|Lauziere, Isabelle - TX EXP STN, TEXAS A&M|
|Legaspi, JR., Benjamin - TX EXP STN, TEXAS A&M|
|Saldana, Robert - TX EXP STN, TEXAS A&M|
Submitted to: Subtropical Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2001
Publication Date: December 1, 2001
Citation: Lauziere, I., Legaspi, J.C., Legaspi, Jr., B.C., Saldana, R. 2001. FIELD RELEASE OF LYDELLA JALISCO WOODLEY (DIPTERA: TACHINIDAE) IN SUGARCANE AND OTHER GRAMINEOUS CROPS FOR BIOLOGICAL CONTROL OF EOREUMA LOFTINI (DYAR) (LEPIDOPTERA: PYRALIDAE) IN TEXAS. Subtropical Plant Science. 53:34-49. Interpretive Summary: The most important pest of Texas sugarcane is the Mexican Rice Borer, a moth that invaded from Mexico in the early 1980s. The sugarcane industry in south Texas is found in the economically depressed Lower Rio Grande Valley and grosses about $65 million. The borer spends much of its life inside the sugarcane stalk where it is protected from insecticides. Farmers in Texas have abandoned insecticides and accept the loss of $10 to $20 million yearly caused by the borer. The borer also damages important crops such as corn, rice and sorghum which are threatened by the northward movement of the borer up the coastal bend of Texas. As part of a program to study insect controls other than insecticides, scientists now at the Center for Biological Control at Tallahassee, Florida tested the Jalisco fly as a biological control agent on several host plants. The fly was collected from Mexico where it survives naturally on the rice borer which is not an important pest. Fly maggots crawl inside the stalk in tunnels made by the borer to find the pest. The immature fly then develops as a parasite inside the borer, thus killing it. We conducted field cage experiments to study the effectiveness of the fly as a parasite on sugarcane, rice, corn and sorghum. The different crops were grown in the field and covered with large screened field cages. Borers were allowed to infest the different crops, and the flies were released inside the cages. We found less than 7% of the borers were parasitized, which is attributed to severe drought and heat in that summer. Field sampling in the fields of local farmers revealed that other parasite species may have been more effective under these conditions.
Technical Abstract: The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Pyralidae), is the key pest of sugarcane in south Texas where it is not only responsible for continued yield reduction, but also threatens a variety of gramineous host crops. With chemical control being of limited success, research interest has focused on the introduction of biological control agents. Originating from Ameca (Jalisco, Mexico), Lydella jalisco Woodley (Diptera: Tachinidae), a recently described larval parasitoid of E. loftini, was re-introduced into Texas in 1998 and its potential in regulating populations of E. loftini was evaluated. During 1999 and 2000, several field-release trials were performed in walk-in field-cages and open-field conditions. Adult L. jalisco parasitoids emerged from E. loftini larvae recovered from sampled sugarcane, corn, rice and sorghum stalks. Percentage parasitism did not exceed 6.8% in field cages. Although considerable sampling efforts were undertaken, no progeny from adult L. jalisco parasitoids released in local sugarcane plantations was ever recovered, whereas a significant number of other natural enemies of E. loftini such as Chelonus sonorensis Cameron, Digonogastra solitaria Wharton & Quicke and Parallorhogas pyralophagus Marsh were collected. Adverse environmental conditions such as the ones encountered in the Lower Rio Grande Valley of Texas from May through September greatly affected the longevity and oviposition performance of L. jalisco females.