ISOLATION OF COTTONSEED-ROTTING PANTOEA SPP. FROM STINK BUGS AND PLANT BUGS

Authors: Bell, Alois - Al; Lopez, Juan De Dios; Esquivel, Jesus; Medrano, Enrique; MAUNEY, JACK - JARMAN ENTERPRISES

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/5/2005
Publication Date: 5/25/2005
Citation: Bell, A.A., Lopez, J., Esquivel, J.F., Medrano, E.G., Mauney, J. 2005. Isolation of cottonseed-rotting Pantoea spp. from stink bugs and plant bugs. In: Proceedings of the Beltwide Cotton Conferences, January 4-7, 2005, New Orleans, Louisiana. 2005 CDROM.

Interpretive Summary: Seed rot in cotton bolls that externally appeared healthy in South Carolina in 2003 and 2004 were associated with infections of symptomatic tissue by various bacteria and fungi. The predominant pathogen was Pantoea agglomerans which caused seed rot symptoms similar to those found in the field, when it was introduced into young bolls through small puncture wounds. Because stink bugs and plant bugs frequently cause such puncture wounds in young to middle aged cotton bolls, both captive and feral bugs were examined for the presence of seed-rotting pathogens. Pantoea spp. were obtained from both the gut and the exterior of southern green stink bugs (SGSB) with similar frequency from the head and thorax compared to the body. Water washings from live bugs (2 ml sterile water per insect) frequently contained sufficient bacteria to cause seed rot when a needle puncture into the boll was made through a drop of wash water placed on the suture of 10- to 14-day-old bolls. The majority of female SGSB collected by black light traps in July, September, and October near cotton fields in the Brazos River Valley in Texas yielded seed-rotting bacteria. Most of the pathogenic bacterial isolates belonged to the Enterobacteriaceae family. Yellow isolates identified as Pantoea spp. had fatty acid profiles most similar to those of Pantoea, Cedecea, and Yersinia species, while white isolates had profiles most similar to those of Citrobacter, Enterobacter, Kluyvera, and Klebsiella spp. Two species of the Pseudomoniaceae family, Flavimonas oryzihabitans and Pseudomonas pudita, caused seed rot and were found in all three SGSB collections. All of these bacteria caused complete rot of 10- to 14-day-old locules of Deltapine 458 B/RR within 7 days of introduction through puncture wounds. Many of the same bacteria were obtained from SGSB males and brown stink bugs (BSB) but at lower frequencies. No Pantoea spp. were obtained from green stink bugs or leaf-footed plant bugs collected in June. Most of the seed rotting bacterial species found on stink bugs in Texas were previously isolated from the rotted seeds in South Carolina. The presence of seed-rotting bacteria on SGSB and BSB may facilitate the spread and inoculation of bacterial pathogens, even though most of the same bacterial species are known to be common epiphytes on the cotton plant including bolls and fiber. The results further indicate that much of the damage attributed to plant bugs is caused by microbial pathogens introduced by the bugs.

Technical Abstract: Seed rot in cotton bolls that externally appeared healthy in South Carolina in 2003 and 2004 were associated with infections of symptomatic tissue by various bacteria and fungi. The predominant pathogen was Pantoea agglomerans which caused seed rot symptoms similar to those found in the field, when it was introduced into young bolls through small puncture wounds. Because stink bugs and plant bugs frequently cause such puncture wounds in young to middle aged cotton bolls, both captive and feral bugs were examined for the presence of seed-rotting pathogens. Pantoea spp. were obtained from both the gut and the exterior of southern green stink bugs (SGSB) with similar frequency from the head and thorax compared to the body. Water washings from live bugs (2 ml sterile water per insect) frequently contained sufficient bacteria to cause seed rot when a needle puncture into the boll was made through a drop of wash water placed on the suture of 10- to 14-day-old bolls. The majority of female SGSB collected by black light traps in July, September, and October near cotton fields in the Brazos River Valley in Texas yielded seed-rotting bacteria. Most of the pathogenic bacterial isolates belonged to the Enterobacteriaceae family. Yellow isolates identified as Pantoea spp. had fatty acid profiles most similar to those of Pantoea, Cedecea, and Yersinia species, while white isolates had profiles most similar to those of Citrobacter, Enterobacter, Kluyvera, and Klebsiella spp. Two species of the Pseudomoniaceae family, Flavimonas oryzihabitans and Pseudomonas pudita, caused seed rot and were found in all three SGSB collections. All of these bacteria caused complete rot of 10- to 14-day-old locules of Deltapine 458 B/RR within 7 days of introduction through puncture wounds. Many of the same bacteria were obtained from SGSB males and brown stink bugs (BSB) but at lower frequencies. No Pantoea spp. were obtained from green stink bugs or leaf-footed plant bugs collected in June. Most of the seed rotting bacterial species found on stink bugs in Texas were previously isolated from the rotted seeds in South Carolina. The presence of seed-rotting bacteria on SGSB and BSB may facilitate the spread and inoculation of bacterial pathogens, even though most of the same bacterial species are known to be common epiphytes on the cotton plant including bolls and fiber. The results further indicate that much of the damage attributed to plant bugs is caused by microbial pathogens introduced by the bugs.