A potential new rice insect pest has been identified in the United States. The insect has been identified as the rice panicle mite Steneotarsonemus spinki, Smiley. On July 13, 2007, USDA’s Animal and Plant Health Inspection Service (APHIS) confirmed the detection of the panicle rice mite at a rice research facility in Alvin (Brazoria County) Texas. This facility, which is operated by a private entity, conducts hybrid rice research. Alvin is located south of Houston and northwest of Galveston.

The rice panicle mite is considered a serious pest of rice in China, the Philippines and Taiwan, where it has caused substantial crop losses. Yield losses can range from 30 percent to 90 percent. In 1997, the pest was detected in the Caribbean region where it is now known to affect Cuba, the Dominican Republic and Haiti. In 2002, the mite was reported in Costa Rica and Nicaragua and, in 2005, in Colombia. Recent reports also indicate its presence in Mexico.

In areas where this pest is prevalent and problematic, it can be very aggressive and cause substantial loss of grain yield and quality. It can feed directly on the developing embryo and cause panicle sterility. The insect injury can also interact with certain rice grain disease such as the sheath rot fungus (Sarocladium oryzae). Injury symptoms appear very similar to those we normally associate with bacterial panicle blight in Louisiana rice production. Grain harvested from affected fields often displays discoloration, which is also associated with the insect injury interacting with the sheath rot organism.

Another major problem with this insect is that it lives in a protected environment inside the leaf sheath and is extremely small and not visible to the naked eye. Its very small size facilitates dispersal, which can occur by wind (airborne), water movement (which is very important in rice production) as well as seed transmission. In addition, several rice weeds, including red rice, can serve as alternate hosts for this insect.

While all of the information above is potentially bad news, the good news is that we don’t know if this insect will ever be found in Louisiana and even if it is, that it will become a major pest of Louisiana rice production. As of this writing, the insect has only been identified in a small localized area near Alvin, Texas. The other bit of good news is that in those rice plants where it has been identified, there is no visible injury associated with the presence of the insect pest. This may suggest that our rice varieties and hybrids may have some genetic resistance to the insect. It has also been suggested that because this insect pest is normally found in tropical areas of rice production, the insect might not be able to survive our winter temperatures. Some very knowledgeable rice entomologists also suggest that this insect pest may have been in the U.S. for some time, but because of the difficulty of identification and lack of injury symptoms, we might have only recently become aware of it.

Dr. Natalie Hummel, LSU AgCenter extension rice entomologist, is working closely with others to survey Louisiana rice for the presence of this insect pest. As of this writing, it has not been found in Louisiana. Whether this will become an additional pest for Louisiana rice production is unknown at this time. It is best for us to be vigilant and develop as much information as possible about the rice panicle mite and hope we never have to use that information.

Louisiana 2007 rice harvest got off to a slow start because of the excessive and lingering rainfall during July. The Rice Research Station recorded measurable rainfall on 10 days during the last two weeks of July. This has slowed harvest as well as made for muddy harvest conditions for many producers. While it is still too early to evaluate the crop, early yield reports for the most part have been good to very good. We hope these good yields will hold up and weather conditions in August will be favorable for harvest.

Permission granted 08/14/07 by B. Leonards (LA Farm & Ranch Magazine) to republish article on www.lsuagcenter.com.