Submitted to: World Cotton Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/2/2007
Publication Date: 1/10/2008
Citation: Bell, A.A., Medrano, E.G., Lopez, Jr., J.D. 2008. Transmission and importance of Pantoea ananatis during feeding on cotton buds (Gossypium hirsutum L.) by cotton fleahoppers (Pseudatomoscelis seriatus Reuter) [abstract]. Proceedings of World Cotton Research Conference, September 10-14, 2007, Lubbock, Texas. 2007 CDROM. Interpretive Summary: The cotton fleahopper is one of the five major causes of field losses from insects in cotton. Cotton plants often shed flower buds after the insect feeds on them. We investigated the possible role of insect transmitted bacteria as causes of the flower bud injury. Nearly 100 percent of fleahoppers caught from the overwintering weed host, croton, were infested with Pantoea species of bacteria. The bacteria caused severe seed rot, boll rot, and bud blight when introduced by the insect or small puncture wounds. More than 90 percent of the Pantoea isolates were identified as Pantoea ananatis, a known pathogen of many crops including melons, pineapple, and onions. We conclude that Pantoea ananatis is normally present in salivary glands or the gut of cotton fleahoppers and is introduced into cotton buds during feeding to cause bud blight. It may be possible to reduce insect damage by developing host resistance to its bacterial companion.
Technical Abstract: Cotton fleahoppers collected from various hosts in the field or raised on green beans in the laboratory were frequently infested with Pantoea spp. These isolates caused a severe internal boll rot in cotton when introduced into young bolls via a small puncture wound caused by a 28-gauge needle. Buds or bolls that abscised following fleahopper feeding consistently showed ovary rot, including the wall, and contained concentrations of 10^8 to 10^10 cfu/g of Pantoea spp., indicating that bacterial rot of the ovary contributed to abscission. A collection of Pantoea isolates from both insects and diseased buds were analyzed using API 20E test strips, fatty acid methyl ester profile analysis and base sequences of 16S ribosomal DNA. The results showed that most isolates were best classified as Pantoea ananatis. Fleahoppers fed on beans contaminated with rifampicin-resistant variants of either Pantoea ananatis or Pantoea agglomerans acquired and transmitted P. ananatis but not P. agglomerans. These data indicate that P. ananatis has developed an endophytic relationship with the cotton fleahopper that results in the presence of this bacteria in most of these insects and, usually, transmission during feeding on cotton buds.