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Title: MEXICAN RICE BORER, EOREUMA LOFTINI (LEPIDOPTERA: PYRALIDAE) IN THE LOWER RIO GRANDE VALLEY OF TEXAS: ITS HISTORY AND CONTROL

Author
item LEGASPI, JESUSA - AGRI EXPER STATION
item LEGASPI, BENJAMIN - AGRI EXPER STATION
item King Jr, Edgar
item SALDANA, ROBERT - AGRI EXPER STATION

Submitted to: Subtropical Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: In the late 1970s and early 1980s, the sugarcane industry in the Lower Rio Grande Valley of Texas was dramatically affected by 3 events: 1) the sugarcane borer declined from a key to a minor pest; 2) the Mexican rice borer rose from an unrecorded pest to the key pest; and 3) a parasitic wasp was used successfully as a control agent against the sugarcane borer. These eevents are probably related. Currently, the rice borer comprises about 95% of sugarcane stalkborers and causes damage of more than $10 million yearly. Several methods are being tried to control the borer. In laboratory experiments, fungi and nematodes have been successful at killing the insect, but they may be less effective in the field. Sugarcane varieties resistant to borers are constantly being developed and tested. Genetic engineering techniques now allow scientists to insert into the sugarcane plant genes that cause the plant to create substances that kill insects. Insecticides and other chemical control agents are also being tested against borer pests. However, preference is given to those chemicals that do not kill beneficial insects. Finally, 21 species of parasitic insects imported from across the world have been released in south Texas for control of the rice borer. However, recent surveys show that the most common parasites are two species already native to south Texas. The Jalisco fly from Mexico is the subject of a new joint research effort between the USDA Subtropical Agricultural Research Center and Texas A&M University and provides the best opportunity to-date for biological control of the rice borer by an introduced parasite.

Technical Abstract: In the late 1970s and early 1980s, the sugarcare industry in the Lower Rio Grande Valley of Texas was dramatically affected by 3 events: 1) the decline of the sugarcane borer, Diatraea saccharalis, from a key to a minor pest; 2) the rise of the Mexican rice borer, Eoreuma loftini, from an unrecorded pest to the key pest; and 3) the establishment of Cotesia flavipes as a control agent against the sugarcane borer. It is interestin to speculate on the degree to which the 3 events may be casually related. Currently, E. loftini comprises about 95% of sugarcane stalkborers, causing damage of 20-30% bored internodes. This represents an annual loss >$10 million. Several research avenues are being explored to control the rice borer. Biopesticide formulations of Beauveria bassiana and Steinernema riobravis display high levels of virulence in the laboratory but may not be as effective in the field. Breeding for resistant varieties sof sugarcane and development of insect-resistant transgenic varieties continue to be exciting research avenues. A synthetic pheromone was evaluated as a mating disruptant, but sugarcane damage in all treated fields was almost identical to that in control fields. Chemical agents such as growth regulators are being tested against stalkborers and their parasites to find those least disruptive to the sugarcane ecosystem. Finally, 21 species of parasitic insects imported from across the world have been released in south Texas for control of the rice borer. Recent surveys indicate that the dominant parasites in the region are 2 species already indigenous to south Texas: Chelonus sonorensis and Digonogastra solitaria. The Jalisco fly, Lydella jalisco, provides the best opportunity to-date for biocontrol of the rice borer.