Temporal analysis of cotton boll symptoms resulting from southern green stink bug feeding and transmission of a bacterial pathogen.
The southern green stink bug, Nezara viridula (L.), is a significant pest of cotton, Gossypium hirsutum L., and is becoming an increasing challenge due to the decrease in use of broad-spectrum insecticides on the crop. The southern green stink bug can vector an opportunistic Pantoea agglomerans strain (designated Sc 1-R) into cotton bolls, resulting in infection. The appearance of stink bug damage varies, and pest managers cannot readily identify its source. This research reports a systematic depiction of green, immature boll responses at various stages of maturity (1, 2, and 3 wk post-anthesis [WPA]) to stink bug injury and to infection by the vectored cotton pathogen by demonstrating the progression of effects 1, 2, and 3 wk after exposure (WAE). When laboratory-reared adult southern green stink bug not harboring Sc 1-R deposited bacteria into greenhouse-grown bolls at 1, 2, or 3 WPA during feeding/probing, bacteria reached concentrations of 10(9), 10(9), and 10(3) colony-forming units (CFUs)/g tissue, respectively, at 3 WAE, yet caused minimal seed and lint damage regardless of the age of the bolls that were penetrated. Bolls at a maturity of 1 or 2 WPA showed similar susceptibility when exposed to stink bugs that vectored Sc 1-R. After a week of infection, seeds were salmon-pink with normal white lint and up to 10(4) CFUs/g tissue when Sc 1-R was detected. Necrosis of the entire inoculated locule(s) with a maximum Sc 1-R concentration detected at 10(8) CFUs/g tissue occurred in samples harvested 2 or 3 WAE. Conversely, seed and lint deterioration due to the transmitted opportunist into bolls exposed 3 WPA was confined to the puncture site. In summary, after a week of development, bolls were tolerant to southern green stink bug feeding/ probing damage and to nonpathogenic bacteria, but they were severely damaged when the opportunistic pathogen Sc 1-R was transmitted. At 3 WPA, the fruit was immune to the spread of the pathogen with infections confined to the puncture site.
Medrano
Enrique Gino
EG
Cotton Pathology Research Unit, USDA-ARS, 2765 F&B Rd., College Station, TX 77845, USA. gino.medrano@ars.usda.gov
Esquivel
Jesus F
JF
Nichols
Robert L
RL
Bell
Alois A
AA
D000818:Animals; D005638:Fruit / Q000254:growth & development / Q000382:microbiology / Q000469:parasitology; D003368:Gossypium / Q000254:growth & development / Q000382:microbiology / Q000469:parasitology*; D020062:Heteroptera / Q000382:microbiology / Q000502:physiology*; D006790:Host-Parasite Interactions; D007303:Insect Vectors / Q000382:microbiology / Q000502:physiology*; D020636:Pantoea / Q000502:physiology*; D010935:Plant Diseases / Q000382:microbiology*; D013997:Time Factors