|Duggan, B. - OREGON STATE UNIVERSITY|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: March 2, 2007
Publication Date: July 5, 2007
Citation: Armstrong, J.S., Coleman, R.J., Duggan, B.L. 2007. Characterizing the damage and oviposition of a Creontiades plant bug to South Texas Cotton. National Cotton Council Beltwide Cotton Conference, January 9-12, 2007, New Orleans, Louisiana. p. 34-37. Interpretive Summary: Our research focused on characterizing the damage caused by a plant bug identified to the genus name Creontiades, and that on occasion infests cotton in the South Texas and Coastal Bend regions after migrating in from coastal host plants. We infested cotton bolls with Creontiades by enclosing them on the plant, and also simulated the damage by injecting a pectinase enzyme into cotton bolls at the same time infesting the bolls. Our objective, other than finding out the damage is caused by Creontiades, was to develop a simulated technique that would help us in determining more about the economics of making treatment decisions. Our findings showed that Creontiades are seed feeders based on the damage that occurred to the developing seeds, and this damage resulted in reduced seed cotton, lint, seed weights, and number of growths on the inside of the carpal wall when compared to the non-infested bolls. When we used 5, 10, and 15% pectinase injections in the bolls, it did simulate the actual feeding injury with the exception that Creontiades probe with their mouthparts and inject digestive enzymes in more places on the boll in an effort to feed on the seed. Our simulated technique of injecting pectinase did not result in as consistent injury to the seed, however, we believe we can improve on this by injecting multiple times with the pectinase.
Technical Abstract: A plant bug Creontiades (Heteroptera: Miridae), has been infesting cotton in the Coastal Bend and South Texas growing regions in high enough densities that insecticide treatments have been applied to reduce feeding damage, even though an economic threshold has not been established. Our research focused on characterizing the damage caused by the Creontiades plant bug by infesting cotton bolls and comparing this to a simulated damage of injecting cotton bolls with 1ul dilutions of pectinase in distilled water. Creontiades enclosed on 8 d old cotton bolls significantly reduced seed cotton, lint, and seed weights, and had significantly higher injury score, number of damaged seeds, and growths on the carpal wall when compared to control (enclosed but not infested bolls). In 2005, 10% pectinase injections were not as injurious to cotton bolls as the Creontiades infestations, but all parameters separated out from the controls. In 2006, when 5% and 15% pectinase injections treatments were added to the Creontiades, 10% pectinase and control treatments, the injury score, injured seeds and growths on the carpal wall all separated out significantly (control<all pectinase injections<Creontiades). However, the Creontiades infestations were not significantly different from any of the pectinase injections in terms of seed cotton weight, lint weight, and seed weight in 2006 partially because of drought conditions where any form of injury was magnified by drought stress.