  The MOA has authorized the release of about US$23 million emergency funds for pesticide spraying (See: oryza.com).

Pest storms common in 2005 attributed to elevated summer temperatures

Planthoppers are secondary pests triggered by ecological disruptions, like floods and droughts and most common and devastating of all are insecticides.  These sprays disorganize predator-prey relationships, favoring pests, thus enabling BPH to grow exponentially (Read:  Impact of insecticides). Coupled with the recent elevated summer temperatures, planthopper outbreaks in China would seem inevitable in the coming months.  To provide more insecticides might not be the answer as insecticide misuse is so rampant. The emergency funds for more insecticides would only provide fuel to the emerging problem.  Besides, the planthoppers in China have developed extreme levels of resistance to many insecticides of different modes of actions.  For instance the brown planthoppers (BPH) in China is more than 1000 times more tolerant to imidacloprid than BPH in the Philippines (Read: Toxicity of imidacloprid).  Similarly high levels of resistance are recorded in carbamates, organophosphates as well as buprofezin (Read: Matsumura et al ) .  Farmers in China are fond of using “cocktails” of 2 or more insecticides and such practices often decrease the potencies of the sprays (Read: Insecticide mixtures). Recently one of the pioneers of the Indonesian IPM program that brought BPH under control and had sustained for more than 20 years reminded us of the need to protect biological control services (Read: History repeats itself). More free distribution of insecticide to combat the rising pest problems would probably be counter-productive.

Rice farmers in China often use “cocktails” of insecticide mixes in blanket spray applications

Providing input factor subsidies has been the practice in the Green Revolution and this has led to misuse that had triggered secondary pest outbreaks in the 1970s and 1980s.  Today such practices continue to dominate policy decisions related to pest control. In the case of rice insect management, it has been shown that insecticide inputs contribute little to yield improvements and in fact they often decrease yields (Read: Insecticide sprays and yields).  In addition the pesticides induce planthopper problems because they disorganize predator-prey relationships favoring pests and provide the conditions for them to multiply exponentially to outbreak proportions.

The US$ 23 million emergency fund that is released would thus be more useful if it is directed at implementing ecological approaches for sustainable pest management that build  ecosystem services as public goods.  Pesticides will in fact destroy these ecosystem services. More insecticides sprayed into the rice ecosystem in China will not only trigger more outbreaks, development of higher resistance, polluting the waterways, wildlife and posing threats to human health.  With the planthoppers having acquired such high resistance to several types of insecticides I think we may be fast approaching a tipping point crisis unless action is taken.

IT IS TIME TO RETHINK PLANTHOPPER MANAGEMENT !!

Posted in Insecticide resistance, Insecticide use, Planthoppers | Tagged | Leave a comment

History Repeats Itself: Chemicals Still Disrupting “Friends of the Rice Farmer”

Posted on August 14, 2010 by moni

by
B. Merle Shepard, Professor Emeritus of Entomology and former Head, Entomology Department, the International Rice Research Institute, Los Baños, Philippines

The rice ecosystem is richly endowed with a great diversity of predators and parasitoids that provide important natural biological control.

Rice, more than any other crop, has evolution on its side.  The rich communities of beneficial insects, spiders and insect pathogens have evolved and have kept tropical rice insect pests in check for thousands of years…long before chemical pesticides were around.  The use of chemical pesticides is fairly recent but they have been the most disruptive forces in the tropical rice ecosystem, almost totally eliminating these natural enemies and causing repeated and massive outbreaks of hoppers, especially the brown plant hopper.  When the new, high-yielding varieties of rice were introduced, many banks required farmers to purchase insecticides which often came as a part of a “package” along with fertilizer and green revolution rice seeds.  This led to massive outbreaks of the brown planthoppers (often called the green revolution pests) in Indonesia and the Philippines.

Hopper outbreaks due to insecticides have been recognized for many years.   Kenmore (1980) reported this in the Philippines and others have described and quantified the ecological impact of insecticides to rice arthropod communities (Read: Heong and Schoenly 1998).  The importance of these natural enemies was emphasized  by Ooi and Shepard (1994) and over 100,000 copies of “Friend of the Rice Farmer:  Helpful Insects, Spiders and Pathogens” by Shepard, Barrion and Litsinger  (first published in 1987 by the International Rice Research Institute) have been printed and distributed in over 25 non-English languages.  Was nothing learned from this?

When President Suharto issued presidential degree 3/86 to ban 57 kinds of insecticides in 1986 aimed at removing the insecticide subsidies that accompanied the rice intensification program. Insecticide use gradually declined when subsidies were removed as the on farm prices increased.  IPM training followed a year of so later. The results were clear and dramatic (see figure below).

Insecticide use and rice production in Indonesia following PD 3/86

However from 2001 insecticide use in Indonesia has been increasing rapidly. Between 1998 and 2008 insecticide imports increase more than 30 folds from US$1.9 million to US$ 60.6 million (Fig. 3).  Areas being attacked by planthoppers and the virus diseases they carry are now being reported (Read: BPH and virus disease outbreaks in Central Java and BPH and virus disease outbreaks threatening rice in West Java) and if this trend continues such problems are likely to be more frequent and more intense.

Insecticide imports (in US$) into Indonesia from 1990 to 2008.

There is apparently a serious shortage of policy makers, research and extension personnel, NGOs, and farmers with the historical knowledge about the disruptive influence of insecticides in tropical rice in Asia.  Thus, history is repeating itself with the direct correlation between with increased insecticide use and increasing populations of planthoppers.

References

Heong, K.L. and Schoenly, K.G.  1998.  Impact of insecticides on herbivore-natural enemy communities in tropical rice ecosystems.  Pp 381-403  ( P. T. Haskell and P. McEwen  Eds.)  Ecotoxicology:  Pesticides and Beneficial Organisms. Chapman and Hall,  London.

Kenmore, P. E. 1980.  Ecology and outbreaks of a tropical insect pest of the green revolution, the brown planthopper, Nilaparvata lugens. Ph.D. Dissertation, Univ. of California, Berkelely.

Ooi, P. A. C. and B. M. Shepard. 1994.  Predators and parasitoids of rice insect pests. Pp. 585-612. In: Biology and management of rice insects.  E. A. Heinrichs (ed.). Wiley Eastern Limited.

Shepard, B. M., A. T. Barrion and J. A. Litsinger.  1987. Friends of the rice farmer: Helpful insects, spiders and pathogens.  127 pp. The International Rice Research Institute, Los Banos, Philippines.

Posted in Ecological engineering, Planthoppers | Tagged , | Leave a comment